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Metabolism of 4-Chloronitrobenzene by the Yeast Rhodosporidium sp
Corbett, Michael D.; Corbett, Bernadette R.
The yeast Rhodosporidium sp. metabolized 4-chloronitrobenzene by a reductive pathway to give 4-chloroacetanilide and 4-chloro-2-hydroxyacetanilide as the major final metabolites. The intermediate production of 4-chloronitrosobenzene, 4-chlorophenylhydroxylamine, and 4-chloroaniline was demonstrated by high-pressure liquid chromatography. Additional studies with selected metabolites established that the metabolite 4-chloro-2-hydroxyacetanilide was produced by an initial Bamberger rearrangement of the hydroxylamine metabolite, followed by acetylation. Direct C hydroxylation of the aromatic ring was not observed in this species. No hydroxamic acid production was detected, even though significant concentrations of the nitroso and hydroxylamine precursors to this functional group were observed. PMID:16345757
Pilot-scale bioelectrochemical system for efficient conversion of 4-chloronitrobenzene.
Yuan, Yuan; You, Shi-Jie; Zhang, Jin-Na; Gong, Xiao-Bo; Wang, Xiu-Heng; Ren, Nan-Qi
4-Chloronitrobenzene (4-CNB) is one of the highly toxic contaminants that may lead to acute, chronic or persistent physiological toxicity to ecology and environment. Conventional methods for removing 4-CNB from aquatic environment may be problematic due to inefficiency, high cost and low sustainability. This study develops a pilot-scale bioelectrochemical system (BES, effective volume of 18 L) and examines its performance of bioelectrochemical transformation of 4-CNB to 4-chloroaniline (4-CAN) under continuous operation. The results demonstrate that the initial 4-CNB concentration in the influent and hydraulic retention time (HRT) has a significant impact on 4-CNB reduction and 4-CAN formation. Compared with the conventional anaerobic process in the absence of external power supplied, the 4-CNB conversion efficiency can be enhanced with power supplied due to microbial-mediated electron transfer at the negative cathode potential. At a voltage of 0.4 V and HRT of 48 h, the 4-CNB reduction and 4-CAN formation efficiency reached 99% and 94.1%, respectively. Based on a small external voltage applied, the pilot-scale BES is effective in the conversion of 4-CNB to 4-CAN, an intermediate that is of less toxicity and higher bioavailability for subsequent treatment. This study provides a new strategy and methods for eliminating 4-CNB, making wastewater treatment more economical and more sustainable. PMID:25650667
Siegrist, R.L.
The traveler attended the Third International Conference on Contaminated Soil, held in Karlsruhe, Germany. The Conference was a status conference for worldwide research and practice in contaminated soil assessment and environmental restoration, with more than 1500 attendees representing over 26 countries. The traveler made an oral presentation and presented a poster. At the Federal Institute for Water, Soil and Air Hygiene, the traveler met with Dr. Z. Filip, Director and Professor, and Dr. R. Smed-Hildmann, Research Scientist. Detailed discussions were held regarding the results and conclusions of a collaborative experiment concerning humic substance formation in waste-amended soils.
Ozone enhanced activity of aqueous titanium dioxide suspensions for photodegradation of 4-chloronitrobenzene.
Ye, Miaomiao; Chen, Zhonglin; Liu, Xiaowei; Ben, Yue; Shen, Jimin
The TiO(2)/UV/O(3) process has been employed to remove 4-chloronitrobenzene (4-CNB) and compared to UV/air, O(3), TiO(2)/O(3), TiO(2)/UV/O(2) and UV/O(3) five parallel oxidation pathways. The reaction activities of these six processes were tested in aqueous using electron paramagnetic resonance (EPR) spin trapping technique with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin trap. Moreover, the effects of ozone dosage, catalyst dosage and initial solution pH on the degradation of 4-CNB by TiO(2)/UV/O(3) process were also investigated. Results showed that the TiO(2)/UV/O(3) is the most efficient process for complete mineralization of 4-CNB since the combination of photocatalytic oxidation with ozone has a synergistic effect. The relative intensity of DMPO-OH follows the order of UV/air
Beyer, W.
The compilation was designed to help U.S. Fish and Wildlife Service contaminant specialists evaluate the degree of contamination of a soil, based on chemical analyses. Included are regulatory criteria, opinions, brief descriptions of scientific articles, and miscellaneous information that might be useful in making risk assessments. The intent was to make hard-to-obtain material readily available to contaminant specialists, but not to critique the material or develop new criteria. The compilation is to be used with its index, which includes about 200 contaminants. Entries include soil contaminant criteria from other countries, contaminant guidelines for applying sewage sludge to soil, guidelines for evaluating sediments, background soil concentrations for various elements, citations to scientific articles that may help estimate the potential movement of soil contaminants into wildlife food chains, and a few odds and ends. Articles on earthworms were emphasized because they are a natural bridge between soil and many species of wildlife.
Remediating munitions contaminated soils
Shea, P.J.; Comfort, S.D.
The former Nebraska Ordnance Plant (NOP) at Mead, NE was a military loading, assembling, and packing facility that produced bombs, boosters and shells during World War II and the Korean War (1942-1945, 1950-1956). Ordnances were loaded with 2,4,6-trinitrotoluene (TNT), amatol (TNT and NH{sub 4}NO{sub 3}), tritonal (TNT and Al) and Composition B (hexahydro-1,3,5-trinitro-1,3,5-triazine [RDX] and TNT). Process waste waters were discharged into wash pits and drainage ditches. Soils within and surrounding these areas are contaminated with TNT, RDX and related compounds. A continuous core to 300 cm depth obtained from an NOP drainage ditch revealed high concentrations of TNT in the soil profile and substantial amounts of monoamino reduction products, 4-amino-2,6-dinitrotoluene (4ADNT) and 2-amino-4,6-dinitrotoluene (2ADNT). Surface soil contained TNT in excess of 5000 mg kg{sup -1} and is believed to contain solid phase TNT. This is supported by measuring soil solution concentrations at various soil to solution ratios (1:2 to 1:9) and obtaining similar TNT concentrations (43 and 80 mg L{sup -1}). Remediating munitions-contaminated soil at the NOP and elsewhere is of vital interest since many of the contaminants are carcinogenic, mutagenic or otherwise toxic to humans and the environment. Incineration, the most demonstrated remediation technology for munitions-containing soils, is costly and often unacceptable to the public. Chemical and biological remediation offer potentially cost-effective and more environmentally acceptable alternatives. Our research objectives are to: (a) characterize the processes affecting the transport and fate of munitions in highly contaminated soil; (b) identify effective chemical and biological treatments to degrade and detoxify residues; and (c) integrate these approaches for effective and practical remediation of soil contaminated with TNT, RDX, and other munitions residues.
Remediation of contaminated soils
Radhakrishnan, R.; Ariza, C.H.
At least three types of zones of contamination exist whenever there is a chemical release. The impact of Non-Aqueous-Phase Liquids (NAPL) on soils and groundwater, together with the ultimate transport and migration of constituent chemicals in their dissolved or sorbed states, had led environmentalists to develop several techniques for cleaning a contaminated soil. Zone 1 represents the unsaturated zone which could be contaminated to retention capacity by both Dense Non-Aqueous-Phase Liquids (DNAPL) and Light Non-Aqueous-Phase Liquids (LNAPL). Zone 2 represents residual DNAPL or LNAPL contamination found below the groundwater table in the saturated zone. Zone 3 is represented by either the presence of NAPL dissolved in the aqueous phase, volatilized in the unsaturated zone or sorbed to either saturated or unsaturated soils. Cleanup of petroleum contaminated soils is presented in this paper. Among several techniques developed for this purpose, in-situ biological remediation is discussed in detail as a technique that does not involve excavation, thus, the costs and disruption of excavating soil are eliminated.
Contaminated soil stabilization demonstration
Kemp, C.J.; Sackschewsky, M.R.; Sampson, A.E.; Phillips, S.J.
Long-term herbicide control along with a shotcrete cover was constructed at the Hanford Site in May 1991. The cover system allows for maintenance-free containment of contaminants by preventing wind and water transport of contaminants from the soil surface, preventing plant uptake of contaminants, and minimizing water infiltration through the soil column. The cover is composed of two parts: a commercial nonwoven geotextile material impregnated with trifluralin, and a >5-centimeter top cover of shotcrete containing polyethylene fibers. The herbicide-impregnated geotextile functions to prevent plant root growth into contaminated soil if any holes or cracks develop in the shotcrete layer. The herbicide component, trifluralin, is mixed into polymer nodules that degrade slowly over many years, thus releasing trifluralin slowly over time. The shotcrete topcover was sprayed using a sludge pump and air compressor to form a hard, impenetrable surface that prevents wind erosion and reduces water infiltration through the contaminated materials underneath. The benefits of the cover system are expected to last 20 to 30 years. 2 refs., 4 figs.
Biological remediation of soils contaminated with organic chemicals is an alternative treatment technology that can often meet the goal of achieving a permanent clean-up remedy at hazardous waste sites, as encouraged by the U.S. Environmental Protection Agency (U.S. EPA) for impl...
Biotreatment of explosive contaminated soils
Shen, C.F.; Guiot, S.R.; Manuel, M.F.
The aim of this research was to develop a process which can be employed to remediate 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) contaminated soils. The TNT and RDX degrading ability of microorganisms in municipal activated sludge and anaerobic sludge was evaluated, along with the toxicity of TNT and RDX to the microorganisms under aerobic and anaerobic conditions. Biotreatment of TNT and RDX contaminated soils was studied in bioslurry reactors. Microcosm tests were also conducted to see if TNT and RDX removal from the slurry reactor is attributed to a mineralization to CO{sub 2}, and to determine the synergetic or antagonistic effct (if any) of TNT and RDX on the mineralization. Both sludge types were found to be rich sources of RDX degrading organisms. The supplement of anaerobic sludge in bioslurry reactor enhances the biodegradation of TNT and RDX, and leads to complete removal of TNT and RDX from the contaminated soil. Bioslurry reactors may be a cost-effective approach to the on-site bioremediation of soils contaminated with high levels of epxlosives.
McKenna, J.; Pickering, E.
Today`s environmental projects involve a variety of complex issues that property owners and environmental professionals have to consider before they embark on a site-remediation program. One of the key things that has to be done during a project is to understand and select the chemical analysis parameters (CAPs) that are needed to characterize the soil. For instance, site investigations to determine if a soil is polluted require engineers to carefully select CAPs that will yield this information. Offsite fusibilities that specialize in waste treatment and disposal, on the other hand, require CAPs that may vary greatly from the CAPs needed for site investigations. However, when offsite treatment and disposal is the preferred remedial option, one can save money and add value to a project by including the CAPs required by a treatment, storage and disposal (TSD) facility to those CAPs selected for the site investigation. To select the right combination of CAPs to cover both site investigations and treatment and disposal requires a clear understanding of the analytical methods underlying the CAPs. The following set of CAPs are typically required by RCRA and non-RCRA TSD facilities: Total petroleum hydrocarbons; EPA method 9045 for corrosivities (pH); Reactivity; Total RCRA-8 metals; EPA Method 8240 for volatile organic compounds; EPA Method 8270 for semi-volatile organic compounds (SVOCs); EPA Method 8080 for polychlorinated biphenyls (PCBs); EPA Method 1010 for ignitability. These are all described.
Contaminant resorption during soil washing
Gombert, D.
To evaluate the applicability of soil washing to a specific site requires some basic research in how contaminants are bound. Much can be learned from sequential extraction methodology based on micronutrient bioavailability studies wherein the soil matrix is chemically dissected to selectively remove particular fixation mechanisms independently. This procedure uses a series of progressively more aggressive solvents to dissolve the principle phases that make up a soil, however, the published studies do not appear to consider the potential for a contaminant released from one type of site to resorb on another site during an extraction. This physical model assumes no ion exchange or adsorption at sites either previously occupied by other ions, or exposed by the dissolution. Therefore, to make engineering use of the sequential extraction data, the release of contamination must be evaluated relative to the effects of resorption. Time release studies were conducted to determine the optimum duration for extraction to maximize complete destruction of the target matrix fraction while minimizing contaminant resorption. Tests with and without a potassium brine present to inhibit cesium resorption indicated extraction efficiency could be enhanced by as much as a factor of ten using the brine.
Biodegradation of 4-chloronitrobenzene by biochemical cooperation between Sphingomonas sp. strain CNB3 and Burkholderia sp. strain CAN6 isolated from activated sludge.
Zhang, Longjiang; Wang, Xin; Jiao, Yiying; Chen, Xu; Zhou, Lingyan; Guo, Kun; Ge, Feng; Wu, Jun
Two bacterial strains were isolated from activated sludge by using 4-chloronitrobenzene (4-CB) as the sole source of carbon for enrichment. One of the isolates was identified as Sphingomonas sp. strain CNB3 and the other as Burkholderia sp. strain CAN6, mainly through morphological and physiological characteristics and 16S rRNA gene sequence analysis. Sphingomonas sp. strain CNB3 could transform 4-CB to 4-chloroaniline, which accumulated in the medium. Burkholderia sp. strain CAN6 could transform 4-chloroaniline but not 4-CB. The co-culture of Sphingomonas sp. strain CNB3 and Burkholderia sp. strain CAN6 could degrade 4-CB completely by the biochemical cooperation of two strains to overcome the degradative limitations of each species alone. In addition, the biochemical pathway of 4-chloroaniline transformation by Burkholderia sp. strain CAN6 was proposed based on the determined related enzyme activities. The results suggested that 4-chloroaniline was completely transformed via the ortho-cleavage and modified ortho-cleavage pathways. PMID:23473429
Nucleotide Sequence of Plasmid pCNB1 from Comamonas Strain CNB-1 Reveals Novel Genetic Organization and Evolution for 4-Chloronitrobenzene Degradation▿
Ma, Ying-Fei; Wu, Jian-Feng; Wang, Sheng-Yue; Jiang, Cheng-Ying; Zhang, Yun; Qi, Su-Wei; Liu, Lei; Zhao, Guo-Ping; Liu, Shuang-Jiang
The nucleotide sequence of a new plasmid pCNB1 from Comamonas sp. strain CNB-1 that degrades 4-chloronitrobenzene (4CNB) was determined. pCNB1 belongs to the IncP-1β group and is 91,181 bp in length. A total of 95 open reading frames appear to be involved in (i) the replication, maintenance, and transfer of pCNB1; (ii) resistance to arsenate and chromate; and (iii) the degradation of 4CNB. The 4CNB degradative genes and arsenate resistance genes were located on an extraordinarily large transposon (44.5 kb), proposed as TnCNB1. TnCNB1 was flanked by two IS1071 elements and represents a new member of the composite I transposon family. The 4CNB degradative genes within TnCNB1 were separated by various truncated genes and genetic homologs from other DNA molecules. Genes for chromate resistance were located on another transposon that was similar to the Tn21 transposon of the class II replicative family that is frequently responsible for the mobilization of mercury resistance genes. Resistance to arsenate and chromate were experimentally confirmed, and transcriptions of arsenate and chromate resistance genes were demonstrated by reverse transcription-PCR. These results described a new member of the IncP-1β plasmid family, and the findings suggest that gene deletion and acquisition as well as genetic rearrangement of DNA molecules happened during the evolution of the 4CNB degradation pathway on pCNB1. PMID:17526790
Phytoremediation of Metal-Contaminated Soils
Shtangeeva, I.; Laiho, J.V-P.; Kahelin, H.; Gobran, G.R.
Recent concerns regarding environmental contamination have necessitated the development of appropriate technologies to assess the presence and mobility of metals in soil and estimate possible ways to decrease the level of soil metal contamination. Phytoremediation is an emerging technology that may be used to cleanup contaminated soils. Successful application of phytoremediation, however, depends upon various factors that must be carefully investigated and properly considered for specific site conditions. To efficiently affect the metal removal from contaminated soils we used the ability of plants to accumulate different metals and agricultural practices to improve soil quality and enhance plant biomass. Pot experiments were conducted to study metal transport through bulk soil to the rhizosphere and stimulate transfer of the metals to be more available for plants' form. The aim of the experimental study was also to find fertilizers that could enhance uptake of metals and their removal from contaminated soil.
[Heterogeneity of parasitic contamination of megalopolis soils].
Aliautdinova, L V; Semenova, T A; Zavoĭkin, V D
A morphological group ofwhipworm (Trichuris trichiura) eggs, which is detectable in the soil samples from the city's different control lands, shows that their origin is heterogeneous and it is possible to differentiate them by morphometric signs. At the same time is necessary to consider the specific biological factors contributing to soil contamination. Priority in parasitic soil contamination should be given to animals, dogs in particular, which is supported by the fact that the dog walking grounds exhibit the highest contamination rates. PMID:21797059
Phytoremediation of Soils Contaminated by Chlorinnated Hydrocarbons
NASA Astrophysics Data System (ADS)
Cho, C.; Sung, K.; Corapcioglu, M.
In recent years, the possible use of deep rooted plants for phytoremediation of soil contaminants has been offered as a potential alternative for waste management, particularly for in situ remediation of large volumes of contaminated soils. Major objectives of this study are to evaluate the effectiveness of a warm season grass (Eastern Gamagrass) and a cool season prairie grass (Annual Ryegrass) in the phytoremediation of the soil contaminated with volatile organic compounds e.g., trichloroethylene (TCE), tetrachloroethylene (PCE), and 1,1,1-trichloroethane (TCA) and to determine the main mechanisms of target contaminant dissipation. The preliminary tests and laboratory scale tests were conducted to identify the main mechanisms for phytoremediation of the target contaminants, and to apply the technique in green house application under field conditions. The results of microcosm and bioreactor experiments showed that volatilization can be the dominant pathway of the target contaminant mass losses in soils. Toxicity tests, conducted in nutrient solution in the growth room, and in the greenhouse, showed that both Eastern gamagrass and Annual ryegrass could grow without harmful effects at up to 400 ppm each of all three contaminants together. Preliminary greenhouse experimentw were conducted with the 1.5 m long and 0.3 m diameter PVC columns. Soil gas concentrations monitored and microbial biomass in bulk and rhizosphere soil, root properties, and contaminant concentration in soil after 100 days were analyzed. The results showed that the soil gas concentration of contaminants has rapidly decreased especially in the upper soil and the contaminant concentraitons in soil were also significantly decreased to 0.024, 0.228, and 0.002 of C/Co for TCE, PCE and TCA, respectively. Significant plant effects were not found however showed contaminant loss through volatilization and plant contamination by air.
The 1987 Sand Creek Operable Unit 5 record of decision (ROD) identified soil washing as the selected technology to remediate soils contaminated with high levels of organochlorine pesticides, herbicides, and metals. Initial treatability tests conducted to assess the applicability...
Surfactants treatment of crude oil contaminated soils.
Urum, Kingsley; Pekdemir, Turgay; Copur, Mehmet
This study reports experimental measurements investigating the ability of a biological (rhamnolipid) and a synthetic (sodium dodecyl sulfate, SDS) surfactant to remove the North Sea Ekofisk crude oil from various soils with different particle size fractions under varying washing conditions. The washing parameters and ranges tested were as follows: temperature (5 to 50 degrees C), time (5 to 20 min), shaking speed (80 to 200 strokes/min), volume (5 to 20 cm3), and surfactant concentration (0.004 to 5 mass%). The contaminated soils were prepared in the laboratory by mixing crude oil and soils using a rotating cylindrical mixer. Two contamination cases were considered: (1) weathered contamination was simulated by keeping freshly contaminated soils in a fan assisted oven at 50 degrees C for 14 days, mimicking the weathering effect in a natural hot environment, and (2) nonweathered contamination which was not subjected to the oven treatment. The surfactants were found to have considerable potential in removing crude oil from different contaminated soils and the results were comparable with those reported in literature for petroleum hydrocarbons. The removal of crude oil with either rhamnolipid or SDS was within the repeatability range of +/-6%. The most influential parameters on oil removal were surfactant concentration and washing temperature. The soil cation exchange capacity and pH also influenced the removal of crude oil from the individual soils. However, due to the binding of crude oil to soil during weathering, low crude oil removal was achieved with the weathered contaminated soil samples. PMID:15271574
In situ removal of contamination from soil
Lindgren, E.R.; Brady, P.V.
A process of remediation of cationic heavy metal contamination from soil utilizes gas phase manipulation to inhibit biodegradation of a chelating agent that is used in an electrokinesis process to remove the contamination. The process also uses further gas phase manipulation to stimulate biodegradation of the chelating agent after the contamination has been removed. The process ensures that the chelating agent is not attacked by bioorganisms in the soil prior to removal of the contamination, and that the chelating agent does not remain as a new contaminant after the process is completed. 5 figs.
In situ removal of contamination from soil
Lindgren, Eric R.; Brady, Patrick V.
A process of remediation of cationic heavy metal contamination from soil utilizes gas phase manipulation to inhibit biodegradation of a chelating agent that is used in an electrokinesis process to remove the contamination, and further gas phase manipulation to stimulate biodegradation of the chelating agent after the contamination has been removed. The process ensures that the chelating agent is not attacked by bioorganisms in the soil prior to removal of the contamination, and that the chelating agent does not remain as a new contaminant after the process is completed.
Bioremediation of PAH contaminated soil samples
Joshi, M.M.; Lee, S.
Soils contaminated with polynuclear aromatic hydrocarbons (PAHs) pose a hazard to life. The remediation of such sites can be done using physical, chemical, and biological treatment methods or a combination of them. It is of interest to study the decontamination of soil using bioremediation. The experiments were conducted using Acinetobacter (ATCC 31012) at room temperature without pH or temperature control. In the first series of experiments, contaminated soil samples obtained from Alberta Research Council were analyzed to determine the toxic contaminant and their composition in the soil. These samples were then treated using aerobic fermentation and removal efficiency for each contaminant was determined. In the second series of experiments, a single contaminant was used to prepare a synthetic soil sample. This sample of known composition was then treated using aerobic fermentation in continuously stirred flasks. In one set of flasks, contaminant was the only carbon source and in the other set, starch was an additional carbon source. In the third series of experiments, the synthetic contaminated soil sample was treated in continuously stirred flasks in the first set and in fixed bed in the second set and the removal efficiencies were compared. The removal efficiencies obtained indicated the extent of biodegradation for various contaminants, the effect of additional carbon source, and performance in fixed bed without external aeration.
Uranium-contaminated soil pilot treatment study
Turney, W.R.J.R.; Mason, C.F.V.; Michelotti, R.A.
A pilot treatment study is proving to be effective for the remediation of uranium-contaminated soil from a site at the Los Alamos National Laboratory by use of a two-step, zero-discharge, 100% recycle system. Candidate uranium-contaminated soils were characterized for uranium content, uranium speciation, organic content, size fractionization, and pH. Geochemical computer codes were used to forecast possible uranium leach scenarios. Uranium contamination was not homogenous throughout the soil. In the first step, following excavation, the soil was sorted by use of the ThemoNuclean Services segmented gate system. Following the sorting, uranium-contaminated soil was remediated in a containerized vat leach process by use of sodium-bicarbonate leach solution. Leach solution containing uranium-carbonate complexes is to be treated by use of ion-exchange media and then recycled. Following the treatment process the ion exchange media will be disposed of in an approved low-level radioactive landfill. It is anticipated that treated soils will meet Department of Energy site closure guidelines, and will be given {open_quotes}no further action{close_quotes} status. Treated soils are to be returned to the excavation site. A volume reduction of contaminated soils will successfully be achieved by the treatment process. Cost of the treatment (per cubic meter) is comparable or less than other current popular methods of uranium-contamination remediation.
A petroleum contaminated soil bioremediation facility
Lombard, K.; Hazen, T.
The amount of petroleum contaminated soil (PCS) at the Savannah River site (SRS) that has been identified, excavated and is currently in storage has increased several fold during the last few years. Several factors have contributed to this problem: (1) South Carolina Department of Health ad Environmental control (SCDHEC) lowered the sanitary landfill maximum concentration for total petroleum hydrocarbons (TPH) in the soil from 500 to 100 parts per million (ppm), (2) removal and replacement of underground storage tanks at several sites, (3) most recently SCDHEC disallowed aeration for treatment of contaminated soil, and (4) discovery of several very large contaminated areas of soil associated with leaking underground storage tanks (LUST), leaking pipes, disposal areas, and spills. Thus, SRS has an urgent need to remediate large quantities of contaminated soil that are currently stockpiled and the anticipated contaminated soils to be generated from accidental spills. As long as we utilize petroleum based compounds at the site, we will continue to generate contaminated soil that will require remediation.
Soil Vapor Extraction of PCE/TCE Contaminated Soil
Bradley, J.M.; Morgenstern, M.R.
The A/M Area of the Savannah River Site soil and groundwater is contaminated with tetrachloroethylene (PCE) and trichloroethylene (TCE). Contamination is the result of previous waste disposal practices, once considered state-of-the-art. Soil Vapor Extraction (SVE) units have been installed to remediate the A/M Area vadose zone. SVE is a proven in-situ method for removing volatile organics from a soil matrix with minimal site disturbance. SVE alleviates the infiltration of contaminants into the groundwater and reduces the total time required for groundwater remediation. Lessons learned and optimization of the SVE units are also discussed.
Bioremediation of uranium contaminated Fernald soils
Delwiche, M.E.; Wey, J.E.; Torma, A.E.
This study investigated the use of microbial bioleaching for removal of uranium from contaminated soils. The ability of bacteria to assist in oxidation and solubilization of uranium was compared to the ability of fungi to produce complexing compounds which have the same effect. Biosorption of uranium by fungi was also measured. Soil samples were examined for changes in mineralogical properties due to these processes. On the basis of these laboratory scale studies a generalized flow sheet is proposed for bioremediation of contaminated Fernald soils.
Soil contamination with radionuclides and potential remediation.
Zhu, Y G; Shaw, G
Soils contaminated with radionuclides, particularly 137Cs and 90Sr, pose a long-term radiation hazard to human health through exposure via the foodchain and other pathways. Remediation of radionuclide-contaminated soils has become increasingly important. Removal of the contaminated surface soil (often up to 40 cm) or immobilization of radionuclides in soils by applying mineral and chemical amendments are physically difficult and not likely cost-effective in practicality. Reducing plant uptake of radionuclides, especially 137CS and 90Sr by competitive cations contained in chemical fertilizers has the general advantage in large scale, low-level contamination incidents on arable land, and has been widely practiced in central and Western Europe after the Chernobyl accident. Phytoextraction of radionuclides by specific plant species from contaminated sites has rapidly stimulated interest among industrialists as well as academics, and is considered to be a promising bio-remediation method. This paper examines the existing remediation approaches and discusses phytoextraction of radionuclides from contaminated soils in detail. PMID:10819188
Regulatory compliance requires the cleanup of soils contaminated with toxic organic and metallic compounds. Several chemical and thermal detoxification technologies have been tested on soils excavated from contaminated sites. Soil washing with aqueous solutions transfers the cont...
Electrokinetic characterization techniques for contaminated soils
Eykholt, G.R.; Hung, H.
One important element to the success of electrokinetic remediation of contaminated soils may be the assessment and control of the soil surface chemistry. This is usually reflected by an operative zeta-potential or electroosmotic coefficient, k{sub eo}, found by an electroosmosis test on a plug of contaminated soil. However, several researchers have shown that both the magnitude and uniformity of k{sub eo} change over the course of testing, as does the electric field intensity and zeta-potential, two basic parameters of the fundamental driving force. The electric field intensity can be measured during the test, but it is more difficult to assess the zeta potential. Independent techniques are needed. A conventional technique is dilute electrophoresis, but this test may not be truly representative or convenient. In this research summary, alternative techniques based on electroacoustic phenomena are presented in conjunction with other electrokinetic tests on reference and contaminated soils.
Soil washing of fluorine contaminated soil using various washing solutions.
Moon, Deok Hyun; Jo, Raehyun; Koutsospyros, Agamemnon; Cheong, Kyung Hoon; Park, Jeong-Hun
Bench-scale soil washing experiments were conducted to remove fluoride from contaminated soils. Five washing solutions including hydrochloric acid (HCl), nitric acid (HNO3), sodium hydroxide (NaOH), sulfuric acid (H2SO4) and tartaric acid (C4H6O6) were tested. The concentration of the washing solutions used ranged from 0.1 to 3 M with a liquid to solid ratio of 10. The soil washing results showed that the most effective washing solution for the removal of fluoride from contaminated soils was HCl. The highest fluoride removal results of approximately 97 % from the contaminated soil were obtained using 3 M HCl. The fluoride removal efficiency of the washing solution increases in the following order: C4H6O6 < NaOH < H2SO4 < HNO3 < HCl. PMID:25552323
Durham, L.A.; Johnson, R.L.; Rieman, C.; Kenna, T.; Pilon, R.
The U.S. Army Corps of Engineers (USACE) is conducting a cleanup of radiologically contaminated properties under the Formerly Utilized Sites Remedial Action Program (FUSRAP). The largest cost element for most of the FUSRAP sites is the transportation and disposal of contaminated soil. Project managers and engineers need an estimate of the volume of contaminated soil to determine project costs and schedule. Once excavation activities begin and additional remedial action data are collected, the actual quantity of contaminated soil often deviates from the original estimate, resulting in cost and schedule impacts to the project. The project costs and schedule need to be frequently updated by tracking the actual quantities of excavated soil and contaminated soil remaining during the life of a remedial action project. A soil volume estimate tracking methodology was developed to provide a mechanism for project managers and engineers to create better project controls of costs and schedule. For the FUSRAP Linde site, an estimate of the initial volume of in situ soil above the specified cleanup guidelines was calculated on the basis of discrete soil sample data and other relevant data using indicator geostatistical techniques combined with Bayesian analysis. During the remedial action, updated volume estimates of remaining in situ soils requiring excavation were calculated on a periodic basis. In addition to taking into account the volume of soil that had been excavated, the updated volume estimates incorporated both new gamma walkover surveys and discrete sample data collected as part of the remedial action. A civil survey company provided periodic estimates of actual in situ excavated soil volumes. By using the results from the civil survey of actual in situ volumes excavated and the updated estimate of the remaining volume of contaminated soil requiring excavation, the USACE Buffalo District was able to forecast and update project costs and schedule. The soil volume
Ecological Role of Soils upon Radioactive Contamination
NASA Astrophysics Data System (ADS)
Tsvetnov, Evgeny; Shcheglov, Alexei; Tsvenova, Olga
The ecological role of soils upon radioactive contamination is clearly manifested in the system of notions about ecosystems services, i.e., benefits gained by humans from ecosystems and their components, including soils (Millennium Ecosystem Assessment, 2005). For the soils, these services are considered on the basis of soil functions in the biosphere that belong to the protective ecosystem functions within the group of soil functions known under the names of "Buffer and protective biogeocenotic shield" (at the level of particular biogeocenoses) and "Protective shield of the biosphere" (at the global biospheric level) (according to Dobrovol'skii & Nikitin, 2005). With respect to radionuclides, this group includes (1) the depositing function, i.e., the accumulation and long-term sequestration of radioactive substances by the soil after atmospheric fallout; (2) the geochemical function, i.e., the regulation of horizontal and vertical fluxes of radionuclides in the system of geochemically conjugated landscapes and in the soil-groundwater and soil-plant systems; and (3) the dose-forming function that is manifested by the shielding capacity of the soil with respect to the external ionizing radiation (lowering of the dose from external radiation) and by the regulation of the migration of radionuclides in the trophic chain (lowering of the dose from internal radiation). The depositing and geochemical functions of the soils are interrelated, which is seen from quantitative estimates of the dynamics of the fluxes of radionuclides in the considered systems (soil-plant, soil-groundwater, etc.). The downward migration of radionuclides into the lower soil layers proceeds very slowly: for decades, more than 90% of the pool of radionuclides is stored in the topmost 10 cm of the soil profile. In the first 3-5 years after the fallout, the downward migration of radionuclides with infiltrating water flows decreases from several percent to decimals and hundredths of percent from the
Some aspects of remediation of contaminated soils
NASA Astrophysics Data System (ADS)
Bech, Jaume; Korobova, Elena; Abreu, Manuela; Bini, Claudio; Chon, Hyo-Taek; Pérez-Sirvent, Carmen; Roca, Núria
Soils are essential components of the environment, a limited precious and fragile resource, the quality of which should be preserved. The concentration, chemical form and distribution of potential harmful elements in soils depends on parent rocks, weathering, soil type and soil use. However, their concentration can be altered by mismanagement of industrial and mining activities, energy generation, traffic increase, overuse of agrochemicals, sewage sludge and waste disposal, causing contamination, environmental problems and health concerns. Heavy metals, some metalloids and radionuclides are persistent in the environment. This persistence hampers the cost/efficiency of remediation technologies. The choice of the most appropriate soil remediation techniques depends of many factors and essentially of the specific site. This contribution aims to offer an overview of the main remediation methods in contaminated soils. There are two main groups of technologies: the first group dealing with containment and confinement, minimizing their toxicity, mobility and bioavailability. Containment measures include covering, sealing, encapsulation and immobilization and stabilization. The second group, remediation with decontamination, is based on the remotion, clean up and/or destruction of contaminants. This group includes mechanical procedures, physical separations, chemical technologies such as soil washing with leaching or precipitation of harmful elements, soil flushing, thermal treatments and electrokinetic technologies. There are also two approaches of biological nature: bioremediation and phytoremediation. Case studies from Chile, Ecuador, Italy, Korea, Peru, Portugal, Russia and Spain, will be discussed in accordance with the time available.
Phytoremediation of soils contaminated by cadmium
NASA Astrophysics Data System (ADS)
Watai, H.; Miyazaki, T.; Fujikawa, T.; Mizoguchi, M.
Phytoremediation is a technique to clean up soils contaminated with heavy metals. Advantages of this method are that (1) This technique is suitable to cleanup soils slightly contaminated with heavy metals in relatively wide area. (2) The expense for clean up is lower than civil engineering techniques. (3) This method can remove heavy metals fundamentally from contaminated. (4) The heavy metals are able to recycle by ashing of plants. Many researches have been done on the phytoremediation up to now, but almost all these researches were devoted to clarify the phytoremediation from the view point of plants themselves. However, few efforts have been devoted to analyze the migrations of heavy metals in soils during the phytoremediation process. The objective of this study is to clarify the features of Cd migration when plant roots are absorbing Cd from the ambient soils. Especially, we focused on finding the Cd migration pattern by changing the soil condition such as plant growing periods, planting densities, and the initial Cd concentration in soils. We planted sunflowers in columns filled with Cd contaminated soils because sunflower is a well-known hyperaccumulator of Cd from soils. By cutting the shoots of plants at the soil surface, and by keeping the plant roots in the soils without disturbance, the Cd concentrations, moisture contents, pH distributions, EC distributions, and dry weight of residual roots in the soils were carefully analyzed. The experimental results showed that (1)The growth of the planted sunflowers were suffered by applying of Cd. (2)The decrease of suction was affected by water uptake by roots at the depth from 0 to 5 cm. Water contents with plants in soils decrease more than without plants. (3)Cd adsorption by roots was predominant within 5cm from soil surface. In addition, it was also shown that there was an optimal Cd concentration where Cd is most effectively adsorbed by the plant. In this experiment we found that 40 to 60 mg kg-1 was the
Soil contamination evaluations: Earthworms as indicators of soil quality
Linder, G.; Wilbom, D.
Earthworms have frequently been evaluated in the field and laboratory as representatives of the soil community that are indicative of their habitat`s quality. Within a landscape or at a contaminated site, soil quality, or soil health, has become increasingly critical to cleanup-related issues that revolve around questions of ``how clean is clean`` and the bioaccumulation of soil contaminants. Through an overview of numerous field and laboratory studies, the role that earthworms have played in evaluating soil contamination will be reviewed with a particular focus on evaluations of the bioaccumulation potential of chemicals in soil. Within ecological contexts, earthworms can provide information regarding immediately observable adverse affects related, for example, to acute toxicity. Additionally, earthworms can provide information directly related to the bioaccumulation potential of a chemical and trophic transfer of environmental chemicals, especially through the food-chain. Within the decision-making process, soil contamination evaluations must consider future land-use, as well as current and future expressions of adverse biological and ecological effects under field conditions, potentially following remediation. Through integrated field and laboratory studies using earthworms, the authors have been able to identify adversely affected soil communities and have been able to provide information for assessing adverse ecological effects potentially caused by contaminants. Field surveys and on-site or in situ biological testing with earthworms, however, can not alone identify causes of effects. As such, standardized biological tests have been routinely completed in the laboratory so linkages between expression of effects and contaminants could be more readily addressed in conjunction with appropriate chemical data from the field.
Incineration treatment of arsenic-contaminated soil
Waterland, L.R.; King, C.; Richards, M.K.; Thurnau, R.C.
An incineration test program was conducted at the US Environmental Protection Agency's Incineration Research Facility to evaluate the potential of incineration as a treatment option for contaminated soils at the Baird and McGuire Superfund site in Holbrook, Massachusetts. The purpose of these tests was to evaluate the incinerability of these soils in terms of the fate of arsenic and lead and the destruction of organic contaminants during the incineration process. The test program consisted of a series of bench-scale experiments with a muffle furnace and a series of incineration tests in a pilot-scale rotary kiln incinerator system.
Soil contamination standards for protection of personnel
Rittmann, P.D.
The objective of this report is to recommend soil contamination levels that will ensure that radionuclide intakes by unprotected workers are likely to give internal doses below selected dose limits during the working year. The three internal dose limits are 1, 100, and 500 mrem per year. In addition, photon, beta, and alpha instrument readings are estimated for these soil concentration limits. Two exposure pathways are considered: the first is inhalation of resuspended dust and the second is ingestion of trace amounts of soil. In addition, radioactive decay and ingrowth of progeny during the year of exposure is included. External dose from the soil contamination is not included because monitoring and control of external exposures is carried out independently from internal exposures, which are the focus of this report. The methods used are similar to those used by Carbaugh and Bihl (1993) to set bioassay criteria for such workers.
Bioremediation of petroleum-contaminated soil
Pearce, K.; Snyman, H.G.; Oellermann, R.A.; Gerber, A.
A pilot-scale study was conducted to evaluate the application of land-farming techniques in bioremediating a soil highly contaminated with petroleum products. A commercial biosupplement, and one prepared with indigenous microorganisms from the contaminated soil, were tested. Application of either of the biosupplements, in addition to the control of pH, moisture, and oxygen levels, resulted in a 94% reduction of the initial total petroleum hydrocarbon concentration (TPHC) (32% mass/mass) over a 70-day period. Implementation of these findings at full scale to bioremediate highly weathered petroleum products showed an average reduction of 89% over 5.5 months. Target levels of 1,400 mg/kg soil were reached from an initial average TPHC concentration of 12,200 mg/kg soil.
Chelant soil-washing technology for metal-contaminated soil.
Voglar, David; Lestan, Domen
We demonstrate here, in a pilot-scale experiment, the feasibility of ethylenediaminetetraacetate (EDTA)based washing technology for soils contaminated with potentially toxic metals. Acid precipitation coupled to initial alkaline toxic metal removal and an electrochemical advanced oxidation process were used for average recovery of 76 +/- 2% of EDTA per batch and total recycle of water in a closed process loop. No waste water was generated; solid wastes were efficiently bitumen-stabilized before disposal. The technology embodiment, using conventional process equipment, such as a mixer for soil extraction, screen for soil/gravel separation, filter chamber presses for soil/liquid and recycled EDTA separation and soil rinsing, continuous centrifuge separator for removal of precipitated metals and electrolytic cells for process water cleansing, removed up to 72%, 25% and 66% of Pb, Zn and Cd from garden soil contaminated with up to 6960, 3797 and 32.6 mg kg(-1) of Pb, Zn and Cd, respectively, in nine 60kg soil batches. Concentrations of Pb and Zn remaining in the remediated soil and bioaccessible from the simulated human intestinal phase soil were reduced by 97% and 96% and were brought under the level of determination for Cd. In the most cost-effective operation mode, the material and energy costs of remediation amounted to 50.5 Euros ton(-1) soil and the total cost to 299 Euros ton(-1). PMID:24701937
Solid phase bioremediation of petroleum contaminated soils
Potter, C.D.
Solid phase bioremediation of petroleum contaminated soil involves aerobic biodegradation in an above grade treatment bed. This treatment technology is proposed for remediating soils contaminated by petroleum from leaking underground fuel storage tanks at various sites at the Oak Ridge Y-12 Plant. The treatment technology uses bacteria to degrade the petroleum hydrocarbons. The environmentally safe end products of the biodegradation process are carbon dioxide and water. A large, relatively level area is required to construct the perimeter berms, place the liner, and spread the contaminated soil in a 1 to 2 foot thick layer. A porous media is placed on top of the liner for protection and for proper drainage of leachate. Water, nutrients, and microorganisms are introduced into the soil in the treatment bed using conventional agricultural spraying techniques. Oxygen is supplied to the soil by periodic tilling on an ``as needed`` basis. To prevent soil erosion and to minimize leachate production during precipitation events, the treatment bed is completely covered by a plastic film. The treatment process is expected to require 3 to 8 months after construction is completed.
Thermal treatment of fuel-contaminated soil
Not Available
A patent has been issued for the apparatus and method for Low Temperature Thermal Stripping (LT/sup 3/) of volatile organic compounds (VOCs) from soil. LT/sup 3/ is a hazardous waste thermal treatment system and is used to clean up fuel-contaminated soil from leaking underground storage tanks. Representing a significant breakthrough in the treatment of polluted soil, LT/sup 3/ is a unique mix of proven techniques combined in an innovative way to provide an efficient cost-effective treatment method.
Evaluation of soil washing for radiologically contaminated soils
Gombert, D. II
Soil washing has been applied internationally to decontaminate soils due to the widespread increase in environmental awareness manifested in the United States by promulgation of the Comprehensive Environmental Response, Compensation and Liability Act, yet we continue to lack understanding on why the technique works in one application and not in another. A soil washing process typically integrates a variety of modules, each designed to decontaminate the matrix by destroying a particular phase or segregating a particle size fraction in which the contaminants are concentrated. The more known about how the contaminants are fixed, the more likely the process will succeed. Much can be learned from bioavailability studies on heavy metals in soils. Sequential extraction experiments designed to destroy one fixation mechanism at a time can be used to determine how contaminants are bound. This knowledge provides a technical basis for designing a processing strategy to efficiently decontaminate soil while creating a minimum of secondary wastes. In this study, a soil from the Idaho National Engineering Laboratory was physically and chemically characterized, then sequentially extracted to determine if soil washing could be effectively used to remove cesium, cobalt and chromium.
A pilot-scale study will be conducted to evaluate the bioremedial techniques of natural attenuation, sequenced anaerobic/aerobic treatment, and addition of a commercially available microbial amendment product for use in treating PCB contaminated soils at Air Force Base sites. Th...
The objective of this study was to demonstrate the application of a physico-chemical separation process for the removal of radium from a sample of contaminated soil at the Ottawa, Illinois, site near Chicago. The size/activity distribution analyzed among the particles coarser tha...
An incineration test program was conducted at the US Environmental Protection Agency's Incineration Research Facility to evaluate the potential of incineration as a treatment option for contaminated soils at the Baird and McGuire Superfund site in Holbrook, Massachusetts. he purp...
Bench-scale solvent extraction studies were performed on soil samples obtained from a Superfund site contaminated with high levels of p,p'-DDT, p,p'-DDD,, p,p'-DDE and toxaphene. The effectiveness of the solvent extraction process was assessed using methanol and 2-propanol as sol...
An incineration test program was conducted at the U.S. Environmental Protection Agency's Incineration Research Facility to evaluate the potential of incineration as a treatment option for contaminated soils at the Baird and McGuire Superfund site in Holbrook, Massachusetts. The p...
Guide to treatment technology for contaminated soils
Tran, H.; Aylward, R.
This document is a guide for the screening of alternative treatment technologies for contaminated soils. The contents of this guide are organized into: 1. Introduction, II. Utilizing the table, III. Tables: Contamination Versus Technology, TV. Contaminant Waste Groups, and V. References. The four Contaminations Versus Technology tables are designed to identify the effectiveness and/or potential applicability of technologies to some or all compounds within specific waste groups. The tables also present limitations and special use considerations for the particular treatment technology. The phase of development of the technology is also included in the table. The phases are: Available, Innovative, and Emerging technologies. The technologies presented in this guide are organized according to the method of treatment. The four (4) treatment methods are Biological, Solidification/Stabilization, Thermal, and Chemical/Physical Treatment. There are several processing methods; some are well developed and proven, and others are in the development stage.
Ecological risk assessment of contaminated soil.
Jensen, John; Pedersen, Marianne Bruus
This review has described three cases of ecological risk assessment. The cases include two heavy metals (Cu and Zn) and an anthropogenic organic chemical (DDT). It concludes that there are at least two major constraints hampering the use of laboratory tests to predict effects under natural field conditions. One key issue is bioavailability, and another is suboptimal conditions or multiple stresses in the field such as climatic stress (drought, frost), predators, competition, or food shortage. On the basis of the presented case studies, it was possible to answer three essential questions often raised in connection to ecological risk assessment of contaminated sites. 1. To what extend does soil screening level (SSL) estimate the risk? The SSL are generally derived at levels corresponding to the lowest observed effect levels in laboratory studies, which often is close to the background levels found in many soils. In the cases of zinc and especially DDT, the SSL seemed quite conservative, whereas for copper they resemble the level at which changes in the community structure of soil microarthropods and the plant community have been observed at contaminated sites. The SSL correspond as a whole relatively well with concentrations where no effects or only minor effects were observed in controlled field studies. However, large variation in field surveys can often make it difficult to conclude to what extent the SSL corresponded to no-effect levels in the field. 2. Do bioassays represent a more realistic risk estimate? Here, there is no firm conclusion. The zinc study in UK showed a better relationship between the outcome of ex situ bioassays and field observations than the SSL. The latter overestimated the risk compared to field observations. However, this would be species dependent, as the sensitivity to metals may vary considerably between recognized test species, even within the same group of organisms, such as Folsomia candida and Folsomia fimetaria or Eisenia fetida
TNT transport and fate in contaminated soil
Comfort, S.D.; Shea, P.J.; Hundal, L.S.
Past disposal practices at munitions production plants have contaminated terrestrial and aquatk ecosystems with 2,4,6-trinitrotoluene (TNT). We determined TNT transport, degradation, and long-term sorption characteristics in soil. Transport experiments were conducted with repacked, unsaturated soil columns containing uncontaminated soil or layers of contaminated and uncontaminated soil. Uncontaminated soil columns received multiple pore volumes (22-50) of a TNT-{sup 3}H{sub 2}O pulse, containing 70 or 6.3 mg TNT L{sup -1} at a constant pore water velocity. TNT breakthrough curves (BTCs) never reached initial solute pulse concentrations. Apex concentrations (C/C{sub o}) were between 0.6 and 0.8 for an initial pulse of 70 mg TNT L{sup -1} and 0.2 to 0.3 for the 6.3 mg TNT L{sup -1} pulse. Earlier TNT breakthrough was observed at the higher pulse concentration. This mobility difference was predicted from the nonlinear adsorption isotherm determined for TNT sorption. In all experiments, a significant fraction of added TNT was recovered as amino degradates of TNT. Mass balance estimates indicated 81% of the added TNT was recovered (as TNT and amino degradates) from columns receiving the 70 mg TNT L{sup -1} pulse compared to 35% from columns receiving the 6.3 mg TNT L{sup -1} pulse. Most of the unaccountable TNT was hypothesized to be unextractable. This was supported by a 168-d sorption experiment, which found that within 14d, 80% of {sup 14}C activity (added as {sup 14}C-TNT) was adsorbed and roughly 40% unextractable. Our observations illustrate that TNT sorption and degradation are concentration-dependent and the assumptions of linear adsorption and adsorption-desorption singularity commonly used in transport modeling, may not be valid for predicting TNT transport in munitions-contaminated soils. 29 refs., 6 figs., 7 tabs.
Method for treatment of soils contaminated with organic pollutants
Wickramanayake, Godage B.
A method for treating soil contaminated by organic compounds wherein an ozone containing gas is treated with acid to increase the stability of the ozone in the soil environment and the treated ozone applied to the contaminated soil to decompose the organic compounds. The soil may be treated in situ or may be removed for treatment and refilled.
Bioremediation of uranium contaminated soils and wastes
Francis, A.J.
Contamination of soils, water, and sediments by radionuclides and toxic metals from uranium mill tailings, nuclear fuel manufacturing and nuclear weapons production is a major concern. Studies of the mechanisms of biotransformation of uranium and toxic metals under various microbial process conditions has resulted in the development of two treatment processes: (1) stabilization of uranium and toxic metals with reduction in waste volume and (2) removal and recovery of uranium and toxic metals from wastes and contaminated soils. Stabilization of uranium and toxic metals in wastes is accomplished by exploiting the unique metabolic capabilities of the anaerobic bacterium, Clostridium sp. The radionuclides and toxic metals are solubilized by the bacteria directly by enzymatic reductive dissolution, or indirectly due to the production of organic acid metabolites. The radionuclides and toxic metals released into solution are immobilized by enzymatic reductive precipitation, biosorption and redistribution with stable mineral phases in the waste. Non-hazardous bulk components of the waste volume. In the second process uranium and toxic metals are removed from wastes or contaminated soils by extracting with the complexing agent citric acid. The citric-acid extract is subjected to biodegradation to recover the toxic metals, followed by photochemical degradation of the uranium citrate complex which is recalcitrant to biodegradation. The toxic metals and uranium are recovered in separate fractions for recycling or for disposal. The use of combined chemical and microbiological treatment process is more efficient than present methods and should result in considerable savings in clean-up and disposal costs.
Remediating pesticide contaminated soils using solvent extraction
Sahle-Demessie, E.; Meckes, M.C.; Richardson, T.L.
Bench-scale solvent extraction studies were performed on soil samples obtained from a Superfund site contaminated with high levels of p,p{prime}-DDT, p,p{prime}-DDE and toxaphene. The effectiveness of the solvent extraction process was assessed using methanol and 2-propanol as solvents over a wide range of operating conditions. It was demonstrated that a six-stage methanol extraction using a solvent-to-soil ratio of 1.6 can decrease pesticide levels in the soil by more than 99% and reduce the volume of material requiring further treatment by 25 times or more. The high solubility of the pesticides in methanol resulted in rapid extraction rates, with the system reaching quasi-equilibrium state in 30 minutes. The extraction efficiency was influenced by the number of extraction stages, the solvent-to-soil ratio, and the soil moisture content. Various methods were investigated to regenerate and recycle the solvent. Evaporation and solvent stripping are low cost and reliable methods for removing high pesticide concentrations from the solvent. For low concentrations, GAC adsorption may be used. Precipitating and filtering pesticides by adding water to the methanol/pesticide solution was not successful when tested with soil extracts. 26 refs., 10 figs., 6 tabs.
Biological degradation of TNT-contaminated soil
Manning, J.F.; Boopathy, R.
The concept of using biological slurry reactors to remediate soil contaminated with TNT has been investigated at the laboratory scale. Important parameters include an organic co-substrate and appropriate amounts of nitrogen and phosphorus added as nutrients. Normally, the degradation requires an organic co-substrate. The type of co-substrate can have a significant impact on the rate and extent of degradation. Succinate, malate, molasses, and glucose are all acceptable co-substrates. Molasses, or succinate with added yeast extract and/or peptone, provides superior rates of removal. Consortia of microorganisms isolated from various sites can also degrade TNT. To exploit the microbial system, laboratory scale soil slurry reactors have been operated, achieving reductions in TNT concentrations on the order of 90-99% from initial TNT concentrations of 7,000-10,000 mg/kg. Laboratory scale tests have shown that all of the intermediates can be removed by microbial degradation. Laboratory reactors operated with 15% volume replacement one, two, or three times a week achieved removal of 95-99% of the TNT in the feed soil. This system can reduce TNT concentrations to less than 20 mg/kg in treated soil. In particular, operation of the reactors in an aerobic-anoxic sequenced pattern promotes the conversion of TNT to CO{sub 2} and microbial biomass. Radiolabeling studies demonstrated that 50% of the TNT is mineralized, with 30% of the original labeled TNT being converted to microbial biomass. To take advantage of this technology, a field demonstration in which the soil slurry reactor is being used to degrade explosives-contaminated soil is currently being conducted.
Procedures for sampling radium-contaminated soils
Fleischhauer, H.L.
Two procedures for sampling the surface layer (0 to 15 centimeters) of radium-contaminated soil are recommended for use in remedial action projects. Both procedures adhere to the philosophy that soil samples should have constant geometry and constant volume in order to ensure uniformity. In the first procedure, a ''cookie cutter'' fashioned from pipe or steel plate, is driven to the desired depth by means of a slide hammer, and the sample extracted as a core or plug. The second procedure requires use of a template to outline the sampling area, from which the sample is obtained using a trowel or spoon. Sampling to the desired depth must then be performed incrementally. Selection of one procedure over the other is governed primarily by soil conditions, the cookie cutter being effective in nongravelly soils, and the template procedure appropriate for use in both gravelly and nongravelly soils. In any event, a minimum sample volume of 1000 cubic centimeters is recommended. The step-by-step procedures are accompanied by a description of the minimum requirements for sample documentation. Transport of the soil samples from the field is then addressed in a discussion of the federal regulations for shipping radioactive materials. Interpretation of those regulations, particularly in light of their application to remedial action soil-sampling programs, is provided in the form of guidance and suggested procedures. Due to the complex nature of the regulations, however, there is no guarantee that our interpretations of them are complete or entirely accurate. Preparation of soil samples for radium-226 analysis by means of gamma-ray spectroscopy is described.
Aromatic plant production on metal contaminated soils.
Zheljazkov, Valtcho D; Craker, Lyle E; Xing, Baoshan; Nielsen, Niels E; Wilcox, Andrew
Field and container experiments were conducted to assess the feasibility of growing aromatic crops in metal contaminated areas and the effect of metals on herbage and oil productivity. The field experiments were conducted in the vicinities of the Non-Ferrous Metals Combine (Zn-Cu smelter) near Plovdiv, Bulgaria using coriander, sage, dill, basil, hyssop, lemon balm, and chamomile grown at various distances from the smelter. Herbage essential oil yields of basil, chamomile, dill, and sage were reduced when they were grown closer to the smelter. Metal removal from the site with the harvestable plant parts was as high as 180 g ha(-1) for Cd, 660 g ha(-1) for Pb, 180 g ha(-1) for Cu, 350 g ha(-1) for Mn, and 205 g ha(-1) for Zn. Sequential extraction of soil demonstrated that metal fractionation was affected by the distance to the smelter. With decreasing distance to the smelter, the transfer factor (TF) for Cu and Zn decreased but increased for Cd, while the bioavailability factor (BF) for Cd, Pb, Cu, Mn, and Zn decreased. Scanning electron microscopy and X-ray microanalyses of contaminated soil verified that most of the Pb, Cd, Mn, Cu, and Zn were in the form of small (<1 microm) particles, although there were larger particles (1-5 microm) with high concentrations of individual metals. This study demonstrated that high concentrations of heavy metals in soil or growth medium did not result in metal transfer into the essential oil. Of the tested metals, only Cu at high concentrations may reduce oil content. Our results demonstrated that aromatic crops may not have significant phytoremediation potential, but growth of these crops in metal contaminated agricultural soils is a feasible alternative. Aromatic crops can provide economic return and metal-free final product, the essential oil. PMID:18353428
Enhanced bioremediation of PAH contaminated soils from coal processing sites
Joshi, M.M.; Lee, S.
The polycyclic aromatic hydrocarbons (PAH) are a potential hazard to health due to their carcinogenic, mutagenic nature and acute toxicity and there is an imminent need for remediation of PAH contaminated soils abounding the several coke oven and town gas sites. Aerobic biological degradation of PAHs is an innovative technology and has shown high decontamination efficiencies, complete mineralization of contaminants, and is environmentally safe. The present study investigates the remediation of PAH contaminated soils achieved using Acinetobacter species and fungal strain Phanerochaete Chrysosporium. The soil used for the experiments was an industrially contaminated soil obtained from Alberta Research Council (ARC) primary cleanup facility, Alberta, Canada. Soil characterization was done using High Performance Liquid Chromatography (HPLC) to qualitatively and quantitatively determine the contaminants in the soil. Artificially contaminated soil was also used for some experiments. All the experiments were conducted under completely mixed conditions with suitable oxygen and nutrient amendments. The removal efficiency obtained for various PAHs using the two microorganisms was compared.
Bioremediation of petroleum contaminated soil using vegetation. A microbial study
Lee, E.; Banks, M.K. )
The degradation of selected petroleum hydrocarbons in the rhizosphere of alfalfa was investigated in a greenhouse experiment. Petroleum contaminated and uncontaminated soils were spiked with 100 ppm of polynuclear aromatic and aliphatic hydrocarbons. Unspiked, uncontaminated soil was used as a control. Microbial counts for soils with and without plants for each soil treatment were performed 4, 8, 16, and 24 weeks after planting. Microbial numbers were substantially greater in soil with plants when compared to soil containing no plants, indicating that plant roots enhanced microbial populations in contaminated soil. Soil treatments had no effect on microbial numbers in the presence of plants. 12 refs., 3 figs., 1 tab.
Contamination of soils, water, and sediments by radionuclides and toxic metals from uranium mill tailings, nuclear fuel manufacturing and nuclear weapons production is a major concern. Studies of the mechanisms of biotransformation of uranium and toxic metals under various microbial process conditions has resulted in the development of two treatment processes: (i) stabilization of uranium and toxic metals with reduction in waste volume and (ii) removal and recovery of uranium and toxic metals from wastes and contaminated soils. Stabilization of uranium and toxic metals in wastes is accomplished by exploiting the unique metabolic capabilities of the anaerobic bacterium, Clostridium sp. The radionuclides and toxic metals are solubilized by the bacteria directly by enzymatic reductive dissolution, or indirectly due to the production of organic acid metabolites. The radionuclides and toxic metals released into solution are immobilized by enzymatic reductive precipitation, biosorption and redistribution with stable mineral phases in the waste. Non-hazardous bulk components of the waste such as Ca, Fe, K, Mg and Na released into solution are removed, thus reducing the waste volume. In the second process uranium and toxic metals are removed from wastes or contaminated soils by extracting with the complexing agent citric acid. The citric-acid extract is subjected to biodegradation to recover the toxic metals, followed by photochemical degradation of the uranium citrate complex which is recalcitrant to biodegradation. The toxic metals and uranium are recovered in separate fractions for recycling or for disposal. The use of combined chemical and microbiological treatment process is more efficient than present methods and should result in considerable savings in clean-up and disposal costs.
Treating large volumes of contaminated soil at Superfund sites is costly. he Superfund Amendments and Reauthorization Act (SARA), and the Resource Conservation and Recovery Act (RCRA) have provisions, which regulate the removal treatment, and ultimate disposal of contaminated soi...
Pesticide contamination results from manufacturing, improper storage, handling, or disposal of pesticides, and from agricultural processes. Since most pesticides are mixtures of different compounds, selecting a remedy for pesticide-contaminated soils can be a complicated process....
Soils as a buffer of contaminants in catchments
NASA Astrophysics Data System (ADS)
Evrard, Olivier
Human activities deliver large quantities of contaminants into the environment through atmospheric emissions or direct releases. As many of those contaminants are particle-reactive, they bind strongly to the finest particles or on their organic matter fraction once they deposit onto soils. Contaminants may subsequently migrate in depth of the soil depending on their physico-chemical characteristics. They may also be redistributed along hillslopes in association with particles during soil erosion events and may be subsequently supplied to rivers, preventing to meet the international environmental targets (e.g. in the framework of the EU Water Framework Directive). In regions where soil erosion rates are low to moderate, a large quantity of particle-reactive contaminants may accumulate in soils that constitute a reservoir of pollutants that may be delivered to rivers during decades or centuries. This session will focus on the specific role played by soils as a reservoir of contaminants at the catchment scale. A better understanding of this role and a quantification of the persistence of contaminants in this reservoir will provide crucial insights to guide the implementation of efficient mitigation measures. Contributions to this session may address any aspect of particle-borne contaminant transfer at the catchment scale, with an emphasis on the role played by soils in their storage and transfer. Field-based or modeling studies may focus either on specific pollutants or on a wider range of substances, e.g. metals, radionuclides, organic contaminants. Key themes may include: • Contaminant budget at the hillslope vs. the catchment scales; • Evaluation of the contribution of the regional vs. local contamination sources; • Evaluation of the contaminant removal from soils by degradation vs. soil erosion; • Quantifying the persistence of contaminants in soils; • Discrimination between the legacy and the contemporary supply of contaminants to soils.
System for the removal of contaminant soil-gas vapors
Weidner, Jerry R.; Downs, Wayne C.; Kaser, Timothy G.; Hall, H. James
A system extracts contaminated vapors from soil or other subsurface regions by using changes in barometric pressure to operate sensitive check valves that control air entry and removal from wells in the ground. The system creates an efficient subterranean flow of air through a contaminated soil plume and causes final extraction of the contaminants from the soil to ambient air above ground without any external energy sources.
System for the removal of contaminant soil-gas vapors
Weidner, J.R.; Downs, W.C.; Kaser, T.G.; Hall, H.J.
A system extracts contaminated vapors from soil or other subsurface regions by using changes in barometric pressure to operate sensitive check valves that control air entry and removal from wells in the ground. The system creates an efficient subterranean flow of air through a contaminated soil plume and causes final extraction of the contaminants from the soil to ambient air above ground without any external energy sources. 4 figs.
Soil contamination in China: current status and mitigation strategies.
Zhao, Fang-Jie; Ma, Yibing; Zhu, Yong-Guan; Tang, Zhong; McGrath, Steve P
China faces great challenges in protecting its soil from contamination caused by rapid industrialization and urbanization over the last three decades. Recent nationwide surveys show that 16% of the soil samples, 19% for the agricultural soils, are contaminated based on China's soil environmental quality limits, mainly with heavy metals and metalloids. Comparisons with other regions of the world show that the current status of soil contamination, based on the total contaminant concentrations, is not worse in China. However, the concentrations of some heavy metals in Chinese soils appear to be increasing at much greater rates. Exceedance of the contaminant limits in food crops is widespread in some areas, especially southern China, due to elevated inputs of contaminants, acidic nature of the soil and crop species or cultivars prone to heavy metal accumulation. Minimizing the transfer of contaminants from soil to the food chain is a top priority. A number of options are proposed, including identification of the sources of contaminants to agricultural systems, minimization of contaminant inputs, reduction of heavy metal phytoavailability in soil with liming or other immobilizing materials, selection and breeding of low accumulating crop cultivars, adoption of appropriate water and fertilizer management, bioremediation, and change of land use to grow nonfood crops. Implementation of these strategies requires not only technological advances, but also social-economic evaluation and effective enforcement of environmental protection law. PMID:25514502
The effect of contaminant aging upon soil washing removal efficiencies for lead contaminated soils
Cline, S.R.; Reed, B.E.; Moore, R.E.
The objective of this research was to investigate lead removal efficiencies from various soils using a variety of washing solutions. Most soil types have a strong affinity for lead. Thus, it is plausible to expect washing solutions that are capable of removing lead could also remove other divalent heavy metals. Four soil samples from the eastern US were collected and characterized for this study. The study soils were then spiked to approximate lead concentrations of 1,000 and 10,000 mg Pb/kg soil. The efficiencies of six washing solutions in removing lead from the contaminated soils were then investigated via lab-scale batch washing experiments. Unlike current field-scale soil washing practices, all particle size fractions were washed and recovered in these experiments. (Solutions investigated include: tap water, HCl, EDTA, HNO{sub 3}, CH{sub 3}COOH, and CaCl{sub 2}.) In order to examine the effect of aging upon soil washing efficiencies, some of the spiked soils were washed a second time after an aging period of nearly 2 years.
Soil vapor phase contaminants commonly include combinations of chlorinated ethenes and petroleum hydrocarbons. Many chlorinated ethenes and petroleum hydrocarbons are readily degradable by a range of aerobic soil microorganisms, making the use of biological systems for degrading ...
Mouse Assay for Determination of Arsenic Bioavailability in Contaminated Soils
Background: Accurate assessment of human exposure estimates from arsenic-contaminated soils depends upon estimating arsenic (As) soil bioavailability. Development of bioavailability assays provides data needed for human health risk assessments and supports development and valida...
Testing amendments for remediation of military range contaminated soil
Technology Transfer Automated Retrieval System (TEKTRAN)
Military range soils are often strongly contaminated with metals. Information on effectiveness of remediation techniques on these soils is scarce. We tested effectiveness of compost and mineral treatments for remediation of military range soil collected in Aberdeen, MD. The soil was barren due to...
Comprehensive methodology for ecological risk assessment of contaminated soils
Kuperman, R.G.
Development of a comprehensive methodology for ecological risk assessment and monitoring of contaminated soils is essential to assess the impacts of environmental contaminants on soil community and biologically-mediated processes in soil. The proposed four-step plan involves (1) a thorough survey of the soil community to establish biodiversity and a base-line community structure, (2) toxicity trials on indicator species and whole soil invertebrate communities, (3) laboratory and field tests on indicator processes and (4) the use of statistical and simulation models to ascertain changes in the soil ecosystems. This methodology was used in portions of the US Army`s Aberdeen Proving Ground, Maryland as part of an ecological risk assessment. Previous soil analyses showed extensive surface soil contamination with metals, nitrate and PCBs. Preliminary results from field surveys of soil invertebrate communities showed significant reductions in total abundance of animals, reductions in the abundance of several taxonomic and functional groups of soil invertebrates, and changes in the activity of epigeic arthropods in contaminated areas when compared with the local ``background`` area. Laboratory tests also demonstrated that microbial activity and success of egg hatching of ground beetle Harpalus pensylvanicus were reduced in contaminated soils. These results suggest that impacts to soil ecosystems should be explicitly considered in ecological risk assessment. The proposed comprehensive methodology appears to offer an efficient and potentially cost saving tool for remedial investigations of contaminated sites.
This project will study electrochemical processes for the in situ treatment of soils contaminated by mixed wastes, i.e., organic and inorganic. Soil samples collected from selected DOE waste sites will be characterized for specific organic and metal contaminants and hydraulic per...
Due to widespread metal contamination, it is necessary to characterize soils suspected of metal contamination and determine if the metal levels in these soils pose a hazard. Metal toxicity is often not directly related to the total concentration of metals present due to a numb...
Evaporation of petroleum products from contaminated soils
Kang, S.H.; Oulman, C.S.
Bioremediation can remove petroleum products from soil that has been contaminated by leaking underground storage tanks, but abiotic processes such as evaporation can contribute significantly to the overall removal process. The mathematical model described in this paper was developed to predict the evaporation rate of volatile liquids from petroleum-contaminated sand. The model is based on simple concepts relating to molecular diffusion embodied in the theory underlying the estimation of binary diffusivities using measurements made with an Arnold diffusion cell. The model in its simplified form indicates that the rate of evaporation for a particular volatile liquid is proportional to the square root of the product of diffusivity and partial pressure divided by the molecular weight of the liquid. This in part explains why evaporative losses from sand are so much higher for gasoline than for diesel fuel. The model also shows that the time for evaporation is directly proportional to the square of the depth dried out and inversely proportional to the vapor pressure of the volatile liquid. The model was tested using gravimetric measurements of the evaporation of n-heptane, unleaded gasoline, and diesel fuel from sand under laboratory conditions.
Current methods for evaluating the bioavailability of chemicals from contaminated soils using soil invertebrates
Lanno, R.P.
Contaminated soils are an extremely complex, variable matrix where many modifying factors of toxicity (e.g., particle size, organic matter content) alter the availability of chemicals to biota. Although many methods have been standardized for assessing the toxicity of contaminated soils to invertebrates and plants, few studies have actually addressed the issue of contaminant bioavailability from soils. Since bioavailability is a measure of uptake of contaminants from the soil by living organisms, one approach to determining bioavailability is to measure residues of contaminants in biota. Body residues related to a specific lethal or sublethal toxicity endpoint offer the unique opportunity to relate bioavailability to biological response. This paper will present an overview of the use of body residues in assessing the bioavailability of soil contaminants by earthworms and soil arthropods. The applications of body residues in the development of soil quality guidelines will also be discussed.
Urban Community Gardeners' Knowledge and Perceptions of Soil Contaminant Risks
Kim, Brent F.; Poulsen, Melissa N.; Margulies, Jared D.; Dix, Katie L.; Palmer, Anne M.; Nachman, Keeve E.
Although urban community gardening can offer health, social, environmental, and economic benefits, these benefits must be weighed against the potential health risks stemming from exposure to contaminants such as heavy metals and organic chemicals that may be present in urban soils. Individuals who garden at or eat food grown in contaminated urban garden sites may be at risk of exposure to such contaminants. Gardeners may be unaware of these risks and how to manage them. We used a mixed quantitative/qualitative research approach to characterize urban community gardeners' knowledge and perceptions of risks related to soil contaminant exposure. We conducted surveys with 70 gardeners from 15 community gardens in Baltimore, Maryland, and semi-structured interviews with 18 key informants knowledgeable about community gardening and soil contamination in Baltimore. We identified a range of factors, challenges, and needs related to Baltimore community gardeners' perceptions of risk related to soil contamination, including low levels of concern and inconsistent levels of knowledge about heavy metal and organic chemical contaminants, barriers to investigating a garden site's history and conducting soil tests, limited knowledge of best practices for reducing exposure, and a need for clear and concise information on how best to prevent and manage soil contamination. Key informants discussed various strategies for developing and disseminating educational materials to gardeners. For some challenges, such as barriers to conducting site history and soil tests, some informants recommended city-wide interventions that bypass the need for gardener knowledge altogether. PMID:24516570
Urban community gardeners' knowledge and perceptions of soil contaminant risks.
Kim, Brent F; Poulsen, Melissa N; Margulies, Jared D; Dix, Katie L; Palmer, Anne M; Nachman, Keeve E
Although urban community gardening can offer health, social, environmental, and economic benefits, these benefits must be weighed against the potential health risks stemming from exposure to contaminants such as heavy metals and organic chemicals that may be present in urban soils. Individuals who garden at or eat food grown in contaminated urban garden sites may be at risk of exposure to such contaminants. Gardeners may be unaware of these risks and how to manage them. We used a mixed quantitative/qualitative research approach to characterize urban community gardeners' knowledge and perceptions of risks related to soil contaminant exposure. We conducted surveys with 70 gardeners from 15 community gardens in Baltimore, Maryland, and semi-structured interviews with 18 key informants knowledgeable about community gardening and soil contamination in Baltimore. We identified a range of factors, challenges, and needs related to Baltimore community gardeners' perceptions of risk related to soil contamination, including low levels of concern and inconsistent levels of knowledge about heavy metal and organic chemical contaminants, barriers to investigating a garden site's history and conducting soil tests, limited knowledge of best practices for reducing exposure, and a need for clear and concise information on how best to prevent and manage soil contamination. Key informants discussed various strategies for developing and disseminating educational materials to gardeners. For some challenges, such as barriers to conducting site history and soil tests, some informants recommended city-wide interventions that bypass the need for gardener knowledge altogether. PMID:24516570
Developing an integration tool for soil contamination assessment
NASA Astrophysics Data System (ADS)
Anaya-Romero, Maria; Zingg, Felix; Pérez-Álvarez, José Miguel; Madejón, Paula; Kotb Abd-Elmabod, Sameh
In the last decades, huge soil areas have been negatively influenced or altered in multiples forms. Soils and, consequently, underground water, have been contaminated by accumulation of contaminants from agricultural activities (fertilizers and pesticides) industrial activities (harmful material dumping, sludge, flying ashes) and urban activities (hydrocarbon, metals from vehicle traffic, urban waste dumping). In the framework of the RECARE project, local partners across Europe are focusing on a wide range of soil threats, as soil contamination, and aiming to develop effective prevention, remediation and restoration measures by designing and applying targeted land management strategies (van Lynden et al., 2013). In this context, the Guadiamar Green Corridor (Southern Spain) was used as a case study, aiming to obtain soil data and new information in order to assess soil contamination. The main threat in the Guadiamar valley is soil contamination after a mine spill occurred on April 1998. About four hm3 of acid waters and two hm3 of mud, rich in heavy metals, were released into the Agrio and Guadiamar rivers affecting more than 4,600 ha of agricultural and pasture land. Main trace elements contaminating soil and water were As, Cd, Cu, Pb, Tl and Zn. The objective of the present research is to develop informatics tools that integrate soil database, models and interactive platforms for soil contamination assessment. Preliminary results were obtained related to the compilation of harmonized databases including geographical, hydro-meteorological, soil and socio-economic variables based on spatial analysis and stakeholder's consultation. Further research will be modellization and upscaling at the European level, in order to obtain a scientifically-technical predictive tool for the assessment of soil contamination.
Spectral induced polarization signature of contaminated soil
NASA Astrophysics Data System (ADS)
Schwartz, N.; Huisman, J. A.; Shefer, I.; Furman, A.
Spectral induced polarization (SIP) signatures of porous media contaminated with non aqueous phase liquids (NAPL) were measured using an accurate impedance meter. The samples were prepared by mixing air-dried sand with 15% by weight of bentonite clay, tap water and either diesel fuel or motor oil. Next, the soil was packed in a column and left for 24 hr before electrical measurements were performed. For all the samples, water saturation was constant (Sw = 0.47) and the NAPL saturation was 0 (control), 5, or 15 percent. Counter-intuitively, the results show that addition of NAPL to the porous media resulted in an increase of the real part of the complex conductivity. Evidently, for each type of contaminant, an increase in the contaminant saturation resulted in an increase in the real part of the conductivity. The imaginary part of the complex conductivity showed a reversed behavior: higher NAPL saturation resulted in a reduction of the imaginary part of the complex conductivity. For both the real and the imaginary part of the complex conductivity, the effect of NAPL on the complex electrical conductivity was more significant for motor oil than for diesel fuel. In addition to the electrical measurements, we also performed an extraction experiment to examine the effect of the presence of NAPL on the electrical conductivity (EC) of the pore water. The results from the extraction experiment showed that addition of NAPL to the porous media resulted in an increase of the pore water EC. We argue that this increase in the real part of the complex conductivity is related to adsorption of organic polar compounds from the NAPL onto the mineral surface and the associated release of inorganic ions from the mineral surface to the pore water. These exchange processes affect both the surface and the pore water conductivity. In addition, we suggest that the decrease in polarization (associated with the imaginary part of the complex conductivity) of the NAPL contaminated porous media
Remediation of contaminated soils and sludges by green plants
Cunningham, S.D.; Berti, W.R.; Huang, J.W.
The potential of green plants to remove, contain, or render harmless contaminants in soils and sludges is actively being explored in an increasing number of laboratories throughout the world. This approach, which has been termed phytoremediation, exploits plants, soil amendments, and plant-associated microbiota to remediate contaminated soils. As an in situ stabilization technique, soil amendment with fertilizers, biosolids, or certain industrial by-products alters the chemical and physical nature of the contaminant in the soil matrix, thus reducing its available to biological processes. The site is then vegetated with plants that can (1) grow in the resulting soil matrix; (2) reduce leaching through the soil profile by absorbing, sequestering, or degrading residual contaminants in the soil solution; and (3) minimize wind and rain erosion. The process is known as phytostabilization, or simply site stabilization, and borrows heavily on mine reclamation techniques. As a site decontamination technique, the soil is treated to increase the availability of the contaminant to biological processes and then planted with plants that (1) accumulate the contaminant and are harvested for further pollutant destruction, sequestration, or reclamation or (2) use plant or plant-associated microbial processes to destroy the pollutant in situ.
Apparatus for treatment of soils contaminated with organic pollutants
Wickramanayake, Godage B.
An apparatus for treating soil contaminated by organic compounds wherein an ozone containing gas is treated with acid to increase the stability of the ozone in the soil environment and the treated ozone applied to the contaminated soil in a manner adapted to decompose the organic compounds; one embodiment of the apparatus comprises a means to supply ozone as a gas-ozone mixture, a stability means to treat ozone obtained from the supply and distribution means to apply the stabilized gas-ozone to soil. The soil may be treated in situ or may be removed for treatment and refilled.
Relative bioavailability of arsenic contaminated soils in a mouse model
Exposure to As contaminated soils compels extensive soil cleanups so that human health risks are minimized. In order to improve exposure estimates and potentially reduce remediation costs, determination of the bioavailability of As in soils is needed. The objective of this study ...
Control and assessment of the hydrocarbon contamination of Ukrainian soils
NASA Astrophysics Data System (ADS)
Miroshnichenko, N. N.
Regularities governing the self-purification of soils from oil hydrocarbons, as well as migration of hydrocarbons, and the effect on the water-physical properties and fertility of soils were revealed in a series of experiments. A system of ecological, economic, and reclamation standards was proposed for regulating economic activities in the case of soil contamination with hydrocarbons.
Reduction in exposure to soil metal contamination has typically been accomplished by soil removal and off site disposal, by covering, or by diluting with uncontaminated soil. Cost, logistical concerns, and regulatory requirements associated with excavation and disposal or ex-situ...
Waste reduction by separation of contaminated soils during environmental restoration
Roybal, J.A.; Conway, R.; Galloway, B.; Vinsant, E.; Slavin, P.; Guerin, D.
During cleanup of contaminated sites, Sandia National Laboratories, New Mexico (SNL/NM) frequently encounters soils with low-level radioactive contamination. The contamination is not uniformly distributed, but occurs within areas of clean soil. Because it is difficult to characterize heterogeneously contaminated soils in detail and to excavate such soils precisely using heavy equipment, it is common for large quantities of uncontaminated soil to be removed during excavation of contaminated sites. This practice results in the commingling and disposal of clean and contaminated material as low-level waste (LLW), or possibly low-level mixed waste (LLMW). Until recently, volume reduction of radioactively contaminated soil depended on manual screening and analysis of samples, which is a costly and impractical approach and does not uphold As Low As Reasonably Achievable (ALARA) principles. To reduce the amount of LLW and LLMW generated during the excavation process, SNL/NM is evaluating two alternative technologies. The first of these, the Segmented Gate System (SGS), is an automated system that located and removes gamma-ray emitting radionuclides from a host matrix (soil, sand, dry sludge). The matrix materials is transported by a conveyor to an analyzer/separation system, which segregates the clean and contaminated material based on radionuclide activity level. The SGS was used to process radioactively contaminated soil from the excavation of the Radioactive Waste Landfill. The second technology, Large Area Gamma Spectroscopy (LAGS), utilizes a gamma spec analyzer suspended over a slab upon which soil is spread out to a uniform depth. A counting period of approximately 30 minutes is used to obtain a full-spectrum analysis for the isotopes of interest. The LAGS is being tested on the soil that is being excavated from the Classified Waste Landfill.
Screening of plants for phytoremediation of oil-contaminated soil.
Ikeura, Hiromi; Kawasaki, Yu; Kaimi, Etsuko; Nishiwaki, Junko; Noborio, Kosuke; Tamaki, Masahiko
Several species of ornamental flowering plants were evaluated regarding their phytoremediation ability for the cleanup of oil-contaminated soil in Japanese environmental conditions. Thirty-three species of plants were grown in oil-contaminated soil, and Mimosa, Zinnia, Gazania, and cypress vine were selected for further assessment on the basis of their favorable initial growth. No significant difference was observed in the above-ground and under-ground dry matter weight of Gazania 180 days after sowing between contaminated and non-contaminated plots. However, the other 3 species of plants died by the 180(th) day, indicating that Gazania has an especially strong tolerance for oil-contaminated soil. The total petroleum hydrocarbon concentration of the soils in which the 4 species of plants were grown decreased by 45-49% by the 180(th) day. Compared to an irrigated plot, the dehydrogenase activity of the contaminated soil also increased significantly, indicating a phytoremediation effect by the 4 tested plants. Mimosa, Zinnia, and cypress vine all died by the 180(th) day after seeding, but the roots themselves became a source of nutrients for the soil microorganisms, which led to a phytoremediation effect by increase in the oil degradation activity. It has been indicated that Gazania is most appropriate for phytoremediation of oil-contaminated soil. PMID:26587892
Biological Treatment of Petroleum in Radiologically Contaminated Soil
This chapter describes ex situ bioremediation of the petroleum portion of radiologically co-contaminated soils using microorganisms isolated from a waste site and innovative bioreactor technology. Microorganisms first isolated and screened in the laboratory for bioremediation of petroleum were eventually used to treat soils in a bioreactor. The bioreactor treated soils contaminated with over 20,000 mg/kg total petroleum hydrocarbon and reduced the levels to less than 100 mg/kg in 22 months. After treatment, the soils were permanently disposed as low-level radiological waste. The petroleum and radiologically contaminated soil (PRCS) bioreactor operated using bioventing to control the supply of oxygen (air) to the soil being treated. The system treated 3.67 tons of PCRS amended with weathered compost, ammonium nitrate, fertilizer, and water. In addition, a consortium of microbes (patent pending) isolated at the Savannah River National Laboratory from a petroleum-contaminated site was added to the PRCS system. During operation, degradation of petroleum waste was accounted for through monitoring of carbon dioxide levels in the system effluent. The project demonstrated that co-contaminated soils could be successfully treated through bioventing and bioaugmentation to remove petroleum contamination to levels below 100 mg/kg while protecting workers and the environment from radiological contamination.
Bioremediation of gasoline-contaminated soil using poultry litter
Gupta, G; Tao, J.
Contaminated soil, excavated from around a leaking underground gasoline storage tank, is commonly subjected to thermal degradation to remove the gasoline. Bioremediation as an alternative treatment technology is now becoming popular. The important hydrocarbon-degrading bacteria include Pseudomonas, Arthrobacter, and Flavobacterium. Poultry litter contains a large number of microorganisms, including Pseudomonas, as well as many inorganic nutrients and organic biomass that may assist in biodegrading gasoline in contaminated soil. During bioremediation of contaminated soil, microbial densities are known to increase by 2-3 orders of magnitude. However, bioremediation may result in a increase in the toxic characteristics of the soil due to the production of potentially toxic degradation intermediates. The objective of this research was to study the influence of the addition of poultry litter on the bioremediation of gasoline-contaminated soil by quantifying the changes in the densities of microorganisms and by monitoring the toxicity of the degradation products. 25 refs., 5 figs., 2 tabs.
Hydrocarbon status of soils under different ages of oil contamination
NASA Astrophysics Data System (ADS)
Gennadiev, A. N.; Pikovskii, Yu. I.; Kovach, R. G.; Koshovskii, T. S.; Khlynina, N. I.
Modifications of the hydrocarbon status (HCS) of soils at the stages of the injection input of oil pollutants and the subsequent self-purification of the soil layer from technogenesis products have been revealed in studies conducted on an oil field. Comparison with the HCS of background soils has been performed. Changes in the composition and concentration of bitumoids, polycyclic aromatic hydrocarbons (PAHs), and hydrocarbon gases have been established. The HCS of a freshly contaminated soil is characterized by the predominance of butane (the highest component) in the gaseous phase, an abrupt increase in the concentration of second-kind bitumoids, and a 100-fold increase in the content of PAHs compared to the background soil. In the old contaminated soil, free and fixed methane becomes the predominant gas; the content of bitumoids in the upper soil horizons is lower than in the freshly contaminated soils by two orders of magnitude but higher than in the background soil by an order of magnitude; the PAH composition in the soil with old residual contamination remains slightly more diverse than in the background soil.
Bioremediation of leachate and soil contaminated with petroleum products
Yocum, P.S.
Petroleum products are generally accepted to be biodegradable, whether they are contaminating a liquid or solid phase. Considerable reference material exist to support this ascertain. However, no parameters exist for design of engineered treatment systems and little is known about how mixed cultures degrade sparingly soluble substrates, particularly in the soil environment. Further the heterogeneity of contaminant distribution in the soil environment, inhibit understanding of the processes involved. This dissertation is an attempt to provide methodologies for the assessment of biodegradation of petroleum products in these environments, together with development of procedures applicable to assessment of remediation in soils with heterogenous distribution of contaminants.
Activity of antibiotics in contaminated wounds containing clay soil.
Roberts, A H; Rye, D G; Edgerton, M T; Rodeheaver, G T; Edlich, R F
Most traumatic wounds are contaminated to some degree by soil and run a high risk of infection. The presence of soil in wounds interferes with natural tissue defenses, which include phagocytosis and serum bactericidal capacity. The experimental studies reported herein clearly demonstrate that soil also limits the antibacterial effects of specific antibiotics. This inactivation appears to be the result of a chemical reaction between the charged antibiotics and the soil particles. PMID:434335
The tolerance efficiency of Panicum maximum and Helianthus annuus in TNT-contaminated soil and nZVI-contaminated soil.
Jiamjitrpanich, Waraporn; Parkpian, Preeda; Polprasert, Chongrak; Laurent, François; Kosanlavit, Rachain
This study was designed to compare the initial method for phytoremediation involving germination and transplantation. The study was also to determine the tolerance efficiency of Panicum maximum (Purple guinea grass) and Helianthus annuus (Sunflower) in TNT-contaminated soil and nZVI-contaminated soil. It was found that the transplantation of Panicum maximum and Helianthus annuus was more suitable than germination as the initiate method of nano-phytoremediation potting test. The study also showed that Panicum maximum was more tolerance than Helianthus annuus in TNT and nZVI-contaminated soil. Therefore, Panicum maximum in the transplantation method should be selected as a hyperaccumulated plant for nano-phytoremediation potting tests. Maximum tolerance dosage of Panicum maximum to TNT-concentration soil was 320 mg/kg and nZVI-contaminated soil was 1000 mg/kg in the transplantation method. PMID:22702809
Soil Contamination and Remediation Strategies. Current research and future challenge
NASA Astrophysics Data System (ADS)
Petruzzelli, G.
Soil contamination: the heritage of industrial development Contamination is only a part of a whole set of soil degradation processes, but it is one of paramount importance since soil pollution greatly influences the quality of water, food and human health. Soil contamination has been identified as an important issue for action in the European strategy for soil protection, it has been estimated that 3.5 million of sites are potentially contaminated in Europe. Contaminated soils have been essentially discovered in industrial sites landfills and energy production plants, but accumulation of heavy metals and organic compounds can be found also in agricultural land . Remediation strategies. from incineration to bioremediation The assessment of soil contamination is followed by remedial action. The remediation of contaminated soils started using consolidates technologies (incineration inertization etc.) previously employed in waste treatment,. This has contributed to consider a contaminated soil as an hazardous waste. This rough approximation was unfortunately transferred in many legislations and on this basis soil knowledge have been used only marginally in the clean up procedures. For many years soil quality has been identified by a value of concentration of a contaminant and excavation and landfill disposal of soil has been largely used. In the last years the knowledge of remediation technology has rapidly grown, at present many treatment processes appear to be really feasible at field scale, and soil remediation is now based on risk assessment procedures. Innovative technologies, largely dependent on soil properties, such as in situ chemical oxidation, electroremediation, bioventing, soil vapor extraction etc. have been successfully applied. Hazardous organic compounds are commonly treated by biological technologies, biorememdiation and phytoremediation, being the last partially applied also for metals. Technologies selection is no longer exclusively based on
Bioremediation of lead contaminated soil with Rhodobacter sphaeroides.
Li, Xiaomin; Peng, Weihua; Jia, Yingying; Lu, Lin; Fan, Wenhong
Bioremediation with microorganisms is a promising technique for heavy metal contaminated soil. Rhodobacter sphaeroides was previously isolated from oil field injection water and used for bioremediation of lead (Pb) contaminated soil in the present study. Based on the investigation of the optimum culturing conditions and the tolerance to Pb, we employed the microorganism for the remediation of Pb contaminated soil simulated at different contamination levels. It was found that the optimum temperature, pH, and inoculum size for R. sphaeroides is 30-35 °C, 7, and 2 × 10(8) mL(-1), respectively. Rhodobacter sphaeroides did not remove the Pb from soil but did change its speciation. During the bioremediation process, more available fractions were transformed to less accessible and inert fractions; in particular, the exchangeable phase was dramatically decreased while the residual phase was substantially increased. A wheat seedling growing experiment showed that Pb phytoavailability was reduced in amended soils. Results inferred that the main mechanism by which R. sphaeroides treats Pb contaminated soil is the precipitation formation of inert compounds, including lead sulfate and lead sulfide. Although the Pb bioremediation efficiency on wheat was not very high (14.78% root and 24.01% in leaf), R. sphaeroides remains a promising alternative for Pb remediation in contaminated soil. PMID:27179240
Kinetics of Cd Release from Some Contaminated Calcareous Soils
Sajadi Tabar, S.; Jalali, M.
Contamination of soils with heavy metals may pose long-term risk to groundwater quality leading to health implications. Bioavailability of heavy metals, like cadmium (Cd) is strongly affected by sorption and desorption processes. The release of heavy metals from contaminated soils is a major contamination risks to natural waters. The release of Cd from contaminated soils is strongly influenced by its mobility and bioavailability. In this study, the kinetics of Cd desorption from ten samples of contaminated calcareous soils, with widely varying physicochemical properties, were studied using 0.01 M EDTA extraction. The median percentage of Cd released was about 27.7% of the total extractable Cd in the soils. The release of Cd was characterized by an initial fast release rate (of labile fractions) followed by a slower release rate (of less labile fractions) and a model of two first-order reactions adequately describes the observed release of Cd from the studied soil samples. There was positive correlation between the amount of Cd released at first phase of release and Cd in exchangeable fraction, indicating that this fraction of Cd is the main fraction controlling the Cd in the kinetic experiments. There was strongly negative correlation between the amount of Cd released at first and second phases of release and residual fraction, suggesting that this fraction did not contribute in Cd release in the kinetic experiments. The results can be used to provide information for evaluation of Cd potential toxicity and ecological risk from contaminated calcareous soils.
Humus-assisted cleaning of heavy metal contaminated soils
NASA Astrophysics Data System (ADS)
Borggaard, Ole K.; Rasmussen, Signe B.
Contamination of soils with non-degradable heavy metals (HMs) because of human acticities is globally a serious problem threatening human health and ecosystem functioning. To avoid negative effects, HMs must be removed either on-site by plant uptake (phytoremediation) or off-site by extraction (soil washing). In both strategies, HM solubility must be augmented by means of a strong ligand (complexant). Often polycarboxylates such as EDTA and NTA are used but these ligands are toxic, synthetic (non-natural) and may promote HM leaching. Instead naturally occurring soluble humic substances (HS) were tested as means for cleaning HM contaminated soils; HS samples from beech and spruce litter, compost percolate and processed cow slurry were tested. Various long-term HM contaminated soils were extracted with solutions of EDTA, NTA or HS at different pH by single-step and multiple-step extraction mode. The results showed that each of the three complexant types increased HM solubility but the pH-dependent HM extraction efficiency decreased in the order: EDTA ≈ NTA > HS. However, the naturally occurring HS seems suitable for cleaning As, Cd, Cu and Zn contaminated soils both in relation to phytoremediation of moderately contaminated soils and washing of strongly contaminated soils. On the other hand, HS was found unsuited as cleaning agent for Pb polluted calcareous soils. If future field experiments confirm these laboratory results, we have a new cheap and environmentally friendly method for solving a great pollution problem, i.e. cleaning of heavy metal contaminated soils. In addition, humic substances possess additional benefits such as improving soil structure and stimulating microbial activity.
As Leaching into Fresh Water from Highly Contaminated Hawaiian Soils
NASA Astrophysics Data System (ADS)
Niklis, N. J.; Rubin, K. H.; El-Kadi, A. I.
Arsenic contamination of current and former agricultural soils in Hawaii is an unfortunate legacy of plantation era agricultural practices. Here, we report an investigation of As mobility in fresh water from highly contaminated (0.8 % As) A-zone Hawaiian andisols from the Hamakua Coast of the Island of Hawai'i. Aliquots of the same acidic soil (pH= 5.0) were exposed to fresh water for varying lengths of time and analyzed to quantify the fraction of As and other elements leached from the soil relative to concentrations determined by total digestion. A maximum of 0.04% of As and 0.05% of Fe were removed from the soils in initial rinses and multi-day leaches using 18 megaohm Millipore water, in experiments lasting up to 35 days. Arsenic concentrations were highest in initial soil rinses, indicating that a small fraction of the total As in the soil is either loosely bound or present as a fine-grained, soluble As-bearing phase. During subsequent leaching experiments, arsenic and most other inorganic ions that we analyzed for reached equilibrium after 3 days; Fe reached equilibrium concentrations after 10 days. All soil solutions contained As levels that exceeded the EPA acceptable drinking water limit of 0.01 ppm. However, contaminant transport modeling suggests that As contaminated leachates would not migrate substantially from this site, so that local isolation and storage of contaminated soils would likely be an acceptable containment method.
Techniques were investigated for in-situ treatment of hazardous wastes that could be applied to contaminated soils. Included were chemical treatment methods, biological treatment, photochemical transformations and combination methods. Techniques were developed based on fundamenta...
Assessing soil and groundwater contamination in a metropolitan redevelopment project.
Yun, Junki; Lee, Ju Young; Khim, Jeehyeong; Ji, Won Hyun
The purpose of this study was to assess contaminated soil and groundwater for the urban redevelopment of a rapid transit railway and a new mega-shopping area. Contaminated soil and groundwater may interfere with the progress of this project, and residents and shoppers may be exposed to human health risks. The study area has been remediated after application of first remediation technologies. Of the entire area, several sites were still contaminated by waste materials and petroleum. For zinc (Zn) contamination, high Zn concentrations were detected because waste materials were disposed in the entire area. For petroleum contamination, high total petroleum hydrocarbon (TPH) and hydrocarbon degrading microbe concentrations were observed at the depth of 7 m because the underground petroleum storage tank had previously been located at this site. Correlation results suggest that TPH (soil) concentration is still related with TPH (groundwater) concentration. The relationship is taken into account in the Spearman coefficient (α). PMID:23307052
Decreasing the contamination and toxicity of a heavily contaminated soil by in situ bioremediation
NASA Astrophysics Data System (ADS)
Groudev, Stoyan; Georgiev, Plamen; Spasova, Irena; Nikolova, Marina
An experimental plot of 140 m2 consisting of acidic soil heavily contaminated with uranium, non-ferrous metals (mainly Cu, Zn and Cd) and arsenic was treated in situ under real field conditions using the activity of the indigenous soil microflora. This activity was enhanced by suitable changes of some essential environmental factors such as pH and water, oxygen and nutrient contents of the soil. The treatment was connected with solubilization and removal of contaminants from the top soil layers (horizon A) due to the joint action of the soil microorganisms (mainly acidophilic chemolithotrophic bacteria) and leach solutions (diluted sulphuric acid). The dissolved contaminants were transferred to the soil horizon B and were removed from the soil profile through a system of drainage collecting pipes. The contaminated soil effluents were treated by means of a multi-component passive system consisting of an anoxic alkalizing drain, a permeable reactive multibarrier and a rock filter. The contamination and toxicity of the soil were regularly tested during the cleaning procedure and were considerably decreased at the end of the treatment.
Toxicity assessment of contaminated soils from an antitank firing range.
Robidoux, Pierre Yves; Gong, Ping; Sarrazin, Manon; Bardai, Ghalib; Paquet, Louise; Hawari, Jalal; Dubois, Charles; Sunahara, Geoffrey I
Explosives are released into the environment at production and processing facilities, as well as through field use. These compounds may be toxic at relatively low concentrations to a number of ecological receptors. A toxicity assessment was carried out on soils from an explosive-contaminated site at a Canadian Forces Area Training Center. Toxicity studies on soil organisms using endpoints such as microbial processes (potential nitrification activity, dehydrogenase activity, substrate-induced respiration, basal respiration), plant seedling and growth (Lactuca sativa and Hordeum vulgare), and earthworm (Eisenia andrei) growth and reproduction were carried out. Results showed that 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX) was the principal polynitro-organic compound measured in soils. Soils from the contaminated site decreased microbial processes and earthworm reproduction; whereas plant growth was not significantly reduced. Toxicity to aquatic organisms and genotoxicity were also assessed on soil elutriates using Microtox (Vibrio fischeri), growth inhibition of algae (Selenastrum capricornutum), and SOS Chromotest (Escherichia coli). Results indicated that soil elutriates were generally not toxic to bacteria (Microtox) and algae. However, genotoxicity was found in a number of soil elutriate samples. Thus, the explosive-contaminated soils from the antitank firing range may represent a hazard for the soil organisms. Nevertheless, the global toxicity might have partially resulted from HMX as well as from other (not identified) contaminants such as heavy metals. PMID:15223256
Microbial ecology and transformations associated with munitions contaminated soils
Martin, J.L.; Li, Z.; Kokjohn, T.A.; Shea, P.J.; Comfort, S.D.
Many acres of soil at the former Nebraska Ordnance Plant (NOP) are contaminated with TNT and other munitions residues. In some areas, solid phase TNT is present and controls the concentration of the soil solution. Native microbial populations in uncontaminated soils similar to those at the NOP site were severely reduced when solid phase TNT was allowed to control the soil solution TNT concentration. However, examination of NOP soil revealed an active population of Pseudomonas sp. A single species that could utilize TNT as a sole C source was isolated from the contaminated soil and tentatively identified as Pseudomonas corrugata through the BIOLOG system. Subsequent growth and characterization experiments indicate that the Pseudomonad metabolizes TNT while in the exponential phase of growth in medium containing glucose as a sole N source. Low TNT mineralization rates (measured by CO{sub 2} evolution) in soil and media using the various isolates suggest reduced availability due to sorption and incorporation of transformation intermediates into the organic matrix and microbial biomass. Pretreatment of TNT by acid-metal catalyzed reduction resulted in an initially higher rate of mineralization following addition to TNT-contaminated soil. Observations indicate more rapid microbial utilization of the 2,4,6-triaminotoluene (TAT) reduction product and its spontaneous decay product, methylphloroglucinol (2,4,6-trihydroxytoluene), than TNT. Abiotic pretreatment may be useful in enhancing microbial transformation and detoxification of TNT in highly contaminated soils.
Selective leaching of uranium from uranium-contaminated soils
Francis, C.W.; Mattus, A.J.; Farr, L.L.; Lee, S.Y.; Elless, M.P. |
Three soils and a sediment contaminated with uranium were used to determine the effectiveness of sodium carbonate and citric acid leaching to decontaminate or remove uranium to acceptable regulatory levels. The objective was to selectively extract uranium using a soil washing/extraction process without seriously degrading the soil`s physicochemical characteristics or generating a secondary waste form that would be difficult to manage and/or dispose of. Two of the soils were surface soils from the DOE facility formerly called the Feed Materials Production Center (FMPC) at Fernald, Ohio. One of the soils is from near the Plant 1 storage pad and the other soil was taken from near a waste incinerator used to burn low-level contaminated trash. The third soil was a surface soil from an area formally used as a landfarm for the treatment of spent oils at the Oak Ridge Y-12 Plant. The sediment sample was material sampled from a storm sewer sediment trap at the Oak Ridge Y-12 Plant. Uranium concentrations in the Fernald soils ranged from 450 to 550 {mu}g U/g of soil while the samples from the Y-12 Plant ranged from 150 to 200 {mu}g U/g of soil.
Remediation of arsenic-contaminated soils and groundwaters
Peters, Robert W.; Frank, James R.; Feng, Xiandong
An in situ method for extraction of arsenic contaminants from a soil medium and remediation of the medium including contacting the medium with an extractant solution, directing the solution within and through the medium, and collecting the solution and contaminants. The method can also be used for arsenate and/or arsenite removal.
Remediation of arsenic-contaminated soils and groundwaters
Peters, R.W.; Frank, J.R.; Feng, X.
An in situ method is described for extraction of arsenic contaminants from a soil medium and remediation of the medium including contacting the medium with an extractant solution, directing the solution within and through the medium, and collecting the solution and contaminants. The method can also be used for arsenate and/or arsenite removal. 8 figs.
Phytoremediation Potential of Lead-Contaminated Soil Using Tropical Grasses
Technology Transfer Automated Retrieval System (TEKTRAN)
The global problem concerning contamination of the environment because of human activities is increasing. Most of the environmental contaminants are chemical by-products and heavy metals such as lead (Pb). Lead released into the environment makes its way into the air, soil and water. Lead contribute...
Electroosmotic flow behaviour of metal contaminated expansive soil.
Sivapullaiah, P V; Prakash, B S Nagendra
It is important to study the flow behaviour through soil during electrokinetic extraction of contaminants to understand their removal mechanism. The flow through the expansive soil containing montmorillonite is monitored during laboratory electrokinetic extraction of heavy metal contaminants. The permeability of soil, which increases due to the presence of contaminants, is further enhanced during electrokinetic extraction of contaminants due to osmotic permeability. The variations in flow rates through the soil while the extracting fluid is changed to dilute acetic acid (used to control the increase of pH) and EDTA solution (used to desorb the metal ions from soil) are studied. The trends of removal of contaminants vis-a-vis the changes in the flow through the soil during different phases of electrokinetic extraction are established. Chromium ions are removed by flushing of water through the soil and increased osmotic flow is beneficial. Removal of iron ions is enhanced by induced osmotic flow and desorption of ions by electrokinetic processes. PMID:17276001
Vertical column hydroclassification of metal-contaminated soils.
Williford, C W; Li, Z; Wang, Z; Bricka, R M
The purpose of this work was to reduce soil volumes requiring aggressive treatment. A second purpose was to determine differences in separation due to distinct forms of the metal contamination and soil texture. The objectives were to apply hydroclassification and find mass and metal-contaminant distribution of four soils contaminated with heavy metals from firing ranges, a small arms incinerator, and an electroplating operation. The soils were slurried in water, sieved, and exposed to upward flowing water to separate the soil particles into four nominal size ranges. The popping furnace soil exhibited substantial lead among all particle size fractions. The firing range soils exhibited bimodal distributions. The electroplating soil exhibited a strong concentration of metals toward the <63 microm fraction. Attrition scrubbing moderately improved the enrichment of metals in several fractions. Extraction revealed the lead and chromium in the electroplating soil to be relatively immobile. These results suggest metal distributions are influenced by the different mechanisms of introduction into the soil. They also help to predict performance of processing options such as sieving hydroclassification and attrition scrubbing. PMID:10379028
Feasibility Process for Remediation of the Crude Oil Contaminated Soil
NASA Astrophysics Data System (ADS)
Keum, H.; Choi, H.; Heo, H.; Lee, S.; Kang, G.
More than 600 oil wells were destroyed in Kuwait by Iraqi in 1991. During the war, over 300 oil lakes with depth of up to 2m at more than 500 different locations which has been over 49km2. Therefore, approximately 22 million m3was crude oil contaminated. As exposure of more than 20 years under atmospheric conditions of Kuwait, the crude oil has volatile hydrocarbons and covered heavy oily sludge under the crude oil lake. One of crude oil contaminated soil which located Burgan Oilfield area was collected by Kuwait Oil Company and got by H-plus Company. This contaminated soil has about 42% crude oil and could not biodegraded itself due to the extremely high toxicity. This contaminated soil was separated by 2mm sieve for removal oil sludge ball. Total petroleum hydrocarbons (TPH) was analysis by GC FID and initial TPH concentration was average 48,783 mg/kg. Ten grams of the contaminated soil replaced in two micro reactors with 20mL of bio surfactant produce microorganism. Reactor 1 was added 0.1g powder hemoglobin and other reactor was not added hemoglobin at time 0 day. Those reactors shake 120 rpm on the shaker for 7 days and CO2 produced about 150mg/L per day. After 7 days under the slurry systems, the rest days operated by hemoglobin as primary carbon source for enhanced biodegradation. The crude oil contaminated soil was degraded from 48,783mg/kg to 20,234mg/kg by slurry process and final TPH concentration degraded 11,324mg/kg for 21days. Therefore, highly contaminated soil by crude oil will be combined bio slurry process and biodegradation process with hemoglobin as bio catalytic source. Keywords: crude-oil contaminated soil, bio slurry, biodegradation, hemoglobin ACKOWLEDGEMENTS This project was supported by the Korea Ministry of Environment (MOE) GAIA Program
The Acid Extraction Treatment System (AETS) reduces the concentrations and/or leachability of heavy metals in contaminated soils so the soil can be returned to the site from which it originated. he objective of the project was to determine the effectiveness and commercial viabili...
Toxicity testing of trinitrotoluene-contaminated soil composts
Honeycutt, M.E.; McFarland, V.A.; Jarvis, A.S.
The Mutatox{trademark} assay and earthworm acute toxicity test were employed to evaluate the efficacy of composting in reducing the toxicity of TNT-contaminated soils. The Mutatox assay is a proprietary bacterial bioluminescence test that determines the mutagenic potential of sample extracts. The earthworm acute toxicity test was chosen because it exposes the organisms to the unaltered contaminant/solid matrix. Rockeye soil, a TNT-contaminated soil collected from a military installation, was composted using two methods. This yielded five samples, Rockeye, Compost A composting. Soil extracts were prepared for Mutatox using the sonification method. Ten serial dilution samples were tested soils/artificial soil were tested in the earthworm toxicity test. In the Rockeye soil samples, a toxic response was shown in both test methods. Mutatox indicated no toxicity in Composts A and B after composting but did not show a positive mutagenic response in the lower serial dilutions. The LC50s for Compost A and B after composting in the earthworm toxicity test were 35.3% and 100%, respectively. Using Mutatox and the earthworm toxicity test together provides a sensitive means of monitoring the effectiveness of various composting techniques for remediating TNT-contaminated soils.
An emerging technology for the remediation of unsaturated subsurface soils involves the use of microorganisms to degrade contaminants which are present in such soils. Understanding the processes which drive in situ bioremediation, as well as the effectiveness and efficiency of th...
Ethanol-enhanced bioremediation of PAH-contaminated soils
Lee, P.H.; Ong, S.K.; Golchin, J.
Bioremediation of soils contaminated with polycyclic aromatic hydrocarbons (PAHs) is highly challenging because of the low solubility and strong sorption properties of PAHs to soil organic matter. Two PAH-contaminated soils from former manufactured gas plant (MGP) sites were pretreated with ethanol to enhance the bioavailability of PAH compounds. The biodegradation of various PAHs in the pretreated soils was assessed using soil slurry reactor studies. The time needed to degrade 90% of the total PAH in the pretreated soils was at least 5 days faster than soils that were not pretreated with ethanol. A distinctive advantage with the pretreatment of soils with ethanol was the enhanced removal of 4-ring compounds such as chrysene. Approximately 90% of chrysene in the ethanol-treated soils were removed within 15 days while soils without pretreatment needed more than 30 days to obtain similar removal levels. After 35 days of biotreatment in the slurry reactors, approximately 40% of benzo(a)pyrene were removed in the ethanol-treated soils while only 20% were removed in soils not pretreated with ethanol.
Toxicity tests of soil contaminated by recycling of scrap plastics
Wong, M.H.; Chui, V.W. )
The present investigation studied the toxicity of soil contaminated by untreated discharge from a factory that recycles used plastics. The nearby agricultural areas and freshwater fish ponds were polluted with high concentrations of Cu, Ni, and Mn. Water extracts from the contaminated soil retarded root growth of Brassica chinensis (Chinese white cabbage) and Cynodon dactylon (Bermuda grass) where their seeds were obtained commercially. The contaminated populations of C. dactylon, Panicum repen (panic grass), and Imperata cylindrica (wooly grass) were able to withstand higher concentrations of Cu, Ni, and Mn, especially C. dactylon, when compared with their uncontaminated counterparts.
Pesticide contamination includes a wide variety of compounds and may result from manufacturing improper storage, handling, disposal; or agricultural processes. It can occur in soil and can lead to secondary contamination of groundwater. Remediation of pesticide-contaminated soils...
Bioremediation Techniques of Oil Contaminated Soils in Ohio
Hodges, David
The objective of this project is to develop environmentally sound and cost-effective remediation techniques for crude oil contaminated soils. By providing a guidance manual to oil and gas operators, the Ohio Division of Oil and Gas regulatory authority hopes to reduce remediation costs while improving voluntary compliance with soil clean-up requirements. This shall be accomplished by conducting a series of field tests to define the optimum range for nutrient and organic enhancement to biologically remediate soils contaminated with brines and crude oil having a wide rage of viscosity.
Bioremediation potential of diesel-contaminated Libyan soil.
Koshlaf, Eman; Shahsavari, Esmaeil; Aburto-Medina, Arturo; Taha, Mohamed; Haleyur, Nagalakshmi; Makadia, Tanvi H; Morrison, Paul D; Ball, Andrew S
Bioremediation is a broadly applied environmentally friendly and economical treatment for the clean-up of sites contaminated by petroleum hydrocarbons. However, the application of this technology to contaminated soil in Libya has not been fully exploited. In this study, the efficacy of different bioremediation processes (necrophytoremediation using pea straw, bioaugmentation and a combination of both treatments) together with natural attenuation were assessed in diesel contaminated Libyan soils. The addition of pea straw was found to be the best bioremediation treatment for cleaning up diesel contaminated Libyan soil after 12 weeks. The greatest TPH degradation, 96.1% (18,239.6mgkg(-1)) and 95% (17,991.14mgkg(-1)) were obtained when the soil was amended with pea straw alone and in combination with a hydrocarbonoclastic consortium respectively. In contrast, natural attenuation resulted in a significantly lower TPH reduction of 76% (14,444.5mgkg(-1)). The presence of pea straw also led to a significant increased recovery of hydrocarbon degraders; 5.7log CFU g(-1) dry soil, compared to 4.4log CFUg(-1) dry soil for the untreated (natural attenuation) soil. DGGE and Illumina 16S metagenomic analyses confirm shifts in bacterial communities compared with original soil after 12 weeks incubation. In addition, metagenomic analysis showed that original soil contained hydrocarbon degraders (e.g. Pseudoxanthomonas spp. and Alcanivorax spp.). However, they require a biostimulant (in this case pea straw) to become active. This study is the first to report successful oil bioremediation with pea straw in Libya. It demonstrates the effectiveness of pea straw in enhancing bioremediation of the diesel-contaminated Libyan soil. PMID:27479774
Temperature effects on propylene glycol-contaminated soil cores
Davis-Hoover, W.J.; Vesper, S.J.
The authors are examining the effect of temperature on the biodegradation of propylene glycol (PPG) in subsurface soil cores. Subsurface soils were contaminated in situ with PPG and allowed to diffuse into the soil for 30 days. The treated soil was reexposed, and intact were incubated for 30 days at temperatures ranging from 9 to 39 C in a temperature gradient incubator. At 30 days, soil moisture, soil pH, microbial activity [fluorescein diacetate (FDA) test], R2A plate counts, and plate counts of PPG degraders were studied. Although the soil moisture and pH remained relatively unchanged, the parameters of microbial activity varied rather consistently with temperature. Multiple populations or subpopulations of bacteria appear to exist between temperatures of 9 and 39 C in these soils.
Bioremediation of an oil-contaminated soil by fungal intervention
McGugan, B.R.; Lees, Z.M.; Senior, E.
The central aim of this study was to determine if indigenous fungal species present in an oil-contaminated soil are capable of bioremediating the contamination. Some of the contamination has been present at a disused oil-recycling plant site for over two decades, and it was felt that the indigenous microbial species should have been subjected to specific selection pressure for a protracted period, thus effecting key enzymatic capabilities for degradation in situ. Two experimental approaches to a landfarming type or remediation were examined. The first involved a simple biostimulation process of soil fungi. The second incorporated an extensive isolation and screening program with subsequent bulking and reinoculation into the contaminated soil.
Chemical oxidation of hexachlorocyclohexanes (HCHs) in contaminated soils.
Usman, M; Tascone, O; Faure, P; Hanna, K
Chemical oxidation of hexachlorocyclohexanes (HCHs) was evaluated in (i) artificially spiked sand with HCH isomers (α, β, γ and δ) and (ii) contaminated soil sampled from a former gravel pit backfilled with wastes of lindane (γ-HCH). Following oxidation treatments were employed: hydrogen peroxide alone (HP), hydrogen peroxide with soluble Fe(II) (Fenton-F), sodium persulfate alone (PS), Fe(II) activated persulfate (AP) and permanganate (PM). GC-MS results revealed a significant degradation of all isomers in spiked soil in the order: F>PS>AP>HP>PM. Soluble Fe(II) enhanced the efficiency of H2O2 but decreased the reactivity of persulfate. Similar trend was observed in contaminated soil, but with less degradation probably caused by scavenging effect of organic matter and soil minerals and/or pollutant unavailability. No significant increase in oxidation efficiency was observed after using availability-enhancement agents in contaminated soil. Other limitation factors (oxidant dose, pH, catalyst type etc.) were also addressed. Among all the isomers tested, β-HCH was the most recalcitrant one which could be explained by higher metabolic and chemical stability. No by-products were observed by GC-MS regardless of the oxidant used. For being the premier study reporting chemical oxidation of HCH isomers in contaminated soils, it will serve as a base for in-situ treatments of sites contaminated by HCH isomers and other persistent organic pollutants. PMID:24486498
Effect of biodegradable amendments on uranium solubility in contaminated soils.
Duquène, L; Tack, F; Meers, E; Baeten, J; Wannijn, J; Vandenhove, H
Chelate-assisted phytoextraction has been proposed as a potential tool for phytoremediation of U contaminated sites. In this context, the effects of five biodegradable amendments on U release in contaminated soils were evaluated. Three soils were involved in this study, one with a relatively high background level of U, and two which were contaminated with U from industrial effluents. Soils were treated with 5 mmol kg(-1) dry weight of either citric acid, NH(4)-citrate/citric acid, oxalic acid, S,S-ethylenediamine disuccinic acid or nitrilotriacetic acid. Soil solution concentration of U was monitored during 2 weeks. All amendments increased U concentration in soil solution, but citric acid and NH(4)-citrate/citric acid mixture were most effective, with up to 479-fold increase. For oxalic acid, S,S-ethylenediamine disuccinic acid and nitrilotriacetic acid, the increase ranged from 10-to 100-fold. The highest concentrations were observed 1 to 7 days after treatment, after which U levels in soil solution gradually decreased. All amendments induced a temporary increase of soil solution pH and TOC that could not be correlated with the release of U in the soil solution. Thermodynamic stability constants (log K) of complexes did not predict the relative efficiency of the selected biodegradable amendments on U release in soil solution. Amendments efficiency was better predicted by the relative affinity of the chelate for Fe compared to U. PMID:18061243
Microemulsion-enhanced remediation of soils contaminated with organochlorine pesticides.
Zhang, Yanlin; Wong, Jonathan W C; Zhao, Zhenyong; Selvam, Ammaiyappan
Soil contaminated by organic pollutants, especially chlorinated aromatic compounds such as DDT (1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane), is an environmental concern because of the strong sorption of organochlorine pesticide onto the soil matrix and persistence in the environment. The remediation of organochlorine pesticide contaminated soils through microemulsion is an innovative technology to expedite this process. The remediation efficiency was evaluated by batch experiments through studying the desorption of DDT and hexachlorocyclohexane (y-HCH) and sorption of microemulsion composed of Triton X-100, 1-pentanol and linseed oil in the soil-surfactant-water suspension system. The reduction of desorption efficiency caused by the sorption loss of microemulsion components onto the soil could be corrected by the appropriate adjustment of C/S (Cosurfactant/Surfactant) and O/S (Oil/Surfactant) ratio. The C/S and O/S ratios of 1:2 and 3:20 were suitable to desorb DDT and gamma-HCH from the studied soils because of the lower sorption of Triton X-100 onto the soil. Inorganic salts added in microemulsion increased the pesticides desorption efficiency of pesticides and calcium chloride has a stronger ability to enhance the desorption of DDT than sodium chloride. From the remediation perspective, the balance of surfactant or cosurfactant sorbed to soil and desorption efficiency should be taken into consideration to enhance the remediation of soils contaminated by organochlorine pesticides. PMID:22439580
Clean-up criteria for remediation of contaminated soils
Nguyen, H.D.; Wilson, J.R.; Sato, Chikashi
{open_quotes}How clean is clean?{close_quotes} is a question commonly raised in the remediation of contaminated soils. To help with the answer, criteria are proposed to serve as guidelines for remedial actions and to define a clean-up level such that the remaining contaminant residuals in the soil will not violate the Drinking Water Standards (DWS). The equations for computing those criteria are developed from the principle of conservation of mass and are functions of the maximum concentration level in the water (MCL) and the sorption coefficient. A multiplier, ranging from 10 to 1000, is also factored into the soil standard equation to reflect the effectiveness of various remediation techniques. Maximum allowable concentration in the soil (MSCL) is presented for several contaminants which are being regulated at the present time. Future modifications are recommended for better estimates of the MSCLs as additional transport mechanisms are incorporated to account for other potentially dominant effects.
Solvent flushing is a potential technique for remediating a waste disposal/spill site contaminated with organic chemicals. This technique involves the injection of a solvent mixture (e.g., water plus alcohols) that enhances contaminant solubility, reduces the retardation factor, ...
Chemical contamination and transformation of soils in hydrocarbon production regions
NASA Astrophysics Data System (ADS)
Zamotaev, I. V.; Ivanov, I. V.; Mikheev, P. V.; Nikonova, A. N.
The current concepts of soil pollution and transformation in the regions of hydrocarbon production have been reviewed. The development of an oil field creates extreme conditions for pedogenesis. Tendencies in the radial migration, spatial distribution, metabolism, and accumulation of pollutants (oil, oil products, and attendant heavy metals) in soils of different bioclimatic zones have been analyzed. The radial and lateral mobility of pollution halos is a universal tendency in the technogenic transformation of soils and soil cover in the regions of hydrocarbon production. The biodegradation time of different hydrocarbon compounds strongly varies under different landscape conditions, from several months to several tens of years. The transformation of original (mineral and organic) soils to their technogenic modifications (mechanically disturbed, chemically contaminated, and chemo soils and chemozems) occurs in the impact zone of technogenic hydrocarbon fluxes under any physiographical conditions. The integrated use of the existing methods for the determination of the total content and qualitative composition of bituminous substances and polyaromatic hydrocarbons in combination with the chromatographic determination of normal alkanes and hydrocarbon gases, as well as innovative methods of studies, allows revealing new processes and genetic relationships in soils and studying the functioning of soils and soil cover. The study of the hydrocarbon contamination of soils is important for development of restoration measures and lays the groundwork for the ecological and hygienic regulation based on the zonation of soil and landscape resistance to different pollutants.
Metagenomic analysis of microbial community in uranium-contaminated soil.
Yan, Xun; Luo, Xuegang; Zhao, Min
Uranium tailing is a serious pollution challenge for the environment. Based on metagenomic sequencing analysis, we explored the functional and structural diversity of the microbial community in six soil samples taken at different soil depths from uranium-contaminated and uncontaminated areas. Kyoto Encyclopedia of Genes and Genomes Orthology (KO) groups were obtained using a Basic Local Alignment Search Tool search based on the universal protein resource database. The KO-pathway network was then constructed using the selected KOs. Finally, alpha and beta diversity analyses were performed to explore the differences in soil bacterial diversity between the radioactive soil and uncontaminated soil. In total, 30-68 million high-quality reads were obtained. Sequence assembly yielded 286,615 contigs; and these contigs mostly annotated to 1699 KOs. The KO distributions were similar among the six soil samples. Moreover, the proportion of the metabolism of other amino acids (e.g., beta-alanine, taurine, and hypotaurine) and signal transduction was significantly lower in radioactive soil than in uncontaminated soil, whereas the proportion of membrane transport and carbohydrate metabolism was higher. Additionally, KOs were mostly enriched in ATP-binding cassette transporters and two-component systems. According to diversity analyses, Actinobacteria and Proteobacteria were the dominant phyla in radioactive and uncontaminated soil, and Robiginitalea, Microlunatus, and Alicyclobacillus were the dominant genera in radioactive soil. Taken together, these results demonstrate that soil microbial community, structure, and functions show significant changes in uranium-contaminated soil. The dominant categories such as Actinobacteria and Proteobacteria may be applied in environmental governance for uranium-contaminated soil in southern China. PMID:26433967
Soil biogeochemistry, plant physiology and phytoremediation of cadmium contaminated soils
Technology Transfer Automated Retrieval System (TEKTRAN)
Cadmium (Cd) loading in soil and the environment has been accelerated worldwide due to enhanced industrialization and intensified agricultural production, particularly in the developing countries. Soil Cd pollution, resulting from both anthropogenic and geogenic sources, has posed an increasing chal...
Solubility measurement of uranium in uranium-contaminated soils
Lee, S.Y.; Elless, M.; Hoffman, F.
A short-term equilibration study involving two uranium-contaminated soils at the Fernald site was conducted as part of the In Situ Remediation Integrated Program. The goal of this study is to predict the behavior of uranium during on-site remediation of these soils. Geochemical modeling was performed on the aqueous species dissolved from these soils following the equilibration study to predict the on-site uranium leaching and transport processes. The soluble levels of total uranium, calcium, magnesium, and carbonate increased continually for the first four weeks. After the first four weeks, these components either reached a steady-state equilibrium or continued linearity throughout the study. Aluminum, potassium, and iron, reached a steady-state concentration within three days. Silica levels approximated the predicted solubility of quartz throughout the study. A much higher level of dissolved uranium was observed in the soil contaminated from spillage of uranium-laden solvents and process effluents than in the soil contaminated from settling of airborne uranium particles ejected from the nearby incinerator. The high levels observed for soluble calcium, magnesium, and bicarbonate are probably the result of magnesium and/or calcium carbonate minerals dissolving in these soils. Geochemical modeling confirms that the uranyl-carbonate complexes are the most stable and dominant in these solutions. The use of carbonate minerals on these soils for erosion control and road construction activities contributes to the leaching of uranium from contaminated soil particles. Dissolved carbonates promote uranium solubility, forming highly mobile anionic species. Mobile uranium species are contaminating the groundwater underlying these soils. The development of a site-specific remediation technology is urgently needed for the FEMP site.
Bench-scale solvent extraction and soil washing studies were performed on soil samples obtained from three abandoned wood preserving sites that included in the NPL. The soil samples from these sites were contaminated with high levels of polyaromatic hydrocarbons (PAHs), pentachlo...
Soil and debris from Superfund sites must be treated to minimize their threat to human health and the environment as part of remedial actions at such sites. Studies were conducted on the effectiveness with which five treatment processes removed or immobilized synthetic soils cont...
Biochar: an effective amendment for remediating contaminated soil.
Kong, Lu-Lu; Liu, Wei-Tao; Zhou, Qi-Xing
Biochar is a carbon-rich material derived from incomplete combustion of biomass.Applying biochar as an amendment to treat contaminated soils is receiving increasing attention, and is a promising way to improve soil quality. Heavy metals are persistent and are not environmentally biodegradable. However, they can be stabilized in soil by adding biochar. Moreover, biochar is considered to be a predominant sorptive agent for organic pollutants, having a removal efficiency of about 1 order of magnitude higher than does soil/sediment organic matter or their precursor substances alone.When trying to stabilize organic and inorganic pollutants in soil, several features of biochar' s sorption capacity should be considered, viz., the nature of the pollutants to be remediated, how the biochar is prepared, and the complexity of the soil systemin which biochar may be used. In addition, a significant portion of the biochar or some of its components that are used to remediate soils do change over time through abiotic oxidation and microbial decomposition. This change process is commonly referred to as "aging:" Biochar "aging" in nature is inevitable, and aged biochar exhibits an effect that is totally different than non-aged biochar on stabilizing heavy metals and organic contaminants in soils.Studies that have been performed to date on the use of biochar to remediate contaminated soil are insufficient to allow its use for wide-scale field application.Therefore, considerable new data are necessary to expand both our understanding of how biochar performs in the field, and where it can be best used in the future for soil remediation. For example, how biochar and soil biota (microbial and faunal communities)interact in soils is still poorly understood. Moreover, studies are needed on how to best remove new species of heavy metals, and on how biochar aging affects sorption capacity are also needed. PMID:24162093
The U.S. Environmental Protection Agency's Office of Research and Development (ORD) is examining processes for remedial action at Superfund sites, and corrective action at operating disposal sites. ecent legislation emphasizes destruction and detoxification of contaminants, rathe...
Environmental projects. Volume 14: Removal of contaminated soil and debris
NASA Technical Reports Server (NTRS)
Kushner, Len
Numerous diverse activities at the Goldstone Deep Space Communications Complex (GDSCC) are carried out in support of six parabolic dish antennas. Some of these activities can result in possible spills or leakages of hazardous materials and wastes stored both above ground in steel drums and below ground in underground storage tanks (UST's). These possible leaks or spills, along with the past practice of burial of solid debris and waste in trenches and pits, could cause local subsurface contamination of the soil. In 1987, the Jet Propulsion Laboratory (JPL), retained Engineering-Science, Inc. (E-S), Pasadena, California, to identify the specific local areas within the GDSCC with subsurface soil contamination. The E-S study determined that some of the soils at the Apollo Site and the Mars Site were contaminated with hydrocarbons, while soil at a nonhazardous waste dumpsite at the Mojave Base site was contaminated with copper. This volume is a JPL-expanded version of the PE209 E-S report, and it also reports that all subsurface contaminated soils at the GDSCC were excavated, removed, and disposed of in an environmentally acceptable way, and the excavations were backfilled and covered in accordance with accepted Federal, State, and local environmental rules and regulations.
Use of passive sampling devices to determine soil contaminant concentrations
Johnson, K.A. |; Hooper, M.J.; Weisskopf, C.P.
The effective remediation of contaminated sites requires accurate identification of chemical distributions. A rapid sampling method using passive sampling devices (PSDs) can provide a thorough site assessment. We have been pursuing their application in terrestrial systems and have found that they increase the ease and speed of analysis, decrease solvent usage and overall cost, and minimize the transport of contaminated soils. Time and cost savings allow a higher sampling frequency than is generally the case using traditional methods. PSDs have been used in the field in soils of varying physical properties and have been successful in estimating soil concentrations ranging from 1 {mu}g/kg (parts per billion) to greater than 200 mg/kg (parts per million). They were also helpful in identifying hot spots within the sites. Passive sampling devices show extreme promise as an analytical tool to rapidly characterize contaminant distributions in soil. There are substantial time and cost savings in laboratory personnel and supplies. By selectively excluding common interferences that require sample cleanup, PSDs can be retrieved from the field and processed rapidly (one technician can process approximately 90 PSDs in an 8-h work day). The results of our studies indicate that PSDs can be used to accurately estimate soil contaminant concentrations and provide lower detection limits. Further, time and cost savings will allow a more thorough and detailed characterization of contaminant distributions. 13 refs., 4 figs., 2 tabs.
Bioremediation of industrially contaminated soil using compost and plant technology.
Taiwo, A M; Gbadebo, A M; Oyedepo, J A; Ojekunle, Z O; Alo, O M; Oyeniran, A A; Onalaja, O J; Ogunjimi, D; Taiwo, O T
Compost technology can be utilized for bioremediation of contaminated soil using the active microorganisms present in the matrix of contaminants. This study examined bioremediation of industrially polluted soil using the compost and plant technology. Soil samples were collected at the vicinity of three industrial locations in Ogun State and a goldmine site in Iperindo, Osun State in March, 2014. The compost used was made from cow dung, water hyacinth and sawdust for a period of twelve weeks. The matured compost was mixed with contaminated soil samples in a five-ratio pot experimental design. The compost and contaminated soil samples were analyzed using the standard procedures for pH, electrical conductivity (EC), organic carbon (OC), total nitrogen (TN), phosphorus, exchangeable cations (Na, K, Ca and Mg) and heavy metals (Fe, Mn, Cu, Zn and Cr). Kenaf (Hibiscus cannabinus) seeds were also planted for co-remediation of metals. The growth parameters of Kenaf plants were observed weekly for a period of one month. Results showed that during the one-month remediation experiment, treatments with 'compost-only' removed 49 ± 8% Mn, 32 ± 7% Fe, 29 ± 11% Zn, 27 ± 6% Cu and 11 ± 5% Cr from the contaminated soil. On the other hand, treatments with 'compost+plant' remediated 71 ± 8% Mn, 63 ± 3% Fe, 59 ± 11% Zn, 40 ± 6% Cu and 5 ± 4% Cr. Enrichment factor (EF) of metals in the compost was low while that of Cu (EF=7.3) and Zn (EF=8.6) were high in the contaminated soils. Bioaccumulation factor (BF) revealed low metal uptake by Kenaf plant. The growth parameters of Kenaf plant showed steady increments from week 1 to week 4 of planting. PMID:26551220
Innovative treatment for TCE-contaminated saturated clay soils
West, O.R.; Cameron, P.A.; Smuin, D.R.
This paper describes the evaluation of mixed region vapor stripping (MRVS) coupled with calcium oxide conditioning for removing trichloroethylene (TCE) for a site underlain by saturated clay soils. Volatile organic compound removal during MRVS with and without calcium oxide conditioning were simulated using a previously developed model. The results of the modeling were compared with laboratory MRVS tests on undisturbed soil cores taken from the study site. The modeling results were consistent with laboratory simulations of MRVS on field-contaminated soils from the study site, and showed that calcium oxide conditioning is an effective method for enhancing VOC removal efficiencies in saturated clay soils.
Hoeffner, S. L.; Navratil, J. D.; Torrao, G.; Smalley, R.
Soils contaminated with radionuclides are an environmental concern at most Department of Energy (DOE) sites. Clean up efforts at many of these sites are ongoing using conventional remediation techniques. These remediation techniques are often expensive and may not achieve desired soil volume reduction. Several studies using alternative remediation techniques have been performed on plutonium-contaminated soils from the Nevada Test Site. Results to date exhibit less than encouraging results, but these processes were often not fully optimized, and other approaches are possible. Clemson University and teaming partner Waste Policy Institute, through a cooperative agreement with the National Environmental Technologies Laboratory, are assisting the Nevada Test Site (NTS) in re-evaluating technologies that have the potential of reducing the volume of plutonium contaminated soil. This efforts includes (1) a through literature review and summary of (a) NTS soil characterization and (b) volume reduction treatment technologies applied to plutonium-contaminated NTS soils, (2) an interactive workshop for vendors, representatives from DOE sites and end-users, and (3) bench scale demonstration of applicable vendor technologies at the Clemson Environmental Technologies Laboratory.
Release of polyaromatic hydrocarbons from coal tar contaminated soils
Priddy, N.D.; Lee, L.S.
A variety of process wastes generated from manufactured gas production (MGP) have contaminated soils and groundwater at production and disposal sites. Coal tar, consisting of a complex mixture of hydrocarbons present as a nonaqueous phase liquid, makes up a large portion of MGP wastes. Of the compounds in coal tar, polyaromatic hydrocarbons (PAHs) are the major constituents of environmental concern due to their potential mutagenic and carcinogenic hazards. Characterization of the release of PAHs from the waste-soil matrix is essential to quantifying long-term environmental impacts in soils and groundwater. Currently, conservative estimates for the release of PAHs to the groundwater are made assuming equilibrium conditions and using relationships derived from artificially contaminated soils. Preliminary work suggests that aged coal tar contaminated soils have much lower rates of desorption and a greater affinity for retaining organic contaminants. To obtain better estimates of desorption rates, the release of PAHs from a coal tar soil was investigated using a flow-interruption, miscible displacement technique. Methanol/water solutions were employed to enhance PAH concentrations above limits of detection. For each methanol/water solution employed, a series of flow interrupts of varying times was invoked. Release rates from each methanol/water solution were estimated from the increase in concentration with duration of flow interruption. Aqueous-phase release rates were then estimated by extrapolation using a log-linear cosolvency model.
Electromigration of Contaminated Soil by Electro-Bioremediation Technique
NASA Astrophysics Data System (ADS)
Azhar, A. T. S.; Nabila, A. T. A.; Nurshuhaila, M. S.; Shaylinda, M. Z. N.; Azim, M. A. M.
Soil contamination with heavy metals poses major environmental and human health problems. This problem needs an efficient method and affordable technological solution such as electro-bioremediation technique. The electro-bioremediation technique used in this study is the combination of bacteria and electrokinetic process. The aim of this study is to investigate the effectiveness of Pseudomonas putida bacteria as a biodegradation agent to remediate contaminated soil. 5 kg of kaolin soil was spiked with 5 g of zinc oxide. During this process, the anode reservoir was filled with Pseudomonas putida while the cathode was filled with distilled water for 5 days at 50 V of electrical gradient. The X-Ray Fluorescent (XRF) test indicated that there was a significant reduction of zinc concentration for the soil near the anode with 89% percentage removal. The bacteria count is high near the anode which is 1.3x107 cfu/gww whereas the bacteria count at the middle and near the cathode was 5.0x106 cfu/gww and 8.0x106 cfu/gww respectively. The migration of ions to the opposite charge of electrodes during the electrokinetic process resulted from the reduction of zinc. The results obtained proved that the electro-bioremediation reduced the level of contaminants in the soil sample. Thus, the electro-bioremediation technique has the potential to be used in the treatment of contaminated soil.
Soil contamination by petroleum products. Southern Algerian case
NASA Astrophysics Data System (ADS)
Belabbas, Amina; Boutoutaou, Djamel; Segaï, Sofiane; Segni, Ladjel
Contamination of soil by petroleum products is a current problem in several countries in the world. In Algeria, this negative phenomenon is highly remarked in Saharan region. Numerous studies at the University of Ouargla that we will review in this paper, have tried to find an effective solution to eliminate the hydrocarbons from the soil by the technique of "biodegradation" which is a natural process based on microorganisms such as Bacillus megaterium and Pseudomonas aeruginosa. Presence of aboriginal strain Bacillus megaterium in the soil samples with different ages of contamination has shown a strong degradation of pollutants. This strain chosen for its short time of generation which is performing as seen the best yields of elimination of hydrocarbons assessed at 98 % biostimule by biosurfactant, also 98% on a sample wich bioaugmente by urea, and 86 % of the sample which biostimule by nutrient solution. The rate of biodegradation of the contaminated soil by crude oil using the strain Pseudomonas aeruginosa is higher in the presence of biosurfactant 53 % that in his absence 35 %. Another elimination technique wich is washing the contaminated soil's sample by centrifugation in the presence of biosurfactant where The rate of hydrocarbons mobilized after washing soil by centrifugation is of 50 % and 76 % but without centrifugation it was of 46% to 79%. Those processes have great capacity in the remobilization of hydrocarbons and acceleration of their biodegradation; thus, they deserve to be further developed in order to prevent environmental degradation in the region of Ouargla.
Hydroxamate siderophore-promoted reactions between iron(II) and nitroaromatic groundwater contaminants
NASA Astrophysics Data System (ADS)
Kim, Dongwook; Duckworth, Owen W.; Strathmann, Timothy J.
Recent studies show that ferrous iron (Fe II), which is often abundant in anaerobic soil and groundwater, is capable of abiotically reducing many subsurface contaminants. However, studies also demonstrate that Fe II redox reactivity in geochemical systems is heavily dependent upon metal speciation. This contribution examines the influence of hydroxamate ligands, including the trihydroxamate siderophore desferrioxamine B (DFOB), on Fe II reactions with nitroaromatic groundwater contaminants (NACs). Experimental results demonstrate that ring-substituted NACs are reduced to the corresponding aniline products in aqueous solutions containing Fe II complexes with DFOB and two monohydroxamate ligands (acetohydroxamic acid and salicylhydroxamic acid). Reaction rates are heavily dependent upon solution conditions and the identities of both the Fe II-complexing hydroxamate ligand and the target NAC. Trends in the observed pseudo-first-order rate constants for reduction of 4-chloronitrobenzene ( kobs, s -1) are quantitatively linked to the formation of Fe II species with standard one-electron reduction potentials, EH0 (Fe III/Fe II), below -0.3 V. Linear free energy relationships correlate reaction rates with the EH0 (Fe III/Fe II) values of different electron-donating Fe II complexes and with the apparent one-electron reduction potentials of different electron-accepting NACs, EH1'(ArNO 2). Experiments describing a redox auto-decomposition mechanism for Fe II-DFOB complexes that occurs at neutral pH and has implications for the stability of hydroxamate siderophores in anaerobic environments are also presented. Results from this study indicate that hydroxamates and other Fe III-stabilizing organic ligands can form highly redox-active Fe II complexes that may contribute to the natural attenuation and remediation of subsurface contaminants.
Field demonstration of soil slurry bioreactor technology for the remediation of explosives-contaminated soils
Hampton, M.L.; Sisk, W.E.
The past production and handling of conventional munitions has resulted in explosives contamination of the soils at various military facilities. The principal explosive contaminants are trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), and cyclotetramethylenetetranitramine (HMX). Depending on the concentrations present, these explosives-contaminated soils pose both a reactivity and toxicity hazard and the potential for groundwater contamination. Bioremediation technologies are currently being developed by the U.S. Army Environmental Center as cost-effective alternatives to the current proven technology, high temperature incineration. A technology which is gaining popularity in the remediation industry is the use of soil slurry biodegradation systems in which an aqueous slurry is created by combining soils or sludge with water. Previous studies using soils contaminated with explosives from Joliet Army Ammunition Plant (JAAP) demonstrated the feasibility of this technology. A field demonstration to determine the feasibility of using Soil Slurry Sequencing Batch Reactors (SS-SBRs) to treat explosives-contaminated soils is being conducted at JAAP. Key factors to be investigated include the percent reduction of explosives and the identification of degradation products. In addition, the efficiency of reactor operations using different soil replacement volumes will be examined.
Sustainable remediation of mercury contaminated soils by thermal desorption.
Sierra, María J; Millán, Rocio; López, Félix A; Alguacil, Francisco J; Cañadas, Inmaculada
Mercury soil contamination is an important environmental problem that needs the development of sustainable and efficient decontamination strategies. This work is focused on the application of a remediation technique that maintains soil ecological and environmental services to the extent possible as well as search for alternative sustainable land uses. Controlled thermal desorption using a solar furnace at pilot scale was applied to different types of soils, stablishing the temperature necessary to assure the functionality of these soils and avoid the Hg exchange to the other environmental compartments. Soil mercury content evolution (total, soluble, and exchangeable) as temperature increases and induced changes in selected soil quality indicators are studied and assessed. On total Hg, the temperature at which it is reduced until acceptable levels depends on the intended soil use and on how restrictive are the regulations. For commercial, residential, or industrial uses, soil samples should be heated to temperatures higher than 280 °C, at which more than 80 % of the total Hg is released, reaching the established legal total Hg level and avoiding eventual risks derived from high available Hg concentrations. For agricultural use or soil natural preservation, conversely, maintenance of acceptable levels of soil quality limit heating temperatures, and additional treatments must be considered to reduce available Hg. Besides total Hg concentration in soils, available Hg should be considered to make final decisions on remediation treatments and potential future uses. Graphical Abstract Solar energy use for remediation of soils affected by mercury. PMID:26545893
Evaluation of electrokinetic remediation of arsenic-contaminated soils.
Kim, Soon-Oh; Kim, Won-Seok; Kim, Kyoung-Woong
The potential of electrokinetic (EK) remediation technology has been successfully demonstrated for the remediation of heavy metal-contaminated fine-grained soils through laboratory scale and field application studies. Arsenic contamination in soil is a serious problem affecting both site use and groundwater quality. The EK technology was evaluated for the removal of arsenic from two soil samples; a kaolinite soil artificially contaminated with arsenic and an arsenic-bearing tailing-soil taken from the Myungbong (MB) gold mine area. The effectiveness of enhancing agents was investigated using three different types of cathodic electrolytes; deionized water (DIW), potassium phosphate (KH(2)PO(4)) and sodium hydroxide (NaOH). The results of the experiments on the kaolinite show that the potassium phosphate was the most effective in extracting arsenic, probably due to anion exchange of arsenic species by phosphate. On the other hand, the sodium hydroxide seemed to be the most efficient in removing arsenic from the tailing-soil. This result may be explained by the fact that the sodium hydroxide increased the soil pH and accelerated ionic migration of arsenic species through the desorption of arsenic species as well as the dissolution of arsenic-bearing minerals. PMID:16237600
Preliminary Experimental Analysis of Soil Stabilizers for Contamination Control
Lagos, L.; Varona, J.; Zidan, A.; Gudavalli, R.; Wu, Kuang-His
A major focus of Department of Energy's (DOE's) environmental management mission at the Hanford site involves characterizing and remediating contaminated soil and groundwater; stabilizing contaminated soil; remediating disposal sites; decontaminating and decommissioning structures, and demolishing former plutonium production process buildings, nuclear reactors, and separation plants; maintaining inactive waste sites; transitioning facilities into the surveillance and maintenance program; and mitigating effects to biological and cultural resources from site development and environmental cleanup and restoration activities. For example, a total of 470,914 metric tons of contaminated soil from 100 Areas remediation activities were disposed at the Environmental Restoration Disposal Facility (ERDF) during 2004. The Applied Research Center (ARC) at Florida International University (FIU) is supporting the Hanford's site remediation program by analyzing the effectiveness of several soil stabilizers (fixatives) for contamination control during excavation activities. The study is focusing on determining the effects of varying soil conditions, temperature, humidity and wind velocity on the effectiveness of the candidate stabilizers. The test matrix consists of a soil penetration-depth study, wind tunnel experiments for determination of threshold velocity, and temperature and moisture-controlled drying/curing experiments. These three set of experiments are designed to verify performance metrics, as well as provide insight into what fundamental forces are altered by the use of the stabilizer. This paper only presents the preliminary results obtained during wind tunnel experiments using dry Hanford soil samples (with 2.7% moisture by weight). These dry soil samples were exposed to varying wind speeds from 2.22 m/sec to 8.88 m/sec. Furthermore, airborne particulate data was collected for the dry Hanford soil experiments using an aerosol analyzer instrument. (authors)
Magnetic mineralogy of heavy metals-contaminated soils
NASA Astrophysics Data System (ADS)
Shenggao, L.
Soils around mine and in urban areas are often contaminated by heavy metals derived from industrial and human activities [1, 2]. These contaminated soils are often characterized by a magnetic enhancement on topsoils. Many studies demonstrated that there are significant correlations between heavy metals and various magnetic parameters in contaminated soils, indicating a strong affinity of heavy metals to magnetic minerals. The magnetic particles in contaminated soils were separated by a magnetic separation technique. The rock magnetism, XRD, field emission scanning electron microscopy equiped with an energy-dispersive X-ray analyzer (FESEM/EDX) were used to characterize their magnetic mineralogy. Results of XRD analysis indicated that the magnetic particles separated from heavy metal-contaminated soils are composed of quartz, magnetite, and hematite. Based on the X-ray diffraction peak intensity, the Fe3O4 was identified as the predominant magnetic mineral phase. The high-temperature magnetization (Ms-T) curves of magnetic particles extracted from contaminated soils show a sharp Ms decrease at about 580C (the Curie temperature of magnetite), suggesting that magnetite is the dominant magnetic carrier. The hysteresis loops of contaminated soils are closed at about 100-200 mT which is consistent with the presence of a dominant ferrimagnetic mineral phase. The FESEM analysis showed a great variety of shapes of magnetic particles in contaminated soils. The most common morphology are observed in the form of spherules, with the sizes ranging from 20 to 100 um. The chemical composition of magnetic particles consist mainly of Fe, Si, Al, and Ca with minor heavy metal elements (Cu, Zn, Hg, and Cr). The semi-quantitative Fe content identified by FESEM/EDX ranged from 40 to 90%. Combined studies of rock magnetism, XRD, and FESEM/EDX indicated that magnetic mineral phases responsible for the magnetic enhancement of contaminated soils are anthropogenic origin which are coarse
In situ bioremediation of contaminated unsaturated subsurface soils
Sims, J.L.; Sims, R.C.; Dupont, R.R.; Matthews, J.E.; Russell, H.H.
An emerging technology for the remediation of unsaturated subsurface soils involves the use of microorganisms to degrade contaminants which are present in such soils. Understanding the processes which drive in situ bioremediation, as well as the effectiveness and efficiency of the utilization of these systems, are issues which have been identified by the Regional Superfund Engineering Forum as concerns of Superfund decision makers. Although in situ bioremediation has been used for a number of years in the restoration of ground water contaminated by petroleum hydrocarbons, it has only been in recent years that in situ systems have been directed toward contaminants in unsaturated subsurface soils. Research has contributed greatly to understanding the biotic, chemical, and hydrologic parameters which contribute to or restrict the application of in-situ bioremediation and has been successful at a number of locations in demonstrating its effectiveness at field scale.
Effects of poultry manure on soil biochemical properties in phthalic acid esters contaminated soil.
Gao, Jun; Qin, Xiaojian; Ren, Xuqin; Zhou, Haifeng
This study aimed to evaluate the effects of poultry manure (PM) on soil biological properties in DBP- and DEHP-contaminated soils. An indoor incubation experiment was conducted. Soil microbial biomass C (Cmic), soil enzymatic activities, and microbial phospholipid fatty acid (PLFA) concentrations were measured during incubation period. The results indicated that except alkaline phosphatase activity, DBP and DEHP had negative effects on Cmic, dehydrogenase, urease, protease activities, and contents of total PLFA. However, 5 % PM treatment alleviated the negative effects of PAEs on the above biochemical parameters. In DBP-contaminated soil, 5 % PM amendment even resulted in dehydroenase activity and Cmic content increasing by 17.8 and 11.8 % on the day 15 of incubation, respectively. During the incubation periods, the total PLFA contents decreased maximumly by 17.2 and 11.6 % in DBP- and DEHP-contaminated soils without PM amendments, respectively. Compared with those in uncontaminated soil, the total PLFA contents increased slightly and the value of bacPLFA/fugalPLFA increased significantly in PAE-contaminated soils with 5 % PM amendment. Nevertheless, in both contaminated soils, the effects of 5 % PM amendment on the biochemical parameters were not observed with 10 % PM amendment. In 10 % PM-amended soils, DBP and DEHP had little effect on Cmic, soil enzymatic activities, and microbial community composition. At the end of incubation, the effects of PAEs on these parameters disappeared, irrespective of PM amendment. The application of PM ameliorated the negative effect of PAEs on soil biological environment. However, further work is needed to study the effect of PM on soil microbial gene expression in order to explain the change mechanisms of soil biological properties. PMID:26298343
Contamination of Austrian soil with caesium-137.
Bossew, P; Ditto, M; Falkner, T; Henrich, E; Kienzl, K; Rappelsberger, U
Austria ranks among the countries that have been most strongly affected by the Chernobyl fallout. The mean contamination with 137Cs is 21.0 kBq/m2, of which 18.7 kBq/m2 is due to the Chernobyl accident, whereas global fallout contributes 2.3 kBq/m2. Maximum values of total 137Cs contamination are nearly 200 kBq/m2. Total deposition of Chernobyl 137Cs on Austrian territory is 1.6 PBq or a fraction of around 2% of the 137Cs released from the reactor. 2115 measurements were used to draw the Austrian "caesium map". The geographical pattern of fallout distribution shows regional differences of contamination as high as 1:100. PMID:11398378
Contaminant bioavailability in soils, sediments, and aquatic environments
Traina, Samuel J.; Laperche, Valérie
The aqueous concentrations of heavy metals in soils, sediments, and aquatic environments frequently are controlled by the dissolution and precipitation of discrete mineral phases. Contaminant uptake by organisms as well as contaminant transport in natural systems typically occurs through the solution phase. Thus, the thermodynamic solubility of contaminant-containing minerals in these environments can directly influence the chemical reactivity, transport, and ecotoxicity of their constituent ions. In many cases, Pb-contaminated soils and sediments contain the minerals anglesite (PbSO4), cerussite (PbCO3), and various lead oxides (e.g., litharge, PbO) as well as Pb2+ adsorbed to Fe and Mn (hydr)oxides. Whereas adsorbed Pb can be comparatively inert, the lead oxides, sulfates, and carbonates are all highly soluble in acidic to circumneutral environments, and soil Pb in these forms can pose a significant environmental risk. In contrast, the lead phosphates [e.g., pyromorphite, Pb5(PO4)3Cl] are much less soluble and geochemically stable over a wide pH range. Application of soluble or solid-phase phosphates (i.e., apatites) to contaminated soils and sediments induces the dissolution of the "native" Pb minerals, the desorption of Pb adsorbed by hydrous metal oxides, and the subsequent formation of pyromorphites in situ. This process results in decreases in the chemical lability and bioavailability of the Pb without its removal from the contaminated media. This and analogous approaches may be useful strategies for remediating contaminated soils and sediments. PMID:10097045
Immobilization of uranium in contaminated soil by natural apatite addition
Mrdakovic Popic, Jelena; Stojanovic, Mirjana; Milosevic, Sinisa; Iles, Deana; Zildzovic, Snezana
Available in abstract form only. Full text of publication follows: The goal of this study was to evaluate the effectiveness of Serbian natural mineral apatite as soil additive for reducing the migration of uranium from contaminated sediments. In laboratory study we investigated the sorption properties of domestic apatite upon different experimental conditions, such as pH, adsorbent mass, reaction period, concentration of P{sub 2}O{sub 5} in apatite, solid/liquid ratio. In second part of study, we did the quantification of uranium in soil samples, taken from uranium mine site 'Kalna', by sequential extraction method. The same procedure was, also, used for uranium determination in contaminated soil samples after apatite addition, in order to determine the changes in U distribution in soil fraction. The obtained results showed the significant level of immobilization (96.7%) upon certain conditions. Increase of %P{sub 2}O{sub 5} in apatite and process of mechano-chemical activation led to increase of immobilization capacity from 17.50% till 91.64%. The best results for uranium binding were obtained at pH 5.5 and reaction period 60 days (98.04%) The sequential extraction showed the presence of uranium (48.2%) in potentially available soil fractions, but with the apatite addition uranium content in these fractions decreased (30.64%), what is considering environmental aspect significant fact. In situ immobilization of radionuclide using inexpensive sequestering agents, such as apatite, is very adequate for big contaminated areas of soil with low level of contamination. This investigation study on natural apatite from deposit 'Lisina' Serbia was the first one of this type in our country. Key words: apatite, uranium, immobilization, soil, contamination. (authors)
Human exposure to soil contaminants in subarctic Ontario, Canada
Reyes, Ellen Stephanie; Liberda, Eric Nicholas; Tsuji, Leonard James S.
Background Chemical contaminants in the Canadian subarctic present a health risk with exposures primarily occurring via the food consumption. Objective Characterization of soil contaminants is needed in northern Canada due to increased gardening and agricultural food security initiatives and the presence of known point sources of pollution. Design A field study was conducted in the western James Bay Region of Ontario, Canada, to examine the concentrations of polychlorinated biphenyls, dichlorodiphenyltrichloroethane and its metabolites (ΣDDT), other organochlorines, and metals/metalloids in potentially contaminated agriculture sites. Methods Exposure pathways were assessed by comparing the estimated daily intake to acceptable daily intake values. Ninety soil samples were collected at random (grid sampling) from 3 plots (A, B, and C) in Fort Albany (on the mainland), subarctic Ontario, Canada. The contaminated-soil samples were analysed by gas chromatography with an electron capture detector or inductively coupled plasma mass spectrometer. Results The range of ΣDDT in 90 soil samples was below the limit of detection to 4.19 mg/kg. From the 3 soil plots analysed, Plot A had the highest ΣDDT mean concentration of 1.12 mg/kg, followed by Plot B and Plot C which had 0.09 and 0.01 mg/kg, respectively. Concentrations of other organic contaminants and metals in the soil samples were below the limit of detection or found in low concentrations in all plots and did not present a human health risk. Conclusion Exposure analyses showed that the human risk was below regulatory thresholds. However, the ΣDDT concentration in Plot A exceeded soil guidelines set out by the Canadian Council of Ministers of the Environment of 0.7 mg/kg, and thus the land should not be used for agricultural or recreational purposes. Both Plots B and C were below threshold limits, and this land can be used for agricultural purposes. PMID:26025557
Extraction of pesticides from contaminated soil using supercritical carbon dioxide
Hunter, G.B.
The demand for processes to clean up contaminated soils without generating additional contaminants, such as hazardous solvents, is increasing. One approach to minimizing this problem is to use supercritical fluids like light hydrocarbons and CO[sub 2] to extract contaminants from soils. Gases exhibit unique properties under supercritical conditions. They retain the ability to diffuse through the interstitial spaces of solid materials, plus they have the solvating power of liquids. Some examples of extractions using SCFs are caffeine from coffee, cholesterol from eggs, drugs from plants, and nicotine from tobacco. Supercritical CO[sub 2] is an attractive, alternative extraction medium for removal of pesticides from soils. Carbon dioxide is readily available, relatively inexpensive, and if recycled, nonpolluting. Contaminants may be easily recovered by evaporating the CO[sub 2] into an expansion vessel. Supercritical fluid extraction technology is discussed and results are given for the extraction of atrazine, bentazon, alachlor, and permethrin from contaminated soil prepared in the laboratory. Initial studies show >95% removal for these pesticides.
Extraction of pesticides from contaminated soil using supercritical carbon dioxide
Hunter, G.B.
The demand for processes to clean up contaminated soils without generating additional contaminants, such as hazardous solvents, is increasing. One approach to minimizing this problem is to use supercritical fluids like light hydrocarbons and CO{sub 2} to extract contaminants from soils. Gases exhibit unique properties under supercritical conditions. They retain the ability to diffuse through the interstitial spaces of solid materials, plus they have the solvating power of liquids. Some examples of extractions using SCFs are caffeine from coffee, cholesterol from eggs, drugs from plants, and nicotine from tobacco. Supercritical CO{sub 2} is an attractive, alternative extraction medium for removal of pesticides from soils. Carbon dioxide is readily available, relatively inexpensive, and if recycled, nonpolluting. Contaminants may be easily recovered by evaporating the CO{sub 2} into an expansion vessel. Supercritical fluid extraction technology is discussed and results are given for the extraction of atrazine, bentazon, alachlor, and permethrin from contaminated soil prepared in the laboratory. Initial studies show >95% removal for these pesticides.
Immobilization of radioactive strontium in contaminated soils by phosphate treatment
Kim, K.H.; Ammons, J.T. . Dept. of Plant and Soil Science); Lee, S.Y. )
The feasibility of in situ phosphate- and metal- (calcium, aluminum, and iron) solution treatment for {sup 90}Sr immobilization was investigated. Batch and column experiments were performed to find optimum conditions for coprecipitation of {sup 90}Sr with Ca-, Al-, and Fe-phosphate compounds in contaminated soils. Separate columns were packed with artificially {sup 85}Sr-contaminated acid soil as well as {sup 90}Sr-contaminated soil from the Oak Ridge Reservation. After metal-phosphate treatment, the columns were then leached successively with either tapwater or 0.001 M CaCl{sub 2} solution. Most of the {sup 85}Sr coprecipitated with the metal phosphate compounds. Immobilization of {sup 85}Sr and {sup 90}Sr was affected by such factors as solution pH, metal and phosphate concentration, metal-to-phosphate ratio, and soil characteristics. Equilibration time after treatments also affected {sup 85}Sr immobilization. Many technology aspects still need to be investigated before field applications are feasible, but these experiments indicate that phosphate-based in situ immobilization should prevent groundwater contamination and will be useful as a treatment technology for {sup 90}Sr-contaminated sites. 15 refs., 3 figs., 1 tab.
Arsenic biotransformation in earthworms from contaminated soils.
Button, Mark; Jenkin, Gawen R T; Harrington, Chris F; Watts, Michael J
Two species of arsenic (As) resistant earthworm, Lumbricus rubellus and Dendrodrillus rubidus, their host soils and soil excretions (casts) were collected from 23 locations at a former As mine in Devon, UK. Total As concentrations, measured by ICP-MS, ranged from 255 to 13,080 mg kg(-1) in soils, 11 to 877 mg kg(-1) in earthworms and 284 to 4221 mg kg(-1) in earthworm casts from a sub-sample of 10 of the 23 investigated sites. The samples were also measured for As speciation using HPLC-ICP-MS to investigate potential As biotransformation pathways. Inorganic arsenate (As(V)) and arsenite (As(III)) were the only species detected in the soil. As(V) and As(III) were also the dominant species found in the earthworms and cast material together with lower proportions of the organic species methylarsonate (MA(V)), dimethylarsinate (DMA(V)), arsenobetaine (AB) and three arsenosugars. Whilst the inorganic As content of the earthworms increased with increasing As body burden, the concentration of organic species remained relatively constant. These results suggest that the biotransformation of inorganic arsenic to organic species does not contribute to As resistance in the sampled earthworm populations. Quantification of As speciation in the soil, earthworms and cast material allows a more comprehensive pathway for the formation of AB in earthworms to be elucidated. PMID:19657532
Magnetic susceptibility properties of pesticide contaminated volcanic soil
NASA Astrophysics Data System (ADS)
Agustine, Eleonora; Fitriani, Dini; Safiuddin, La Ode; Tamuntuan, Gerald; Bijaksana, Satria
Pesticides, unfortunately, are still widely used in many countries as way to eradicate agricultural pests. As they are being used continuously over a long period of time, they accumulate as residues in soils posing serious threats to the environment. In this study, we study the changes in magnetite-rich volcanic soils that were deliberately contaminated by pesticide. Such changes, in any, would be useful in the detection of pesticide residue in contaminated soils. Two different types of magnetically strong volcanic soil from the area near Lembang, West Java, Indonesia were used in this study where they were contaminated with varying concentrations of pesticide. The samples were then measured for magnetic susceptibility at two different frequencies. The measurements were then repeated after a period of three months. We found a reduction of magnetic susceptibility as well as a reduction in SP (superparamagnetic) grains proportion in contaminated soil. These might be caused by pesticide-induced magnetic dissolution as supported by SEM analyses. However the impact of pesticide concentration as well as exposure time on magnetic dissolution is still inconclusive.
Extraction of copper in a contaminated soil onto chabazite
NASA Astrophysics Data System (ADS)
Liao, P.-H.; Wang, H. Paul; Hsiao, M.-C.; Eyring, Edward M.; Huang, C.-H.; Jou, C.-J. G.
Copper in a contaminated soil nearby a printed-circuit board waste recycling plant has been extracted onto a microporous molecular sieve (chabazite). The chabazite supported CuO can be used as a chemical looping combustion (CLC) oxygen carrier for CO2 capture. Speciation of copper in the contaminated soil and on the chabazite during CLC has been studied by X-ray absorption near edge structure (XANES) and X-ray absorption fine structure (EXAFS) spectroscopy. By XANES, it is found that about 90% of copper (mainly Cu2+) in the contaminated soil can be extracted and adsorbed on the chabazite, in which CuO can be formed on the chabazite after calcination at 773 K for two hours. The EXAFS data show that copper in the soil and chabazite possesses Cu-O bond distances of 1.96 and 1.95 Å, respectively and coordination numbers (CNs) of 1-3. After CLC, CuO on chabazite has been reduced to Cu with a C-C bond distance of 2.4 Å and a CN of 8. This work also exemplifies the utilization of EXAFS and XANES to reveal the migration path of copper between a contaminated soil and a molecular sieve and interconversion of Cu-CuO in the CLC process.
Chemical and toxicological testing of composted explosives-contaminating soil
Griest, W.H.; Steward, A.J.; Tyndall, R.L.; Caton, J.E.; Ho, C.H.; Ironside, K.S.; Caldwell, W.M.; Tan, E. )
Static-pile and mechanically stirred composts of explosives-contaminated soil at the Umatilla Army Depot Activity (UMDA, Umatilla, OR) in a field composting optimization study were characterized chemically and toxicologically. The concentrations of extractable explosives (e.g., 2,4,6-trinitrotoluene) in the composts and their aqueous leachates, the mutagenicity of organic solvent extracts from the composts, and the toxicity of compost aqueous leachates to Ceriodaphnia dubia all decreased considerably with 20 d of composting. After 44 d or 90 d of composting, the toxicity, mutagenicity, and concentrations of extractable explosives decreased more than 90% in some cases. The composting efficiency was generally inversely proportional to the percentage (v/v) of contaminated soil. Composting in static piles was efficient up to about 20% (v/v) of contaminated soil; composting in the mechanically stirred composters was efficient up to about 25% soil. Mechanical composting was more efficient than composting in static piles. The main conclusion of this study is that composting can effectively remediate explosives contaminated soil and sediment. However, low levels of explosives and metabolites, bacterial mutagenicity, and leachable toxicity to Ceriodaphnia may remain after composting. The sources of residual toxicity and mutagenicity and the ultimate fate of the explosives are unknown.
Treatment of NORM contaminated soil from the oilfields.
Abdellah, W M; Al-Masri, M S
Uncontrolled disposal of oilfield produced water in the surrounding environment could lead to soil contamination by naturally occurring radioactive materials (NORM). Large volumes of soil become highly contaminated with radium isotopes ((226)Ra and (228)Ra). In the present work, laboratory experiments have been conducted to reduce the activity concentration of (226)Ra in soil. Two techniques were used, namely mechanical separation and chemical treatment. Screening of contaminated soil using vibratory sieve shaker was performed to evaluate the feasibility of particle size separation. The fractions obtained were ranged from less than 38 μm to higher than 300 μm. The results show that (226)Ra activity concentrations vary widely from fraction to fraction. On the other hand, leaching of (226)Ra from soil by aqueous solutions (distilled water, mineral acids, alkaline medias and selective solvents) has been performed. In most cases, relatively low concentrations of radium were transferred to solutions, which indicates that only small portions of radium are present on the surface of soil particles (around 4.6%), while most radium located within soil particles; only concentrated nitric acid was most effective where 50% of (226)Ra was removed to aqueous phase. However, mechanical method was found to be easy and effective, taking into account safety procedures to be followed during the implementation of the blending and homogenization. Chemical extraction methods were found to be less effective. The results obtained in this study can be utilized to approach the final option for disposal of NORM contaminated soil in the oilfields. PMID:24378731
Geochemistry of lead contaminated wetland soils amended with phosphorus
NASA Astrophysics Data System (ADS)
Strawn, Daniel G.; Hickey, Patrick; Knudsen, Andrew; Baker, Leslie
To remediate Pb contaminated soils it is proposed that phosphorus can be amended to the soils to transform the Pb into poorly soluble Pb-phosphate mineral phases. However, remediation strategies must account for variable Pb speciation and site-specific factors. In this study soil mineralogy and Pb speciation in soils from P-amended field trials at sites within the Coeur d'Alene River Basin in Idaho, USA were investigated. The soils are contaminated from mining activities and are enriched with Fe and Mn. Selective extraction of the soils indicated that the Fe oxides are poorly crystalline. XRD of the soil clay size fractions identified quartz, muscovite, kaolinite, siderite, lepidocrocite, and chlorite minerals. Amendment with P fertilizer dissolved the siderite. No Pb-phosphate minerals were detected by XRD. Electron microprobe analysis showed direct correlations between Pb, Fe, and Mn in the unamended soils, and negative correlations between Pb and Si. Lead and Mn were strongly correlated. In the amended soils Fe and P were strongly correlated. Results indicate that the Pb is associated with poorly crystalline Fe and Mn oxides, and that added P is primarily associated with Fe oxide phases. Comparisons of pore water Pb concentrations with chloropyromorphite and plumbogummite solubility suggest that in the phosphate-amended soils the pore waters are undersaturated in these phases, whereas several of the control soil pore waters were oversaturated, indicating the added phosphate suppressed the Pb solubility. Results from this research provide insight into the geochemistry occurring in the P-remediated soils that will help in making management and remediation decisions.
Vitrification testing of soil fines from contaminated Hanford 100 Area and 300 Area soils
Ludowise, J.D.
The suitability of Hanford soil for vitrification is well known and has been demonstrated extensively in other work. The tests reported here were carried out to confirm the applicability of vitrification to the soil fines (a subset of the Hanford soil potentially different in composition from the bulk soil) and to provide data on the performance of actual, vitrified soil fines. It was determined that the soil fines were generally similar in composition to the bulk Hanford soil, although the fraction <0.25 mm in the 100 Area soil sample appears to differ somewhat from the bulk soil composition. The soil fines are readily melted into a homogeneous glass with the simple additions of CaO and/or Na{sub 2}O. The vitrified waste (plus additives) occupies only 60% of the volume of the initial untreated waste. Leach testing has shown the glasses made from the soil fines to be very durable relative to natural and man-made glasses and has demonstrated the ability of the vitrified waste to greatly reduce the release of radionuclides to the environment. Viscosity and electrical conductivity measurements indicate that the soil fines will be readily processable, although with levels of additives slightly greater than used in the radioactive melts. These tests demonstrate the applicability of vitrification to the contaminated soil fines and the exceptional performance of the waste form resulting from the vitrification of contaminated Hanford soils.
Environmental effects of soil contamination by shale fuel oils.
Kanarbik, Liina; Blinova, Irina; Sihtmäe, Mariliis; Künnis-Beres, Kai; Kahru, Anne
Estonia is currently one of the leading producers of shale oils in the world. Increased production, transportation and use of shale oils entail risks of environmental contamination. This paper studies the behaviour of two shale fuel oils (SFOs)--'VKG D' and 'VKG sweet'--in different soil matrices under natural climatic conditions. Dynamics of SFOs' hydrocarbons (C10-C40), 16 PAHs, and a number of soil heterotrophic bacteria in oil-spiked soils was investigated during the long-term (1 year) outdoor experiment. In parallel, toxicity of aqueous leachates of oil-spiked soils to aquatic organisms (crustaceans Daphnia magna and Thamnocephalus platyurus and marine bacteria Vibrio fischeri) and terrestrial plants (Sinapis alba and Hordeum vulgare) was evaluated. Our data showed that in temperate climate conditions, the degradation of SFOs in the oil-contaminated soils was very slow: after 1 year of treatment, the decrease of total hydrocarbons' content in the soil did not exceed 25 %. In spite of the comparable chemical composition of the two studied SFOs, the VKG sweet posed higher hazard to the environment than the heavier fraction (VKG D) due to its higher mobility in the soil as well as higher toxicity to aquatic and terrestrial species. Our study demonstrated that the correlation between chemical parameters (such as total hydrocarbons or total PAHs) widely used for the evaluation of the soil pollution levels and corresponding toxicity to aquatic and terrestrial organisms was weak. PMID:24865504
Assessment of combined electro-nanoremediation of molinate contaminated soil.
Gomes, Helena I; Fan, Guangping; Mateus, Eduardo P; Dias-Ferreira, Celia; Ribeiro, Alexandra B
Molinate is a pesticide widely used, both in space and time, for weed control in rice paddies. Due to its water solubility and affinity to organic matter, it is a contaminant of concern in ground and surface waters, soils and sediments. Previous works have showed that molinate can be removed from soils through electrokinetic (EK) remediation. In this work, molinate degradation by zero valent iron nanoparticles (nZVI) was tested in soils for the first time. Soil is a highly complex matrix, and pollutant partitioning between soil and water and its degradation rates in different matrices is quite challenging. A system combining nZVI and EK was also set up in order to study the nanoparticles and molinate transport, as well as molinate degradation. Results showed that molinate could be degraded by nZVI in soils, even though the process is more time demanding and degradation percentages are lower than in an aqueous solution. This shows the importance of testing contaminant degradation, not only in aqueous solutions, but also in the soil-sorbed fraction. It was also found that soil type was the most significant factor influencing iron and molinate transport. The main advantage of the simultaneous use of both methods is the molinate degradation instead of its accumulation in the catholyte. PMID:24946031
In situ recycling of contaminated soil uses bioremediation
Shevlin, P.J.; Reel, D.A.
OxyChem Pipeline Operations, primarily an ethylene and propylene products mover, has determined that substantial savings can be realized by adopting a bioremediation maintenance and recycling approach to hydrocarbon-contaminated soil. By this method, the soil can be recycled in situ, or in containers. To implement the soil-recycling program, OxyChem elected to use a soil remediator and natural absorbent product, Oil Snapper. This field maintenance material, based on an Enhanced Urea Technology, provides a diet to stimulate the growth of hydrocarbon-eating microbes. It works well either with indigenous soil microbes or with commercial microbes. The product is carried in field vehicles, which makes it immediately available when leaks or spills are discovered. Procedure for clean-up is to apply product and mix it into affected soil. Thus the contaminant is contained, preventing further migration; the contaminant is dispersed throughout the product, making it more accessible to the microbes; nutrients are immediately available to the microbes; and the material contributes aeration and moisture-retention properties.
Application of Ultrasonic for Decontamination of Contaminated Soil - 13142
Vasilyev, A.P.; Lebedev, N.M.; Savkin, A.E.
The trials of soil decontamination were carried out with the help of a pilot ultrasonic installation in different modes. The installation included a decontamination bath equipped with ultrasonic sources, a precipitator for solution purification from small particles (less than 80 micrometer), sorption filter for solution purification from radionuclides washing out from soil, a tank for decontamination solution, a pump for decontamination solution supply. The trials were carried out on artificially contaminated sand with specific activity of 4.5 10{sup 5} Bk/kg and really contaminated soil from Russian Scientific Center 'Kurchatovsky Institute' (RSC'KI') with specific activity of 2.9 10{sup 4} Bk/kg. It was established that application of ultrasonic intensify the process of soil reagent decontamination and increase its efficiency. The decontamination factor for the artificially contaminated soil was ∼200 and for soil from RSC'KI' ∼30. The flow-sheet diagram has been developed for the new installation as well as determined the main technological characteristics of the equipment. (authors)
Remediation of Contaminated Soils By Supercritical Carbon Dioxide Extraction
NASA Astrophysics Data System (ADS)
Ferri, A.; Zanetti, M. C.; Banchero, M.; Fiore, S.; Manna, L.
The contaminants that can be found in soils are many, inorganic, like heavy metals, as well as organic. Among the organic contaminants, oil and coal refineries are responsi- ble for several cases of soil contamination with PAHs (Polycyclic Aromatic Hydrocar- bons). Polynuclear aromatic hydrocarbons (PAHs) have toxic, carcinogenic and mu- tagenic effects. Limits have been set on the concentration of most contaminants, and growing concern is focusing on soil contamination issues. USA regulations set the maximum acceptable level of contamination by PAHs equal to 40 ppm at residential sites and 270 ppm at industrial sites. Stricter values are usually adopted in European Countries. Supercritical carbon dioxide extraction is a possible alternative technology to remove volatile organic compounds from contaminated soils. Supercritical fluid extraction (SFE) offers many advantages over conventional solvent extraction. Super- critical fluids combine gaseous properties as a high diffusion coefficient, and liquid properties as a high solvent power. The solvent power is strongly pressure-dependent near supercritical conditions: selective extractions are possible without changing the solvent. Solute can be separate from the solvent depressurising the system; therefore, it is possible to recycle the solvent and recover the contaminant. Carbon dioxide is frequently used as supercritical fluid, because it has moderate critical conditions, it is inert and available in pure form. In this work, supercritical fluid extraction technology has been used to remove a polynuclear aromatic hydrocarbon from contaminated soils. The contaminant choice for the experiment has been naphthalene since several data are available in literature. G. A. Montero et al. [1] studied soil remediation with supercrit- ical carbon dioxide extraction technology; these Authors have found that there was a mass-transfer limitation. In the extraction vessel, the mass transfer coefficient in- creases with the
Recycling Ni from Contaminated and Mineralized Soils.
Technology Transfer Automated Retrieval System (TEKTRAN)
Rare plant species accumulate potentially valuable concentrations of some metals. Alyssum murale readily accumulates over 2% Ni in aboveground dry matter when grown on Ni-mineralized serpentine soils in Oregon, allowing production of "hay" biomass with at least 400 kg Ni ha-1 with low levels of fer...
Transport of agricultural contaminants through karst soil
Technology Transfer Automated Retrieval System (TEKTRAN)
Karst landscapes are common in many agricultural regions in the US. Well-developed karst landscapes are characterized by shallow soils, sinkholes, sinking streams, underground conduits, and springs. In these landscapes surface runoff is minimal and most recharge enters the subsurface relatively quic...
Hydraulic fracturing is a physical process that creates fractures in silty clay soil to enhance its permeability. The technology, developed by the Risk Reduction Engineering Laboratory (RREL) and the University of Cincinnati, creates sand-filled horizontal fractures up to 1 in. i...
Electrokinetic remediation of fluorine-contaminated soil and its impact on soil fertility.
Zhou, Ming; Wang, Hui; Zhu, Shufa; Liu, Yana; Xu, Jingming
Compared to soil pollution by heavy metals and organic pollutants, soil pollution by fluorides is usually ignored in China. Actually, fluorine-contaminated soil has an unfavorable influence on human, animals, plants, and surrounding environment. This study reports on electrokinetic remediation of fluorine-contaminated soil and the effects of this remediation technology on soil fertility. Experimental results showed that electrokinetic remediation using NaOH as the anolyte was a considerable choice to eliminate fluorine in contaminated soils. Under the experimental conditions, the removal efficiency of fluorine by the electrokinetic remediation method was 70.35%. However, the electrokinetic remediation had a significant impact on the distribution and concentrations of soil native compounds. After the electrokinetic experiment, in the treated soil, the average value of available nitrogen was raised from 69.53 to 74.23 mg/kg, the average value of available phosphorus and potassium were reduced from 20.05 to 10.39 mg/kg and from 61.31 to 51.58 mg/kg, respectively. Meanwhile, the contents of soil available nitrogen and phosphorus in the anode regions were higher than those in the cathode regions, but the distribution of soil available potassium was just the opposite. In soil organic matter, there was no significant change. These experiment results suggested that some steps should be taken to offset the impacts, after electrokinetic treatment. PMID:26109225
Biological attributes of rehabilitated soils contaminated with heavy metals.
Valentim Dos Santos, Jessé; Varón-López, Maryeimy; Fonsêca Sousa Soares, Cláudio Roberto; Lopes Leal, Patrícia; Siqueira, José Oswaldo; de Souza Moreira, Fatima Maria
This study aimed to evaluate the effects of two rehabilitation systems in sites contaminated by Zn, Cu, Pb, and Cd on biological soil attributes [microbial biomass carbon (Cmic), basal and induced respiration, enzymatic activities, microorganism plate count, and bacterial and fungal community diversity and structure by denaturing gradient gel electrophoresis (DGGE)]. These systems (S1 and S2) consisted of excavation (trenching) and replacement of contaminated soil by uncontaminated soil in rows with Eucalyptus camaldulensis planting (S1-R and S2-R), free of understory vegetation (S1-BR), or completely covered by Brachiaria decumbens (S2-BR) in between rows. A contaminated, non-rehabilitated (NR) site and two contamination-free sites [Cerrado (C) and pasture (P)] were used as controls. Cmic, densities of bacteria and actinobacteria, and enzymatic activities (β-glucosidase, acid phosphatase, and urease) were significantly higher in the rehabilitated sites of system 2 (S2-R and S2-BR). However, even under high heavy metal contents (S1-R), the rehabilitation with eucalyptus was also effective. DGGE analysis revealed similarity in the diversity and structure of bacteria and fungi communities between rehabilitated sites and C site (uncontaminated). Principal component analysis showed clustering of rehabilitated sites (S2-R and S2-BR) with contamination-free sites, and S1-R was intermediate between the most and least contaminated sites, demonstrating that the soil replacement and revegetation improved the biological condition of the soil. The attributes that most explained these clustering were bacterial density, acid phosphatase, β-glucosidase, fungal and actinobacterial densities, Cmic, and induced respiration. PMID:26662102
Assessing Metal Contamination in Lead Arsenate Contaminated Orchard Soils Using Near and Mid-Infrared Diffuse Reflectance Spectroscopy
Technology Transfer Automated Retrieval System (TEKTRAN)
Historic use of lead-arsenate as pesticide in apple orchards left many soils contaminated with arsenic (As) and lead (Pb). Notorious health effects and their severe soil contamination are of primary concerns for major regulatory agencies, and community at large. Wet chemistry methods for soil anal...
Soil Washing Experiment for Decontamination of Contaminated NPP Soil
Son, J.K.; Kang, K.D.; Kim, K.D.; Ha, J.H.; Song, M.J.
The preliminary experiment was performed to obtain the operating conditions of soil washing decontamination process such as decontamination agent, decontamination temperature, decontamination time and ratio of soil and decontamination agent. To estimate decontamination efficiency, particle size of soil was classified into three categories; {>=} 2.0 mm, 2.0 {approx} 0.21 mm and {<=} 0.21 mm. Major target of this experiment was decontamination of Cs-137. The difference of decontamination efficiency using water and neutral salts as decontamination agent is not high. It is concluded that the best temperature of decontamination agent is normal temperature and the best decontamination time was about 60 minutes. And the best ratio of soil and decontamination agent is 1:10. In case of Cs decontamination for fine soils, the decontamination results using neutral salts such as Na{sub 2}CO{sub 3} and Na{sub 3}PO{sub 4} shows some limits while using strong acid such as sulfuric acid or hydrochloric acid shows high decontamination efficiency ({>=}90%). But we conclude that decontamination using strong acid is also inappropriate because of the insufficiency of decontamination efficiency for highly radioactive fine soils and the difficulty for treatment of secondary liquid waste. It is estimated that the best decontamination process is to use water as decontamination agent for particles which can be decontaminated to clearance level, after particle size separation. (authors)
Phytoremediation of contaminated soils and groundwater: lessons from the field
Vangronsveld, J.; van der Lelie, D.; Herzig, R.; Weyens, N.; Boulet, J.; Adriaensen, K.; Ruttens, A.; Thewys, T.; Vassilev, A.; Meers, E.; Nehnevajova, E.; Mench, M.
The use of plants and associated microorganisms to remove, contain, inactivate, or degrade harmful environmental contaminants (generally termed phytoremediation) and to revitalize contaminated sites is gaining more and more attention. In this review, prerequisites for a successful remediation will be discussed. The performance of phytoremediation as an environmental remediation technology indeed depends on several factors including the extent of soil contamination, the availability and accessibility of contaminants for rhizosphere microorganisms and uptake into roots (bioavailability), and the ability of the plant and its associated microorganisms to intercept, absorb, accumulate, and/or degrade the contaminants. The main aim is to provide an overview of existing field experience in Europe concerning the use of plants and their associated microorganisms whether or not combined with amendments for the revitalization or remediation of contaminated soils and undeep groundwater. Contaminations with trace elements (except radionuclides) and organics will be considered. Because remediation with transgenic organisms is largely untested in the field, this topic is not covered in this review. Brief attention will be paid to the economical aspects, use, and processing of the biomass. It is clear that in spite of a growing public and commercial interest and the success of several pilot studies and field scale applications more fundamental research still is needed to better exploit the metabolic diversity of the plants themselves, but also to better understand the complex interactions between contaminants, soil, plant roots, and microorganisms (bacteria and mycorrhiza) in the rhizosphere. Further, more data are still needed to quantify the underlying economics, as a support for public acceptance and last but not least to convince policy makers and stakeholders (who are not very familiar with such techniques).
Electrokinetic treatment of an agricultural soil contaminated with heavy metals.
Figueroa, Arylein; Cameselle, Claudio; Gouveia, Susana; Hansen, Henrik K
The high organic matter content in agricultural soils tends to complex and retain contaminants such as heavy metals. Electrokinetic remediation was tested in an agricultural soil contaminated with Co(+2), Zn(+2), Cd(+2), Cu(+2), Cr(VI), Pb(+2) and Hg(+2). The unenhanced electrokinetic treatment was not able to remove heavy metals from the soil due to the formation of precipitates in the alkaline environment in the soil section close to the cathode. Moreover, the interaction between metals and organic matter probably limited metal transportation under the effect of the electric field. Citric acid and ethylenediaminetetraacetic acid (EDTA) were used in the catholyte as complexing agents in order to enhance the extractability and removal of heavy metals from soil. These complexing agents formed negatively charged complexes that migrated towards the anode. The acid front electrogenerated at the anode favored the dissolution of heavy metals that were transported towards the cathode. The combined effect of the soil pH and the complexing agents resulted in the accumulation of heavy metals in the center of the soil specimen. PMID:27127923
Deep soil mixing for reagent delivery and contaminant treatment
Korte, N.; Gardner, F.G.; Cline, S.R.; West, O.R.
Deep soil mixing was evaluated for treating clay soils contaminated with TCE and its byproducts at the Department of Energy`s Kansas City Plant. The objective of the project was to evaluate the extent of limitations posed by the stiff, silty-clay soil. Three treatment approaches were tested. The first was vapor stripping. In contrast to previous work, however, laboratory treatability studies indicated that mixing saturated, clay soil was not efficient unless powdered lime was added. Thus, powder injection of lime was attempted in conjunction with the mixing/stripping operation. In separate treatment cells, potassium permanganate solution was mixed with the soil as a means of destroying contaminants in situ. Finally, microbial treatment was studied in a third treatment zone. The clay soil caused operational problems such as breakage of the shroud seal and frequent reagent blowouts. Nevertheless, treatment efficiencies of more than 70% were achieved in the saturated zone with chemical oxidation. Although expensive ($1128/yd{sup 3}), there are few alternatives for soils of this type.
Tool samples subsurface soil free of surface contaminants
NASA Technical Reports Server (NTRS)
Kemmerer, W. W.; Wooley, B. C.
Sampling device obtains pure subsurface soil that is free of any foreign substance that may exist on the surface. It is introduced through a contaminated surface area in a closed condition, opened, and a subsurface sample collected, sealed while in the subsurface position, and then withdrawn.
Crude oil contamination of soil often occurs adjacent to wellheads and storage facilities. Phytoremediation is a promising tool that can be used to remediate such sites and uses plants and agronomic techniques to enhance biodegradation of hydrocarbons. This project has conduct...
This document summarizes the contents of a seminar on treatment of lead-contaminated soils presented on August 28, 1990, to Region V Superfund and RCRA personnel by members of EPA's Engineering and Treatment Technology Support Center located in the Risk Reduction Engineering Labo...
This handbook comprises an update of Volume1 of the 1984 USEPA document entitled "Review of In-Place Treatment Techniques for Contaminated Surface Soils." The purpose of this handbook is the same as that of the original document - to provide state-of-the-art information on in sit...
The mechanisms by which contaminants are released from sediments/soils and absorbed into the skin are poorly understood. The project will first conduct invitro experiments to study the effects of particle layering and chemical saturation. Secondly, mechanistic models will be de...
This report summarizes the results of Mine Waste Technology Program (MWTP) Activity III, Project 38, Linking Waterfowl with Contaminant Speciation in Riparian Soils, implemented and funded by the U.S. Environmental Protection Agency (EPA) and jointly administered by EPA and the U...
This report provides the results of a study that examined the quantities of explosives-contaminated soils at Army installations in the United States in order to understand the user requirements for environmental technology research and development work. This report provides a tim...
A critical review of biological treatment processes for remediation of contaminated soils is presented. The focus of the review is on documented cost and performance of biological treatment technologies demonstrated at full- or
field-scale. Some of the data were generated b...
The Robert S. Kerr Environmental Research Laboratory (RSKERL) has developed a number of Issue Papers and Briefing Documents which are designed to exchange up-to-date information related to the remediation of contaminated soil and ground water at hazardous waste sites. In an attem...
Bioremediation of contaminated soils is considered an effective method for reducing potential health hazards. Although it is assumed that (bio)remediation is a detoxifying process, degradation products of compounds such as polycyclic aromatic compounds (PACs) can be more toxic th...
Chemical methods and phytoremediation of soil contaminated with heavy metals.
Chen, H M; Zheng, C R; Tu, C; Shen, Z G
The effects of chemical amendments (calcium carbonate (CC), steel sludge (SS) and furnace slag (FS)) on the growth and uptake of cadmium (Cd) by wetland rice, Chinese cabbage and wheat grown in a red soil contaminated with Cd were investigated using a pot experiment. The phytoremediation of heavy metal contaminated soil with vetiver grass was also studied in a field plot experiment. Results showed that treatments with CC, SS and FS decreased Cd uptake by wetland rice, Chinese cabbage and wheat by 23-95% compared with the unamended control. Among the three amendments, FS was the most efficient at suppressing Cd uptake by the plants, probably due to its higher content of available silicon (Si). The concentrations of zinc (Zn), lead (Pb) and Cd in the shoots of vetiver grass were 42-67%, 500-1200% and 120-260% higher in contaminated plots than in control, respectively. Cadmium accumulation by vetiver shoots was 218 g Cd/ha at a soil Cd concentration of 0.33 mg Cd/kg. It is suggested that heavy metal-contaminated soil could be remediated with a combination of chemical treatments and plants. PMID:10819205
Antimony release from contaminated mine soils and its migration in four typical soils using lysimeter experiments.
Shangguan, Yu-Xian; Zhao, Long; Qin, Yusheng; Hou, Hong; Zhang, Naiming
Antimony (Sb) can pose great risks to the environment in mining and smelting areas. The migration of Sb in contaminated mine soil was studied using lysimeter experiments. The exchangeable concentration of soil Sb decreased with artificial leaching. The concentrations of Sb retained in the subsoil layers (5-25cm deep) were the highest for Isohumosol and Ferrosol and the lowest for Sandy soil. The Sb concentrations in soil solutions decreased with soil depth, and were adequately simulated using a logarithmic function. The Sb migration pattern in Sandy soil was markedly different from the patterns in the other soils which suggested that Sb may be transported in soil colloids. Environmental factors such as water content, soil temperature, and oxidation-reduction potential of the soil had different effects on Sb migration in Sandy soil and Primosol. The high Fe and Mn contents in Ferrosol and Isohumosol significantly decreased the mobility of Sb in these soils. The Na and Sb concentrations in soils used in the experiments positively correlated with each other (P<0.01). The Sb concentrations in soil solutions, the Sb chemical fraction patterns, and the Sb/Na ratios decreased in the order Sandy soil>Primosol>Isohumosol>Ferrosol, and we concluded that the Sb mobility in the soils also decreased in that order. PMID:27395817
Sources and remediation techniques for mercury contaminated soil.
Xu, Jingying; Bravo, Andrea Garcia; Lagerkvist, Anders; Bertilsson, Stefan; Sjöblom, Rolf; Kumpiene, Jurate
Mercury (Hg) in soils has increased by a factor of 3 to 10 in recent times mainly due to combustion of fossil fuels combined with long-range atmospheric transport processes. Other sources as chlor-alkali plants, gold mining and cement production can also be significant, at least locally. This paper summarizes the natural and anthropogenic sources that have contributed to the increase of Hg concentration in soil and reviews major remediation techniques and their applications to control soil Hg contamination. The focus is on soil washing, stabilisation/solidification, thermal treatment and biological techniques; but also the factors that influence Hg mobilisation in soil and therefore are crucial for evaluating and optimizing remediation techniques are discussed. Further research on bioremediation is encouraged and future study should focus on the implementation of different remediation techniques under field conditions. PMID:25454219
Electrokinetic In Situ Treatment of Metal-Contaminated Soil
NASA Technical Reports Server (NTRS)
Quinn, Jacqueline; Clausen, Christian A., III; Geiger, Cherie; Reinhart, Debra
An electrokinetic technique has been developed as a means of in situ remediation of soils, sludges, and sediments that are contaminated with heavy metals. Examples of common metal contaminants that can be removed by this technique include cadmium, chromium, zinc, lead, mercury, and radionuclides. Some organic contaminants can also be removed by this technique. In the electrokinetic technique, a low-intensity direct current is applied between electrodes that have been implanted in the ground on each side of a contaminated soil mass. The electric current causes electro-osmosis and migration of ions, thereby moving aqueous-phase subsurface contaminants from one electrode to the other. The half reaction at the anode yields H+, thereby generating an acid front that travels from the anode toward the cathode. As this acid front passes through a given location, the local increase in acidity increases the solubility of cations that were previously adsorbed on soil particles. Ions are transported towards one electrode or the other which one depending on their respective electric charges. Upon arrival at the electrodes, the ionic contaminants can be allowed to become deposited on the electrodes or can be extracted to a recovery system. Surfactants and other reagents can be introduced at the electrodes to enhance rates of removal of contaminants. Placements of electrodes and concentrations and rates of pumping of reagents can be adjusted to maximize efficiency. The basic concept of electrokinetic treatment of soil is not new. What is new here are some of the details of application and the utilization of this technique as an alternative to other techniques (e.g., flushing or bioremediation) that are not suitable for treating soils of low hydraulic conductivity. Another novel aspect is the use of this technique as a less expensive alternative to excavation: The cost advantage over excavation is especially large in settings in which contaminated soil lies near and/or under
Phytoremediation of Metal-Contaminated Soil for Improving Food Safety
NASA Astrophysics Data System (ADS)
Shilev, Stefan; Benlloch, Manuel; Dios-Palomares, R.; Sancho, Enrique D.
The contamination of the environment is a serious problem which provokes great interest in our society and in the whole scientific community. The input of metals into soils has increased during the last few decades as a consequence of different human activities (storage of industrial and municipal wastes, burning of fuels, mining and wastewater treatments, functioning of non-ferrous-metal-producing smelters, etc.). Nowadays, this type of contamination is one of the most serious concerning the chronic toxic effect which it renders on human health and the environment. As a consequence of all these activities, a huge number of toxic metals and metalloids, such as Cu, Zn, Pb, Cd, Hg and As, among many others, have been accumulated in soils, reaching toxic values. Unfortunately, much contaminated land is still in use for crop production, despite the danger that the metal content poses.
Chemical fingerprinting of hydrocarbon-contamination in soil.
Boll, Esther S; Nejrup, Jens; Jensen, Julie K; Christensen, Jan H
Chemical fingerprinting analyses of 29 hydrocarbon-contaminated soils were performed to assess the soil quality and determine the main contaminant sources. The results were compared to an assessment based on concentrations of the 16 priority polycyclic aromatic hydrocarbons pointed out by the U.S. Environmental Protection Agency (EPAPAH16) and total petroleum hydrocarbon (TPH). The chemical fingerprinting strategy proposed in this study included four tiers: (i) qualitative analysis of GC-FID chromatograms, (ii) comparison of the chemical composition of both un-substituted and alkyl-substituted polycyclic aromatic compounds (PACs), (iii) diagnostic ratios of selected PACs, and (iv) multivariate data analysis of sum-normalized PAC concentrations. The assessment criteria included quantitative analysis of 19 PACs and C1-C4 alkyl-substituted homologues of naphthalene, fluorene, dibenzothiophene, phenanthrene, pyrene, and chrysene; and 13 oxygenated polycyclic aromatic compounds (O-PACs). The chemical composition of un-substituted and alkyl-substituted PACs and visual interpretation of GC-FID chromatograms were in combination successful in differentiating pyrogenic and petrogenic hydrocarbon sources and in assessing weathering trends of hydrocarbon contamination in the soils. Multivariate data analysis of sum-normalized concentrations could as a stand-alone tool distinguish between hydrocarbon sources of petrogenic and pyrogenic origin, differentiate within petrogenic sources, and detect weathering trends. Diagnostic ratios of PACs were not successful for source identification of the heavily weathered hydrocarbon sources in the soils. The fingerprinting of contaminated soils revealed an underestimation of PACs in petrogenic contaminated soils when the assessment was based solely on EPAPAH16. As alkyl-substituted PACs are dominant in petrogenic sources, the evaluation of the total load of PACs based on EPAPAH16 was not representative. Likewise, the O-PACs are not
Changes in the structure and function of soil ecosystems in soils contaminated with heavy metals
Kuperman, R.; Parmelee, R.; Carreiro, M. ||
The structure and function of soil communities in an area with a wide range of concentrations of heavy metals was studied in portions of the U.S. Army`s Aberdeen Proving Ground, Maryland. The study included survey of soil macro- and microinvertebrate communities, soil microorganisms, enzyme activities and the rates of nutrient dynamics in soil. Soil macroinvertebrate communities showed significant reductions in the abundance of several taxonomic and functional groups in contaminated areas. The total numbers of nematodes and numbers of fungivore, bacterivore and omnivore-predator nematodes were lower in the more contaminated areas. The numbers of active bacteria and fungi were lower in areas of soil contamination. Significant reduction in the activities of all enzymes closely paralleled the increase in heavy metal concentrations. Ten-to-fifty fold reductions in enzyme activities were observed as heavy metal concentrations increased. These results suggest that soil contamination with heavy metals may have detrimental effects on soil biota and the rates of organic matter degradation and subsequent release of nutrients to aboveground communities in the area.
Changes in the structure and function of soil ecosystems in soils contaminated with heavy metals
Kuperman, R.; Parmelee, R.; Carreiro, M. ||
The structure and function of soil communities in an area with a wide range of concentrations of heavy metals was studied in portions of the U.S. Army`s Aberdeen Proving Ground, Maryland. The study included survey of soil macro- and microinvertebrate communities, soil microorganisms, enzyme activities and the rates of nutrient dynamics in soil. Soil macroinvertebrate communities showed significant reductions in the adundance of several taxonomic and functional groups in contaminated areas. The total numbers of nematodes and numbers of fungivore, bacterivore and omnivore-predator nematodes were lower in the more contaminated areas. The numbers of active bacteria and fungi were lower in areas of soil contamination. Significant reduction in the activities of all enzymes closely paralleled the increase in heavy metal concentrations. Ten-to-fifty fold reductions in enzyme activities were observed as heavy metal concentrations increased. These results suggest that soil contamination with heavy metals may have detrimental effects on soil biota and the rates of organic matter degradation and subsequent release of nutrients to aboveground communities in the area.
Heavy metal and organic chemical contamination of soils is a worldwide problem posing a risk to humans and more directly, soil organisms. Metal toxicity is often not directly related to the total concentration of metals present due to a number of modifying factors that depend,...
Interactive effects of Cd and PAHs on contaminants removal from co-contaminated soil planted with hyperaccumulator plant Sedum alfredii
Technology Transfer Automated Retrieval System (TEKTRAN)
Soil contamination by multiple organic and inorganic contaminants is common but its remediation by hyperaccumulator plants is rarely reported. The growth of a cadmium (Cd) hyperaccumulator Sedum alfredii and removal of contaminants from Cd and polycyclic aromatic hydrocarbons(PAHs) co-contaminated s...
[Bio-remediation techniques of crude oil contaminated soils].
Li, Peijun; Guo, Shuhai; Sun, Tieheng; Tai, Peidong; Zhang, Chungui; Bai, Yuxing; Sun, Qiang; Sheng, Ping
The bioremediation of soils contaminated by different types of petroleum were carried out with composting process in a prepared bed. By the measures of nutrient- and microbiological agent addition, and moisture- and pH control, an ideal environment for microbes were obtained. When total petroleum hydrocarbons, which consist of thin oil, high condensation oil, special viscous oil, and viscous oil, were in the range of 25.8-77.2 g.kg-1 dry soil, the petroleum removal rate could reach 38.37-56.74% by 2 months operation. The contents of aromatic hydrocarbon, asphaltum and resin were important factors controlling the degradation of petroleum. 6 fungi, 6 bacteria and 1 actinomyces were found to be the dominant strains for petroleum degradation. The results could provide theoretical bases for remediation of soil contaminated by petroleum. PMID:12625007
Phytoremediation of heavy metal contaminated soil by Jatropha curcas.
Chang, Fang-Chih; Ko, Chun-Han; Tsai, Ming-Jer; Wang, Ya-Nang; Chung, Chin-Yi
This study employed Jatropha curcas (bioenergy crop plant) to assist in the removal of heavy metals from contaminated field soils. Analyses were conducted on the concentrations of the individual metals in the soil and in the plants, and their differences over the growth periods of the plants were determined. The calculation of plant biomass after 2 years yielded the total amount of each metal that was removed from the soil. In terms of the absorption of heavy metal contaminants by the roots and their transfer to aerial plant parts, Cd, Ni, and Zn exhibited the greatest ease of absorption, whereas Cu, Cr, and Pb interacted strongly with the root cells and remained in the roots of the plants. J. curcas showed the best absorption capability for Cd, Cr, Ni, and Zn. This study pioneered the concept of combining both bioremediation and afforestation by J. curcas, demonstrated at a field scale. PMID:25236867
Electrokinetic treatment of firing ranges containing tungsten-contaminated soils.
Braida, Washington; Christodoulatos, Christos; Ogundipe, Adebayo; Dermatas, Dimitris; O'Connor, Gregory
Tungsten-based alloys and composites are being used and new formulations are being considered for use in the manufacturing of different types of ammunition. The use of tungsten heavy alloys (WHA) in new munitions systems and tungsten composites in small caliber ammunition could potentially release substantial amounts of this element into the environment. Although tungsten is widely used in industrial and military applications, tungsten's potential environmental and health impacts have not been thoroughly addressed. This necessitates the research and development of remedial technologies to contain and/or remove tungsten from soils that may serve as a source for water contamination. The current work investigates the feasibility of using electrokinetics for the remediation of tungsten-contaminated soils in the presence of other heavy metals of concern such as Cu and Pb with aim to removing W from the soil while stabilizing in situ, Pb and Cu. PMID:17686582
Electrokinetic remediation of six emerging organic contaminants from soil.
Guedes, Paula; Mateus, Eduardo P; Couto, Nazaré; Rodríguez, Yadira; Ribeiro, Alexandra B
Some organic contaminants can accumulate in organisms and cause irreversible damages in biological systems through direct or indirect toxic effects. In this study the feasibility of the electrokinetic (EK) process for the remediation of 17β-oestradiol (E2), 17α-ethinyloestradiol (EE2), bisphenol A (BPA), nonylphenol (NP), octylphenol (OP) and triclosan (TCS) in soils was studied in a stationary laboratory cell. The experiments were conducted using a silty loam soil (S2) at 0, 10 and 20mA and a sandy soil (S3) at 0 and 10 mA. A pH control in the anolyte reservoir (pH>13) at 10 mA was carried out using S2, too. Photo and electrodegradation experiments were also fulfilled. Results showed that EK is a viable method for the remediation of these contaminants, both through mobilization by electroosmotic flow (EOF) and electrodegradation. As EOF is very sensible to soil pH, the control in the anolyte increased EOF rate, consequently enhancing contaminants mobilization towards the cathode end. The extent of the mobilization towards the electrode end was mainly dependent on compounds solubility and octanol-water partition coefficient. In the last 24h of experiments, BPA presented the highest mobilization rate (ca. 4 μg min(-1)) with NP not being detected in the catholyte. At the end of all experiments the percentage of contaminants that remained in the soil ranged between 17 and 50 for S2, and between 27 and 48 for S3, with no statistical differences between treatments. The mass balance performed showed that the amount of contaminant not detected in the cell is similar to the quantity that potentially may suffer photo and electrodegradation. PMID:24997283
Identifying root exudates in field contaminated soil systems
NASA Astrophysics Data System (ADS)
Rosenfeld, C.; Martinez, C. E.
Carbon (C) compounds exuded from plant roots comprise a significant and reactive fraction of belowground C pools. These exudates substantially alter the soil directly surrounding plant roots and play a vital role in the global C cycle, soil ecology, and ecosystem mobility of both nutrients and contaminants. In soils, the solubility and bioavailability of metals such as iron, zinc, and cadmium are intricately linked to the quantity and chemical characteristics of the C compounds allocated to the soil by plants. Cadmium (Cd), a toxic heavy metal, forms stronger bonds with reduced S- and N-containing compounds than with carboxylic acids, which may influence exudate composition in hyperaccumulator and tolerant plants grown in Cd contaminated soils. We hypothesize that hyperaccumulator plants will exude a larger quantity of aromatic N and chelating di- and tri-carboxylic acid molecules, while plants that exclude heavy metals from uptake will exude a larger proportion of reduced S containing molecules. This study examines how a variety of techniques can measure the low concentrations of complex organic mixtures exuded by hyperaccumulator and non-hyperaccumulator plants grown in Cd-contaminated soils. Two congeneric plants, Thlaspi caerulescens (Ganges ecotype), and T. caerulescens (Prayon ecotype) were grown in 0.5 kg pots filled with Cd-contaminated field soils from Chicago, IL. Field soils were contaminated as a result of the application of contaminated biosolids in the 1960's and 1970's. Pots were fitted for rhizon soil moisture samplers, micro-lysimeters developed for in situ collection of small volumes in unsaturated soils, prior to planting. Plants were grown for 8 weeks before exudate collection. After the 8 weeks of growth, a pulse-chase isotope tracer method using the C stable isotope, 13C, was employed to differentiate plant-derived compounds from background soil and microbial-derived compounds. Plants were placed in a CO2 impermeable chamber, and the soil
Assessment of lead bioaccessibility in peri-urban contaminated soils.
Smith, Euan; Weber, John; Naidu, Ravi; McLaren, Ronald G; Juhasz, Albert L
Lead (Pb) bioaccessibility was assessed in a range of peri-urban soils (n=31) with differing sources of Pb contamination, including shooting range soils, and soils affected by incinerator, historical fill, mining/smelting, and gasworks activities. A gossan soil sample was also included. Lead bioaccessibility was determined using both gastric and intestinal phases of the SBRC in vitro assay and in vitro data was then incorporated into in vivo-in vitro regression equations to calculate Pb relative bioavailability. Lead bioaccessibility ranged from 26.8-105.2% to 5.5-102.6% for gastric and intestinal phase extractions respectively. Generally, Pb bioaccessibility was highest in the shooting range soils and lowest in the gossan soil. Predictions of relative Pb bioavailability derived from in vitro data were comparable for shooting ranges soils, but highly variable for the other soils examined. For incinerator, historical fill, gasworks and gossan soils, incorporating in vitro gastric data into the in vivo-in vitro regression equation resulting in more conservative Pb relative bioavailability values than those derived using the intestinal in vitro data. PMID:21115224
Overcoming phytoremediation limitations. A case study of Hg contaminated soil
NASA Astrophysics Data System (ADS)
Barbafieri, Meri
Phytoremediation is a broad term that comprises several technologies to clean up water and soil. Despite the numerous articles appearing in scientific journals, very few field applications of phytoextraction have been successfully realized. The research here reported on Phytoextraction, the use the plant to "extract" metals from contaminated soil, is focused on implementations to overcome two main drawbacks: the survival of plants in unfavorable environmental conditions (contaminant toxicity, low fertility, etc.) and the often lengthy time it takes to reduce contaminants to the requested level. Moreover, to overcome the imbalance between the technology's potential and its drawbacks, there is growing interest in the use of plants to reduce only the fraction that is the most hazardous to the environment and human health, that is to target the bioavailable fractions of metals in soil. Bioavailable Contaminant Stripping (BCS) would be a remediation approach focused to remove the bioavailable metal fractions. BCS have been used in a mercury contaminated soil from Italian industrial site. Bioavailable fractions were determined by sequential extraction with H2O and NH4Cl.Combined treatments of plant hormone and thioligand to strength Hg uptake by crop plants (Brassica juncea and Helianthus annuus) were tested. Plant biomass, evapotranspiration, Hg uptake and distribution following treatments were compared. Results indicate the plant hormone, cytokinine (CK) foliar treatment, increased evapotranspiration rate in both tested plants. The Hg uptake and translocation in both tested plants increased with simultaneous addition of CK and TS treatments. B. juncea was the most effective in Hg uptake. Application of CK to plants grown in TS-treated soil lead to an increase in Hg concentration of 232% in shoots and 39% in roots with respect to control. While H. annuus gave a better response in plant biomass production, the application of CK to plants grown in TS-treated soil lead to
This project involved the evaluation of solidification/stabilization technology as a BDAT for contaminated soil. Three binding agents were used on four different synthetically contaminated soils. Performance evaluation data included unconfined compressive strength (UCS) and the T...
Assessing the bioavailability and risk from metal-contaminated soils and dusts
Exposure to contaminated soil and dust is an important pathway in human health risk assessment. Physical and chemical characteristics, as well as biological factors, determine the bioaccessibility/bioavailability of soil and dust contaminants. Within a single sample, contaminat...
Enhancing agents for phytoremediation of soil contaminated by cyanophos.
Ali Romeh, Ahmed
Cyanophos is commonly used in Egypt to control various agricultural and horticultural pests. It is a strong contaminant in the crop culturing environments because it is highly persistent and accumulates in the soil. This contaminant can be removed by phytoremediation, which is the use of plants to clean-up pollutants. Here we tested several several strategies to improve the effectiveness of this technology, which involved various techniques to solubilize contaminants. The phytoremediation efficiency of Plantago major L. was improved more by liquid silicon dioxide (SiO₂) than by other solubility-enhancing agents, resulting in the removal of significant amounts of cyanophos from contaminated soil. Liquid SiO₂ increased the capacity of P. major L. to remove cyanophos from soil by 45.9% to 74.05%. In P. major L. with liquid SiO₂, leaves extracted more cyanophos (32.99 µg/g) than roots (13.33 µg/g) over 3 days. The use of solubilization agents such as surfactants, hydroxypropyl-ß-cyclodextrin (HPßCD), natural humic acid acid (HA), and Tween 80 resulted in the removal of 60 convergents of cyanophos from polluted soil. Although a batch equilibrium technique showed that use of HPßCD resulted in the efficient removal of cyanophos from soil, a greater amount of cyanophos was removed by P. major L. with SiO₂. Moreover, a large amount of cyanophos was removed from soil by rice bran. This study indicates that SiO₂ can improve the efficiency of phytoremediation of cyanophos. PMID:25847752
Ecotoxicity of a polycyclic aromatic hydrocarbon (PAH)-contaminated soil.
Eom, I C; Rast, C; Veber, A M; Vasseur, P
Soil samples from a former cokery site polluted with polycyclic aromatic hydrocarbons (PAHs) were assessed for their toxicity to terrestrial and aquatic organisms and for their mutagenicity. The total concentration of the 16 PAHs listed as priority pollutants by the US Environmental Protection Agency (US-EPA) was 2634+/-241 mg/kgdw in soil samples. The toxicity of water-extractable pollutants from the contaminated soil samples was evaluated using acute (Vibrio fischeri; Microtox test, Daphnia magna) and chronic (Pseudokirchneriella subcapitata, Ceriodaphnia dubia) bioassays and the EC values were expressed as percentage water extract in the test media (v/v). Algal growth (EC50-3d=2.4+/-0.2% of the water extracts) and reproduction of C. dubia (EC50-7d=4.3+/-0.6%) were the most severely affected, compared to bacterial luminescence (EC50-30 min=12+/-3%) and daphnid viability (EC50-48 h=30+/-3%). The Ames and Mutatox tests indicated mutagenicity of water extracts, while no response was found with the umu test. The toxicity of the soil samples was assessed on the survival and reproduction of earthworms (Eisenia fetida) and collembolae (Folsomia candida), and on the germination and growth of higher plants (Lactuca sativa L.: lettuce and Brassica chinensis J.: Chinese cabbage). The EC50 values were expressed as percentage contaminated soil in ISO soil test medium (weight per weight-w/w) and indicated severe effects on reproduction of the collembola F. candida (EC50-28 d=5.7%) and the earthworm E. fetida (EC50-28 d=18% and EC50-56 d=8%, based on cocoon and juvenile production, respectively). Survival of collembolae was already affected at a low concentration of the contaminated soil (EC50-28 d=11%). The viability of juvenile earthworms was inhibited at much lower concentrations of the cokery soil (EC50-14 d=28%) than the viability of adults (EC50-14 d=74%). Only plant growth was inhibited (EC50-17d=26%) while germination was not. Chemical analyses of water extracts allowed
Evaluation of soil flushing of complex contaminated soil: an experimental and modeling simulation study.
Yun, Sung Mi; Kang, Christina S; Kim, Jonghwa; Kim, Han S
The removal of heavy metals (Zn and Pb) and heavy petroleum oils (HPOs) from a soil with complex contamination was examined by soil flushing. Desorption and transport behaviors of the complex contaminants were assessed by batch and continuous flow reactor experiments and through modeling simulations. Flushing a one-dimensional flow column packed with complex contaminated soil sequentially with citric acid then a surfactant resulted in the removal of 85.6% of Zn, 62% of Pb, and 31.6% of HPO. The desorption distribution coefficients, KUbatch and KLbatch, converged to constant values as Ce increased. An equilibrium model (ADR) and nonequilibrium models (TSNE and TRNE) were used to predict the desorption and transport of complex contaminants. The nonequilibrium models demonstrated better fits with the experimental values obtained from the column test than the equilibrium model. The ranges of KUbatch and KLbatch were very close to those of KUfit and KLfit determined from model simulations. The parameters (R, β, ω, α, and f) determined from model simulations were useful for characterizing the transport of contaminants within the soil matrix. The results of this study provide useful information for the operational parameters of the flushing process for soils with complex contamination. PMID:25698434
Sand amendment enhances bioelectrochemical remediation of petroleum hydrocarbon contaminated soil.
Li, Xiaojing; Wang, Xin; Ren, Zhiyong Jason; Zhang, Yueyong; Li, Nan; Zhou, Qixing
Bioelectrochemical system is an emerging technology for the remediation of soils contaminated by petroleum hydrocarbons. However, performance of such systems can be limited by the inefficient mass transport in soil. Here we report a new method of sand amendment, which significantly increases both oxygen and proton transports, resulting to increased soil porosity (from 44.5% to 51.3%), decreased Ohmic resistance (by 46%), and increased charge output (from 2.5 to 3.5Cg(-1)soil). The degradation rates of petroleum hydrocarbons increased by up to 268% in 135d. The degradation of n-alkanes and polycyclic aromatic hydrocarbons with high molecular weight was accelerated, and denaturing gradient gel electrophoresis showed that the microbial community close to the air-cathode was substantially stimulated by the induced current, especially the hydrocarbon degrading bacteria Alcanivorax. The bioelectrochemical stimulation imposed a selective pressure on the microbial community of anodes, including that far from the cathode. These results suggested that sand amendment can be an effective approach for soil conditioning that will enhances the bioelectrochemical removal of hydrocarbons in contaminated soils. PMID:26135976
Cytotoxic and genotoxic potential of tannery waste contaminated soils.
Masood, Farhana; Malik, Abdul
Soil samples from agricultural fields in the vicinity of industrial area of Jajmau, Kanpur (India) were collected and found to be heavily contaminated with various toxic heavy metals. GC-MS analysis revealed the presence of organic compounds mainly phthalates in contaminated soils. Samples were extracted using dichloromethane (DCM) and hexane solvents, and the extracts were assayed for genotoxic potential using three different bioassays namely Ames Salmonella/mammalian microsome test, DNA repair defective Escherichia coli K-12 mutants and Allium cepa chromosomal aberration assay. TA98 was found to be the most sensitive strain to all the soil extracts tested. The highest mutagenic potential was observed in DCM extracts of soil as compared with hexane extracts for each strain of Salmonella typhimurium. DCM extracts of the soil exhibited maximum damage to the cells at a dose of 40 μl of soil extracts/ml of culture after a 6-h treatment. The survival was 23% in polA, 40% in lexA and 53% in recA mutants when treated with DCM extract of site I. In A. cepa assay, all the test concentrations of soil extracts (5-100%) affected mitotic index in a dose-dependent manner and several types of abnormalities were observed at different mitotic stages with the treatments: C-mitosis, anaphase bridges, laggards, binucleated cells, stickiness, broken and unequal distributions of chromosomes at anaphase stage of cell division. The soil is accumulating a large number of pollutants as a result of wastewater irrigation and this practice of accumulation has an adverse impact on soil health. PMID:23268142
[Mixture Leaching Remediation Technology of Arsenic Contaminated Soil].
Chen, Xun-feng; Li, Xiao-ming; Chen, Can; Yang, Qi; Deng, Lin-jing; Xie, Wei-qiang; Zhong, Yui; Huang, Bin; Yang, Wei-qiang; Zhang, Zhi-bei
Soil contamination of arsenic pollution has become a severely environmental issue, while soil leaching is an efficient method for remediation of arsenic-contaminated soil. In this study, batch tests were primarily conducted to select optimal mixture leaching combination. Firstly, five conventional reagents were selected and combined with each other. Secondly, the fractions were analyzed before and after the tests. Finally, to explore the feasibility of mixed leaching, three soils with different arsenic pollution levels were used to compare the leaching effect. Comparing with one-step washing, the two-step sequential washing with different reagents increased the arsenic removal efficiency. These results showed that the mixture of 4 h 0.5 mol · L⁻¹ NaOH + 4 h 0.1 mol · L⁻¹ EDTA was found to be practicable, which could enhance the removal rate of arsenic from 66.67% to 91.83%, and the concentration of arsenic in soil was decreased from 186 mg · kg⁻¹ to 15.2 mg · kg⁻¹. Furthermore, the results indicated that the distribution of fractions of arsenic in soil changed apparently after mixture leaching. Leaching process could significantly reduce the available contents of arsenic in soil. Moreover, the mixture of 0.5 mol · L⁻¹ NaOH + 0.1 mol L⁻¹ EDTA could well decrease the arsenic concentration in aluminum-type soils, while the mixture of 0.5 mol · L⁻¹ OX + 0.5 mol · L⁻¹ NaOH could well decrease the arsenic concentration in iron-type soils. PMID:27337912
Chelant extraction of heavy metals from contaminated soils.
Peters, R W
The current state of the art regarding the use of chelating agents to extract heavy metal contaminants has been addressed. Results are presented for treatability studies conducted as worst-case and representative soils from Aberdeen Proving Ground's J-Field for extraction of copper (Cu), lead (Pb), and zinc (Zn). The particle size distribution characteristics of the soils determined from hydrometer tests are approximately 60% sand, 30% silt, and 10% clay. Sequential extractions were performed on the 'as-received' soils (worst case and representative) to determine the speciation of the metal forms. The technique speciates the heavy metal distribution into an easily extractable (exchangeable) form, carbonates, reducible oxides, organically-bound, and residual forms. The results indicated that most of the metals are in forms that are amenable to soil washing (i.e. exchangeable+carbonate+reducible oxides). The metals Cu, Pb, Zn, and Cr have greater than 70% of their distribution in forms amenable to soil washing techniques, while Cd, Mn, and Fe are somewhat less amenable to soil washing using chelant extraction. However, the concentrations of Cd and Mn are low in the contaminated soil. From the batch chelant extraction studies, ethylenediaminetetraacetic acid (EDTA), citric acid, and nitrilotriacetic acid (NTA) were all effective in removing copper, lead, and zinc from the J-Field soils. Due to NTA being a Class II carcinogen, it is not recommended for use in remediating contaminated soils. EDTA and citric acid appear to offer the greatest potential as chelating agents to use in soil washing the Aberdeen Proving Ground soils. The other chelating agents studied (gluconate, oxalate, Citranox, ammonium acetate, and phosphoric acid, along with pH-adjusted water) were generally ineffective in mobilizing the heavy metals from the soils. The chelant solution removes the heavy metals (Cd, Cu, Pb, Zn, Fe, Cr, As, and Hg) simultaneously. Using a multiple-stage batch extraction
The effect of soil type on the bioremediation of petroleum contaminated soils.
Haghollahi, Ali; Fazaelipoor, Mohammad Hassan; Schaffie, Mahin
In this research the bioremediation of four different types of contaminated soils was monitored as a function of time and moisture content. The soils were categorized as sandy soil containing 100% sand (type I), clay soil containing more than 95% clay (type II), coarse grained soil containing 68% gravel and 32% sand (type III), and coarse grained with high clay content containing 40% gravel, 20% sand, and 40% clay (type IV). The initially clean soils were contaminated with gasoil to the concentration of 100 g/kg, and left on the floor for the evaporation of light hydrocarbons. A full factorial experimental design with soil type (four levels), and moisture content (10 and 20%) as the factors was employed. The soils were inoculated with petroleum degrading microorganisms. Soil samples were taken on days 90, 180, and 270, and the residual total petroleum hydrocarbon (TPH) was extracted using soxhlet apparatus. The moisture content of the soils was kept almost constant during the process by intermittent addition of water. The results showed that the efficiency of bioremediation was affected significantly by the soil type (Pvalue < 0.05). The removal percentage was the highest (70%) for the sandy soil with the initial TPH content of 69.62 g/kg, and the lowest for the clay soil (23.5%) with the initial TPH content of 69.70 g/kg. The effect of moisture content on bioremediation was not statistically significant for the investigated levels. The removal percentage in the clay soil was improved to 57% (within a month) in a separate experiment by more frequent mixing of the soil, indicating low availability of oxygen as a reason for low degradation of hydrocarbons in the clay soil. PMID:27233045
Electrokinetic treatment of contaminated soils, sludges, and lagoons. Final report
Wittle, J.K.; Pamukcu, S.
The electrokinetic process is an emerging technology for in-situ soil decontamination, in which chemical species, both ionic and nonionic are transported to an electrode site in soil. These products are subsequently removed from the ground via collection systems engineered for each specific application. Electrokinetics refer to movement of water, ions and charged particles relative to one another under the action of an applied direct current electric field. In a porous compact matrix of surface charged particles such as soil, the ion containing pore fluid may be made to flow to collection sites under the applied field. This report describes the effort undertaken to investigate electrokinetically enhanced transport of soil contaminants in synthetic systems. These systems consisted of clay or clay-sand mixtures containing known concentration of a selected heavy metal salt solution or an organic compound. Metals, surrogate radio nuclides and organic compounds evaluated in the program were representatives of those found at a majority of DOE sites. Degree of removal of these metals from soil by the electrokinetic treatment process was assessed through the metal concentration profiles generated across the soil between the electrodes. The best removals, from about 85 to 95% were achieved at the anode side of the soil specimens. Transient pH change had an effect on the metal movement via transient creation of different metal species with different ionic mobilities, as well as changing of the surface characteristics of the soil medium.
Subchronic exposure of mice to Love Canal soil contaminants
Silkworth, J.B.; McMartin, D.N.; Rej, R.; Narang, R.S.; Stein, V.B.; Briggs, R.G.; Kaminsky, L.S.
The health hazard potential of soil collected from the surface of the Love Canal chemical dump site in Niagara Falls, New York, was assessed in 90-day exposure studies. Female CD-1 mice were exposed to two concentrations of the volatile components of 1 kg of soil with and without direct soil contact. Control mice were identically housed but without soil. The soil was replaced weekly and 87 compounds were detected in the air in the cages above fresh and 7-day-old soil as analyzed by gas chromatography/mass spectrometry. The concentration of many of these compounds decreased during the 7-day exposure cycle. Histopathologic, hematologic, and serum enzyme studies followed necropsy of all mice. There was no mortality of mice exposed for up to 90 days under any condition. Thymus and spleen weights relative to body weight were increased after 4 weeks of exposure by inhalation but not after 8 or 12 weeks of exposure. alpha-, beta-, and delta- Benzenehexachlorides , pentachlorobenzene, and hexachlorobenzene were detected in liver tissue from these animals. Mice exposed to 5- to 10-fold elevated concentration of volatiles had increased body and relative kidney weights. There was no chemically induced lesion in any animal exposed only to the volatile soil contaminants. Mice exposed by direct contact with the soil without elevated volatile exposure had increased body (10%) and relative liver weights (169%). Centrolobular hepatocyte hypertrophy, which involved 40 to 70% of the lobules, was observed in all mice in this group.
Investigating the control of mercury volatilization from contaminated soil
NASA Astrophysics Data System (ADS)
Steffy, D. A.; Nichols, A.
In previous investigations of growing earthworms, Lumbricus terrestris, in contaminated soil, we have found that volatilization of mercury (Hg) to be an active process. The question to be answered is what causes the reduction of Hg to a more volatile state in the soil, could it be the earthworms? A series of laboratory tests were conducted to determine the mechanism of Hg reduction. The tests revealed that earthworms bioaccumulate the Hg in their tissue, but do not aid in the reduction process. Microbial reduction of the Hg appears to be the mechanism. Two dissimilar soil types were tested; both were heated for 96 hours at 100oC. After cooling, both soil types were spiked with 100 mg of Hg per Kg of soil. Integrated Hg vapor samples were collected immediately above the soil surface over a 3 day period and analyzed by cold vapor atomic adsorption. After heat treatment both soil types had a statistically significantly higher rate of volatilization than unheated soils. We interpret this result as indicating that heating preferentially selected microbial spores that facilitated the Hg reduction.
Effects of past copper contamination and soil structure on copper leaching from soil.
Paradelo, Marcos; Moldrup, Per; Arthur, Emmanuel; Naveed, Muhammad; Holmstrup, Martin; López-Periago, Jose E; de Jonge, Lis W
Copper contamination affects biological, chemical, and physical soil properties and associated ecological functions. Changes in soil pore organization as a result of Cu contamination can dramatically affect flow and contaminant transport in polluted soils. This study assessed the influence of soil structure on the movement of water and Cu in a long-term polluted soil. Undisturbed soil cores collected along a Cu gradient (from about 20 to about 3800 mg Cu kg soil) were scanned using X-ray computed tomography (CT). Leaching experiments were performed to analyze tracer transport, colloid leaching, and dissolved organic carbon (DOC) and Cu losses. The 5% arrival time () and apparent dispersivity (λ) for tracer breakthrough were calculated by fitting the experimental data to a nonparametric, double-lognormal probability density function. Soil bulk density, which did not follow the Cu gradient, was the main driver of preferential flow, while macroporosity determined by X-ray CT (for pores >180 μm) proved the best predictor of solute transport. Higher preferential flow due to the presence of well-aligned pores and small cracks controlled water movement in compacted soil. Transport of Cu was rapid during the first flush (≈1 pore volume) in association with the movement of colloid particles, followed by slower transport in association with the movement of DOC in the soil solution. The relative amount of Cu released was strongly correlated with macroporosity as determined by X-ray CT, indicating the promising potential of this visualization technique for predicting contaminant transport through soil. PMID:25602425
Electroremediation of PCB contaminated soil combined with iron nanoparticles: Effect of the soil type.
Gomes, Helena I; Dias-Ferreira, Celia; Ottosen, Lisbeth M; Ribeiro, Alexandra B
Polychlorinated biphenyls (PCB) are carcinogenic and persistent organic pollutants that accumulate in soils and sediments. Currently, there is no cost-effective and sustainable remediation technology for these contaminants. In this work, a new combination of electrodialytic remediation and zero valent iron particles in a two-compartment cell is tested and compared to a more conventional combination of electrokinetic remediation and nZVI in a three-compartment cell. In the new two-compartment cell, the soil is suspended and stirred simultaneously with the addition of zero valent iron nanoparticles. Remediation experiments are made with two different historically PCB contaminated soils, which differ in both soil composition and contamination source. Soil 1 is a mix of soils with spills of transformer oils, while Soil 2 is a superficial soil from a decommissioned school where PCB were used as windows sealants. Saponin, a natural surfactant, was also tested to increase the PCB desorption from soils and enhance dechlorination. Remediation of Soil 1 (with highest pH, carbonate content, organic matter and PCB concentrations) obtained the maximum 83% and 60% PCB removal with the two-compartment and the three-compartment cell, respectively. The highest removal with Soil 2 were 58% and 45%, in the two-compartment and the three-compartment cell, respectively, in the experiments without direct current. The pH of the soil suspension in the two-compartment treatment appears to be a determining factor for the PCB dechlorination, and this cell allowed a uniform distribution of the nanoparticles in the soil, while there was iron accumulation in the injection reservoir in the three-compartment cell. PMID:25841071
Migration of Contaminated Soil and Airborne Particulates to Indoor Dust
Layton, David W.; Beamer, Paloma I.
We have developed a modeling and measurement framework for assessing transport of contaminated soils and airborne particulates into a residence, their subsequent distribution indoors via resuspension and deposition processes, and removal by cleaning and building exhalation of suspended particles. The model explicitly accounts for the formation of house dust as a mixture of organic matter (OM) such as shed skin cells and organic fibers, soil tracked-in on footwear, and particulate matter (PM) derived from the infiltration of outdoor air. We derived formulas for use with measurements of inorganic contaminants, crustal tracers, OM, and PM to quantify selected transport parameters. Application of the model to residences in the U.S. Midwest indicates that As in ambient air can account for nearly 60% of the As input to floor dust, with soil track-in representing the remainder. Historic data on Pb contamination in Sacramento, CA, was used to reconstruct sources of Pb in indoor dust, showing that airborne Pb was likely the dominant source in the early 1980s. However, as airborne Pb levels declined due to the phase out of leaded gasoline, soil resuspension and track-in eventually became the primary sources of Pb in house dust. PMID:19924944
Organochlorinated pesticide degrading microorganisms isolated from contaminated soil.
Lovecka, Petra; Pacovska, Iva; Stursa, Petr; Vrchotova, Blanka; Kochankova, Lucie; Demnerova, Katerina
Degradation of selected organochlorinated pesticides (γ-hexachlorocyclohexane - γ-HCH, dichlorodiphenyltrichloroethane - DDT, hexachlorobenzene - HCB) by soil microorganisms was studied. Bacterial strains isolated from contaminated soil from Klatovy-Luby, Hajek and Neratovice, Czech Republic, capable of growth on the selected pesticides were isolated and characterised. These isolates were subjected to characterisation and identification by MS MALDI-TOF of whole cells and sequence analysis of 16S rRNA genes. The isolates were screened by gas chromatography for their ability to degrade the selected pesticides. Some isolates were able to degrade pesticides, and the formation of degradation products (γ-pentachlorocyclohexane (γ-PCCH), dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD)) observed in liquid culture confirmed their degradation capability. The isolates and DNA samples isolated from the contaminated soil were also screened for the bphA1 gene (encoding biphenyl-2,3-dioxygenase, the first enzyme in the PCB degradation pathway) and its occurrence was demonstrated. The isolates were also screened for the presence of linA, encoding dehydrochlorinase, the first enzyme of the HCH degradation pathway. The linA gene could not be found in any of the tested isolates, possibly due to the high specificity of the primers used. The isolates with the most effective degradation abilities could be used for further in situ bioremediation experiments with contaminated soil. PMID:25094051
Characterization of bacterial communities in heavy metal contaminated soils.
Roane, T M; Kellogg, S T
Heavy metal pollution is a principle source of environmental contamination. We analyzed heavy metal impacted soil microbial communities and found that, in general, although lead adversely affected biomass, metabolic activity, and diversity, autochthonous lead- and cadmium-resistant isolates were found. In several metal-stressed soils, the microbial community consisted of two populations, either resistant or sensitive to lead. Additionally, a lead-resistant isolate was isolated from a control soil with no known previous exposure to lead, suggesting widespread lead resistance. Lead-resistant genera isolated included Pseudomonas, Bacillus, Corynebacterium, and Enterobacter species. Plasmids, ranging from 5 to 260 kb, were not detected through standard purifications from lead-resistant isolates. Positive correlations existed between antibiotic resistance and isolation habitat for lead-resistant strains, microbial metabolic activity and soil type, soluble lead concentration and microbial diversity, and arsenic concentration and total or viable cell concentrations. PMID:8801006
Metal contamination of vineyard soils in wet subtropics (southern Brazil).
Mirlean, Nicolai; Roisenberg, Ari; Chies, Jaqueline O
The vine-growing areas in Brazil are the dampest in the world. Copper maximum value registered in this study was as much as 3200 mg kg(-1), which is several times higher than reported for vineyard soils in temperate climates. Other pesticide-derived metals accumulate in the topsoil layer, surpassing in the old vineyards the background value several times for Zn, Pb, Cr and Cd. Copper is transported to deeper soils' horizons and can potentially contaminate groundwater. The soils from basaltic volcanic rocks reveal the highest values of Cu extracted with CaCl(2), demonstrating a high capacity of copper transference into plants. When evaluating the risks of copper's toxic effects in subtropics, the soils from rhyolitic volcanic rocks are more worrisome, as the Cu extracted with ammonium acetate 1M surpasses the toxic threshold as much as 4-6 times. PMID:17321651
Sources of arsenic and fluoride in highly contaminated soils causing groundwater contamination in Punjab, Pakistan
Farooqi, A.; Masuda, H.; Siddiqui, R.; Naseem, M.
Highly contaminated groundwater, with arsenic (As) and fluoride (F{sup -}) concentrations of up to 2.4 and 22.8 mg/L, respectively, has been traced to anthropogenic inputs to the soil. In the present study, samples collected from the soil surface and sediments from the most heavily polluted area of Punjab were analyzed to determine the F{sup -} and As distribution in the soil. The surface soils mainly comprise permeable aeolian sediment on a Pleistocene terrace and layers of sand and silt on an alluvial flood plain. Although the alluvial sediments contain low levels of F, the terrace soils contain high concentrations of soluble F{sup -} (maximum, 16 mg/kg; mean, 4 mg/kg; pH > 8.0). Three anthropogenic sources were identified as fertilizers, combusted coal, and industrial waste, with phosphate fertilizer being the most significance source of F{sup -} accumulated in the soil. The mean concentration of As in the surface soil samples was 10.2 mg/kg, with the highest concentration being 35 mg/kg. The presence of high levels of As in the surface soil implies the contribution of air pollutants derived from coal combustion and the use of fertilizers. Intensive mineral weathering under oxidizing conditions produces highly alkaline water that dissolves the F{sup -} and As adsorbed on the soil, thus releasing it into the local groundwater.
Geochemistry Of Lead In Contaminated Soils: Effects Of Soil Physico-Chemical Properties
NASA Astrophysics Data System (ADS)
Saminathan, S.; Sarkar, D.; Datta, R.; Andra, S. P.
Lead (Pb) is an environmental contaminant with proven human health effects. When assessing human health risks associated with Pb, one of the most common exposure pathways typically evaluated is soil ingestion by children. However, bioaccessibility of Pb primarily depends on the solubility and hence, the geochemical form of Pb, which in turn is a function of site specific soil chemistry. Certain fractions of ingested soil-Pb may not dissociate during digestion in the gastro-intestinal tract, and hence, may not be available for transport across the intestinal membrane. Therefore, this study is being currently performed to assess the geochemical forms and bioaccessibility of Pb in soils with varying physico-chemical properties. In order to elucidate the level of Pb that can be ingested and assimilated by humans, an in-vitro model that simulates the physiological conditions of the human digestive system has been developed and is being used in this study. Four different types of soils from the Immokalee (an acid sandy soil with minimal Pb retention potential), Millhopper (a sandy loam with high Fe/Al content), Pahokee (a muck soil with more than 80% soil organic matter), and Tobosa series (an alkaline soil with high clay content) were artificially contaminated with Pb as lead nitrate at the rate equivalent to 0, 400, 800, and 1200 mg/kg dry soil. Analysis of soils by a sequential extraction method at time zero (immediately after spiking) showed that Immokalee and Millhopper soils had the highest amount of Pb in exchangeable form, whereas Pahokee and Tobosa soils had higher percentages of carbonate-bound and Fe/Al-bound Pb. The results of in-vitro experiment at time zero showed that majority of Pb was dissolved in the acidic stomach environment in Immokalee, Millhopper, and Tobosa, whereas it was in the intestinal phase in Pahokee soils. Because the soil system is not in equilibrium at time zero, the effect of soil properties on Pb geochemistry is not clear as yet. The
Diuron mobility through vineyard soils contaminated with copper.
Jacobson, Astrid R; Dousset, Sylvie; Guichard, Nathalie; Baveye, Philippe; Andreux, Francis
The herbicide diuron is frequently applied to vineyard soils in Burgundy, along with repeated treatments with Bordeaux mixture (a blend of copper sulfate and calcium hydroxide) that result in elevated copper concentrations. Cu could in principle affect the fate and transport of diuron or its metabolites in the soil either directly by complexation or indirectly by altering the populations or activity of microbes involved in their degradation. To assess the effect of high Cu concentrations on diuron transport, an experiment was designed with ten undisturbed columns of calcareous and acidic soils contaminated with 17--509 mg kg(-1) total Cu (field-applied). Grass was planted on three columns. Diuron was applied to the soils in early May and in-ground lysimeters were exposed to outdoor conditions until November. Less than 1.2% of the diuron applied was found in the leachates as diuron or its metabolites. Higher concentrations were found in the effluents from the grass-covered columns (0.1--0.45%) than from the bare-soil columns (0.02--0.14%), and they were correlated with increases in dissolved organic carbon. The highest amounts of herbicide were measured in acidic-soil column leachates (0.98--1.14%) due to the low clay and organic matter contents of these soils. Cu also leached more readily through the acidic soils (32.8--1042 microg) than in the calcareous soils (9.5--63.4 microg). Unlike in the leachates, the amount of diuron remaining in the soils at the end of the experiment was weakly related to the Cu concentrations in the soils. PMID:15951080
Effect Of Soil Properties On The Geochemical Speciation Of Arsenic In Contaminated Soils: A Greenhouse Study
NASA Astrophysics Data System (ADS)
Sharma, S.; Sarkar, D.; Datta, R.
Land-applied arsenical pesticides have contributed elevated soil arsenic (As) levels. Many baseline risk assessments As-contaminated sites assume that all As present in the soil is bioavailable, thereby potentially overestimating the actual health risk. However, risk from As exposure is associated only with those forms of As that are potentially extractable by the human gastrointestinal juices. It has been demonstrated that As may exist in several geochemical forms depending on soil chemical properties, which may or may not be bioavailable. The current study aims at addressing the issue of soil variability on As bioavailability as a function of soil physico-chemical properties in a greenhouse setting involving dynamic interactions between soil, water and plants. Four different soils were chosen based on their potential differences with respect to As reactivity: Immokalee, an acid sand with low extractable Fe/Al, having minimal arsenic retention capacity; Millhopper, an acid sandy loam with high extractable Fe/Al oxides; Pahokee Muck soil with 85% soil organic matter (SOM) as well as high Fe/Al content; and Orelia soil with high clay and Fe/Al content. Soils were amended with sodium arsenate (675 and 1500 mg/Kg). Rice (Oryza sativa) was used as the test crop. A sequential extraction scheme was employed to identify the geochemical forms of As in soils (soluble, exchangeable, organic, Fe/Al-bound, Ca/Mg-bound, residual) immediately after spiking; after 3 mo; and after 6 mo of equilibration time. Concentrations of these As forms were correlated with the in-vitro bioavailable As fractions to identify those As fractions that are most likely to be bioavailable. Results from this study showed that there was little to no plant growth in the contaminated soils. Sequential extractions of the soil indicated that arsenic is strongly adsorbed onto soil amorphous iron/aluminum oxides, and the degree of arsenic retention is a direct function of equilibration time.
Remediation of lead and cadmium-contaminated soils.
Salama, Ahmed K; Osman, Khaled A; Gouda, Neama Abdel-Razeek
The research was designated to study the ability of plants to bio-accumulate, translocate and remove the heavy metals, lead and cadmium from contaminated soil. The herbal plant ryegrass, Lolium multiflorum was investigated as a bio-accumulator plant for these metals. The translocation of these heavy metals in the herbal plant was compared considering root to shoot transport and redistribution of metals in the root and shoot system. The trace metal contents from root and shoot parts were determined using atomic absorption spectrometer. The results showed that the percent of lead and cadmium transferred to ryegrass plant were averaged as 51.39, and 74.57%, respectively, while those remained in the soil were averaged as 48.61 and 25.43% following 60 days of treatment. The soil-plant transfer index in root and shoot system of ryegrass was found to be 0.32 and 0.20 for lead, and 0.50 and 0.25 for cadmium. These findings indicated that the herbal plant ryegrass, Lolium multiflorum is a good accumulator for cadmium than lead. The soil-plant transfer factor (the conc. of heavy metal in plant to the conc. in soil) indicated that the mechanism of soil remedy using the investigated plant is phytoextraction where the amounts of heavy metals transferred by plant roots into the above ground portions were higher than that remained in the soil. The method offers green technology solution for the contamination problem since it is effective technology with minimal impact on the environment and can be easily used for soil remedy. PMID:26515924
Electrokinetic electrode system for extraction of soil contaminants from unsaturated soils
Lindgren, E.R.; Mattson, E.D.
An electrokinetic electrode assembly is described for use in extraction of soil contaminants from unsaturated soil in situ. The assembly includes a housing for retaining a liquid comprising an electrolyte solution, pure water, and soil water, the housing being in part of porous material capable of holding a vacuum. An electrode is mounted in the housing. The housing is provided with a vacuum orifice for effecting a vacuum within the housing selectively to control flow of soil water through the housing into the chamber and to control outflow of the liquid from the chamber. The assembly further includes conduit means for removing the liquid from the housing and returning the electrolyte solution to the housing, and a conduit for admitting pure water to the housing. An electrode system and method are also revealed for extraction of soil contaminants. The system and method utilize at least two electrode assemblies as described above. 5 figs.
Electrokinetic electrode system for extraction of soil contaminants from unsaturated soils
Lindgren, Eric R.; Mattson, Earl D.
There is presented an electrokinetic electrode assembly for use in extraction of soil contaminants from unsaturated soil in situ. The assembly includes a housing for retaining a liquid comprising an electrolyte solution, pure water, and soil water, the housing being in part of porous material capable of holding a vacuum. An electrode is mounted in the housing. The housing is provided with a vacuum orifice for effecting a vacuum within the housing selectively to control flow of soil water through the housing into the chamber and to control outflow of the liquid from the chamber. The assembly further includes conduit means for removing the liquid from the housing and returning the electrolyte solution to the housing, and a conduit for admitting pure water to the housing. There is further presented an electrode system and method for extraction of soil contaminants, the system and method utilizing at least two electrode assemblies as described above.
Remediation of Mercury Contaminated Soils at the Miramas Site - 12243
Potier, G.; Chambon, F.
Beneficial 'new' use of the Miramas Site is the remediation objective for a former light isotope manufacturing facility. Remediation operations will remove contaminated soils and materials and deconstruct facilities. The remediation objective is faced with project challenges and regulatory requirements that dictate/influence the outcome. The operation consists of the remediation of approximately 100,000 cubic meters of soil and the decommissioning of facilities. The types and ranges of waste are the result of historical processing activities (chemical facilities, pyrotechnic components storage, mining component treatment and light isotope manufacturing activities). Mercury is the primary component of the waste, but metals and organic compounds are also possible waste components. A thermal desorption process is used to remove Mercury from the polluted soil while a biological treatment is considered to the organic nitrate compound removal. A focus is done on the technologies used to remediate the Mercury contaminated soil. After few months of operation, the first results confirm that the technology choices were relevant and the soil remediation project is a success. The first successful month of operation at an industrial scale demonstrate that the Thermal Desorption is an efficient and relevant process to remediate large quantity of mercury contaminated soils. The project is on cost and the mercury removal should be end by 2014. The scrubbing is a good way to limit the volume of material to be treated with the Thermal Desorption Unit. The biological treatment is a promising process for the organic nitrate compound removal and testing at a pilot scale will be done in 2012. (authors)
Ecotoxicity of pentachlorophenol in contaminated soil as affected by soil type.
Banks, M K; Schwab, A P
Four uncontaminated soils were chosen with a wide range of pH, organic carbon, and clay content to allow us to determine the properties that were most influential on pentachlorophenol (PCP) toxicity. The soils were contaminated in the laboratory at concentrations of 50 and 100 mg/kg and target organisms were exposed to the contaminated soil. Germination and emergence of lettuce seedlings was found to be dependent upon PCP concentration and soil type, and responses were highly correlated to extractable concentrations. Earthworms were sensitive to PCP, regardless of soil properties, and mortality was observed in most samples at the 100 mg/kg concentration. Toxic responses by the worms were not strongly related to soil properties or extractable concentrations. The importance of soil chemical and physical properties on toxicity and bioavailability depends upon the target organism. In the case of lettuce seedlings, PCP is acquired through the aqueous phase; therefore, the chemical interaction between PCP and soil controls toxicity. Since earthworms ingest soil and potentially can change the chemical environment of exposure, the impact of soil properties on PCP toxicity is less apparent. PMID:16423718
Combining phytoextraction and biochar addition improves soil biochemical properties in a soil contaminated with Cd.
Lu, Huanping; Li, Zhian; Fu, Shenglei; Méndez, Ana; Gascó, Gabriel; Paz-Ferreiro, Jorge
The main goal of phytoremediation is to improve ecosystem functioning. Soil biochemical properties are considered as effective indicators of soil quality and are sensitive to various environmental stresses, including heavy metal contamination. The biochemical response in a soil contaminated with cadmium was tested after several treatments aimed to reduce heavy metal availability including liming, biochar addition and phytoextraction using Amaranthus tricolor L. Two biochars were added to the soil: eucalyptus pyrolysed at 600 °C (EB) and poultry litter at 400 °C (PLB). Two liming treatments were chosen with the aim of bringing soil pH to the same values as in the treatments EB and PLB. The properties studied included soil microbial biomass C, soil respiration and the activities of invertase, β-glucosidase, β-glucosaminidase, urease and phosphomonoesterase. Both phytoremediation and biochar addition improved soil biochemical properties, although results were enzyme specific. For biochar addition these changes were partly, but not exclusively, mediated by alterations in soil pH. A careful choice of biochar must be undertaken to optimize the remediation process from the point of view of metal phytoextraction and soil biological activity. PMID:25010741
Characterization and remediation of soils contaminated with uranium.
Gavrilescu, Maria; Pavel, Lucian Vasile; Cretescu, Igor
Environmental contamination caused by radionuclides, in particular by uranium and its decay products is a serious problem worldwide. The development of nuclear science and technology has led to increasing nuclear waste containing uranium being released and disposed in the environment. The objective of this paper is to develop a better understanding of the techniques for the remediation of soils polluted with radionuclides (uranium in particular), considering: the chemical forms of uranium, including depleted uranium (DU) in soil and other environmental media, their characteristics and concentrations, and some of the effects on environmental and human health; research issues concerning the remediation process, the benefits and results; a better understanding of the range of uses and situations for which each is most appropriate. The paper addresses the main features of the following techniques for uranium remediation: natural attenuation, physical methods, chemical processes (chemical extraction methods from contaminated soils assisted by various suitable chelators (sodium bicarbonate, citric acid, two-stage acid leaching procedure), extraction using supercritical fluids such as solvents, permeable reactive barriers), biological processes (biomineralization and microbial reduction, phytoremediation, biosorption), and electrokinetic methods. In addition, factors affecting uranium removal from soils are furthermore reviewed including soil characteristics, pH and reagent concentration, retention time. PMID:18771850
Enhanced thermal desorption -- Facile removal of PCBs from contaminated soils
Krabbenhoft, H.O.; Webb, J.L.; Gascoyne, D.G.
The use of certain organic and inorganic materials, when admixed with soils contaminated with polychlorinated biphenyls (PCBs), greatly facilitates the removal of the PCBs by means of an ex situ thermal desorption process. Thus, for example, heating a soil (with an initial PCB concentration of {approximately}700 ppm A-1260) from 25 C to 300 C over a 30-minute period provided remediated soil with a residual PCB level of 53 ppm (92.4% PCB removal). When the experiment was repeated using a sweep of steam (corresponding to a water delivery rate of 1.0 mL/min), the residual PCB level was 10 ppm (98.6% PCB removal). And when steam was passed through the soil admixed with 5% sodium formate, the residual PCB level was only 0.9 ppm (99.9% PCB removal). Several other additives (such as sodium acetate, ammonium carbamate, formic acid) have been shown to be efficacious for enhanced PCB removal via thermal desorption. A design of experiments study was carried out to optimize the process parameters of temperature, time, additive level, and steam flow. A logarithmic transformation of the data afforded a mathematical model (correlation coefficient 0.96) that allows one to employ the enhanced thermal desorption process in a cost-effective manner to remediate contaminated soil (with an initial PCB level of {approximately}8,000 ppm A-1260) such that residual PCB levels of {<=}2 ppm (99.98% PCB removal) are routinely achieved.
Remediation of PCB contaminated soils using iron nano-particles.
Varanasi, Patanjali; Fullana, Andres; Sidhu, Sukh
In this study, iron nano-particles were used to remediate PCB contaminated soil and an attempt was made to maximize PCB destruction in each treatment step. The results show that nano-particles do aid in the dechlorination process and high PCB destruction efficiencies can be achieved. The destruction efficiency during the preliminary treatment (mixing of soil and iron nano-particles in water) can be increased by increasing the water temperature. The maximum thermal destruction (pyrolysis/combustion of soil after preliminary treatment) of soil-bound PCBs occurs at 300 degrees C in air. A minimum total PCB destruction efficiency of 95% can be achieved by this process. The effect of changing treatment parameters such as type of mixing, time of mixing and mixing conditions and application of other catalysts like iron oxide and V(2)O(5)/TiO(2) was also investigated. It was found that at 300 degrees C in air, iron oxide and V(2)O(5)/TiO(2) are also good catalysts for remediating PCB contaminated soils. PMID:16962632
Phytoremediation of mercury-contaminated soils by Jatropha curcas.
Marrugo-Negrete, José; Durango-Hernández, José; Pinedo-Hernández, José; Olivero-Verbel, Jesús; Díez, Sergi
Jatropha curcas plants species were tested to evaluate their phytoremediation capacity in soils contaminated by different levels of mercury. The experimental treatments consisted of four levels of mercury concentrations in the soil - T0, T1, T5, and T10 (0, 1, 5, and 10 μg Hg per g soil, respectively). The total mercury content absorbed by the different plant tissues (roots, stems and leaves) was determined during four months of exposure. The growth behavior, mercury accumulation, translocation (TF) and bioconcentration (BCF) factors were determined. The different tissues in J. curcas can be classified in order of decreasing accumulation Hg as follows: roots>leaves>stems. The highest cumulative absorption of the metal occurred between the second and third month of exposure. Maximum TF was detected during the second month and ranged from 0.79 to 1.04 for the different mercury concentrations. Values of BCF ranged from 0.21 to 1.43. Soils with T1 showed significantly higher BCF (1.43) followed by T10 (1.32) and T5 (0.91), all of them at the fourth month. On the other hand TFs were low (range 0.10-0.26) at the en of the experiment. The maximum reduction of biomass (16.3%) occurred for T10 (10 μg Hg g(-1)). In sum, J. curcas species showed high BCFs and low TFs, and their use could be a promising approach to remediating mercury-contaminated soils. PMID:25655698
Copper phytoavailability and uptake by Elsholtzia splendens from contaminated soil as affected by soil amendments.
Peng, Hong-Yun; Yang, Xiao-E; Jiang, Li-Ying; He, Zhen-Li
Pot and field experiments were conducted to evaluate bioavailability of Cu in contaminated paddy soil (PS) and phytoremediation potential by Elsholtzia splendens as affected by soil amendments. The results from pot experiment showed that organic manure (M) applied to the PS not only remarkably raised the H2O exchangeable Cu, which were mainly due to the increased exchangeable and organic fractions of Cu in the PS by M, but also stimulated plant growth and Cu accumulation in E. splendens. At M application rate of 5.0%, shoot Cu concentration in the plant increased by four times grown on the PS, so as to the elevated shoot Cu accumulation by three times as compared to the control. In the field trial, soil amendments by M and furnace slag (F), and soil preparations like soil capping (S) and soil discing (D) were performed in the PS. Soil capping and discing considerably declined total Cu in the PS. Application of M solely or together with F enhanced plant growth and increased H2O exchangeable Cu levels in the soil. The increased extractability of Cu in the rhizosphere of E. splendens was noted, which may have mainly attributed to the rhizospheric acidification and chelation by dissolved organic matter (DOM), thus resulting in elevating Cu uptake and accumulation by E. splendens. Amendments with organic manure plus furnace slag (MF) to the PS caused the highest exactable Cu with saturated H2O in the rhizospheric soil of E. splendens after they were grown for 170 days in the PS, thus achieving 1.74 kg Cu ha(-1) removal from the contaminated soil by the whole plant of E. splendens at one season, which is higher than those of the other soil treatments. The results indicated that application of organic manure at a proper rate could enhance Cu bioavailability and increase effectiveness of Cu phytoextraction from the contaminated soil by the metal-tolerant and accumulating plant species (E. splendens). PMID:15792303
Assessing the Educational Needs of Urban Gardeners and Farmers on the Subject of Soil Contamination
ERIC Educational Resources Information Center
Harms, Ashley Marie Raes; Presley, DeAnn Ricks; Hettiarachchi, Ganga M.; Thien, Stephen J.
Participation in urban agriculture is growing throughout the United States; however, potential soil contaminants in urban environments present challenges. Individuals in direct contact with urban soil should be aware of urban soil quality and soil contamination issues to minimize environmental and human health risks. The study reported here…
The performance of a soil remediation process can be determined by measuring the reduction in target soil contaminant concentrations and by assessing the treatment's ability to lower soil toxicity. Land treatment of polycyclic armomatic hydrocarbon (PAH)-contaminated soil from a ...
The performance of a soil remediation process can be determined by measuring the reduction in target soil contaminant concentrations and by assessing the treatment's ability to lower soil toxicity. Land treatment of polycyclic aromatic hydrocarbon (PAH)-contaminated soil from a ...
Evaluation of the Effect of Arsenic Contamination on Selected Soil Enzyme Activities and Microbial Diversity
Technology Transfer Automated Retrieval System (TEKTRAN)
Environmental impact of different contaminants which enter the soil can alter the diversity of the soil microflora thus disrupting their ability to maintain soil quality and health. Due to the vital role played by the diverse soil microbes in soil, the measurement of the soil microbial diversity has...
[Soil contamination with Toxocara spp. eggs in the Elblag area].
Jarosz, W
The distribution of Toxocara spp. eggs in Elbl4g was studied. Out of 72 soil samples collected in public places of the city 13.9% were positive and the mean egg density was 3.75/100g soil. The city backyards were much more contaminated with Toxocara spp. eggs (18.0%) than the playgrounds (4.5%). In sandpits examined the eggs were not found. Almost 80% of Toxocara spp. eggs recovered were infective. T. cati eggs were more frequent than T. canis eggs. Additionally in examined samples two eggs of Ancylostoma caninum and one egg of Ascaris lumbricoides were recognized. PMID:16888965
Functioning of metal contaminated garden soil after remediation.
Jelusic, Masa; Grcman, Helena; Vodnik, Dominik; Suhadolc, Metka; Lestan, Domen
The effect of remediation using three EDTA doses (10, 30, 60 mmol kg(-1)) on soil functioning was assessed using column experiment and Brassica rapa. Soil washing removed up to 77, 29 and 72% of metals from soil contaminated with 1378, 578 and 8.5 mg kg(-1) of Pb, Zn and Cd, respectively. Sequential extraction indicated removal from the carbonate soil fraction. Metal oral-accessibility from the stomach phase was reduced by up to 75 and from the small intestine by up to 79% (Pb). Part of metals (up to 0.8% Cd) was lost due to leaching from columns. Remediation reduced toxic metal soil-root transfer by up to 61% but did not prevent metal accumulation in leaves. The fitness of plants grown on EDTA washed soils (gas exchange, fluorescence) was not compromised. Remediation initially reduced the soil DNA content (up to 29%, 30 mmol kg(-1) EDTA) and changed the structure of microbial population. PMID:23246748
Remediation of Nitrobenzene Contaminated Soil by Combining Surfactant Enhanced Soil Washing and Effluent Oxidation with Persulfate
Yan, Jingchun; Gao, Weiguo; Qian, Linbo; Han, Lu; Chen, Yun; Chen, Mengfang
The combination of surfactant enhanced soil washing and degradation of nitrobenzene (NB) in effluent with persulfate was investigated to remediate NB contaminated soil. Aqueous solution of sodium dodecylbenzenesulfonate (SDBS, 24.0 mmol L-1) was used at a given mass ratio of solution to soil (20:1) to extract NB contaminated soil (47.3 mg kg-1), resulting in NB desorption removal efficient of 76.8%. The washing effluent was treated in Fe2+/persulfate and Fe2+/H2O2 systems successively. The degradation removal of NB was 97.9%, being much higher than that of SDBS (51.6%) with addition of 40.0 mmol L-1 Fe2+ and 40.0 mmol L-1 persulfate after 15 min reaction. The preferential degradation was related to the lone pair electron of generated SO4•−, which preferably removes electrons from aromatic parts of NB over long alkyl chains of SDBS through hydrogen abstraction reactions. No preferential degradation was observed in •OH based oxidation because of its hydrogen abstraction or addition mechanism. The sustained SDBS could be reused for washing the contaminated soil. The combination of the effective surfactant-enhanced washing and the preferential degradation of NB with Fe2+/persulfate provide a useful option to remediate NB contaminated soil. PMID:26266532
Hanford Site surface soil radioactive contamination control plan, March 1993
Mix, P.D.; Winship, R.A.
The Decommissioning and Resource Conservation and Recovery Act Closure Program is responsible to the US Department of Energy Richland Field Office, for the safe and cost-effective surveillance, maintenance, and decommissioning of surplus facilities and Resource Conservation and Recovery Act of 1976 closures at the Hanford Site. This program also manages the Radiation Area Remedial Action that includes the surveillance, maintenance, decontamination, and/or interim stabilization of inactive burial grounds, cribs, ponds, trenches, and unplanned release sites. This plan addresses only the Radiation Area Remedial Action activity requirements for managing and controlling the contaminated surface soil areas associated with these inactive sites until they are remediated as part of the Hanford Site environmental restoration process. All officially numbered Radiation Area Remedial Action and non-Radiation Area Remedial Action contaminated surface soil areas are listed in this document so that a complete list of the sites requiring remediation is contained in one document.
Soils and sediments contaminated with toxic organic and inorganic compounds harmful to the environment and to human health are common in the urban environment. We report here on aspects of a program being carried out in the New York/New Jersey Port region to develop methods for processing dredged material from the Port to make products that are safe for introduction to commercial markets. We discuss some of the results of the program in Computational Environmental Science, Laboratory Environmental Science, and Applied Environmental Science and indicate some possible directions for future work. Overall, the program elements integrate the scientific and engineering aspects with regulatory, commercial, urban planning, local governments, and community group interests. Well-developed connections between these components are critical to the ultimate success of efforts to cope with the problems caused by contaminated urban soils and sediments.
Jannik, T; P Fledderman, P; Michael Paller, M
In the early 1960s, an area of privately-owned swamp adjacent to the US Department of Energy's Savannah River Site (SRS), known as Creek Plantation, was contaminated by site operations. Studies conducted in 1974 estimated that approximately 925 GBq of {sup 137}Cs was deposited in the swamp. Subsequently, a series of surveys--composed of 52 monitoring locations--was initiated to characterize and trend the contaminated environment. The annual, potential, maximum doses to a hypothetical hunter were estimated by conservatively using the maximum {sup 137}Cs concentrations measured in the soil. The purpose of this report is to calculate an 'effective dosimetric' half-life for {sup 137}Cs in soil (based on the maximum concentrations) and compare it to the effective environmental half-life (based on the geometric mean concentrations).
Advanced Assay Systems for Radionuclide Contamination in Soils
J. R. Giles; L. G. Roybal; M. V. Carpenter; C. P. Oertel; J. A. Roach
Through the support of the Department of Energy (DOE) Office of Environmental Management (EM) Technical Assistance Program, the Idaho National Laboratory (INL) has developed and deployed a suite of systems that rapidly scan, characterize, and analyze surface soil contamination. The INL systems integrate detector systems with data acquisition and synthesis software and with global positioning technology to provide a real-time, user-friendly field deployable turn-key system. INL real-time systems are designed to characterize surface soil contamination using methodologies set forth in the Multi-Agency Radiation Surveys and Site Investigation Manual (MARSSIM). MARSSIM provides guidance for planning, implementing, and evaluating environmental and facility radiological surveys conducted to demonstrate compliance with a dose or risk-based regulation and provides real-time information that is immediately available to field technicians and project management personnel. This paper discusses the history of the development of these systems and describes some of the more recent examples and their applications.
Large-scale experience with biological treatment of contaminated soil
Schulz-Berendt, V.; Poetzsch, E.
The efficiency of biological methods for the cleanup of soil contaminated with total petroleum hydrocarbons (TPH) and polycyclic aromatic hydrocarbons (PAH) was demonstrated by a large-scale example in which 38,000 tons of TPH- and PAH-polluted soil was treated onsite with the TERRAFERM{reg_sign} degradation system to reach the target values of 300 mg/kg TPH and 5 mg/kg PAH. Detection of the ecotoxicological potential (Microtox{reg_sign} assay) showed a significant decrease during the remediation. Low concentrations of PAH in the ground were treated by an in situ technology. The in situ treatment was combined with mechanical measures (slurry wall) to prevent the contamination from dispersing from the site.
Bioventing vs. prepared beds for remediation of petroleum contaminated soil
Hazen, T.C.; Lombard, K.H.; Kastner, J.R.
Bioventing is an in situ biostimulation technique that has become extremely popular recently for remediation of near-surface sediment (soil) contaminated with petroleum products. Prepared Bed bioremediation of petroleum contaminated soil involves the use of a centralized controlled above ground facility that uses contained land-farming techniques. Several sites at the U.S. DOE Savannah River Site have been evaluated and remediated using these two technologies. The characterization cost, capital costs, safety, implementation time, remediation rate, monitoring requirements, final disposition requirements, regulatory requirements, and public acceptance make these techniques better then any other conventional technology, e.g. incineration, and make it difficult to decide which of the two is the best alternative. New rapid site characterization and treatability techniques e.g. laser induced fluorescence and microrespirometry, have allowed better decisions as to which of these two technologies is the most appropriate for a given site.
Bioremediation of oil-contaminated soil -- A rate model
Li, K.Y.; Zhang, Y.; Xu, T.
Three rate equations, a modified Monod equation and two mass transfer rate equations, were used to calculate the biodegradation rate, oxygen transfer rate and oil transfer rate during a bioremediation process of oil-contaminated soil. Based on experimental rate constants, these three rates were calculated and compared. It was found the bioremediation rate of oil-contaminated soil could be controlled by the mass transfer process of oil into aqueous solution (0.12 mg BOD/(1-h)). When the oil transfer rate is enhanced by at least 10 times, the oxygen transfer process (0.1--1.0 mg BOD/(1-h)) becomes the rate-controlling step. For most of the cases, the biodegradation of oil in aqueous solution is not the limiting step unless the microbial population in the aqueous solution is less than 100 mg VSS/1.
Microbial and enzymatic activity of soil contaminated with azoxystrobin.
Baćmaga, Małgorzata; Kucharski, Jan; Wyszkowska, Jadwiga
The use of fungicides in crop protection still effectively eliminates fungal pathogens of plants. However, fungicides may dissipate to various elements of the environment and cause irreversible changes. Considering this problem, the aim of the presented study was to evaluate changes in soil biological activity in response to contamination with azoxystrobin. The study was carried out in the laboratory on samples of sandy loam with a pH of 7.0 in 1 Mol KCl dm(-3). Soil samples were treated with azoxystrobin in one of four doses: 0.075 (dose recommended by the manufacturer), 2.250, 11.25 and 22.50 mg kg(-1) soil DM (dry matter of soil). The control soil sample did not contain fungicide. Bacteria were identified based on 16S rRNA gene sequencing, and fungi were identified by internal transcribed spacer (ITS) region sequencing. The study revealed that increased doses of azoxystrobin inhibited the growth of organotrophic bacteria, actinomycetes and fungi. The fungicide also caused changes in microbial biodiversity. The lowest values of the colony development (CD) index were recorded for fungi and the ecophysiological (EP) index for organotrophic bacteria. Azoxystrobin had an inhibitory effect on the activity of dehydrogenases, catalase, urease, acid phosphatase and alkaline phosphatase. Dehydrogenases were found to be most resistant to the effects of the fungicide, while alkaline phosphatase in the soil recovered the balance in the shortest time. Four species of bacteria from the genus Bacillus and two species of fungi from the genus Aphanoascus were isolated from the soil contaminated with the highest dose of azoxystrobin (22.50 mg kg(-1)). PMID:26343782
Simplified method for detecting tritium contamination in plants and soil.
Andraski, B J; Sandstrom, M W; Michel, R L; Radyk, J C; Stonestrom, D A; Johnson, M J; Mayers, C J
Cost-effective methods are needed to identify the presence and distribution of tritium near radioactive waste disposal and other contaminated sites. The objectives of this study were to (i) develop a simplified sample preparation method for determining tritium contamination in plants and (ii) determine if plant data could be used as an indicator of soil contamination. The method entailed collection and solar distillation of plant water from foliage, followed by filtration and adsorption of scintillation-interfering constituents on a graphite-based solid phase extraction (SPE) column. The method was evaluated using samples of creosote bush [Larrea tridentata (Sessé & Moc. ex DC.) Coville], an evergreen shrub, near a radioactive disposal area in the Mojave Desert. Laboratory tests showed that a 2-g SPE column was necessary and sufficient for accurate determination of known tritium concentrations in plant water. Comparisons of tritium concentrations in plant water determined with the solar distillation-SPE method and the standard (and more laborious) toluene-extraction method showed no significant difference between methods. Tritium concentrations in plant water and in water vapor of root-zone soil also showed no significant difference between methods. Thus, the solar distillation-SPE method provides a simple and cost-effective way to identify plant and soil contamination. The method is of sufficient accuracy to facilitate collection of plume-scale data and optimize placement of more sophisticated (and costly) monitoring equipment at contaminated sites. Although work to date has focused on one desert plant, the approach may be transferable to other species and environments after site-specific experiments. PMID:12809299
Simplified method for detecting tritium contamination in plants and soil
Andraski, B.J.; Sandstrom, M.W.; Michel, R.L.; Radyk, J.C.; Stonestrom, D.A.; Johnson, M.J.; Mayers, C.J.
Cost-effective methods are needed to identify the presence and distribution of tritium near radioactive waste disposal and other contaminated sites. The objectives of this study were to (i) develop a simplified sample preparation method for determining tritium contamination in plants and (ii) determine if plant data could be used as an indicator of soil contamination. The method entailed collection and solar distillation of plant water from foliage, followed by filtration and adsorption of scintillation-interfering constituents on a graphitebased solid phase extraction (SPE) column. The method was evaluated using samples of creosote bush [Larrea tridentata (Sesse?? & Moc. ex DC.) Coville], an evergreen shrub, near a radioactive disposal area in the Mojave Desert. Laboratory tests showed that a 2-g SPE column was necessary and sufficient for accurate determination of known tritium concentrations in plant water. Comparisons of tritium concentrations in plant water determined with the solar distillation-SPE method and the standard (and more laborious) toluene-extraction method showed no significant difference between methods. Tritium concentrations in plant water and in water vapor of root-zone soil also showed no significant difference between methods. Thus, the solar distillation-SPE method provides a simple and cost-effective way to identify plant and soil contamination. The method is of sufficient accuracy to facilitate collection of plume-scale data and optimize placement of more sophisticated (and costly) monitoring equipment at contaminated sites. Although work to date has focused on one desert plant, the approach may be transferable to other species and environments after site-specific experiments.
Firm contracts for treatability tests on contaminated soils
Not Available
Geosafe Corporation, a Pacific Northwest-headquartered hazardous waste remediation company, announced that is has successfully completed treatability testing of contaminated soils under contract with Woodward Clyde Consultants of Denver, Colorado, the prime contractor for a major hazardous waste site in the Western United States. The tests are being conducted at the University of Washington with Geosafe's specially-designed test equipment. The recently concluded testing confirms the ability of Geosafe's patented in situ vitrification (ISV) technology to treat soils containing a variety of organic and inorganic contaminants. ISV, for which Geosafe has worldwide rights, is the only technology available today that will fully comply with the Superfund Amendments and Reauthorization Act. The ability of ISV to treat mixtures of organic, inorganic and radioactive wastes in situ, in a single process, offers distinct advantages over excavation, transportation and incineration. During the ISV process, organic contaminants are pyrolized and the inorganics present are chemically incorporated into the molten soil which, when cooled, resembles naturally-occurring obsidian.
Coupling bioleaching and electrokinetics to remediate heavy metal contaminated soils.
Huang, Qingyun; Yu, Zhen; Pang, Ya; Wang, Yueqiang; Cai, Zhihong
In this study, bioleaching was coupled with electrokinetics (BE) to remove heavy metals (Cu, Zn, Cr and Pb) from contaminated soil. For comparison, bioleaching (BL), electrokinetics (EK), and the chemical extraction method were also applied alone to remove the metals. The results showed that the BE method removed more heavy metals from the contaminated soil than the BL method or the EK method alone. The BE method was able to achieve metal solubilization rates of more than 70 % for Cu, Zn and Cr and of more than 40 % for Pb. Within the range of low current densities (<1 mA cm(-2)), higher current density led to more metal removal. However, the metal solubilization rates did not increase with increasing current density when the current density was higher than 1 mA cm(-2). Therefore, it is suggested that bioleaching coupled with electrokinetics can effectively remediate heavy metal-contaminated soils and that preliminary tests should be conducted before field operation to detect the lowest current density for the greatest metal removal. PMID:25680933
Uptake of cesium-137 by crops from contaminated soils
Demirel, H.; Oezer, I.; Celenk, I.; Halitligil, M.B.; Oezmen, A.
The Turkish tea crop was contaminated following the Chernobyl nuclear accident. Finding ways to dispose of the contaminated tea (Camellia sinensis L.) without damaging the environment was the goal of this research conducted at the Turkish Atomic Energy Authority (TAEA). In this study, an investigation was made of {sup 137}Cs activities of the plants and the ratios of transfer of {sup 137}Cs activity to plants when the contaminated tea was applied to the soil. Experiments were conducted in the field and in pots under greenhouse conditions. The activities of the tea applied in the field ranged from 12 500 to 72 800 Bq/m{sup 2}, whereas this activity was constant at 8000 Bq/pot in the greenhouse experiment. The transfer of {sup 137}Cs from soil to the plants was between 0.037 and 1.057% for wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), corn (Zea mays indentata Sturt), bean (Phaseolus vulgaris L.), lettuce (Lactuca sativa L.), and grass (Lolium perenne L.). The ratio of the transfer of {sup 137}Cs activity to plants increased as the activity {sup 137}Cs in tea applied to soil was increased. The activity in the plants increased due to increased uptake of {sup 137}Cs by plants. 12 refs., 2 figs., 2 tabs.
Restoration of contaminated soils in abandoned mine areas (Tuscany, Italy)
NASA Astrophysics Data System (ADS)
Bini, Claudio; Wahsha, Mohammad
In Italy ore research and exploitation have been nearly exhausted since the end of the last century, and have left on the land a huge amount of mine waste, therefore provoking evident environmental damage including surface and groundwater, soils, vegetation and the food chain, and a potential threat to human health. The main processes occurring at these sites are: rock disgregation, fragments migration, dust dispersion, oxidation (Eh>250mV), acidification (pH<7), hydrolisis and metal leaching, precipitation of oxides and sulphates. The restoration of these sites, therefore, is a primary objective, in order to reduce/eliminate the risk associated to the contamination sources of past activities, and the consequent environmental and human health hazard. The increasing environmental consciousness of general population compelled Public Administrators to set down effective legislation acts on this subject (e.g. D.L. 152/2006), and more generally on environmental contamination. In this work we present the results of a survey carried out at several mixed sulphides mine sites in Tuscany, exploited for at least a millennium, and closed in the last century. Biogeochemical analyses carried out on representative soil profiles (Spolic Technosols) and vegetation in the proximal and distal areas of ore exploitation show heavy metal concentrations (Cd, Cu, Fe, Pb, Zn) overcoming legislation limits on average. Ni, Cr and Mn concentrations, instead, are generally below the reference levels. The results obtained suggest that the abandoned mine sites represent actual natural laboratories where to experiment new opportunities for restoration of anthropogenically contaminated areas, and to study new pedogenetic trends from these peculiar parent materials. Moreover, plants growing on these substrates are genetically adapted to metal-enriched soils, and therefore may be utilized in phytoremediation of contaminated sites. Furthermore, the institution of natural parks in these areas could
In-Situ Containment and Extraction of Volatile Soil Contaminants
Varvel, Mark Darrell
The invention relates to a novel approach to containing and removing toxic waste from a subsurface environment. More specifically the present invention relates to a system for containing and removing volatile toxic chemicals from a subsurface environment using differences in surface and subsurface pressures. The present embodiment generally comprises a deep well, a horizontal tube, at least one injection well, at least one extraction well and a means for containing the waste within the waste zone (in-situ barrier). During operation the deep well air at the bottom of well (which is at a high pressure relative to the land surface as well as relative to the air in the contaminated soil) flows upward through the deep well (or deep well tube). This stream of deep well air is directed into the horizontal tube, down through the injection tube(s) (injection well(s)) and into the contaminate plume where it enhances volatization and/or removal of the contaminants.
In-Situ Contained And Of Volatile Soil Contaminants
Varvel, Mark Darrell
The invention relates to a novel approach to containing and removing toxic waste from a subsurface environment. More specifically the present invention relates to a system for containing and removing volatile toxic chemicals from a subsurface environment using differences in surface and subsurface pressures. The present embodiment generally comprises a deep well, a horizontal tube, at least one injection well, at least one extraction well and a means for containing the waste within the waste zone (in-situ barrier). During operation the deep well air at the bottom of well (which is at a high pressure relative to the land surface as well as relative to the air in the contaminated soil) flows upward through the deep well (or deep well tube). This stream of deep well air is directed into the horizontal tube, down through the injection tube(s) (injection well(s)) and into the contaminate plume where it enhances volatization and/or removal of the contaminants.
A study of augmented bioremediation for gasoline-contaminated soil
Gross, M.A.; Thoma, G.J.; Tunnel, A.T.
A field-scale study was performed to evaluate the efficacy of augmenting bioremediation of gasoline-contaminated soil using commercially available products. A portion of the contaminated backfill from recently removed underground storage tanks (UST`s) at a bulk fuel facility in Northeast Arkansas was used in this bioremediation study. Seven polyethylene lined bermed areas (cells), were filled with 3.8 cubic meters (5 cubic yards) of contaminated soil. The USTs had leaked gasoline, diesel and kerosene into the surrounding soil. Four bioaugmentation product vendors participated; each one demonstrated their product in a separate cell. An additional cell was subjected to soil vapor extraction, and the remaining two were used as experimental controls. One control cell remained covered with polyethylene sheeting for the duration of the study period. The other control cell was subjected to mechanical processes similar to the bloaugmented cells. That is, if a vendor rototilled his cell, the control cell was rototilled with a clean rototiller, however, no soil amendments or microorganisms were added. Samples were collected from each comer and the center of each cell over a 39 week period. A composite sample for each cell was placed in a glass sample, container with a lid, packed on ice and delivered to an analytical laboratory for total petroleum hydrocarbon (TPH) analysis. After 39 weeks, the covered control showed little or no decrease in TPH concentration. The remaining cells all had varying degrees of TPH loss. However, the bioaugmentation products did not significantly outperform the tilled control. Both the fertilized control and the oil vapor extraction treatments proved to be nearly as effective as the best of the products and significantly better than two of the products in terms of final TPH and the first order removal rate constant.
Comparison of Kriging and coKriging for soil contamination mapping in abandoned mine sites
NASA Astrophysics Data System (ADS)
Lee, Hyeongyu; Choi, Yosoon
Soil contamination mapping around abandoned mines is an important task for the planning and design of mine reclamation. This study compared the ordinary Kriging and the co-Kriging methods for the soil contamination mapping in abandoned mine sites. Four approaches were conducted as follows: (1) soil contamination mapping using the ordinary Kriging and Inductively Coupled Plasma (ICP) data only; (2) soil contamination mapping using the ordinary Kriging and Portable X-Ray Fluorescence (PXRF) data only; (3) soil contamination mapping using the ordinary Kriging and integrated data from ICP and PXRF; and (4) soil contamination mapping using the co-Kriging and integrated data from ICP and PXRF. Results indicate that the approach 3 provides substantial improvements over other three approaches including a more reasonable spatial pattern of soil contamination and reduction in the error of its estimates.
Effect of clays and cement on the solidification/stabilization of phenol-contaminated soils
Vipulanandan, C.
Solidification/stabilization of phenol-contaminated soil was investigated by studying the interaction between soil, phenol and cement. The soil (with 20% kaolinite or bentonite clay) was contaminated with phenol up to 2,000 mg/kg. Type I Portland cement was used as the binder (20% by weight of contaminated soil) in the solidification/stabilization (S/S) treatment. In the phenol-cement interaction studies, the effect of various phenol concentrations on cement setting time, strength and pore fluid composition was studied. Phenol increased the initial and final setting time of cement and reduced the compressive strength. More than 85% of the phenol was desorped from the contaminated soils. The compressive strength of treated, contaminated soil decreased with higher phenol content but increased with curing time. Leachability of phenol from the solidified cement and treated, contaminated soil cured up to 180 days, was evaluated using the US EPA recommended Toxicity Characteristic Leaching Procedure (TCLP) and the American Nuclear Society`s ANS 16.1 leaching test. The percentage of phenol leached from the solidified contaminated soil was independent of the initial concentration of phenol in the contaminated soil. While the TCLP tests on treated soils showed that over 70% of phenol in the contaminated soil was leached out, the ANS 16.1 tests showed less than 35% phenol in the leachate. A simple model has been proposed to quantify the phenol leached from the cement-solidified, contaminated soil during both leaching tests.
Electrokinetic removal of uranium from contaminated, unsaturated soils
Booher, W.F.; Lindgren, E.R.; Brady, P.V.
Electrokinetic remediation of uranium-contaminated soil was studied in a series of laboratory-scale experiments in test cells with identical geometry using quartz sand at approximately 10 percent moisture content. Uranium, when present in the soil system as an anionic complex, could be migrated through unsaturated soil using electrokinetics. The distance that the uranium migrated in the test cell was dependent upon the initial molar ratio of citrate to uranium used. Over 50 percent of the uranium was recovered from the test cells using the citrate and carbonate complexing agents over of period of 15 days. Soil analyses showed that the uranium remaining in the test cells had been mobilized and ultimately would have been extracted. Uranium extraction exceeded 90 percent in an experiment that was operated for 37 days. Over 70 percent of the uranium was removed from a Hanford waste sample over a 55 day operating period. Citrate and carbonate ligand utilization ratios required for removing 50 percent of the uranium from the uranium-contaminated sand systems were approximately 230 moles ligand per mole uranium and 1320 moles ligand per mole uranium for the waste. Modifying the operating conditions to increasing the residence time of the complexants is expected to improved the utilization efficiency of the complexing agent.
Environmental toxicity testing of contaminated soil based on microcalorimetry.
Gruiz, K; Feigl, V; Hajdu, Cs; Tolner, M
Contaminated site assessment and monitoring requires efficient risk-management tools including innovative environmental toxicity tests. The first application of microcalorimetry for toxicity testing draw the attention to a possible new tool to increase sensitivity, to eliminate matrix effect and to study effect-mechanism. A Thermal Activity Monitor (TAM) microcalorimeter was used for measuring the heat production of various test organisms when getting in contact with sterile toxic soils. Well known bacterial (Azomonas agilis), animal (Folsomia candida) and plant test organisms (Sinapis alba) were tested for heat production. The heat response of selected testorganisms was measured in case of metal (Cu and Zn) and organic pollutant (Diesel oil, DBNPA and PCP) contaminated soils. In addition to the quantitative determination of the heat production, the mechanism of the toxic effect can be characterized from the shape of the power-time curve (slope of the curve, height and time of the maximum). In certain concentration ranges the higher the pollutant concentration of the soil the lower the maximum of the time-heat curve. At low pollutant concentrations an increased heat production was measured in case of A. agile and 20 and 200 mg Zn kg(-1) soil. The microcalorimetric testing was more sensitive in all cases than the traditional test methods. Our results showed that the microcalorimetric test method offers a new and sensitive option in environmental toxicology, both for research and routine testing. PMID:20549622
Development of Fungal Inocula for Bioaugmentation of Contaminated Soils
Lestan, D.; Lamar, R. T.
This report describes novel fungal inocula for bioaugmentation of soils contaminated with hazardous organic compounds. The inocula are in the form of pelleted solid substrates coated with a sodium alginate suspension of fungal spores or mycelial fragments and incubated until overgrown with the mycelium of selected lignin-degrading fungi. The organisms evaluated were Phanerochaete chrysosporium (BKM F-1767, ATCC 42725), P. sordida (HHB-8922-Sp), Irpex lacteus (Mad-517, ATCC 11245), Bjerkandera adusta (FP-135160-Sp, ATCC 62023), and Trametes versicolor (MD-277). The pelleted fungal inocula resisted competition and proliferation from indigenous soil microbes, were lower in moisture content than current fungal inocula, and had sufficient mechanical strength to allow handling and introduction into the soil without a change in the mechanical consistency of the pellets. Inoculated at a rate of 3% in artificially contaminated nonsterile soil, I. lacteus, B. adusta, and T. versicolor removed 86, 82, and 90%, respectively, of the pentachlorophenol in 4 weeks. A mathematical model was developed to explain moisture distribution in a hydrogel-coated pelleted substrate. PMID:16535337
Analytical characterization of contaminated soils from former manufactured gas plants
Haeseler, F.; Blanchet, D.; Vandecasteele, J.P.; Druelle, V.; Werner, P.
Detailed analytical characterization of the organic matter (OM) of aged polluted soils from five former manufactured gas plants (MGP) and of two coal tars was completed. It was aimed at obtaining information relevant to the physicochemical state of the polycyclic aromatic hydrocarbon (PAH) pollutants and to their in-situ evolution in time. Overall characterization of total OM (essentially polluting OM) was carried out directly on soil samples with or without prior extraction with solvent. It involved a technique of pyrolysis/oxidation coupled to flame ionization/thermal conductivity detection. Extracts in solvent were fractionated by liquid chromatography into saturated hydrocarbons, PAH, and resins, the first two fractions being further characterized by gas chromatography and mass spectrometry. The compositions of OM of soils were found to be very similar. A total of 28% of organic carbon, including all PAH, was extractable by solvent. The compositions of coal tars were qualitatively similar to those of OM of MGP soils but with a higher proportion (48%) of total extractable OM and of PAH, in particular lower PAH. Contamination of MGP soils appeared essentially as coal tar having undergone natural attenuation. The constant association of PAH with heavy OM in MGP soils is important with respect to the mobility and bioaccessibility of these pollutants.
Fixation of soil surface contamination using natural polysaccharides
Sackschewsky, M.R.
Natural polysaccharides were evaluated as alternatives to commercially available dust-control agents for application in buried-waste and contaminated-soil remediation situations. Materials were identified and evaluated with specific criteria in mind: the materials must be environmentally benign and must not introduce any additional hazardous materials; they must be effective for at least 2 or 3 days, but they do not necessarily have to be effective for more than 2 to 3 weeks; they should be relatively resistant to light traffic; they must not interfere with subsequent soil treatment techniques, especially soil washing; and they must be relatively inexpensive. Two products, a pregelled potato starch and a mixture of carbohydrates derived from sugar beets, were selected for evaluation. Testing included small- and large-scale field demonstrations, laboratory physical property analyses, and wind-tunnel evaluations.
[Stabilization and long-term effect of chromium contaminated soil].
Wang, Jing; Luo, Qi-Shi; Zhang, Chang-Bo; Tan, Liang; Li, Xu
Short-term (3 d and 28 d) and long-term (1 a) stabilization effects of Cr contaminated soil were investigated through nature curing, using four amendments including ferrous sulfide, ferrous sulfate, zero-valent iron and sodium dithionite. The results indicated that ferrous sulfide and zero-valent iron were not helpful for the stabilization of Cr(VI) when directly used because of their poor solubility and immobility. Ferrous sulfate could effectively and rapidly decrease total leaching Cr and Cr(VI) content. The stabilization effect was further promoted by the generation of iron hydroxides after long-term curing. Sodium dithionite also had positive effect on soil stabilization. Appropriate addition ratio of the two chemicals could help maintain the soil pH in range of 6-8. PMID:24364328
Enhanced bioremediation of petroleum contaminated soils with higher plants
Schwab, A.P.; Banks, M.K.
Introduction of higher plants into a bioremediation system can enhance degradation of total petroleum hydrocarbons and target compounds, particularly relatively immobile and recalcitrant organic molecules. Over the past several years, an interdisciplinary team of civil engineers, chemical engineers, soil chemists, soil microbiologists, and plant scientists at Kansas State University have been studying phytoremediation systems. Greenhouse experiments have focused on selecting plants that are most adapted to degrading target compounds and to surviving in soils highly contaminated with petroleum hydrocarbons. Plant species do not seem to differ in their ability to aid in the decomposition of pyrene and anthracene, but benzo[a]pyrene is much more difficult to degrade. Most species are ineffective in enhancing the degradation of benzo[a]pyrene. Four field studies have been initiated in California, Texas, New Jersey, and Virginia to test some of our greenhouse observations.
Effect of soil properties, heavy metals and emerging contaminants in the soil nematodes diversity.
Gutiérrez, Carmen; Fernández, Carlos; Escuer, Miguel; Campos-Herrera, Raquel; Beltrán Rodríguez, M Eulalia; Carbonell, Gregoria; Rodríguez Martín, Jose Antonio
Among soil organisms, nematodes are seen as the most promising candidates for bioindications of soil health. We hypothesized that the soil nematode community structure would differ in three land use areas (agricultural, forest and industrial soils), be modulated by soil parameters (N, P, K, pH, SOM, CaCO3, granulometric fraction, etc.), and strongly affected by high levels of heavy metals (Cd, Pb, Zn, Cr, Ni, Cu, and Hg) and emerging contaminants (pharmaceuticals and personal care products, PPCPs). Although these pollutants did not significantly affect the total number of free-living nematodes, diversity and structure community indices vastly altered. Our data showed that whereas nematodes with r-strategy were tolerant, genera with k-strategy were negatively affected by the selected pollutants. These effects diminished in soils with high levels of heavy metals given their adaptation to the historical pollution in this area, but not to emerging pollutants like PPCPs. PMID:26895540
Evaluation of the phytostabilisation efficiency in a trace elements contaminated soil using soil health indicators.
Pardo, T; Clemente, R; Epelde, L; Garbisu, C; Bernal, M P
The efficiency of a remediation strategy was evaluated in a mine soil highly contaminated with trace elements (TEs) by microbiological, ecotoxicological and physicochemical parameters of the soil and soil solution (extracted in situ), as a novel and integrative methodology for assessing recovery of soil health. A 2.5-year field phytostabilisation experiment was carried out using olive mill-waste compost, pig slurry and hydrated lime as amendments, and a native halophytic shrub (Atriplex halimus L.). Comparing with non-treated soil, the addition of the amendments increased soil pH and reduced TEs availability, favoured the development of a sustainable vegetation cover (especially the organic materials), stimulated soil microorganisms (increasing microbial biomass, activity and functional diversity, and reducing stress) and reduced direct and indirect soil toxicity (i.e., its potential associated risks). Therefore, under semi-arid conditions, the use of compost and pig slurry with A. halimus is an effective phytostabilisation strategy to improve soil health of nutrient-poor soils with high TEs concentrations, by improving the habitat function of the soil ecosystem, the reactivation of the biogeochemical cycles of essential nutrients, and the reduction of TEs dissemination and their environmental impact. PMID:24468528
The effects of soil amendments on heavy metal bioavailability in two contaminated Mediterranean soils.
Walker, David J; Clemente, Rafael; Roig, Asuncion; Bernal, M Pilar
Two heavy metal contaminated calcareous soils from the Mediterranean region of Spain were studied. One soil, from the province of Murcia, was characterised by very high total levels of Pb (1572 mg kg(-1)) and Zn (2602 mg kg(-1)), whilst the second, from Valencia, had elevated concentrations of Cu (72 mg kg(-1)) and Pb (190 mg kg(-1)). The effects of two contrasting organic amendments (fresh manure and mature compost) and the chelate ethylenediaminetetraacetic acid (EDTA) on soil fractionation of Cu, Fe, Mn, Pb and Zn, their uptake by plants and plant growth were determined. For Murcia soil, Brassica juncea (L.) Czern. was grown first, followed by radish (Raphanus sativus L.). For Valencia soil, Beta maritima L. was followed by radish. Bioavailability of metals was expressed in terms of concentrations extractable with 0.1 M CaCl2 or diethylenetriaminepentaacetic acid (DTPA). In the Murcia soil, heavy metal bioavailability was decreased more greatly by manure than by the highly-humified compost. EDTA (2 mmol kg(-1) soil) had only a limited effect on metal uptake by plants. The metal-solubilising effect of EDTA was shorter-lived in the less contaminated, more highly calcareous Valencia soil. When correlation coefficients were calculated for plant tissue and bioavailable metals, the clearest relationships were for Beta maritima and radish. PMID:12531318
Evaluation of a soil slurry reactor system for treating soil contaminated with munitions compounds
Boopathy, R.; Manning, J.; Montemagno, C.; Kulpa, C.F.
Two 0.5-L semicontinuous soil slurry reactors were operated for seven months to evaluate the performance of the slurry reactor system in bioremediating soil contaminated with munitions compounds. Nitrogen and carbon were supplemented. The soil slurry was mixed continuously and aerated 10 min/day. Ten percent of the contaminated soil was replaced every week. The 2,4,6-trinitrotoluene (TNT) concentration in soil began to drop after 15 days of treatment, falling to less than 0.5 mg/kg from 7800 mg/kg. Total plate counts in both reactors indicated that the bacterial population was maintained, with an average plate count of about 10{sup 8} CFU/mL. The soil slurry was slightly acidic. In addition to TNT, the slurry reactor also removed the other munitions compounds trinitrobenzene (TNB), 2,4-dinitrotoluene (2,4-DNT), RDX, and HMX. Radiolabeling studies on the reactor biomass showed that 23% of [{sup C}14]TNT was mineralized, while 27% was used as biomass and 8% was adsorbed on to the soil. The rest of the [{sup 14}C]TNT was accounted for as TNT metabolites. Increasing the frequency of soil replacement from once to two or three times weekly did not affect the TNT removal rates. However, the slurry system showed signs of stress, with highly acidic conditions and low oxygen uptake rates.
Effects of temperature and soil components on emissions from pyrolysis of pyrene-contaminated soil.
Risoul, Véronique; Richter, Henning; Lafleur, Arthur L; Plummer, Elaine F; Gilot, Patrick; Howard, Jack B; Peters, William A
Effects of temperature and soil on yields and identities of light gases (H2, CH4, C2H2, C2H4, C2H6, CO, and CO2) and polycyclic aromatic hydrocarbons (PAH) from thermal treatment of a pyrene-contaminated (5 wt%) soil in the absence of oxygen were determined for a U.S. EPA synthetic soil matrix prepared to proxy U.S. Superfund soils. Shallow piles (140-170 mg) of contaminated soil particles and as controls, neat (non-contaminated) soil (140-160 mg), neat pyrene (10-15 mg), neat sand (230 mg), and pyrene-contaminated sand (160 mg), were heated in a ceramic boat inside a 1.65 cm i.d. pyrex tube at temperatures from 500 to 1100 degrees C under an axial flow of helium. Volatile products spent 0.2-0.4s at temperature before cooling. Light gases, PAH and a dichloromethane extract of the residue in the ceramic boat, were analyzed by gas chromatography or high pressure liquid chromatography (HPLC). Over 99% pyrene removal was observed when heating for a few tens of seconds in all investigated cases, i.e., at 500, 650, 750, 1000, and 1100 degrees C for soil, and 750 and 1000 degrees C for sand. However, each of these experiments gave significant yields (0.2-16 wt% of the initial pyrene) of other PAH, e.g., cyclopenta[cd]pyrene (CPP), which mutates bacterial cells and human cells in vitro. Heating pyrene-polluted soil gave pyrene conversions and yields of acetylene, CPP, and other PAH exceeding those predicted from similar, but separate heating of neat soil and neat pyrene. Up to 750 degrees C, recovered pyrene, other PAH, and light gases accounted for all or most of the initial pyrene whereas at 1000 and 1100 degrees C conversion to soot was significant. A kinetic analysis disentangled effects of soil-pyrene interactions and vapor phase pyrolysis of pyrene. Increase of residence time was found to be the main reason for the enhanced conversion of pyrene in the case of the presence of a solid soil or sand matrix. Light gas species released due to the thermal treatment, such as
Accumulation of heavy metals from contaminated soil to plants and evaluation of soil remediation by vermiculite.
Malandrino, Mery; Abollino, Ornella; Buoso, Sandro; Giacomino, Agnese; La Gioia, Carmela; Mentasti, Edoardo
We evaluated the distribution of 15 metal ions, namely Al, Cd, Cu, Cr, Fe, La, Mn, Ni, Pb, Sc, Ti, V, Y, Zn and Zr, in the soil of a contaminated site in Piedmont (Italy). This area was found to be heavily contaminated with Cu, Cr and Ni. The availability of these metal ions was studied using Tessier's sequential extraction procedure: the fraction of mobile species, which potentially is the most harmful for the environment, was much higher than that normally present in unpolluted soils. This soil was hence used to evaluate the effectiveness of treatment with vermiculite to reduce the availability of the pollutants to two plants, Lactuca sativa and Spinacia oleracea, by pot experiments. The results indicated that the addition of vermiculite significantly reduces the uptake of metal pollutants by plants, confirming the possibility of using this clay in amendment treatments of metal-contaminated soils. The effect of plant growth on metal fractionation in soils was investigated. Finally, the sum of the metal percentages extracted into the first two fractions of Tessier's protocol was found to be suitable in predicting the phytoavailability of most of the pollutants present in the investigated soil. PMID:21055788
Subchronic exposure of mice to Love Canal soil contaminants.
Silkworth, J B; McMartin, D N; Rej, R; Narang, R S; Stein, V B; Briggs, R G; Kaminsky, L S
The health hazard potential of soil collected from the surface of the Love Canal chemical dump site in Niagara Falls, New York, was assessed in 90-day exposure studies. Female CD-1 mice were exposed to two concentrations of the volatile components of 1 kg of soil with and without direct soil contact. Control mice were identically housed but without soil. The soil was replaced weekly and 87 compounds were detected in the air in the cages above fresh and 7-day-old soil as analyzed by gas chromatography/mass spectrometry. The concentration of many of these compounds decreased during the 7-day exposure cycle. Histopathologic, hematologic, and serum enzyme studies followed necropsy of all mice. There was no mortality of mice exposed for up to 90 days under any condition. Thymus and spleen weights relative to body weight were increased after 4 weeks of exposure by inhalation but not after 8 or 12 weeks of exposure. alpha-, beta-, and delta- Benzenehexachlorides , pentachlorobenzene, and hexachlorobenzene were detected in liver tissue from these animals. Mice exposed to 5- to 10-fold elevated concentration of volatiles had increased body and relative kidney weights. There was no chemically induced lesion in any animal exposed only to the volatile soil contaminants. Mice exposed by direct contact with the soil without elevated volatile exposure had increased body (10%) and relative liver weights (169%). Centrolobular hepatocyte hypertrophy, which involved 40 to 70% of the lobules, was observed in all mice in this group.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:6724196
Effect of soil texture on phytoremediation of arsenic-contaminated soils
NASA Astrophysics Data System (ADS)
Pallud, C. E.; Matzen, S. L.; Olson, A.
Soil arsenic (As) contamination is a global problem, resulting in part from anthropogenic activities, including the use of arsenical pesticides and treated wood, mining, and irrigated agriculture. Phytoextraction using the hyperaccumulating fern Pteris vittata is a promising new technology to remediate soils with shallow arsenic contamination with minimal site disturbance. However, many challenges still lie ahead for a global application of phytoremediation. For example, remediation times using P. vittata are on the order of decades. In addition, most research on As phytoextraction with P. vittata has examined As removal from sandy soils, where As is more available, with little research focusing on As removal from clayey soils, where As is less available. The objective of this study is to determine the effects of soil texture and soil fertilization on As extraction by P. vittata, to optimize remediation efficiency and decrease remediation time under complex field conditions. A field study was established 2.5 years ago in an abandoned railroad grade contaminated with As (average 85.5 mg kg-1) with texture varying from sandy loam to silty clay loam. Organic N, inorganic N, organic P, inorganic P, and compost were applied to separate sub-plots; control ferns were grown in untreated soil. In a parallel greenhouse experiment, ferns were grown in sandy loam soil extracted from the field (180 mg As kg-1), with similar treatments as those used at the field site, plus a high phosphate treatment and treatments with arbuscular mycorrhizal fungi. In the field study, fern mortality was 24% higher in clayey soil than in sandy soil due to waterlogging, while As was primarily associated with sandy soil. Results from the sandy loam soil indicate that soil treatments did not significantly increase As phytoextraction, which was lower in phosphate-treated ferns than in control ferns, both in the field and greenhouse study. Under greenhouse conditions, ferns treated with organic N were
Sodium hypochlorite oxidation of petroleum aliphatic contaminants in calcareous soils.
Picard, François; Chaouki, Jamal
This research project investigated the sodium hypochlorite (NaClO) oxidation of aliphatic petroleum contaminants (C10-C50) in a calcareous soil (average 5473 ppm C10-C50, 15 wt% Ca), which had been excavated from a contaminated industrial site. The decontamination objective was to lower the C10-C50 concentration to 700 ppm. CO2 acidity was used in the project to boost the NaClO oxidation yield and seems to have played a role in desorbing the natural organic matter. The experimental conditions were a 2- to 16-h reaction time, at room temperature, with a 1 to 12.5 wt% NaClO oxidative solution and a fixed 2:1 solution-to-soil ratio. With a 3 wt% NaClO solution and with a CO2 overhead, the NaClO dosage requirement was maintained below 60 g NaClO/g of oxidized C10-C50 over the entire decontamination range. The strong chlorine smell remaining after the reaction was completed suggests that part of the NaClO requirement can be recycled. Except traces of chloroform, there were no regulation-listed organochloride contaminants detected on either the treated soil samples or leachates and the total count of chlorinated compounds in treated soil samples was below the detection limit of 250 mg/kg. The NaClO oxidation mechanism on aliphatic substrates might be triggered by transition metals, such as manganese, but no attempt has been made to investigate the oxidation mechanism. Further investigations would include a constant-fed NaClO system and other techniques to lower the required NaClO dosage. PMID:26702553
Estimated association between dwelling soil contamination and internal radiation contamination levels after the 2011 Fukushima Daiichi nuclear accident in Japan
Tsubokura, Masaharu; Nomura, Shuhei; Sakaihara, Kikugoro; Kato, Shigeaki; Leppold, Claire; Furutani, Tomoyuki; Morita, Tomohiro; Oikawa, Tomoyoshi; Kanazawa, Yukio
Objectives Measurement of soil contamination levels has been considered a feasible method for dose estimation of internal radiation exposure following the Chernobyl disaster by means of aggregate transfer factors; however, it is still unclear whether the estimation of internal contamination based on soil contamination levels is universally valid or incident specific. Methods To address this issue, we evaluated relationships between in vivo and soil cesium-137 (Cs-137) contamination using data on internal contamination levels among Minamisoma (10–40 km north from the Fukushima Daiichi nuclear power plant), Fukushima residents 2–3 years following the disaster, and constructed three models for statistical analysis based on continuous and categorical (equal intervals and quantiles) soil contamination levels. Results A total of 7987 people with a mean age of 55.4 years underwent screening of in vivo Cs-137 whole-body counting. A statistically significant association was noted between internal and continuous Cs-137 soil contamination levels (model 1, p value <0.001), although the association was slight (relative risk (RR): 1.03 per 10 kBq/m2 increase in soil contamination). Analysis of categorical soil contamination levels showed statistical (but not clinical) significance only in relatively higher soil contamination levels (model 2: Cs-137 levels above 100 kBq/m2 compared to those <25 kBq/m2, RR=1.75, p value <0.01; model 3: levels above 63 kBq/m2 compared to those <11 kBq/m2, RR=1.45, p value <0.05). Conclusions Low levels of internal and soil contamination were not associated, and only loose/small associations were observed in areas with slightly higher levels of soil contamination in Fukushima, representing a clear difference from the strong associations found in post-disaster Chernobyl. These results indicate that soil contamination levels generally do not contribute to the internal contamination of residents in Fukushima; thus, individual
Copper removal from contaminated soils by soil washing process using camellian-derived saponin
NASA Astrophysics Data System (ADS)
Reyes, Arturo; Fernanda Campos, Maria; Videla, Álvaro; Letelier, María Victoria; Fuentes, Bárbara
Antofagasta Region in North of Chile has been the main copper producer district in the world. As a consequence of a lack of mining closure regulation, a large number of abandon small-to-medium size metal-contaminated sites have been identified in the last survey performed by the Chilean Government. Therefore, more research development on sustainable reclamation technologies must be made in this extreme arid-dry zone. The objective of this study is to test the effectiveness of soil remediation by washing contaminated soil using camellian-derived saponin for the mobilization of copper. Soil samples were taken from an abandoned copper mine site located at 30 km North Antofagasta city. They were dried and sieved at 75 µm for physico-chemical characterization. A commercial saponin extracted from camellias seed was used as biosurfactant. The soil used contains 67.4 % sand, 26.3 % silt and 6.3 % clay. The soil is highly saline (electric conductivity, 61 mScm-1), with low organic matter content (0.41%), with pH 7.30, and a high copper concentration (2200 mg Kg-1 soil). According to the sequential extraction procedure of the whole soil, copper species are mainly as exchangeable fraction (608.2 mg Kg-1 soil) and reducible fraction (787.3 mg Kg-1 soil), whereas the oxidizable and residual fractions are around 205.7 and 598.8 mg Kg-1 soil, respectively. Soil particles under 75 µm contain higher copper concentrations (1242 mg Kg-1 soil) than the particle fraction over 75 µm (912 mg Kg-1 soil). All washing assays were conducted in triplicate using a standard batch technique with and without pH adjustment. The testing protocols includes evaluation of four solid to liquid ratio (0.5:50; 1.0:50; 2.0:50, and 5.0:50) and three saponin concentrations (0, 1, and 4 mg L-1). After shaking (24 h, 20±1 °C) and subsequently filtration (0.45 µm), the supernatants were analyzed for copper and pH. The removal efficiencies of copper by saponin solutions were calculated in according to the
Remediation of hexachlorobenzene contaminated soils by rhamnolipid enhanced soil washing coupled with activated carbon selective adsorption.
Wan, Jinzhong; Chai, Lina; Lu, Xiaohua; Lin, Yusuo; Zhang, Shengtian
The present study investigates the selective adsorption of hexachlorobenzene (HCB) from rhamnolipid solution by a powdered activated carbon (PAC). A combined soil washing-PAC adsorption technique is further evaluated on the removal of HCB from two soils, a spiked kaolin and a contaminated real soil. PAC at a dosage of 10 g L(-1) could achieve a HCB removal of 80-99% with initial HCB and rhamnolipid concentrations of 1 mg L(-1) and 3.3-25 g L(-1), respectively. The corresponding adsorptive loss of rhamnolipid was 8-19%. Successive soil washing-PAC adsorption tests (new soil sample was subjected to washing for each cycle) showed encouraging leaching and adsorption performances for HCB. When 25 g L(-1) rhamnolipid solution was applied, HCB leaching from soils was 55-71% for three cycles of washing, and HCB removal by PAC was nearly 90%. An overall 86% and 88% removal of HCB were obtained for kaolin and real soil, respectively, by using the combined process to wash one soil sample for twice. Our investigation suggests that coupling AC adsorption with biosurfactant-enhanced soil washing is a promising alternative to remove hydrophobic organic compounds from soils. PMID:21397398
PCP and creosote PAHs are found in most of the contaminated soils at wood-treatment sites. The treatment methods currently being used for such soils include soil washing, incineration, and biotreatment. Soil washing involves removal of the hazardous chemicals from soils ...
Enhancement of bioremediation of a creosote-contaminated soil
Carriere, P.P.E.; Mesania, F.A.
There is a growing concern in the US about the increasing number of industrial sites containing concentration of polynuclear aromatic hydrocarbons (PAHs) in their soil and waste sludge above background levels. PAHs, neutral and non-polar organic compounds, consist of two or more fused benzene rings which are generated from industrial activities such as creosote wood treating, gas manufacturing, coke making, coal tar refining, petroleum refining, and aluminum smelting. Low molecular weight PAHs are generally considered as extremely toxic compounds, whereas the higher molecular weight PAHs are carcinogenic in nature. Bioremediation, a viable option for treatment of PAHs contaminated soil, can be enhanced by the use of surfactant. In this study a nonionic surfactant Triton X-100, was investigated. Abiotic soil desorption experiments were performed to determine the kinetics of release of selected PAH compounds from the soil matrix to the aqueous phase. Respirometric experiments were also conducted to evaluate the effect of nonionic surfactant on biodegradation. The N-Con system respirometer was used to monitor the oxygen uptake by the microorganisms. The abiotic experiments results indicated that the addition of surfactant to soil/water systems increases the desorption of PAH compounds. The increase in PAHs availability to the microorganisms produced an increase in oxygen uptake.
Risk of antibiotic resistance from metal contaminated soils
NASA Astrophysics Data System (ADS)
Knapp, Charles
It is known that contaminated soils can lead to increased incidence of illness and disease, but it may also prevent our ability to fight disease. Many antibiotic resistant genes (ARG) acquired by bacteria originate from the environment. It is important to understand factors that influence levels of ARG in the environment, which could affect us clinically and agriculturally. The presence of elevated metal content in soils often promotes antibiotic resistance in exposed microorganisms. Using qPCR, the abundances of ARG to compare levels with geochemical conditions in randomly selected soils from several countries. Many ARG positively correlated with soil metal content, especially copper, chromium, nickel, lead, and iron. Results suggest that geochemical metal conditions influence the potential for antibiotic resistance in soil, which might be used to estimate baseline gene presence on various landscape scales and may translate to epidemiological risk of antibiotic-resistance transmission from the environment. This suggests that we may have to reconsider tolerances of metal pollution in the environment.
Toxicity Assessment of Contaminated Soils of Solid Domestic Waste Landfill
NASA Astrophysics Data System (ADS)
Pasko, O. A.; Mochalova, T. N.
The paper delivers the analysis of an 18-year dynamic pattern of land pollutants concentration in the soils of a solid domestic waste landfill. It also presents the composition of the contaminated soils from different areas of the waste landfill during its operating period. The authors calculate the concentrations of the following pollutants: chrome, nickel, tin, vanadium, lead, cuprum, zinc, cobalt, beryllium, barium, yttrium, cadmium, arsenic, germanium, nitrate ions and petrochemicals and determine a consistent pattern of their spatial distribution within the waste landfill area as well as the dynamic pattern of their concentration. Test-objects are used in experiments to make an integral assessment of the polluted soil's impact on living organisms. It was discovered that the soil samples of an animal burial site are characterized by acute toxicity while the area of open waste dumping is the most dangerous in terms of a number of pollutants. This contradiction can be attributed to the synergetic effect of the polluted soil, which accounts for the regularities described by other researchers.
Stabilization of lead-contaminated soil saves time
Hasbach, A.
The Wisconsin Department of Transportation (WisDOT) acquired property adjacent to a former battery-cracking facility. The soil contained extremely high levels of lead from past waste disposal activities. The Wisconsin Department of Natural Resources (WDNR) required WisDOT to perform a remedial investigation and take corrective action. WisDOT retained RMT Inc., Madison, Wisc., to do the work. RMT`s investigation discovered lead levels as high as 50,000 mg/kg in the soil. An action level of 500 mg/kg was negotiated with WDNR. A total of 11 acres exceeded this level; 7.5 acres contained lead exceeding 1,000 mg/kg. In some areas, contamination reached a depth of 12 feet, while in others lead was found only in the top 12 inches. A total of 55,000 cubic yards of soil required treatment. A dig and haul approach to remediation would have cost $200 to $300 per ton. Instead, RMT called for in situ treatment using a patented chemical mixture to tie the lead up in a stable and immobile compound. While it does not render the soil lead free, it does prevent the lead from leaching into nearby soil or groundwater.
Rate controlling model for bioremediation of oil contaminated soil
Li, K.Y.; Annamali, S.N.; Hopper, J.R. )
A mathematical model of bio-remediation of hydrocarbons in a soil matrix has been developed to predict the rate controlling step and the remediation rate during the bioremediation of a contaminated soil. The model is based on mass transfer of oxygen and oil into the aqueous solution in the soil matrix and the biodegradation of the hydrocarbons in the aqueous solution. Monod's equation was used to describe the biodegradation rate in aqueous solution while the mass transfer equations were used to describe the mass transfer rates of oxygen and oil in the soil matrix. Results from model calculations indicate that the bio-remediation rate increases and approaches a limiting value when one of the rates becomes controlling. When the parameters of the site soil samples are measured and the solubilities of oxygen and oil in aqueous solution are obtained, the bioremediation rate can be predicted by this model. The rate controlling step of the bioremediation site may be identified quickly and steps to improve the bioremediation rate can be recommended. 8 refs., 7 figs.
[Effects and Biological Response on Bioremediation of Petroleum Contaminated Soil].
Yang, Qian; Wu, Man-li; Nie, Mai-qian; Wang, Ting-ting; Zhang, Ming-hui
Bioaugmentation and biostimulation were used to remediate petroleum-contaminated soil which were collected from Zichang city in North of Shaanxi. The optimal bioremediation method was obtained by determining the total petroleum hydrocarbon(TPH) using the infrared spectroscopy. During the bioremediation, number of degrading strains, TPH catabolic genes, and soil microbial community diversity were determined by Most Probable Number (MPN), polymerase chain reaction (PCR) combined agarose electrophoresis, and PCR-denaturing gradient electrophoresis (DGGE). The results in different treatments showed different biodegradation effects towards total petroleum hydrocarbon (TPH). Biostimulation by adding N and P to soils achieved the best degradation effects towards TPH, and the bioaugmentation was achieved by inoculating strain SZ-1 to soils. Further analysis indicated the positive correlation between catabolic genes and TPH removal efficiency. During the bioremediation, the number of TPH and alkanes degrading strains was higher than the number of aromatic degrading strains. The results of PCR-DGGE showed microbial inoculums could enhance microbial community functional diversity. These results contribute to understand the ecologically microbial effects during the bioremediation of petroleum-polluted soil. PMID:26314140
Leaching of Contamination from Stabilization/Solidification Remediated Soils of Different Texture
NASA Astrophysics Data System (ADS)
Burlakovs, Juris; Kasparinskis, Raimonds; Klavins, Maris
Development of soil and groundwater remediation technologies is a matter of great importance to eliminate historically and currently contaminated sites. Stabilization/solidification (S/S) refers to binding of waste contaminants to a more chemically stable form and thus diminishing leaching of contamination. It can be performed using cement with or without additives in order to stabilize and solidify soil with the contamination in matrix. A series of experiments were done to determine leaching properties of spiked soils of different texture bound with cement. Results of experiments showed, that soil texture (content of sand, silt and clay particles) affects the leaching of heavy metals from stabilized soils.
Rhizoremediation of phenanthrene and pyrene contaminated soil using wheat.
Shahsavari, Esmaeil; Adetutu, Eric M; Taha, Mohamed; Ball, Andrew S
Rhizoremediation, the use of the plant rhizosphere and associated microorganisms represents a promising method for the clean up of soils contaminated with polycyclic aromatic hydrocarbons (PAHs) including phenanthrene and pyrene, two model PAHs. Although numerous studies have been published reporting the degradation of phenanthrene and pyrene, very few evaluate the microbial basis of the rhizoremediation process through the application of molecular tools. The aim of this study was to investigate the effect of wheat on the degradation of two model PAHs (alone or in combination) and also on soil bacterial, fungal and nidA gene (i.e. a key gene in the degradation of pyrene) communities. The addition of wheat plants led to a significant enhancement in the degradation of both phenanthrene and pyrene. In pyrene-contaminated soils, the degradation rate increased from 15% (65 mg/kg) and 18% (90 mg/kg) in unplanted soils to 65% (280 mg/kg) and 70% (350 mg/kg) in planted treatments while phenanthrene reduction was enhanced from 97% (394 mg/kg) and 87% (392 mg/kg) for unplanted soils to 100% (406 mg/kg) and 98% (441 mg/kg) in the presence of wheat. PCR-DGGE results showed that the plant root let to some changes in the bacterial and fungal communities; these variations did not reflect any change in hydrocarbon-degrading communities. However, plate counting, traditional MPN and MPN-qPCR of nidA gene revealed that the wheat rhizosphere led to an increase in the total microbial abundance including PAH degrading organisms and these increased activities resulted in enhanced degradation of phenanthrene and pyrene. This clearer insight into the mechanisms underpinning PAH degradation will enable better application of this environmentally friendly technique. PMID:25819570
Olive mill waste biochar: a promising soil amendment for metal immobilization in contaminated soils.
Hmid, Amine; Al Chami, Ziad; Sillen, Wouter; De Vocht, Alain; Vangronsveld, Jaco
The potential use of biochar from olive mill waste for in situ remediation of metal contaminated soils was evaluated. Biochar was mixed with metal contaminated soil originating from the vicinity of an old zinc smelter. Soil-biochar mixtures were equilibrated for 30 and 90 days. At these time points, Ca(NO3)2 exchangeable metals were determined, and effects of the biochar amendment on soil toxicity were investigated using plants, bacteria, and earthworms. Bean (Phaseolus vulgaris) growth, metal content, antioxidative enzymes activities, and soluble protein contents were determined. Furthermore, effects on soil microbial communities (activity, diversity, richness) were examined using Biolog ECOplates. After 120 days of soil-biochar equilibration, effects on weight and reproduction of Eisenia foetida were evaluated. With increasing biochar application rate and equilibration period, Ca(NO3)2 exchangeable metals decreased, and growth of bean plants improved; leaf metal contents reduced, the activities of antioxidative stress enzymes decreased, and soluble protein contents increased. Soil microbial activity, richness, and diversity were augmented. Earthworm mortality lowered, and their growth and reproduction showed increasing trends. PMID:25146122
Spectroscopy as a diagnostic tool for urban soil contaminants
NASA Astrophysics Data System (ADS)
Brook, Anna; Kopel, Daniella
Urbanization has become one of the major forces of change around the globe. Land use transformation, especially urbanization has the most profound influences of human activities because it affects so many of the planet's physical and biological systems. Land use changes directly impact the ability of the earth to continue to provide ecological services to human society and the other occupants of the ecosystems. The urban process gradually degrades and transforms agricultural and natural ecosystems into built environments. The urban environment includes cities, suburbs, peri-urban areas and towns. Urban ecosystems are highly heterogeneous due to the variety of land covers and land purposes. Thus, the choices on managing the extent and arranging the land cover patches (e.g., lawns) assist to shape the emergent structure and function of the urban ecosystems. As a result of ecological conditions and current management status the urban soils show substantial spatial heterogeneity. Whereas, adverse effects of pollutants on ecosystems have been demonstrated, one important need for environmental impact assessment have been defined as maintenance of long-term monitoring systems, which can enable to improve monitoring, modelling and assessment of various stressors in agriculture environment. Diffuse reflectance spectroscopy and diffuse reflectance Fourier-transform infrared (FTIR) spectroscopy across visible-near- short- mid- and long- wave infrared (0.4-14μm) has the potential to meet this demand. Relationships between spectral reflectance and soil properties, such as grain size distribution, moisture, iron oxides, carbonate content, and organic matter, have already been established in many studies (Krishnan et al. 1980, Ben-Dor and Banin 1995, Jarmer et al. 2008, Richter et al. 2009). The aims of this study are to develop diagnostic tool for heavy metals, polycyclic aromatic hydrocarbons, asbestos and other anthropogenic contaminants in urban soil using spectroscopy
Phytoremediation`s role in bioremediation of recalcitrant soil contaminants
Fletcher, J.S.
Flavonoid and coumarin compounds produced by plants supported the growth of polychlorinated biphenyl (PCB)-degrading bacteria, and the bacteria retained their PCB-degrading properties. Root leachates and washings from mulberry trees also supported the growth of a PCB-degrading bacterium. The release of phenolics into the soil by the network of finely separated plant roots may be thought of as a naturally occurring injection system capable of delivering desired substrates into the soil that fosters the growth and action of PCB-degrading bacteria. However, it is important to recognize that the roots of all plant species do not produce and release equal amounts and kinds of phenolic compounds; therefore, the rhizosphere zone of all plants must not be considered a haven for PCB-degrading bacteria. It may be that only a few plant species have the desired characteristics. Awareness of such species would be extremely valuable, because growing such plants at contaminated sites has the potential of selectively fostering the growth of PCB-degrading bacteria over competing organisms. The outcome could be a sustained population of PCB-degrading bacteria that would degrade PCBs over an extended time period. Plant-microbe systems have the potential of providing inexpensive, ecologically stable bioremediation systems, and thereby play a major role in bioremediation of recalcitrant soil contaminants.
Microbial mobilization of plutonium and other actinides from contaminated soil.
Francis, A J; Dodge, C J
We examined the dissolution of Pu, U, and Am in contaminated soil from the Nevada Test Site (NTS) due to indigenous microbial activity. Scanning transmission x-ray microscopy (STXM) analysis of the soil showed that Pu was present in its polymeric form and associated with Fe- and Mn- oxides and aluminosilicates. Uranium analysis by x-ray diffraction (μ-XRD) revealed discrete U-containing mineral phases, viz., schoepite, sharpite, and liebigite; synchrotron x-ray fluorescence (μ-XRF) mapping showed its association with Fe- and Ca-phases; and μ-x-ray absorption near edge structure (μ-XANES) confirmed U(IV) and U(VI) oxidation states. Addition of citric acid or glucose to the soil and incubated under aerobic or anaerobic conditions enhanced indigenous microbial activity and the dissolution of Pu. Detectable amount of Am and no U was observed in solution. In the citric acid-amended sample, Pu concentration increased with time and decreased to below detection levels when the citric acid was completely consumed. In contrast, with glucose amendment, Pu remained in solution. Pu speciation studies suggest that it exists in mixed oxidation states (III/IV) in a polymeric form as colloids. Although Pu(IV) is the most prevalent and generally considered to be more stable chemical form in the environment, our findings suggest that under the appropriate conditions, microbial activity could affect its solubility and long-term stability in contaminated environments. PMID:26406590
Humic substances-enhanced electroremediation of heavy metals contaminated soil.
Bahemmat, Mahdi; Farahbakhsh, Mohsen; Kianirad, Mehran
The effects of catholyte conditioning and the use of humic acids (HAs) and fulvic acids (FAs) as chelating agents to improve electrokinetic (EK) remediation efficiency were investigated using a real and highly contaminated soil. By applying a constant voltage (2.0V/cm) to the soil, pH and current changes and heavy metals (HMs) concentration were investigated through a range of durations and positions. The observations demonstrated that both catholyte conditioning with 0.1N HNO3 and using humic substances (HSs) enhance remediation efficiency. After 20 days of EK treatment, the removal efficiency of HMs in HS-enhanced EK remediation was about 2.0-3.0 times greater than when unenhanced. The quantity of HMs moving toward the cathode exceeded the anode, from which it could be reasonably inferred that most negatively charged HM-HS complexes were moved by electroosmotic forces. Further, free HM cations and positively charged complexed HMs migrated to the catholyte compartment by electromigration. The results obtained in this study, demonstrate the suitability of HS-enhanced EK remediation in HMs contaminated soil. PMID:27058638
Effect of oxygen amendments and soil pH on bioremediation of industrially contaminated soils
Joshi, M.M.; Lee, S.
Polynuclear aromatic hydrocarbons (PAHs), by-products of coal conversion processes, have contaminated soils near coal plant sites either through accidental spills or systematic discharge. Because these compounds are carcinogenic, mutagenic, and teratogenic, remediation of such sites is a legitimate concern. For this study, contaminated soil samples were obtained from the Alberta Research Council (ARC) primary clean-up facility. Preliminary analysis of the soil was done for contaminant characterization and determination of initial contamination levels. Acinetobacter sp. was used for aerobic treatment of soil over a five-week period under optimum conditions. Because the rate of biodegradation is influenced by the pH, it is of interest to study the effect of pH on remediation efficiency in the physiological pH range of 5.0 to 9.0. Also, oxygen amendment via hydrogen peroxide solution was used to improve remediation in a packed bed, and the results were compared with those obtained under completely mixed conditions.
Arsenic and chromium speciation in an urban contaminated soil.
Landrot, Gautier; Tappero, Ryan; Webb, Samuel M; Sparks, Donald L
The distribution and speciation of As and Cr in a contaminated soil were studied by synchrotron-based X-ray microfluorescence (μ-XRF), microfocused X-ray absorption spectroscopy (μ-XAS), and bulk extended X-ray absorption fine structure spectroscopy (EXAFS). The soil was taken from a park in Wilmington, DE, which had been an important center for the leather tanning industry along the Atlantic seaboard of the United States, until the early 20th century. Soil concentrations of As, Cr, and Pb measured at certain locations in the park greatly exceeded the background levels of these heavy metals in the State of Delaware. Results show that Cr(III) and As(V) species are mainly present in the soil, with insignificant amounts of Cr(VI) and As(III). Micro-XRF maps show that Cr and Fe are distributed together in regions where their concentrations are diffuse, and at local spots where their concentrations are high. Iron oxides, which can reduce Cr(VI) to Cr(III), are present at some of these hot spots where Cr and Fe are highly concentrated. Arsenic is mainly associated with Al in the soil, and to a minor extent with Fe. Arsenate may be sorbed to aluminum oxides, which might have transformed after a long period of time into an As-Al precipitate phase, having a structure and chemical composition similar to mansfieldite (AlAsO(4)⋅2H(2)O). The latter hypothesis is supported by the fact that only a small amount of As present in the soil was desorbed using the characteristic toxicity leaching procedure tests. This suggests that As is immobilized in the soil. PMID:22520924
Land contamination and soil evolution in abandoned mine areas (Italy)
NASA Astrophysics Data System (ADS)
Bini, Claudio; Wahsha, Mohammad; Spiandorello, Massimo
In Italy ore research and exploitation are nearly exhausted since the end of the last century, leaving on the land a huge amount of mine waste, therefore provoking evident environmental damage including landscape, vegetation and the food chain, and a potential threat to human health. The increasing environmental consciousness of general population compelled Public Administrators to set down effective legislation acts on this subject (e.g. D.L. 152/2006), and more generally on environmental contamination. In this work we present the results of a survey carried out at several mixed sulphides mine sites in Italy, exploited for at least a millennium, and closed in the '60s of the last century. Biogeochemical analyses carried out on 50 soil profiles (mostly Entisols and Inceptisols) and vegetation in the proximal and distal areas of ore exploitation show metal concentrations overcoming legislation limits on average (Cu up to 3160 mg kg-1 , Pb up to 23600 mg kg-1, Zn up to 1588 mg kg-1, Fe up to 52,30 %). Ni, Cr and Mn concentrations, instead, are generally below the reference levels. Metal concentrations in native vegetation of the examined areas are moderately to highly elevated. Significant amounts of Cu, Pb, Zn in roots of Plantago major and Silene dioica, in leaves of Taraxacum officinale, and Salix spp, have been recorded. Essential elements, in particular, present Translocation Coefficients (TC) >1, with Mn>Zn>Cu>Fe. Toxic elements (Cd, Cr, Pb), instead, present TC<1, suggesting a synergic/antagonist effect to occur among metals and plants, according to their role in mineral nutrition. The results obtained suggest the abandoned mine sites to represent actual natural aboratories where to experiment new opportunities for restoration of anthropogenically contaminated areas, and to study new pedogenetic trends from these peculiar parent materials. Moreover, the examined plants are genetically adapted to naturally metal-enriched soils, and therefore may be utilized in
Remediation of transuranic-contaminated coral soil at Johnston Atoll using the segmented gate system
Bramlitt, E.; Johnson, N.
Thermo Analytical, Inc. (TMA) has developed a system to remove clean soil from contaminated soil. The system consists of a soil conveyor, an array of radiation detectors toward the conveyor feed end, a gate assembly at the conveyor discharge end, and two additional conveyors which move discharged soil to one or another paths. The gate assembly is as wide as the ``sorter conveyor,`` and it has eight individual gates or segments. The segments automatically open or close depending on the amount of radioactivity present. In one position they pass soil to a clean soil conveyor, and in the other position they let soil fall to a hot soil conveyor. The soil sorting process recovers clean soil for beneficial use and it substantially reduces the quantity of soil which must be decontaminated or prepared for waste disposal. The Segmented Gate System (SGS) was developed for the cleanup of soil contaminated with some transuranium elements at Johnston Atoll. It has proven to be an effective means for recovering clean soil and verifying that soil is clean, minimizing the quantity of truly contaminated soil, and providing measures of contamination for waste transport and disposal. TMA is constructing a small, transportable soil cleanup as it is confident the SGS technology can be adapted to soils and contaminants other than those at Johnston Atoll. It will use this transportable plant to demonstrate the technology and to develop site specific parameters for use in designing plants to meet cleanup needs.
Steam Injection/Vacuum Extraction (SIVE) is a method to enable vacuum extraction to treat soils contaminated with semivolatile organic compounds (SVOCS) and to speed the cleanup of soils contaminated with volatile organic compounds (VOCs). he steam injection raises the soil tempe...
Assessing the bioavailability and risk from metal contaminated soils and dusts#
Exposure to contaminated soil and dust is an important pathway in human and ecological risk assessment and often is the "risk-driver" for metal contaminated soil. Site-specific soil physical and chemical characteristics, as well as biological factors, determine the bioavailabilit...
Mining nd smelting of Pb, Zn and Cd ores have caused widespread soil contamination in many countries. In locations with severe soil contamination, and strongly acidic soil or mine waste, ecosystems are devastated. Research has shown that An phytotoxicity, Pb-induced phosphate def...
Performance of the thermal desorption process for removal of organic contaminants, mostly polynuclear aromatic hydrocarbons (PAHs), from soils was evaluated. The Superfund Site soil tested was a fine sandy soil contaminated with creosote. An optimum operating temperature of 550 C...
Performance of the thermal desorption process for removal of organic contaminants, mostly polynuclear aromatic hydrocarbons (PAHs), from soils was evaluated. he Superfund Site soil tested was a fine sandy soil contaminated with creosote. n optimum operating temperature of 550 deg...
[Biological treatments for contaminated soils: hydrocarbon contamination. Fungal applications in bioremediation treatment].
Martín Moreno, Carmen; González Becerra, Aldo; Blanco Santos, María José
Bioremediation is a spontaneous or controlled process in which biological, mainly microbiological, methods are used to degrade or transform contaminants to non or less toxic products, reducing the environmental pollution. The most important parameters to define a contaminated site are: biodegradability, contaminant distribution, lixiviation grade, chemical reactivity of the contaminants, soil type and properties, oxygen availability and occurrence of inhibitory substances. Biological treatments of organic contaminations are based on the degradative abilities of the microorganisms. Therefore the knowledge on the physiology and ecology of the biological species or consortia involved as well as the characteristics of the polluted sites are decisive factors to select an adequate biorremediation protocol. Basidiomycetes which cause white rot decay of wood are able to degrade lignin and a variety of environmentally persistent pollutants. Thus, white rot fungi and their enzymes are thought to be useful not only in some industrial process like biopulping and biobleaching but also in bioremediation. This paper provides a review of different aspects of bioremediation technologies and recent advances on ligninolytic metabolism research. PMID:15709784
8. Atmospheric, water, and soil contamination after Chernobyl.
Yablokov, Alexey V; Nesterenko, Vassily B; Nesterenko, Alexey V
Air particulate activity over all of the Northern Hemisphere reached its highest levels since the termination of nuclear weapons testing--sometimes up to 1 million times higher than before the Chernobyl contamination. There were essential changes in the ionic, aerosol, and gas structure of the surface air in the heavily contaminated territories, as measured by electroconductivity and air radiolysis. Many years after the catastrophe aerosols from forest fires have dispersed hundreds of kilometers away. The Chernobyl radionuclides concentrate in sediments, water, plants, and animals, sometimes 100,000 times more than the local background level. The consequences of such a shock on aquatic ecosystems is largely unclear. Secondary contamination of freshwater ecosystems occurs as a result of Cs-137 and Sr-90 washout by the high waters of spring. The speed of vertical migration of different radionuclides in floodplains, lowland moors, peat bogs, etc., is about 2-4 cm/year. As a result of this vertical migration of radionuclides in soil, plants with deep root systems absorb them and carry the ones that are buried to the surface again. This transfer is one of the important mechanisms, observed in recent years, that leads to increased doses of internal irradiation among people in the contaminated territories. PMID:20002050
Phosphate sources and their suitability for remediation of contaminated soils.
Knox, A S; Kaplan, D I; Paller, M H
Phosphate minerals and specifically apatite show promise for environmental cleanup because they can form stable compounds with a wide range of cationic contaminants. However, phosphate minerals naturally accumulate some heavy metals that may cause additional contamination of the environment if used improperly. Nine commercially available phosphate materials were evaluated for remediation of contaminated soil based on solubility, concentration of metal/metalloid impurities, and leachability of impurity metal/metalloids. The phosphate materials consisted of three groups: processed (i.e., fertilizers), mined (rock phosphates from different formations), and biogenic (ground fish bone). Processed and mined rock phosphates contained relatively high total concentrations of As, Co, Cr, and Cu but did not exceed the RCRA toxicity characteristic leaching procedure (TCLP) limits. Biogenic apatite contained much lower metal concentrations than processed and mined rock phosphate and was appreciably more soluble. By combining biogenic and mined phosphate it is possible to obtain a wide range of phosphate release rates, permitting rapid immobilization of contaminants while providing a slow release of phosphate for continued long-term treatment. PMID:16150478
Phytotoxicity of trace metals in spiked and field-contaminated soils: Linking soil-extractable metals with toxicity.
Hamels, Fanny; Malevé, Jasmina; Sonnet, Philippe; Kleja, Dan Berggren; Smolders, Erik
Soil tests have been widely developed to predict trace metal uptake by plants. The prediction of metal toxicity, however, has rarely been tested. The present study was set up to compare 8 established soil tests for diagnosing phytotoxicity in contaminated soils. Nine soils contaminated with Zn or Cu by metal mining, smelting, or processing were collected. Uncontaminated reference soils with similar soil properties were sampled, and series of increasing contamination were created by mixing each with the corresponding soil. In addition, each reference soil was spiked with either ZnCl2 or CuCl2 at several concentrations. Total metal toxicity to barley seedling growth in the field-contaminated soils was up to 30 times lower than that in corresponding spiked soils. Total metal (aqua regia-soluble) toxicity thresholds of 50% effective concentrations (EC50) varied by factors up to 260 (Zn) or 6 (Cu) among soils. For Zn, variations in EC50 thresholds decreased as aqua regia > 0.43 M HNO3 > 0.05 M ethylenediamine tetraacetic acid (EDTA) > 1 M NH4 NO3 > cobaltihexamine > diffusive gradients in thin films (DGT) > 0.001 M CaCl2 , suggesting that the last extraction is the most robust phytotoxicity index for Zn. The EDTA extraction was the most robust for Cu-contaminated soils. The isotopically exchangeable fraction of the total soil metal in the field-contaminated soils markedly explained the lower toxicity compared with spiked soils. The isotope exchange method can be used to translate soil metal limits derived from soils spiked with metal salts to site-specific soil metal limits. PMID:25053440
Stabilization/Solidification Remediation Method for Contaminated Soil: A Review
NASA Astrophysics Data System (ADS)
Tajudin, S. A. A.; Azmi, M. A. M.; Nabila, A. T. A.
Stabilization/Solidification (S/S) is typically a process that involves a mixing of waste with binders to reduce the volume of contaminant leachability by means of physical and chemical characteristics to convert waste in the environment that goes to landfill or others possibly channels. Stabilization is attempts to reduce the solubility or chemical reactivity of the waste by changing the physical and chemical properties. While, solidification attempt to convert the waste into easily handled solids with low hazardous level. These two processes are often discussed together since they have a similar purpose of improvement than containment of potential pollutants in treated wastes. The primary objective of this review is to investigate the materials used as a binder in Stabilization/Solidification (S/S) method as well as the ability of these binders to remediate the contaminated soils especially by heavy metals.
Mercury mobility and bioavailability in soil from contaminated area
NASA Astrophysics Data System (ADS)
Boszke, Leonard; Kowalski, Artur; Astel, Aleksander; Barański, Andrzej; Gworek, Barbara; Siepak, Jerzy
The mobility and bioavailability of mercury in the soil from the area near a plant using elemental mercury for manufacturing thermometers, areometers, glass energy switches and other articles made of technical glass has been evaluated. Mercury has been determined by sequential extraction method and with additional thermo desorption stage to determine elemental mercury. The procedure of sequential extraction involves five subsequent stages performed with the solutions of chloroform, deionized water, 0.5 M HCl, 0.2 M NaOH and aqua regia. The mean concentration of total mercury in soil was 147 ± 107 μg g-1 dry mass (range 62-393), and the fractionation revealed that mercury was mainly bound to sulfides 56 ± 8% (range 45-66), one of the most biounavailable and immobile species of mercury in the environment. The fractions that brought lower contribution to the total mercury content were semi-mobile humic matter 22 ± 9% (range 11-34) and elemental mercury 17 ± 5% (range 8-23). The contributions brought by the highly mobile and toxic organomercury compounds were still lower 2.3 ± 2.7% (range 0.01-6.5). The lowest contributions brought the acid-soluble mercury 1.5 ± 1.3% (range 0.1-3.5) and water-soluble mercury 1.0 ± 0.3% (range 0.6-1.7). The surface layer of soil (0-20 cm) was characterized by higher mercury concentrations than that of the subsurface soil (60-80 cm), but the fractional contributions were comparable. The comparison of mercury fractionation results obtained in this study for highly polluted soils with results of fractionation of uncontaminated or moderately contaminated samples of soil and sediments had not shown significant statistical differences; however, in the last samples elemental mercury is usually present at very low concentrations. On the basis of obtained correlation coefficients it seems that elemental mercury soils from "Areometer" plant are contaminated; the main transformation is its vaporization to atmosphere and oxidation to
Using Iron to Treat Chlorohydrocarbon-Contaminated Soil
NASA Technical Reports Server (NTRS)
Hitchens, G. Duncan; Hodko, Dalibor; Kim, Heekyung; Rogers, Tom; Singh, Waheguru Pal; Giletto, Anthony; Cisar, Alan
A method of in situ remediation of soil contaminated with chlorinated hydrocarbon solvents involves injection of nanometer-size iron particles. The present method exploits a combination of prompt chemical remediation followed by longer-term enhanced bioremediation and, optionally, is practiced in conjunction with the method of bioremediation described earlier. Newly injected iron particles chemically reduce chlorinated hydrocarbons upon contact. Thereafter, in the presence of groundwater, the particles slowly corrode via chemical reactions that effect sustained release of dissolved hydrogen. The hydrogen serves as an electron donor, increasing the metabolic activity of the anaerobic bacteria and thereby sustaining bioremediation at a rate higher than the natural rate.
TXRF analysis of soils and sediments to assess environmental contamination.
Bilo, Fabjola; Borgese, Laura; Cazzago, Davide; Zacco, Annalisa; Bontempi, Elza; Guarneri, Rita; Bernardello, Marco; Attuati, Silvia; Lazo, Pranvera; Depero, Laura E
Total reflection x-ray fluorescence spectroscopy (TXRF) is proposed for the elemental chemical analysis of crustal environmental samples, such as sediments and soils. A comparative study of TXRF with respect to flame atomic absorption spectroscopy and inductively coupled plasma optical emission spectroscopy was performed. Microwave acid digestion and suspension preparation methods are evaluated. A good agreement was found among the results obtained with different spectroscopic techniques and sample preparation methods for Cr, Mn, Fe, Ni, Cu, and Zn. We demonstrated that TXRF is suitable for the assessment of environmental contamination phenomena, even if the errors for Pb, As, V, and Ba are ingent. PMID:24122164
Biochemical remediation of a TNT contaminated soil. Doctoral thesis
Young, D.G.
This research presents the first field evidence for the phytoremediation of a TNT contaminated soil by the emersed aquatic plant, Myriophyllum brasiliense. Commonly known as Parrotfeather, this plant features a nitroreductase enzyme capable of promoting the reduction of the nitro groups on TNT to the corresponding amino groups. The proposed reductive pathway takes the TNT through isomers of monoamino and diamino to the final triaminonitrotoluene (TNT) Once in the TAT form and in the presence of oxygen, the final oxidative step quickly yields ring opened products and complete phytoremediation of TNT.
DDT remediation in contaminated soils: a review of recent studies.
Sudharshan, Simi; Naidu, Ravi; Mallavarapu, Megharaj; Bolan, Nanthi
Over the past few decades significant progress has been made in research on DDT degradation in the environment. This review is an update of some of the recent studies on the degradation and biodegradation pathways of DDT and its metabolites, particularly in soils. The latest reports on human toxicity shows that DDT intake is still occurring even in countries that banned its use decades ago. Ageing, sequestration and formation of toxic metabolites during the degradation processes pose environmental challenges and result in difficulties in bioremediation of DDT contaminated soils. Degradation enhancement strategies such as the addition of chelators, low molecular organic acids, co-solvent washing and the use of sodium and seaweeds as ameliorant have been studied to accelerate degradation. This review describes and discusses the recent challenges and degradation enhancement strategies for DDT degradation by potentially cost effective procedures based on bioremediation. PMID:22907383
Assessing microbial activities in metal contaminated agricultural volcanic soils - An integrative approach.
Parelho, C; Rodrigues, A S; Barreto, M C; Ferreira, N G C; Garcia, P
Volcanic soils are unique naturally fertile resources, extensively used for agricultural purposes and with particular physicochemical properties that may result in accumulation of toxic substances, such as trace metals. Trace metal contaminated soils have significant effects on soil microbial activities and hence on soil quality. The aim of this study is to determine the soil microbial responses to metal contamination in volcanic soils under different agricultural land use practices (conventional, traditional and organic), based on a three-tier approach: Tier 1 - assess soil microbial activities, Tier 2 - link the microbial activity to soil trace metal contamination and, Tier 3 - integrate the microbial activity in an effect-based soil index (Integrative Biological Response) to score soil health status in metal contaminated agricultural soils. Our results showed that microbial biomass C levels and soil enzymes activities were decreased in all agricultural soils. Dehydrogenase and β-glucosidase activities, soil basal respiration and microbial biomass C were the most sensitive responses to trace metal soil contamination. The Integrative Biological Response value indicated that soil health was ranked as: organic>traditional>conventional, highlighting the importance of integrative biomarker-based strategies for the development of the trace metal "footprint" in Andosols. PMID:27057992
[Study on composite stabilization of arsenic (As) contaminated soil].
Wang, Hao; Pan, Li-xiang; Zhang, Xiang-yu; Li, Meng; Song, Bao-hua
Since the contaminated soil may contain various kinds of heavy metals, use of single chemical reagent leads to poor remediation and high cost. In this study, soil containing As, Zn, Cd was sampled, and different reagents were selected to carry out the rapid stabilization of contaminated soil. The TCLP (toxicity characteristic leaching procedure) was used to evaluate the leachate toxicity of heavy metals and the results indicated that calcium-containing, sulphur-containing and iron-containing reagents had good performance in reducing the metal mobility. The stabilization efficiency of the six reagents tested ranked in the order of CaO > Na2S > organic sulfur > Chitosan > FeSO4 > (C2H5)2NCS2Na. Two types of reagents (six reagents) were combined based on the target properties of different reagents and the stabilization efficiency was evaluated and analyzed. The results indicated that the composite reagents had higher stabilization efficiency: the efficiency of 3% FeSO4 + 5% CaO was 81.7%, 97.2% and 68.2% for As, Cd and Zn, respectively, and the efficiency of 3% CaO + 5% organic sulfur was 76.6%, 95.7% and 93.8% for these three metals, respectively. Speciation analysis was carried out in this study and the results suggested that it was the change of metals from the exchangeable state to the reduction (for inorganic reagent) or oxidation state (for organic reagent) that caused the soil stabilization and the degree of change determined the stabilization efficiency. PMID:24289009
Remediation of Cu-contaminated soil using chelant and EAOP.
Pociecha, Maja; Sircelj, Helena; Lestan, Domen
An electrochemical advanced oxidation process (EAOP) was used for treatment of the washing solution obtained during leaching of Cu (364 +/- 2 mg kg(-1)) contaminated soil, with chelant S,S isomer of ethylenediamine disuccinate ([S,S]-EDDS). In the EAOP (constant current density 40 mA cm(-2)), a boron-doped diamond anode was used for the generation of hydroxyl radicals and oxidative decomposition of [S,S]-EDDS-metal complexes in the washing solution. The released Cu was mostly electro-deposited on the stainless-steel cathode. Three consecutive additions of 5 mmol kg(-1) [S,S]-EDDS removed 46% of the Cu from the soil, mostly from carbonate and oxide soil fractions (87 and 99% Cu reduction). The soil Cu oral availability in the simulated stomach and intestinal phases (in vitro physiologically based extraction test) was reduced by 5.5 and 4.6-times. Cu plant availability (in vitro diethylenetriamine pentaacetate test) was reduced by 3.6-times. The discharge solution was clear, almost colorless, with pH 8.4, 0.45 mg L(-1) Cu and 0.01 mM EDDS. PMID:19847704
Weeds ability to phytoremediate cadmium-contaminated soil.
Hammami, Hossein; Parsa, Mehdi; Mohassel, Mohammad Hassan Rashed; Rahimi, Salman; Mijani, Sajad
An alternative method to other technologies to clean up the soil, air and water pollution by heavy metals is phytoremediation. Therefore, a pot culture experiment was conducted at the College of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran, in 2014 to determine the potential absorption of cadmium by Portulaca oleracea (Common purslane), Solanum nigrum (Black nightshade), Abutilon theophrasti (Velvetleaf) and Taraxacum officinale (Dandelion). The type of experiment was completely randomized design with factorial arrangement and four replications. The soil in pot was treated with different rates of CdCl2.H2O (0 (control), 10, 20, 40, 60, and 80 mg Cd/kg soil) and the plants were sown. With increasing concentration levels, fresh weight and dry weight of shoots and roots of all plant species were reduced. The reduction severity was ranked according the following order, P. oleracea > A. theophrasti > S. nigrum > T. officinale. Bioconcentration factor (BCF), Translocation factor (TF) and Translocation efficiency (TE%) was ranked according the following order, T. officinale > S. nigrum > A. theophrasti > P. oleracea. The results of this study revealed that T. officinale and S. nigrum are effective species to phytoremediate Cd-contaminated soil. PMID:26125671
Physical properties of soils contaminated by oil lakes, Kuwait
Mohammad, A.S.; Wahba, S.A.; Al-Khatieb, S.O.
In preparation for a marine assault by the coalition forces, the Iraqi Army heavily mined Kuwait`s coastal zone and the oil fields. Over a million mines were placed on the Kuwait soil. Burning of 732 oil wells in the State of Kuwait due to the Iraqi invasion caused damages which had direct and indirect effect on environment. A total of 20-22 million barrels of spilled crude oil were collected in natural desert depressions and drainage network which formed more than 300 oil lakes. The total area covered with oil reached 49 km{sup 2}. More than 375 trenches revealed the existence of hard, massive caliche (CaCO{sub 3}) subsoil which prevent leached oil from reaching deeper horizons, and limited the maximum depth of penetration to 1.75 m. Total volume of soil contaminated reached 22,652,500 m{sup 3} is still causing environmental problems and needs an urgent cleaning and rehabilitation. Kuwait Oil Company has recovered approximately 21 million barrels from the oil lakes since the liberation of Kuwait. In our examined representative soil profiles the oil penetration was not deeper than 45 cm. Infiltration rate, soil permeability, grain size distribution, aggregates formation and water holding capacity were assessed. 15 refs., 5 figs., 5 tabs.
Bioremediation treatment of hydrocarbon-contaminated Arctic soils: influencing parameters.
Naseri, Masoud; Barabadi, Abbas; Barabady, Javad
The Arctic environment is very vulnerable and sensitive to hydrocarbon pollutants. Soil bioremediation is attracting interest as a promising and cost-effective clean-up and soil decontamination technology in the Arctic regions. However, remoteness, lack of appropriate infrastructure, the harsh climatic conditions in the Arctic and some physical and chemical properties of Arctic soils may reduce the performance and limit the application of this technology. Therefore, understanding the weaknesses and bottlenecks in the treatment plans, identifying their associated hazards, and providing precautionary measures are essential to improve the overall efficiency and performance of a bioremediation strategy. The aim of this paper is to review the bioremediation techniques and strategies using microorganisms for treatment of hydrocarbon-contaminated Arctic soils. It takes account of Arctic operational conditions and discusses the factors influencing the performance of a bioremediation treatment plan. Preliminary hazard analysis is used as a technique to identify and assess the hazards that threaten the reliability and maintainability of a bioremediation treatment technology. Some key parameters with regard to the feasibility of the suggested preventive/corrective measures are described as well. PMID:24903252
Chromium and arsenic in contaminated soils (Review of publications)
NASA Astrophysics Data System (ADS)
Vodyanitskii, Yu. N.
In the last decades, the chromium clarke in the world's soils has been revised and reduced; at present, it is equal to 70 mg/kg. No maximal permissible concentration is accepted for the total chromium content in the soils of Russia; it appears reasonable to use the Western European and North American standards in Russia and to take the average value of the maximal permissible concentration equal to 200 mg Cr/kg. Chromium toxicity depends on its oxidizing status. The hazardous effect decreases with the reduction of Cr(VI) to Cr(III). There are various chemical reducers of Cr(VI), including sulfides, dissolved organic substance, aqueous Fe(II) and minerals enriched in Fe(II), and Fe(0). As-containing ore tailings represent a powerful source of technogenic arsenic. Significant environment contamination with natural As is registered in a number of Asian countries. The maximal permissible concentration of total arsenic is equal to 2 mg/kg in Russian soils; it is probably underestimated, because it is lower than the As clarke in soil (5 mg/kg). The approximately permissible concentration (APC) values for As look more reasonable. Arsenic toxicity depends on its oxidation degree: As(III) is 2-3 times more toxic than As(V).
Plumbum contamination detecting model for agricultural soil using hyperspectral data
NASA Astrophysics Data System (ADS)
Liu, Xiangnan; Huang, Fang; Wang, Ping
The issue of environmental pollution due to toxic heavy metals in agricultural land has caused worldwide growing concern in recent years. Being one of toxic heavy metals, the accumulation of Plumbum (Pb) may have negative effects on natural and agricultural vegetation growth, yield and quality. It can also constitute short-term and long-term health risks by entering the food chain. In this study, we analyze the relationships between physical and chemical characteristics, biological parameters of soil-vegetation system and hyperspectral spectrum responses systematically. The relation between hyperspectral data and the biological parameters of Pb polluted wheat canopy such as leaf pigments, leaf moisture, cell structure and leaf area index (LAI) are discussed. We detect the changes in the wheat biological parameters and spectral response associated with Pb concentration in soil. To reveal the impact mechanisms of Pb concentration on agricultural soil, six models including chlorophyll-leaf moisture model, chlorophyll-cell structure model, chlorophyll-LAI model, leaf moisture-cell structure model, leaf moisture-LAI model, cell structure- LAI model are explored. We find that changes in Pb concentration present various features in different models. Pb contamination in agricultural soil can be identified and assessed effectively while integrating the characteristics of those developed models.
Bioremediation of coal contaminated soil under sulfate-reducing condition.
Kuwano, Y; Shimizu, Y
The objective of this study was to investigate the biodegradation of coal-derived hydrocarbons, especially high molecular weight (HMW) components, under anaerobic conditions. For this purpose biodegradation experiments were performed, using specifically designed soil column bioreactors. For the experiment, coal-contaminated soil was prepared, which contains high molecular weight hydrocarbons at high concentration (approx. 55.5 mgC g-drysoil(-1)). The experiment was carried out in two different conditions: sulfate reducing (SR) condition (SO4(2-) = 10 mmol l(-1) in the liquid medium) and control condition (SO4(2-)<0.5 mmol l(-1)). Although no degradation was observed under the control condition, the resin fraction decreased to half (from 6,541 to 3,386 mgC g-soil(-1)) under SR condition, with the concomitant increase of two PAHs (phenanthrene and fluoranthene, 9 and 2.5 times, respectively). From these results, we could conclude that high molecular hydrocarbons were biodegradable and transformed to low molecular weight PAHs under the sulfate-reducing condition. Since these PAHs are known to be biologically degraded under aerobic condition, a serial combination of anaerobic (sulfate reducing) and then aerobic bioremediations could be effective and useful for the soil pollution by petroleum and/or coal derived hydrocarbons. PMID:16457179
Thermal treatment of soils contaminated with gas oil: influence of soil composition and treatment temperature.
Piña, Juliana; Merino, Jerónimo; Errazu, Alberto F; Bucalá, Verónica
Samples of two soils containing different organic matter contents, neat or contaminated with gas oil (diesel fuel oil) at 2.5 wt.% were heated from room temperature to different final temperatures (200-900 degrees C). The experiments, performed in an anaerobic media, simulate conditions pertinent to ex situ thermal desorptive and thermal destructive treatments. The products generated during the heating were collected and light gases were analyzed by gas chromatography. The results indicate that the chemical composition of the soil is a key factor since it strongly influences the quantity and composition of the off-gases. According to the liquid and light gas yields, the gas oil does not affect appreciably the generation of pyrolysis products of the own soil constituents and the gas oil does not suffer significant chemical transformations even at high operating temperatures (e.g. 900 degrees C). With surface areas of 16000 cm(2)/g (Soil A) and 85000 cm(2)/g (Soil B) based on the monolayer adsorbed model, 4 and 20%, respectively, of the original gas oil can be adsorbed. These values are in good agreement with experimental data. Even for high temperatures, the employed thermal treatment is capable to practically remove the gas oil from the soil bed without changing appreciably the original chemical composition of the contaminant. PMID:12220829
Remediation of Cr(VI)-Contaminated Soil Using the Acidified Hydrazine Hydrate.
Ma, Yameng; Li, Fangfang; Jiang, Yuling; Yang, Weihua; Lv, Lv; Xue, Haotian; Wang, Yangyang
Acidified hydrazine hydrate was used to remediate Cr(VI)-contaminated soil. The content of water-soluble Cr(VI) in contaminated soil was 4977.53 mg/kg. The optimal initial pH of hydrazine hydrate solution, soil to solution ratio and molar ratio of Cr(VI) to hydrazine hydrate for remediation of Cr(VI)-contaminated soil were 5.0, 3:1 and 1:3, respectively. Over 99.50 % of water-soluble Cr(VI) in the contaminated soil was reduced at the optimal condition within 30 min. The remediated soil can keep stable within 4 months. Meanwhile the total phosphorus increased from 0.47 to 4.29 g/kg, indicating that using of acidified hydrazine hydrate is an effective method to remediate Cr(VI)-contaminated soil. PMID:27351195
Evaluation of soil-washing technology: Results of bench-scale experiments on petroleum-fuels contaminated soils
Loden, M.E.
The U.S. Environmental Protection Agency through its Risk Reduction Engineering Laboratory's Releases Control Branch has undertaken research and development efforts to address the problem of leaking underground storage tanks (USTs). Under this effort, EPA is currently evaluating soil washing technology for cleaning up soil contaminated by the release of petroleum products from leaking underground storage tanks. Soil washing is a dynamic physical process which remediates contaminated soil via two mechanisms--particle separation and dissolution of the contaminants into the washwater. As a result of the washing process, a significant fraction of the contaminated soil is cleaned and can be returned into the original excavation or used as cleaned secondary fill or aggregate material. Since the contaminants are more concentrated in the fine soil fractions, their separation and removal from the bulk soil increases the overall effectiveness of the process. Subsequent treatment will be required for the spent washwaters and the fine soil fractions. The soil washing program evaluated the effectiveness of soil washing technology in removing petroleum products (unleaded gasoline, diesel/home heating fuel, and waste crankcase oil) from an EPA-developed Synthetic Soil Matrix (SSM) and from actual site soils. Operating parameters such as contact time, washwater volume, rinsewater volume, washwater temperature, and effectiveness of additives were investigated.
Stabilization and solidification of chromium-contaminated soil
Cherne, C.A.; Thomson, B.M.; Conway, R.
Chromium-contaminated soil is a common environmental problem in the United States as a result of numerous industrial processes involving chromium. Hexavalent chromium [Cr(VI)] is the species of most concern because of its toxicity and mobility in groundwater. One method of diminishing the environmental impact of chromium is to reduce it to a trivalent oxidation state [Cr(III)], in which it is relatively insoluble and nontoxic. This study investigated a stabilization and solidification process to minimize the chromium concentration in the Toxicity Characteristic Leaching Procedure (TCLP) extract and to produce a solidified waste form with a compressive strength in the range of 150 to 300 pounds per square inch (psi). To minimize the chromium in the TCLP extract, the chromium had to be reduced to the trivalent oxidation state. The average used in this study was an alluvium contaminated with chromic and sulfuric acid solutions. The chromium concentration in the in the in situ soil was 1212 milligrams per kilogram (mg/kg) total chromium and 275 mg/kg Cr(VI). The effectiveness of iron, ferrous sulfate to reduce Cr(VI) was tested in batch experiments.
Chemometric assessment of enhanced bioremediation of oil contaminated soils.
Soleimani, Mohsen; Farhoudi, Majid; Christensen, Jan H
Bioremediation is a promising technique for reclamation of oil polluted soils. In this study, six methods for enhancing bioremediation were tested on oil contaminated soils from three refinery areas in Iran (Isfahan, Arak, and Tehran). The methods included bacterial enrichment, planting, and addition of nitrogen and phosphorous, molasses, hydrogen peroxide, and a surfactant (Tween 80). Total petroleum hydrocarbon (TPH) concentrations and CHEMometric analysis of Selected Ion Chromatograms (SIC) termed CHEMSIC method of petroleum biomarkers including terpanes, regular, diaromatic and triaromatic steranes were used for determining the level and type of hydrocarbon contamination. The same methods were used to study oil weathering of 2 to 6 ring polycyclic aromatic compounds (PACs). Results demonstrated that bacterial enrichment and addition of nutrients were most efficient with 50% to 62% removal of TPH. Furthermore, the CHEMSIC results demonstrated that the bacterial enrichment was more efficient in degradation of n-alkanes and low molecular weight PACs as well as alkylated PACs (e.g. C₃-C₄ naphthalenes, C₂ phenanthrenes and C₂-C₃ dibenzothiophenes), while nutrient addition led to a larger relative removal of isoprenoids (e.g. norpristane, pristane and phytane). It is concluded that the CHEMSIC method is a valuable tool for assessing bioremediation efficiency. PMID:23644688
Legacy soil contamination at abandoned mine sites: making a case for guidance on soil protection.
Kostarelos, Konstantinos; Gavriel, Ifigenia; Stylianou, Marinos; Zissimos, Andreas M; Morisseau, Eleni; Dermatas, Dimitris
Within the European Union, guidance in the form of a uniform Soil Directive does not exist and member states are left to enact their own legislation governing historic soil contamination. Several historic or "legacy" sites exist in Cyprus - an EU member state with a long history of mining and a significant number of abandoned mining sites. The gold-silver enrichment plant of Mitsero village was abandoned 70 years ago, yet soil samples inside and outside the plant were extremely low in pH, exhibited high leachability of heavy metals and high cyanide levels. Water samples collected from an ephemeral stream located down-gradient of the site contained high levels of heavy metals. Two abandoned open-pit mines (Kokkinopezoula and Mathiatis) were investigated, where elevated metal content in soil samples from the surrounding streams and spoil heaps, and extremely low pH and high metal content in water samples from the mine crater were measured. PMID:25600021
40 CFR 267.116 - What must I do with contaminated equipment, structure, and soils?
Code of Federal Regulations, 2011 CFR
... that waste following all applicable requirements of 40 CFR part 262. ... equipment, structure, and soils? 267.116 Section 267.116 Protection of Environment ENVIRONMENTAL PROTECTION..., structure, and soils? You must properly dispose of or decontaminate all contaminated equipment,...
40 CFR 267.116 - What must I do with contaminated equipment, structure, and soils?
Code of Federal Regulations, 2013 CFR
... that waste following all applicable requirements of 40 CFR part 262. ... equipment, structure, and soils? 267.116 Section 267.116 Protection of Environment ENVIRONMENTAL PROTECTION..., structure, and soils? You must properly dispose of or decontaminate all contaminated equipment,...
40 CFR 267.116 - What must I do with contaminated equipment, structure, and soils?
Code of Federal Regulations, 2014 CFR
... that waste following all applicable requirements of 40 CFR part 262. ... equipment, structure, and soils? 267.116 Section 267.116 Protection of Environment ENVIRONMENTAL PROTECTION..., structure, and soils? You must properly dispose of or decontaminate all contaminated equipment,...
40 CFR 267.116 - What must I do with contaminated equipment, structure, and soils?
Code of Federal Regulations, 2012 CFR
... that waste following all applicable requirements of 40 CFR part 262. ... equipment, structure, and soils? 267.116 Section 267.116 Protection of Environment ENVIRONMENTAL PROTECTION..., structure, and soils? You must properly dispose of or decontaminate all contaminated equipment,...
Relative Bioavailability and Bioaccessability and Speciation of Arsenic in Contaminated Soils
Background: Assessment of soil arsenic (As) bioavailability may profoundly affect the extent of remediation required at contaminated sites by improving human exposure estimates. Because small adjustments in soil As bioavailability estimates can significantly alter risk assessment...
Effect of OSE(II)-Enhanced Soil Washing(OESW) for TPH -Contaminated Soil Remediation
NASA Astrophysics Data System (ADS)
Hwang, J. H.; Lee, D. H.; Woo, N. C.
The objectives of this study were to perform potentially suitable active agent that solubilize total petroleum hydrocarbon (TPH) present as contaminants and to evaluate the optimal range of process parameters that can increase the removal efficiency in OSE(II)-enhanced soil washing (OESW) pilot tests. Used experimental method for solubilisation of TPH by using OSE(II) was batch experiments. The active agent solution parameters for OESW pilot tests were solution concentration, solution pH in the OESW pilot tests. Based on the batch experiments, OSE(II) was proved as a suitable active agent that solubilizes TPH present as contaminants. The highest recovery (92-95 %) of the contaminants was obtained using a OSE(II) in the batch experiments. The pilot test results revealed that the optimum conditions were achieved with a OSE(II) surfactant solution concentration of 10 % (v/v), a OSE(II) surfactant solution pH of 6.5-7.5 of OSE(II) active agent solution. The maximum removal of contaminants (88 %) was obtained when optimum conditions were simultaneously met in pilot-scale OESW operations. These results confirm the viability of OESW for treating TPH-contaminated soil.
Repeated phytoextraction of four metal-contaminated soils using the cadmium/zinc hyperaccumulator Sedum plumbizincicola.
Li, Zhu; Wu, Longhua; Hu, Pengjie; Luo, Yongming; Zhang, Hao; Christie, Peter
A cadmium/zinc hyperaccumulator extracted metals from four contaminated soils over three years in a glasshouse experiment. Changes in plant metal uptake and soil total (aqua regia-extractable) and available metals were investigated. Plant Cd concentrations in a high-Cd acid soil and plant Zn concentrations in two acid soils decreased during repeated phytoextraction and were predicted by soil available metal concentrations. However, on repeated phytoextraction, plant Cd concentrations remained constant in lightly Cd-polluted acid soils, as did plant Cd and Zn in alkaline soils, although soil available metal concentrations decreased markedly. After phytoextraction acid soils showed much higher total metal removal efficiencies, indicating possible suitability of phytoextraction for acid soils. However, DGT-testing, which takes soil metal re-supply into consideration, showed substantial removal of available metal and distinct decreases in metal supply capacity in alkaline soils after phytoextraction, suggesting that a strategy based on lowering the bioavailable contaminant might be feasible. PMID:24675367
Bioremediation of a weathered and a recently oil-contaminated soils from Brazil: a comparison study.
Trindade, P V O; Sobral, L G; Rizzo, A C L; Leite, S G F; Soriano, A U
The facility with which hydrocarbons can be removed from soils varies inversely with aging of soil samples as a result of weathering. Weathering refers to the result of biological, chemical and physical processes that can affect the type of hydrocarbons that remain in a soil. These processes enhance the sorption of hydrophobic organic contaminants (HOCs) to the soil matrix, decreasing the rate and extent of biodegradation. Additionally, pollutant compounds in high concentrations can more easily affect the microbial population of a recently contaminated soil than in a weathered one, leading to inhibition of the biodegradation process. The present work aimed at comparing the biodegradation efficiencies obtained in a recently oil-contaminated soil (spiked one) from Brazil and an weathered one, contaminated for four years, after the application of bioaugmentation and biostimulation techniques. Both soils were contaminated with 5.4% of total petroleum hydrocarbons (TPHs) and the highest biodegradation efficiency (7.4%) was reached for the weathered contaminated soil. It could be concluded that the low biodegradation efficiencies reached for all conditions tested reflect the treatment difficulty of a weathered soil contaminated with a high crude oil concentration. Moreover, both soils (weathered and recently contaminated) submitted to bioaugmentation and biostimulation techniques presented biodegradation efficiencies approximately twice as higher as the ones without the aforementioned treatment (natural attenuation). PMID:15620743
[Washing copper (II)-contaminated soil using surfactant solutions].
Zhao, Bao-wei; Wu, Yong-qi; Ma, Chan-Yuan; Zhu, Rui-jia
The batch equilibrium washing of copper (II) in the soil matrix by anionic surfactant, sodium dodecylbenzyl sulfonate (SDBS), nonionic surfactant, octylphenoxypolyethoxyethanol (TX100), and their mixture (SDBS-TX100), was studied and compared. The influences of surfactant concentrations, washing time, pH values of solutions, ratios of soil to water and inorganic salts on washing efficiency were investigated. It was shown that the washing efficiency differed with the kinds of surfactants. Given the initial surfactant concentrations, the washing of copper (II) by single SDBS was greater than those by single TX100 and the mixed SDBS-TX100. The washing efficiency by 6 000 mg x L(-1) of SDBS was up to 46.3%, which was 5.8, 10.8, 10.8 and 19.3 times as those by SDBS-TX100 (3:1), SDBS-TX100 (1:1), SDBS-TX100 (1:3) and single TX100 respectively. When the ratio of soil to water was 1 to 10 and washing time reached 24 h, the washing efficiency achieved the maximum. pH values of solutions had obvious effect on the washing of copper (II). The washing efficiency of copper decreased sharply with the increase of pH. At the high acidity (pH = 1.50), the washing efficiency of copper (II) was up to 95%. The smaller the ratios of soil to water were, the higher the washing efficiencies would be. The existence of inorganic salts with the certain concentrations, such as Na+, Ca2+ and Mg2+, could not influence the washing capacity of surfactants, but the excessive Mg2+ (more than 500 mg x L(-1)) could resulted in the precipitation of SDBS. The results will make an implication for surfactant-enhanced remediation of soils contaminated with heavy metals. PMID:19968132
Characterization and remediation of highly radioactive contaminated soil at Hanford
Buckmaster, M.A.; Erickson, J.K.
The Hanford Site, Richland, Washington, contains over 1,500 identified waste sites and numerous groundwater plumes that will be characterized and remediated over the next 30 years. As a result of the Hanford Federal Facility Agreement and Consent Order, the US Department of Energy (DOE) has initiated a remedial investigation/feasibility study (RI/FS) at the 200-BP-1 operable unit. The 200-BP-1 RI/FS is the first Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) investigation on the Hanford Site that involves highly radioactive and chemically contaminated soils. The initial phase of site characterization was designed to assess the nature and extent of contamination associated with the source waste sites within the 200-BP-1 operable unit. Characterization activities consisted of drilling and sampling, chemical and physical analysis of samples, and development of a conceptual vadose zone model. These data were then used. to develop remedial alternatives during the FS evaluation. The preferred alternative resulting from the RI/FS process for the 200-BP-1 operable unit is to construct a surface isolation barrier. The multi-layered earthen barrier will be designed to prevent migration of contaminants resulting from water infiltration, biointrusion, and wind and water erosion.
Thermal desorption of PCBs from contaminated soil with copper dichloride.
Liu, Jie; Qi, Zhifu; Li, Xiaodong; Chen, Tong; Buekens, Alfons; Yan, Jianhua; Ni, Mingjiang
Copper dichloride is an important catalyst both in the dechlorination of chlorinated aromatic compounds and the formation of PCDD/Fs. The effect of copper dichloride on polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) was studied in treated soil and off gas after thermal desorption of PCB-contaminated soil at 300, 400, 500, 600 °C. The presence of copper dichloride clearly enhances thermal desorption by promoting PCBs removal, destruction, and dechlorination. After thermal treatment at 600 °C for 1 h, the removal efficiency and destruction efficiency for PCBs reached 98.1 and 93.9%, respectively. Compared with the positive influence on PCBs, copper dichloride catalyzed large amount of PCDFs formation at 300 °C, with the concentration ratio of 2.35. The effect of CuCl2 on PCDFs formation weakened with the rising temperature since PCDFs destruction became dominant under higher temperature. Different from PCDFs, PCDDs concentration in treated soil and off gas decreased continuously with the increasing temperature. PMID:26233752
Impact of coal mine dump contaminated soils on elemental uptake by Spinacia oleracea (spinach)
Chunilall, V.; Kindness, A.; Jonnalagadda, S.B.
The elemental uptake and the growth response of Spinacia oleracea (spinach) to the soil contaminated with the South African bituminous coal mine dump soil, viz. 0%, 5%, 15%, and 25% w/w, was investigated. The contaminated soils were analyzed for pH, cation exchange capacity (CEC), soil organic matter (SOM), and concentrations of selected heavy metals. The pH, SOM, and CEC decreased with an increase in contamination indicating the acidic nature of coal mine soil and the raise in the soil binding sites. The distribution of Fe, Mn, Ni, Cd, and Pb in the roots and leaves of the plants was determined in two stages of plant growth. Spinach showed high accumulation of Fe and increased levels of Ni and Cd with an increase in contamination. No plant growth was recorded with 25% contamination.
Test plan for the soils facility demonstration: A petroleum contaminated soil bioremediation facility
Lombard, K.H.
The objectives of this test plan are to show the value added by using bioremediation as an effective and environmentally sound method to remediate petroleum contaminated soils (PCS) by: demonstrating bioremediation as a permanent method for remediating soils contaminated with petroleum products; establishing the best operating conditions for maximizing bioremediation and minimizing volatilization for SRS PCS during different seasons; determining the minimum set of analyses and sampling frequency to allow efficient and cost-effective operation; determining best use of existing site equipment and personnel to optimize facility operations and conserve SRS resources; and as an ancillary objective, demonstrating and optimizing new and innovative analytical techniques that will lower cost, decrease time, and decrease secondary waste streams for required PCS assays.
The effects of treating contaminated soils with various soil amendments on the bioavailability of lead were assessed in the weanling rat model. The effect of treatment was assessed by comparing the adsorption of Pb of animals fed soil samples treated with (0.5%, 1% P and 2.5% Fe ...
Physicochemical and mineralogical characterization of transuranic contaminated soils for uranium soil integrated demonstration
Elless, M.P.; Lee, S.Y.
DOE has initiated the Uranium Soils Integrated Demonstration (USID) project. The objective of the USID project is to develop a remediation strategy that can be adopted for use at other DOE sites requiring remediation. Four major task groups within the USID project were formed, namely the Characterization Task Group (CTG), the Treatability Task Group (TTG), the Secondary Waste Treatment and Disposal Task Group (SWTDTG), and the Risk and Performance Assessment Task Group (RPATG). The CTG is responsible for determining the nature of the uranium contamination in both untreated and treated soil. The TTG is responsible for the selective removal of uranium from these soils in such a manner that the leaching does not seriously degrade the soil`s physicochemical characteristics or generate a secondary waste form that is difficult to manage and/or dispose. The SWTDTG is responsible for developing strategies for the removal of uranium from all wastewaters generated by the TTGs. Finally the RPATG is responsible for developing the human health and environmental risk assessment of the untreated and treated soils. Because of the enormity of the work required to successfully remediate uranium-contaminated soils, an integrated approach was designed to avoid needless repetition of activities among the various participants in the USID project. Researchers from Oak Ridge National Laboratory (ORNL), Los Alamos National Laboratory (LANL), Argonne National Laboratory (ANL), and Idaho National Engineering Laboratory (INEL) were assigned characterization and/or treatability duties in their areas of specialization. All tasks groups are involved in the integrated approach; however, the thrust of this report concentrates on the utility of the integrated approach among the various members of the CTG. This report illustrates the use of the integrated approach for the overall CTG and to provide the results generated specifically by the CTG or ORNL from FY1993 to the present.
[Strengthening Effects of Sodium Salts on Washing Kerosene Contaminated Soil with Surfactants].
Huang, Zhao-lu; Chen, Quan-yuan; Zhou, Juan; Xie, Mo-han
The impact of sodium salt on kerosene contaminated soil washing with surfactants was investigated. The results indicated that sodium silicate greatly enhanced the washing efficiency of SDS. Sodium tartrate can largely enhance the washing efficiency of SDBS and Brij35. Sodium salts can enhance the washing efficiency on kerosene contaminated with TX-100. No significant differences were observed between different sodium salts. Sodium salt of humic acid and sodium silicate had similar enhancement on kerosene contaminated soil washing with saponin. Sodium humate can be a better choice since its application can also improve soil quality. The enhancement of sodium silicate on kerosene contaminated soil washing with Tw-80 increased with the increase of Tw-80 dosage. However, the impact of sodium chloride and sodium tartrate was opposite to sodium silicate. Sodium salts can reduce surface tension and critical micelle concentration of ionic surfactants to enhance the washing. Sodium salts can also reduce re-adsorption of oil to soil with nonionic surfactants to enhance the washing. Kerosene contamination can increase the contact angle of soil, which indicated the increase of hydrophilicity of soil. Washing with surfactants can reduce the hydrophilicitiy of soil according to contact angle measurement, which indicated that kerosene contaminated soil remediation with surfactant can also benefit nutrient and water transportation in the contaminated soil. PMID:26314139
Testing of in situ vitrification on soils contaminated with explosive compounds
Campbell, B.E.; Schultz, S.; Cichelli, J.
A treatability test using the In Situ Vitrification (ISV) process was successfully completed on explosives-contaminated soils from the former Nebraska Ordinance Plant (NOP). Contaminated soil from various regions of the plant were gathered, homogenized, and then submitted to Geosafe for testing. ISV is a thermal treatment process in which contaminated soils are heated to melting by the use of electrical current. Upon cooling, the melted soil forms a glass and crystalline (vitrified) product. Organic compounds present in the soil predominantly pyrolyze (thermally decompose into elemental hydrogen and carbon); the pyrolysis products are eventually oxidized when they reach the oxygen-rich hood plenum area at the soil surface. Non-volatile compounds are permanently immobilized within the vitrified product, and volatile heavy metals are removed from the off-gas stream by a gas treatment system. The treatability test had the primary objective of determining the effectiveness and feasibility of treating the explosives-contaminated soil using the ISV technology.
Contamination of soils in the urbanized areas of Belarus with polycyclic aromatic hydrocarbons
NASA Astrophysics Data System (ADS)
Kukharchyk, T. I.; Khomich, V. S.; Kakareka, S. V.; Kurman, P. V.; Kozyrenko, M. I.
The content of polycyclic aromatic hydrocarbons (PAHs) in the soils of urbanized areas, including the impact zones of Belarus, were studied. The concentrations of 16 PAHs in the soils were determined for individual and high-rise building zones, forests, and forest parks of Belarus. The levels of the PAH accumulation in the soils of different industrial enterprises and boiler stations were analyzed. Possible sources of soil contamination with PAHs were considered, and the structure of the PAHs in the soils was shown. The levels of the soil contamination were determined from the regulated parameters for individual compounds and the sum of 16 PAHs.
Phytoremediation of dye contaminated soil by Leucaena leucocephala (subabul) seed and growth assessment of Vigna radiata in the remediated soil
Jayanthy, V.; Geetha, R.; Rajendran, R.; Prabhavathi, P.; Karthik Sundaram, S.; Dinesh Kumar, S.; Santhanam, P.
The present study was investigated for soil bioremediation through sababul plant biomass (Leucaena leucocephala). The soil contaminated with textile effluent was collected from Erode (chithode) area. Various physico-chemical characterizations like N, P, and K and electrical conductivity were assessed on both control and dye contaminated soils before and after remediation. Sababul (L. leucocephala) powder used as plant biomass for remediation was a tool for textile dye removal using basic synthetic dyes by column packing and eluting. The concentration of the dye eluted was compared with its original concentration of dye and were analyzed by using UV–vis spectrophotometer. Sababul plant biomass was analyzed for its physico-chemical properties and active compounds were detected by GC–MS, HPTLC and FTIR. Plant growth was assessed with green gram on the textile contaminated soil and sababul had the potential of adsorbing the dye as the contaminated soil and also check the growth of green gram. PMID:25183943
Biochar- and phosphate-induced immobilization of heavy metals in contaminated soil and water: implication on simultaneous remediation of contaminated soil and groundwater.
Liang, Yuan; Cao, Xinde; Zhao, Ling; Arellano, Eduardo
Long-term wastewater irrigation or solid waste disposal has resulted in the heavy metal contamination in both soil and groundwater. It is often separately implemented for remediation of contaminated soil or groundwater at a specific site. The main objective of this study was to demonstrate the hypothesis of simultaneous remediation of both heavy metal contaminated soil and groundwater by integrating the chemical immobilization and pump-and-treat methods. To accomplish the objective, three experiments were conducted, i.e., an incubation experiment was first conducted to determine how dairy-manure-derived biochar and phosphate rock tailing induced immobilization of Cd in the Cd-contaminated soils; second, a batch sorption experiment was carried out to determine whether the pre-amended contaminated soil still had the ability to retain Pb, Zn and Cd from aqueous solution. BCR sequential extraction as well as XRD and SEM analysis were conducted to explore the possible retention mechanism; and last, a laboratory-scale model test was undertaken by leaching the Pb, Zn, and Cd contaminated groundwater through the pre-amended contaminated soils to demonstrate how the heavy metals in both contaminated soil and groundwater were simultaneously retained and immobilized. The incubation experiment showed that the phosphate biochar were effective in immobilizing soil Cd with Cd concentration in TCLP (toxicity characteristics leaching procedure) extract reduced by 19.6 % and 13.7 %, respectively. The batch sorption experiment revealed that the pre-amended soil still had ability to retain Pb, Zn, and Cd from aqueous solution. The phosphate-induced metal retention was mainly due to the metal-phosphate precipitation, while both sorption and precipitation were responsible for the metal stabilization in the biochar amendment. The laboratory-scale test demonstrated that the soil amended with phosphate removed groundwater Pb, Zn, and Cd by 96.4 %, 44.6 %, and 49.2 %, respectively, and the
Straw Compost and Bioremediated Soil as Inocula for the Bioremediation of Chlorophenol-Contaminated Soil
Laine, M. M.; Jorgensen, K. S.
We evaluated the use of straw compost and remediated soil as inocula for bioremediation of chlorophenol-contaminated soil. The in situ biotransformation of pentachlorophenol (PCP) and mineralization of radiolabeled [U-(sup14)C]PCP by straw compost and remediated soil were studied under field-simulating conditions before and after 3 months of adaptation with PCP in a percolator. After PCP adaptation, the straw compost mineralized up to 56% of the [(sup14)C]PCP. No partial dechlorination of PCP was found. The native straw compost did not mineralize PCP, but partial dechlorination of PCP occurred (i) at pH 8 under near-thermophilic conditions (45(deg)C) and (ii) at pH 7 under aerobic and mesophilic conditions. No biotransformation reactions occurred at room temperature (25(deg)C) at pH 8. Enrichment in the percolator enhanced the mineralization rate of remediated soil to 56% compared with that of the native remediated soil, which mineralized 24% of [(sup14)C]PCP added. Trace amounts of chloroanisoles as the only biotransformation products were detected in PCP-adapted remediated soil. Both inoculants studied here showed effective mineralization of PCP when they were adapted to PCP in the percolator. No harmful side reactions, such as extensive methylation, were observed. PMID:16535304
In-situ characterization technique for screening contaminated soils
Jaselskis, E.J.; Anderson, M.S.; D`Silva, A.P.; Baldwin, D.P.; Zamzow, D.S.
An innovative field sampling system for screening contaminated soils has been developed using laser ablation coupled with inductively coupled plasma-atomic emission spectrometry (LA-ICP-AES) technology. This sampling approach provides in-situ real-time analysis of trace inorganic elements and is conducted through a mobile testing facility that consists of an instrumentation vehicle called the Mobile Demonstration Laboratory for Environmental Screening Technologies (MDLEST) and an attached trailer called the Robotic Sampling Accessory (RSA). The RSA provides automated sampling capabilities through an attached three-degree-of-freedom robot that is equipped with a surface-sampling probe. The MDLEST-RSA was successfully tested at a Department of Energy (DOE) site in Fernald, Ohio, during the fall of 1992. This paper provides a description of the analysis technique, the MDLEST and RSA, and results of the field demonstration. In addition, benefits, limitations, and future plans are also discussed.
Evaluation of soil amendments as a remediation alternative for cadmium-contaminated soils under cacao plantations.
Chavez, E; He, Z L; Stoffella, P J; Mylavarapu, R; Li, Y; Baligar, V C
Elevated plant-available cadmium (Cd) in soils results in contamination to cacao (Theobroma cacao L) beans. Effectiveness of vermicompost and zeolite in reducing available Cd in three cacao-growing soils was studied under laboratory conditions. Sorption-desorption experiments were conducted in soils and amendments. Cadmium was added at 0 or 5 mg kg(-1) (spiked), then, amendments were incorporated at 0, 0.5, or 2 %. Amended soils were incubated at room temperature for 28 days. Plant-available Cd was determined using 0.01 M CaCl2 (WSE) and Mehlich 3 (M3) extraction procedures in subsamples taken from individual bags at six time intervals. Soils and amendments displayed different sorption characteristics and a better fit was attained with Freundlich model (R (2) > 0.82). Amendments were ineffective in reducing extractable Cd in non-spiked soils. In Cd-spiked soils, vermicompost at 2 % significantly reduced WSE-Cd (P < 0.01) from 3.36, 0.54, and 0.38 mg kg(-1) to values lower that instrument's detection in all the three soils and significantly diminished M3-extractable Cd (P < 0.05) from 4.62 to 4.11 mg kg(-1) in only one soil. Vermicompost at 0.5 % significantly decreased WSE-Cd (P < 0.01) from 3.04 and 0.31 to 1.69 and 0.20 mg kg(-1), respectively, in two soils with low sorption capacity for Cd. In contrast, zeolite failed to reduce WSE- or M3-extractable Cd in all studied soils. A negative correlation occurred between soil pH and WSE-Cd (r > -0.89, P < 0.01). The decrease in WSE-Cd appears to be associated with the increase in pH of the vermicompost-amended soils. PMID:27234831
Two incineration test programs were conducted at EPA's Incineration Research Facility to evaluate the suitability of incineration as an option to treat-contaminated Superfund site soils. he soils from the Purity Oil Sales site in Region 9 are contaminated with lead, up to several...
Contaminant Immobilization and Nutrient Release by Biochar Soil Amendment: Roles of Natural Organic Matter
Technology Transfer Automated Retrieval System (TEKTRAN)
Contamination of soil interstitial waters by labile heavy metals such as CuII, CdII, and NiII is of worldwide concern. Carbonaceous materials such as char and activated carbon have received considerable attention in recent years as soil amendment for both sequestering heavy metal contaminants and r...
Phytoremediation was evaluated as a potential treatment for the creosote-contaminated surface soil at the McCormick and Baxter (M&B) Superfund Site in Portland, OR. Soil a the M&B site is contaminated with pentachlorophenol (PCP) and polyaromatic hydrocarbons (PAHs). Eight indivi...
Pentachlorophenol (PCP) is a wood preserving agent that is commonly found in contaminated soils at wood treatment sties. The extraction of PCP from contaminated soils was evaluated using water-ethanol mixtures as solvents. A mixed solvent containing equal proportions of water and...
The report updates a 1992 report that summarizes available information on air emissions from the treatment of soils contaminated with fuels. Soils contaminated by leaks or spills of fuel products, such as gasoline or jet fuel, are a nationwide concern. Air emissions during remedi...
Phosphate Treatment of Lead-Contaminated Soil: Effects on Water Quality, Plant Uptake, and Lead Speciation
Water quality threats associated with using phosphate-based amendments to remediate Pb-contaminated soils are a concern, particularly in riparian areas. This study investigated the effects of P application rates to a Pb-contaminated alluvial soil on Pb and P loss via surface wat...
Throughout the U.S., the need for effective treatment of petroleum contaminated soil has escalated due to the increase in the number of underground storage tank (UST) systems being upgraded in response to EPA regulations. ptions for excavated contaminated soil have in the past be...
Isolation and identification of dioxin degrading bacteria found in soils contaminated with dioxins
Technology Transfer Automated Retrieval System (TEKTRAN)
There is a need to identify bacteria that can degrade environmental contaminants; a fruitful place to identify such bacteria is within contaminated soil. The dioxin content and congener distribution in soils collected from adjacent to old railroad track that were treated with pentachlorophenol (PCP...
Chelant extraction and REDOX manipulation for mobilization of heavy metals from contaminated soils
Brewster, M.D.; Peters, R.W.; Miller, G.A.; Patton, T.L.; Martino, L.E.
Was the result of open burning and open detonation of chemical agents and munitions in the Toxic Burning Pits area at J-Field, located in the Edgewood Area of Aberdeen Proving Ground in Harford County, Maryland, soils have been contaminated with heavy metals. Simultaneous extraction is complicated because of the multitude of contaminant forms that exist. This paper uses data from a treatability study performed at Argonne National Laboratory to discuss and compare several treatment methods that were evaluated for remediating metals-contaminated soils. J-Field soils were subjected to a series of treatability experiments designed to determine the feasibility of using soil washing/soil flushing, enhancements to soil washing/soil flushing, solidification/stabilization, and electrokinetics for remediating soils contaminated with metals. Chelating and mobilizing agents evaluated included ammonium acetate, ethylenediaminetetraacetic acid, citric acid, Citranox, gluconic acid, phosphoric acid, oxalic acid, and nitrilotriacetic acid, in addition to pH-adjusted water. REDOX manipulation can maximize solubilities, increase desorption, and promote removal of heavy metal contaminants. Reducing agents that were studied included sodium borohydride, sodium metabisulfite, and thiourea dioxide. The oxidants studied included hydrogen peroxide, sodium percarbonate, sodium hypochlorite, and potassium permanganate. This paper summaries the results from the physical/chemical characterization, soil washing/soil flushing, and enhancements to soil washing/soil flushing portions of the study.
Plutonium contamination in soils and sediments at Mayak PA, Russia.
Skipperud, Lindis; Salbu, Brit; Oughton, Deborah H; Drozcho, Eugeny; Mokrov, Yuri; Strand, Per
The Mayak Production Association (Mayak PA) was established in the late 1940's to produce plutonium for the Soviet Nuclear Weapons Programme. In total, seven reactors and two reprocessing plants have been in operation. Today, the area comprises both military and civilian reactors as well as reprocessing and metallurgical plants. Authorized and accidental releases of radioactive waste have caused severe contamination to the surrounding areas. In the present study, [alpha]-spectrometry and inductively coupled plasma-mass spectrometry (ICP-MS) have been used to determine plutonium activities and isotope ratios in soil and sediment samples collected from reservoirs of the Techa River at the Mayak area and downstream Techa River. The objective of the study was to determine the total inventory of plutonium in the reservoirs and to identify the different sources contributing to the plutonium contamination. Results based on [alpha]-spectrometry and ICP-MS measurements show the presence of different sources and confirmed recent reports of civilian reprocessing at Mayak. Determination of activity levels and isotope ratios in soil and sediment samples from the Techa River support the hypothesis that most of the plutonium, like other radionuclides in the Techa River, originated from the very early waste discharges to the Techa River between 1949 and 1951. Analysis of reservoir sediment samples suggest that about 75% of the plutonium isotopes could have been released to Reservoir 10 during the early weapons production operation of the plant, and that the majority of plutonium in Reservoir 10 originates from discharges from power production or reprocessing. Enhanced 240Pu/239Pu atom ratios in river sediment upper layers (0-2 cm) between 50 and 250 km downstream from the plant indicate a contribution from other, non-fallout sources. PMID:16096501
Remediation of metal-contaminated urban soil using flotation technique.
Dermont, G; Bergeron, M; Richer-Laflèche, M; Mercier, G
A soil washing process using froth flotation technique was evaluated for the removal of arsenic, cadmium, copper, lead, and zinc from a highly contaminated urban soil (brownfield) after crushing of the particle-size fractions >250microm. The metal contaminants were in particulate forms and distributed in all the particle-size fractions. The particle-by-particle study with SEM-EDS showed that Zn was mainly present as sphalerite (ZnS), whereas Cu and Pb were mainly speciated as various oxide/carbonate compounds. The influence of surfactant collector type (non-ionic and anionic), collector dosage, pulp pH, a chemical activation step (sulfidization), particle size, and process time on metal removal efficiency and flotation selectivity was studied. Satisfactory results in metal recovery (42-52%), flotation selectivity (concentration factor>2.5), and volume reduction (>80%) were obtained with anionic collector (potassium amyl xanthate). The transportation mechanisms involved in the separation process (i.e., the true flotation and the mechanical entrainment) were evaluated by the pulp chemistry, the metal speciation, the metal distribution in the particle-size fractions, and the separation selectivity indices of Zn/Ca and Zn/Fe. The investigations showed that a great proportion of metal-containing particles were recovered in the froth layer by entrainment mechanism rather than by true flotation process. The non-selective entrainment mechanism of the fine particles (<20 microm) caused a flotation selectivity drop, especially with a long flotation time (>5 min) and when a high collector dose is used. The intermediate particle-size fraction (20-125 microm) showed the best flotation selectivity. PMID:19959208
[Immobilization remediation of Cd and Pb contaminated soil: remediation potential and soil environmental quality].
Sun, Yue-Bing; Wang, Peng-Chao; Xu, Ying-Ming; Sun, Yang; Qin, Xu; Zhao, Li-Jie; Wang, Lin; Liang, Xue-Feng
A pot experiment was conducted to investigate the immobilization remediation effects of sepiolite on soils artificially combined contamination by Cd and Pb using a set of various pH and speciation of Cd and Pb in soil, heavy metal concentration in Oryza sativa L., and soil enzyme activity and microbial quantity. Results showed that the addition of sepiolite increased the soil pH, and the exchangeable fraction of heavy metals was converted into Fe-Mn oxide, organic and residual forms, the concentration of exchangeable form of Cd and Pb reduced by 1.4% - 72.9% and 11.8% - 51.4%, respectively, when compared with the control. The contents of heavy metals decreased with increasing sepiolite, with the maximal Cd reduction of 39.8%, 36.4%, 55.2% and 32.4%, respectively, and 22.1%, 54.6%, 43.5% and 17.8% for Pb, respectively, in the stems, leaves, brown rice and husk in contrast to CK. The addition of sepiolite could improve the soil environmental quality, the catalase and urease activities and the amount of bacteria and actinomycete were increased to some extents. Although the fungi number and invertase activity were inhibited compared with the control group, it was not significantly different (P > 0.05). The significant correlation between pH, available heavy metal content, urease and invertase activities and heavy metal concentration in the plants indicated that these parameters could be used to evaluate the effectiveness of stabilization remediation of heavy metal contaminated soil. PMID:25826946
Efficiency of non-ionic surfactants - EDTA for treating TPH and heavy metals from contaminated soil
Introduction of fuel hydrocarbons and inorganic compounds (heavy metals) into the soil, resulting in a change of the soil quality, which is likely to affect use of the soil or endangering public health and ground water. This study aimed to determine a series of parameters to remediation of TPH and heavy metals contaminated soil by non-ionic surfactants- chelating agents washing process. In this experimental study, the effects of soil washing time, agitation speed, concentration of surfactant, chelating agent and pH on the removal efficiency were studied. The results showed that TPH removal by nonionic surfactants (Tween 80, Brij 35) in optimal condition were 70–80% and 60–65%, respectively. Addition of chelating agent (EDTA) significantly increases Cd and Pb removal. The washing of soil by non- ionic surfactants and EDTA was effective in remediation of TPH and heavy metals from contaminated soil, thus it can be recommended for remediation of contaminated soil. PMID:24359927
Selection of surfactant in remediation of DDT-contaminated soil by comparison of surfactant effectiveness.
Guo, Ping; Chen, Weiwei; Li, Yueming; Chen, Tao; Li, Linhui; Wang, Guanzhu
With an aim to select the most appropriate surfactant for remediation of DDT-contaminated soil, the performance of nonionic surfactants Tween80, TX-100, and Brij35 and one anionic surfactant sodium dodecyl benzene sulfonate (SDBS) in enhancement of DDT water solubility and desorption of DDT from contaminated soil and their adsorption onto soil and ecotoxicities were investigated in this study. Tween80 had the highest solubilizing and soil-washing ability for DDT among the four experimental surfactants. The adsorption loss of surfactants onto soil followed the order of TX-100 > Tween80 > Brij35 > SDBS. The ecotoxicity of Tween80 to ryegrass (Lolium perenne L.) was lowest. The overall performance considering about the above four aspects suggested that Tween80 should be selected for the remediation of DDT-contaminated soil, because Tween80 had the greatest solubilizing and soil-washing ability for DDT, less adsorption loss onto soil, and the lowest ecotoxicity in this experiment. PMID:23900948
Bioremediation: An effective remedial alternative for petroleum hydrocarbon-contaminated soil
Autry, A.R.; Ellis, G.M. )
Bioremediation technologies applied to contaminated soil usually mitigate environmental rate-limiting factors so that biodegradation rates are maximized for any given compound. A newer approach to soil bioremediation mitigates these environmental rate-limiting factors simultaneously, initially allowing biodegradation to proceed at a maximal rate without the need for additional action. This technology involves intensive mixing of contaminated soil in a ribbon blender, introduction of a protein-based, surfactant-containing nutrient additive to the soil while in the mixer, physical entrainment of oxygen-containing air into the soil, discharge of the mixed soil from the mixer, and placement of the mixed soil in curing piles, for curing, during which time biodegradation can occur. No additional treatment actions (e.g., tillage, fertilizer or water applications) are typically required. The remediation, using this approach, of a former distribution facility which possessed soil contaminated with gasoline, is summarized. 22 refs., 6 figs.
Impact of system chemistry on electroosmosis in contaminated soil
Eykholt, G.R. . Corporate Research and Development); Daniel, D.E. )
Electroosmosis in a copper-contaminated kaolinite was highly sensitive to chemical treatment schemes designed to remove the contamination. Nonuniform profiles of electric field intensity and pH as well as negative pore-water pressure develop during sustained electrokinetic treatment of clays. These nonlinearities and nonuniform pore-water pressures cannot be adequately described by classical analysis. Classical analysis is based on assumptions of a uniform and constant electroosmotic permeability coefficient, for instance. An extended capillary model which includes nonuniform contributions to electroosmosis and pore pressures that vary with space and time, is developed and compared with experimental findings. Subtle changes in initial and boundary conditions of the system chemistry have a very large effect on electroosmosis in soils. For instance, acid addition at the cathode reservoir may cause reversal of the direction of electroosmotic flow. Other species, such as the citrate, may form stable complexes with copper ions, thus reducing the impact of copper on the zeta potential of the clay. The model is used to simulate these effects.
Soil pollution in the railway junction Niš (Serbia) and possibility of bioremediation of hydrocarbon-contaminated soil
NASA Astrophysics Data System (ADS)
Jovanovic, Larisa; Aleksic, Gorica; Radosavljevic, Milan; Onjia, Antonije
Mineral oil leaking from vehicles or released during accidents is an important source of soil and ground water pollution. In the railway junction Niš (Serbia) total 90 soil samples polluted with mineral oil derivatives were investigated. Field work at the railway Niš sites included the opening of soil profiles and soil sampling. The aim of this work is the determination of petroleum hydrocarbons concentration in the soil samples and the investigation of the bioremediation technique for treatment heavily contaminated soil. For determination of petroleum hydrocarbons in the soil samples method of gas-chromatography was carried out. On the basis of measured concentrations of petroleum hydrocarbons in the soil it can be concluded that: Obtained concentrations of petroleum hydrocarbons in 60% of soil samples exceed the permissible values (5000 mg/kg). The heavily contaminated soils, according the Regulation on the program of systematic monitoring of soil quality indicators for assessing the risk of soil degradation and methodology for development of remediation programs, Annex 3 (Official Gazette of RS, No.88 / 2010), must be treated using some of remediation technologies. Between many types of phytoremediation of soil contaminated with mineral oils and their derivatives, the most suitable are phytovolatalisation and phytostimulation. During phytovolatalisation plants (poplar, willow, aspen, sorgum, and rye) absorb organic pollutants through the root, and then transported them to the leaves where the reduced pollutants are released into the atmosphere. In the case of phytostimulation plants (mulberry, apple, rye, Bermuda) secrete from the roots enzymes that stimulates the growth of bacteria in the soil. The increase in microbial activity in soil promotes the degradation of pollutants. Bioremediation is performed by composting the contaminated soil with addition of composting materials (straw, manure, sawdust, and shavings), moisture components, oligotrophs and
Phyotoxicity of diesel soil contamination on the germination of Lactuca sativa and Ipomoea batatas.
Fatokun, Kayode; Lewu, Francis Bayo; Zharare, Godfrey Elijah
Phytotoxic effect of diesel contaminated soil on germination rate of Lactuca sativa and Ipomoea batatas, at two concentrations ranges (0-6ml and 0-30ml), were investigated and compared. Diesel soil contamination was simulated and soil samples were taken from contaminated soil at 1, 5,10, 15, 25, 50, 75 and 100 days should be after planting. The result showed that in both plant species, diesel inhibited germination in a concentration dependent manner, Also, the influence of diesel contamination diminished with increased time duration; suggesting possible reduction in diesel toxicity over time. However, germination of lettuce was significant and negatively correlated (r2 = -0.941) with diesel contamination as compared to sweet potato (r2 = -0.638).Critical concentration of diesel in relation to seed germination of L. sativa was lower than vegetative germination of I. batatas, indicating that germination of I. batatas was less sensitive to diesel contamination as compared to L. sativa. PMID:26688970
Chemically enhanced phytoextraction of lead-contaminated soils.
Perry, V Ryan; Krogstad, Eirik J; El-Mayas, Hanan; Greipsson, Sigurdur
The effects of the combined application of soil fungicide (benomyl) and ethylenediaminetetraacetic acid (EDTA) on lead (Pb) phytoextraction by ryegrass (Lolium perenne) were examined. Twenty-five pots of Pb-contaminated soil (200 mg Pb kg(-1)) were seeded with ryegrass and randomly arranged into the following treatments: (1) Control, (2) benomyl, (3) EDTA, (4) benomyl and EDTA (B+E), and (5) benomyl followed by an application of EDTA 14 days later (B .. . E). Chemicals were applied when plants had reached maximum growth. Plants were analyzed for foliage Pb concentration using inductively coupled argon plasma (ICAP) spectrometry. The synergistic effects of the combined benomyl and EDTA application (treatments 4 and 5) were made evident by the significantly (p < 0.05) highest foliage Pb concentrations. However, the foliage dry biomass was significantly lowest for plants in treatments 4 and 5. The bioaccumulation factor (BF) and phytoextraction ratio (PR) were highest for plants in treatment 5 followed by plants in treatment 4. PMID:22908638
[Immobilization impact of different fixatives on heavy metals contaminated soil].
Wu, Lie-shan; Zeng, Dong-mei; Mo, Xiao-rong; Lu, Hong-hong; Su, Cui-cui; Kong, De-chao
Four kinds of amendments including humus, ammonium sulfate, lime, superphosphate and their complex combination were added to rapid immobilize the heavy metals in contaminated soils. The best material was chosen according to the heavy metals' immobilization efficiency and the Capacity Values of the fixative in stabilizing soil heavy metals. The redistributions of heavy metals were determined by the European Communities Bureau of Referent(BCR) fraction distribution experiment before and after treatment. The results were as follows: (1) In the single material treatment, lime worked best with the dosage of 2% compared to the control group. In the compound amendment treatments, 2% humus combined with 2% lime worked best, and the immobilization efficiency of Pb, Cu, Cd, Zn reached 98.49%, 99.40%, 95.86%, 99.21%, respectively. (2) The order of Capacity Values was lime > humus + lime > ammonium sulfate + lime > superphosphate > ammonium sulfate + superphosphate > humus + superphosphate > humus > superphosphate. (3) BCR sequential extraction procedure results indicated that 2% humus combined with 2% lime treatment were very effective in immobilizing heavy metals, better than 2% lime treatment alone. Besides, Cd was activated firstly by 2% humus treatment then it could be easily changed into the organic fraction and residual fraction after the subsequent addition of 2% lime. PMID:25898680
Release of contaminant U(VI) from soils
Zheng, Zuoping; Wan, Jiamin
The retention, mobility, and bio-availability of U(VI) incontaminated soils depend strongly on release of U(VI). Laboratory batchexperiments were performed to evaluate the factors controlling therelease of U(VI) from contaminated soil at Oak Ridge, Tennessee. We foundthat the ionic strength of the extraction solution strongly affectsrelease of U(VI). Increase in ionic strength shows a strong effect onU(VI) release as indicated by the increase in release rates andassociated release of U(VI) concentrations. We also found that the ratioof solution volume to solid mass (V/M) has a significant impact on therelease of U(VI). Increase in the V/M ratio shows a negligible effect onthe U(VI) release over a 4-day period. However, at Day 30 and Day 120,larger V/M ratios cause greater U(VI) release. The maximum U(VI)concentrations observed in the release experiments are in the range ofschoepite estimated under conditions relevant to the experiments,suggesting that schoepite solubility primarily controls the U(VI)release, but that solubilization and desorption effects cannot bedistinguished using macroscopic methods.
Assessing the technogenic contamination of urban soils from the profile distribution of heavy metals and the soil bulk density
NASA Astrophysics Data System (ADS)
Korchagina, K. V.; Smagin, A. V.; Reshetina, T. V.
The contamination of soils with heavy metals in the city of Moscow has been assessed using the conventional procedure and a new resource approach developed at the Faculty of Soil Science of Moscow State University. The approach involved the consideration of the profile distribution of a pollutant and the variation in the bulk density of the enclosing soil. The integral parameter of contamination was the reserve of the pollutant in a conventional normative soil layer 1 m in thickness according to the Moscow Law On the Urban Soils. In the soil samples taken in the main administrative districts of Moscow, the contents of heavy metals of the first (zinc, lead, cadmium, arsenic, and mercury) and second (nickel and copper) hazard classes were determined. For each profile, distribution graphs of all of the above elements have been developed, and the element reserves have been calculated in the upper 1-m-thick layer with consideration for the changes in the soil density with depth. The obtained data have been compared with the normative reserves of heavy metals and the estimates of technogenic contamination derived using the conventional procedure. An increase in the total reserves of pollutants has been observed at the increase in their concentrations with depth; therefore, a clean soil according to the conventional procedure can be classified as contaminated. Analogously, a decrease in the total reserve of a pollutant in the upper 1-m-thik layer and, hence, a decrease in the degree of soil contamination have been observed when the concentration of the pollutant reduced with the depth. In general, the profile distributions of heavy metals and the soil bulk density strongly interfere with the estimation of the contamination of the soil as a spatially heterogeneous body and should be taken into consideration in the development of a present-day system of quality criteria and norms for urban soils.
Microbial interactions with organic contaminants in soil: definitions, processes and measurement.
Semple, Kirk T; Doick, Kieron J; Wick, Lukas Y; Harms, Hauke
There has been and continues to be considerable scientific interest in predicting bioremediation rates and endpoints. This requires the development of chemical techniques capable of reliably predicting the bioavailability of organic compounds to catabolically active soil microbes. A major issue in understanding the link between chemical extraction and bioavailability is the problem of definition; there are numerous definitions, of varying degrees of complexity and relevance, to the interaction between organic contaminants and microorganisms in soil. The aim of this review is to consider the bioavailability as a descriptor for the rate and extent of biodegradation and, in an applied sense, bioremediation of organic contaminants in soil. To address this, the review will (i) consider and clarify the numerous definitions of bioavailability and discuss the usefulness of the term 'bioaccessibility'; (ii) relate definition to the microbiological and chemical measurement of organic contaminants' bioavailability in soil, and (iii) explore the mechanisms employed by soil microorganisms to attack organic contaminants in soil. PMID:17881105
Bioremediation of a tropical clay soil contaminated with diesel oil.
Chagas-Spinelli, Alessandra C O; Kato, Mario T; de Lima, Edmilson S; Gavazza, Savia
The removal of polyaromatic hydrocarbons (PAH) in tropical clay soil contaminated with diesel oil was evaluated. Three bioremediation treatments were used: landfarming (LF), biostimulation (BS) and biostimulation with bioaugmentation (BSBA). The treatment removal efficiency for the total PAHs differed from the efficiencies for the removal of individual PAH compounds. In the case of total PAHs, the removal values obtained at the end of the 129-day experimental period were 87%, 89% and 87% for LF, BS and BSBA, respectively. Thus, the efficiency was not improved by the addition of nutrients and microorganisms. Typically, two distinct phases were observed. A higher removal rate occurred in the first 17 days (P-I) and a lower rate occurred in the last 112 days (P-II). In phase P-I, the zero-order kinetic parameter (μg PAH g(-1) soil d(-1)) values were similar (about 4.6) for all the three treatments. In P-II, values were also similar but much lower (about 0.14). P-I was characterized by a sharp pH decrease to less than 5.0 for the BS and BSBA treatments, while the pH remained near 6.5 for LF. Concerning the 16 individual priority PAH compounds, the results varied depending on the bioremediation treatment used and on the PAH species of interest. In general, compounds with fewer aromatic rings were better removed by BS or BSBA, while those with 4 or more rings were most effectively removed by LF. The biphasic removal behavior was observed only for some compounds. In the case of naphthalene, pyrene, chrysene, benzo[k]fluoranthene and benzo[a]pyrene, removal occurred mostly in the P-I phase. Therefore, the best degradation process for total or individual PAHs should be selected considering the target compounds and the local conditions, such as native microbiota and soil type. PMID:22727951
Technology Transfer Automated Retrieval System (TEKTRAN)
The Environmental Protection Agency lists more than 17,000 contaminated sites in the United States, many of which are contaminated with heavy metals including lead (Pb) and zinc (Zn). Lead contamination in soil has been shown to be a threat to human health and ecosystem functioning through adverse e...
Toxicity assessment for petroleum-contaminated soil using terrestrial invertebrates and plant bioassays.
Hentati, Olfa; Lachhab, Radhia; Ayadi, Mariem; Ksibi, Mohamed
The assessment of soil quality after a chemical or oil spill and/or remediation effort may be measured by evaluating the toxicity of soil organisms. To enhance our understanding of the soil quality resulting from laboratory and oil field spill remediation, we assessed toxicity levels by using earthworms and springtails testing and plant growth experiments. Total petroleum hydrocarbons (TPH)-contaminated soil samples were collected from an oilfield in Sfax, Tunisia. Two types of bioassays were performed. The first assessed the toxicity of spiked crude oil (API gravity 32) in Organization for Economic Co-operation and Development artificial soil. The second evaluated the habitat function through the avoidance responses of earthworms and springtails and the ability of Avena sativa to grow in TPH-contaminated soils diluted with farmland soil. The EC50 of petroleum-contaminated soil for earthworms was 644 mg of TPH/kg of soil at 14 days, with 67 % of the earthworms dying after 14 days when the TPH content reached 1,000 mg/kg. The average germination rate, calculated 8 days after sowing, varied between 64 and 74 % in low contaminated soils and less than 50 % in highly contaminated soils. PMID:22773148
Study of Soil Washing for Remediation of Pb and Zn Contaminated Coastal Landfill
NASA Astrophysics Data System (ADS)
Park, S.; Kim, S.; Lee, M.
As a result of analyzing the pre-treatment process of Pb, Zn in contaminated coastal landfill soil presented by Korean Soil Analysis Method, the each concentration was presented 577.00mg/kg, 3894.34mg/kg. This soil was critically contaminated with Pb and Zn because it was exceeded the Standard of soil contamination(2area: Pb-400mg/kg, Zn-600mg/kg). Soil remediation efficiency of the soil washing process for the removal of Pb and Zn was determined to be consistent with the results. The batch experiment on the several washing solutions(HCl, HNO3), washing solutions concentrations(0.1-0.8M) and the ratio of soil vs. solution for soil washing(1:3, 1:5 and 1:10) was performed. The results of experiments, washing time was appropriate in 30 minutes. The removal efficiency of soil washing increased as the ratio of soil vs. washing solution increased. But, in the case of heavy metals, the soil vs. solution for soil washing was determined as the optimal ratio of 1 : 5. Five consecutive soil washing with 0.5M of HCl and HNO3 solutions were performed. Results of experiments, in case of Pb was removed by target removal efficiency from soil on the twice washing. With in case of Zn was over on the first washing by target removal efficiency, but suggesting that twice consecutive soil washing is desirable as stability at field. Results of consecutive soil washing experiments, the removal efficiency maintained lower than 10 % after the 4th washing. From the results, demanding consecutive washing is not recommended. Results about the heavy metal contaminated soil washing experiments of the coastal landfill, in the case of HCl with more than 0.5 M of solution was performed at 1:5 of soil ratio vs. solution, 30 minutes of washing time and 2-3 consecutive soil washing. And in the case of HNO3 with 0.8 M of solution was performed various ratios of soil vs. washing solution, suggesting that 2-3 consecutive soil washing was reached to Pb and Zn target removal efficiency. Key words
Risk perception of heavy metal soil contamination and attitudes toward decontamination strategies.
Weber, O; Scholz, R W; Bühlmann, R; Grasmück, D
Contaminated soils are a common environmental risk all over the world. One major source of risk is heavy metal soil contamination caused by industrial emissions. This quasiexperimental study investigated the perception of these risks by exposed and nonexposed people, their attitudes toward bioremediation methods using hyperaccumulating plants, and the influence of long-term aspects of sustainability on the acceptance of bioremediation methods. Major findings were that people living in a contaminated area perceived the risk of the heavy metal soil contamination as higher than the general risk of contamination. Second, a factor analysis showed that the factors dread, control, and catastrophic potential were relevant for the perception and valuation of low-dose environmental risks such as the contamination of the investigated area. In addition, a cluster analysis showed that the risk of heavy metal soil contamination was perceived as similar to that of oil contamination, ozone layer, preservatives and genetic technology. It was perceived indifferently with regard to dread. The uncontrollability of heavy metal soil contamination was estimated as medium, and its catastrophic potential as low. Third, exposed and nonexposed participants preferred bioremediation methods to classical methods (e.g., excavation and chemical treatment of the soil), because they perceived the environmental and esthetical performance of the bioremediation as important criteria. Sustainability or precautionary issues, such as the prevention of harm for future generations, were highly correlated with the acceptance of the use of bioremediation methods in people's residential areas. PMID:11798130
Biochar as possible long-term soil amendment for phytostabilisation of TE-contaminated soils.
Bopp, Charlotte; Christl, Iso; Schulin, Rainer; Evangelou, Michael W H
Soils contaminated by trace elements (TEs) pose a high risk to their surrounding areas as TEs can spread by wind and water erosion or leaching. A possible option to reduce TE transfer from these sites is phytostabilisation. It is a long-term and cost-effective rehabilitation strategy which aims at immobilising TEs within the soil by vegetation cover and amendment application. One possible amendment is biochar. It is charred organic matter which has been shown to immobilise metals due to its high surface area and alkaline pH. Doubts have been expressed about the longevity of this immobilising effect as it could dissipate once the carbonates in the biochar have dissolved. Therefore, in a pot experiment, we determined plant metal uptake by ryegrass (Lolium perenne) from three TE-contaminated soils treated with two biochars, which differed only in their pH (acidic, 2.80; alkaline, 9.33) and carbonate (0.17 and 7.3 %) content. Root biomass was increased by the application of the alkaline biochar due to the decrease in TE toxicity. Zinc and Cu bioavailability and plant uptake were equally reduced by both biochars, showing that surface area plays an important role in metal immobilisation. Biochar could serve as a long-term amendment for TE immobilisation even after its alkalinity effect has dissipated. PMID:27230149
Soil water and vegetation management for cleanup of selenium contaminated soils
Not Available
Over the past year scientists have initiatived a new effort aimed at developing a soil water and vegetation management plan for Kesterson Reservoir. The plan is intended to result in a gradual depletion of the inventory of soluble selenium at the Reservoir through a combination agriculturally oriented practices that enhance dissipation of selenium from near surface soils. Agriculturally oriented processes that will contribute to depletion include microbial volatilization from the soils, direct volatilization by living plants, decomposition and volatilization of selenium-bearing vegetation, harvest and removal of seleniferous vegetation, and leaching. The benefits of using this integrated approach are that (1) no single mechanism needs to be relied upon to detoxify the soils, (2) a stable plant community can be established during this period so that impacts to wildlife can be more easily evaluated and controlled, (3) cleanup and management of the site can be carried out in a cost-effective manner. The management plan is also intended to facilitate control over wildlife exposure to selenium contaminated biota by creating a well managed environment. The majority of research associated with this new effort is being carried out at a 200 m by 50 m test plot in Pond 7. A two-line irrigation system , providing local groundwater as an irrigation supply, has been installed. Through an intensive program of soil water sampling, soil gas sampling, vegetation sampling, groundwater monitoring, and soil moisture monitoring, the mass balance for selenium under irrigated conditions is being evaluated. These studies, in conjunction with supplementary laboratory experiments will provide the information needed to develop an optimal management plan for the site. 23 refs., 38 figs., 10 tabs.
The effects of freezing and thawing on the aqueous availability of creosote contamination in soil
Bevel, A.; Hrudey, S.; Dudas, M.; Sego, D.
A variety of methods have been tested in attempts to remediate contaminated sites. Fine-grained soils are extremely problematic to remediate, due to the high adsorption capacity of the fine soil particles and the trapping effect of soil particle micropores. It is well documented that freezing of soil causes particle restructuring and reorganization, with different pore structures found after freezing. Some factors affecting restructuring include soil moisture content, freezing rate, freezing end-point temperature, and number of freezing cycles. This poster presents an experiment that determines if freezing creosote contaminated soil improves accessibility of the creosote, by measuring aqueous phase contaminant dissolution. This method was selected since water is the most common solvent in naturally occurring systems, and water represents a worst-case scenario since many contaminants have low aqueous solubilities. Freezing is carried out under controlled laboratory conditions. Variables examined include moisture content, freezing rate, and soil contamination level. If contaminant availability is increased through soil freezing, remediation becomes an easier task in fine grained soils.
Assessment of the effects of Cr, Cu, Ni and Pb soil contamination by ecotoxicological tests.
Maisto, Giulia; Manzo, Sonia; De Nicola, Flavia; Carotenuto, Rita; Rocco, Annamaria; Alfani, Anna
This study aimed to assess soil quality by chemical and ecotoxicological investigations and to check the correspondence between soil metal concentrations and ecotoxicity. For these purposes, surface soils collected at four adjacent roadside urban parks and at a former industrial area were characterized for C/N, organic matter content, texture, and pH. Cr, Cu, Ni and Pb, chosen among the most representative soil metal contaminants, were measured as total content and as available and water soluble fractions. In addition, the total concentrations of the investigated metals were used to calculate two chemical indices: the contamination and the potential ecological risk factors. The toxicity of the investigated soils was evaluated by an ecotoxicity test battery carried out on both soil samples (Vibrio fischeri, Heterocypris incongruens and Sinapis alba) and elutriates (Vibrio fischeri, Daphnia magna and Selenastrum capricornutum). The findings, both by the chemical and ecotoxicological approaches, would suggest that the soils with high metal contamination pose ecological risks. On the other hand, moderately metal contaminated soils did not exclude soil ecotoxicity. In fact, toxic effects were also highlighted in soils with low metal content, toxicity being affected by metal availability and soil characteristics. Moreover, the results suggest the importance of using a battery of tests to assess soil ecotoxicity. PMID:21918769
A solvent washing procedure for the removal of pentachlorophenol (PCP) from contaminated soils is presented. his procedure can be used in both in-situ and above ground soil washing applications. he in-situ solvent washing (flushing) of soil was simulated by continuously flushing ...
solvent washing was evaluated as a method to remove pentachlorophenol (PCP) from aged field soils contaminated with wood treating wastes. Several soil:solvent contact ratios were considered. Solvent washing processes were evaluated based on the removal of PCP from the soil throug...
To evaluate conversion of soil Pb to pyromorphite, a Pb contaminated soil collected adjacent to a historical smelter was reacted with hydroxyapatite in a traditional incubation experiment and in a dialysis system in which the soil and hydroxyapatite solids were separated by a dia...
Earthworm acute toxicity, plant seed germination/root elongation (SG/RE) and plant genotoxicity bioassays were employed to evaluate the remediation of a lead-contaminated soil. The remediation involved removal of heavy metals by a soil washing/soil leaching treatment process. A p...
Effects of soil oxygen conditions and soil pH on remediation of DDT-contaminated soil by laccase from white rot fungi.
Zhao, Yuechun; Yi, Xiaoyun
High residues of DDT in agricultural soils are of concern because they present serious threats to food security and human health. This article focuses on remediation of DDT-contaminated soil using laccase under different soil oxygen and soil pH conditions. The laboratory experiment results showed significant effects of soil oxygen conditions and soil pH on remediation of DDT-contaminated soil by laccase at the end of a 25-d incubation period. This study found the positive correlation between the concentration of oxygen in soil and the degradation of DDT by laccase. The residue of DDTs in soil under the atmosphere of oxygen decreased by 28.1% compared with the atmosphere of nitrogen at the end of the incubation with laccase. A similar pattern was observed in the remediation of DDT-contaminated soil by laccase under different flooding conditions, the higher the concentrations of oxygen in soil, the lower the residues of four DDT components and DDTs in soils. The residue of DDTs in the nonflooding soil declined by 16.7% compared to the flooded soil at the end of the incubation. The residues of DDTs in soils treated with laccase were lower in the pH range 2.5-4.5. PMID:20617049
Assessment of Soil Moisture and Fixatives Performance in Controlling Wind Erosion of Contaminated Soil at the Hanford Site
Lagos, L.E.; Gudavalli, R.K.
During the remediation of burial grounds at the US Department of Energy's (DOE's) Hanford Site in Washington State, the dispersion of contaminated soil particles and dust is an issue that is faced by site workers on a daily basis. This contamination issue is even more of a concern when one takes into account the semi-arid characteristics of the region where the site is located. To mitigate this problem, workers at the site use a variety of engineered methods to minimize the dispersion of contaminated soil and dust particles. Once such methods is the use of water and/or suppression agents (fixatives) that stabilizes the soil prior to soil excavation, segregation, and removal activities. A primary contributor to the dispersion of contaminated soil and dust is wind soil erosion. The erosion process occurs when the wind speed exceeds a certain threshold value (threshold shear velocity), which depends on a number of factors including wind force loading, particle size, surface soil moisture, and the geometry of the soil. Thus under these circumstances the mobility of contaminated soil and generation and dispersion of particulate matter are significantly influenced by these parameters. Wind tunnel experiments were conducted at the Florida International University's Applied Research Center (FIU-ARC) to evaluate the effectiveness of three commercially available fixatives in controlling the mobility of soil particles on soil mounds when exposed to varying wind forces. The fixatives tested included: (1) a calcium chloride solution; (2) a petroleum hydrocarbon emulsion; and 3) a synthetic organic. As an initial step, approximately 500 lbs of uncontaminated soil was obtained from the Hanford Reservation in Washington State. Soil samples were placed in an open-loop, low speed wind tunnel and exposed to wind forces ranging from 10 to 30 miles per hour (mph). Wind erosion controlling capabilities of commercially available fixatives and soil moisture were tested at a laboratory
Assessment of Soil-Gas and Soil Contamination at the Former Military Police Range, Fort Gordon, Georgia, 2009-2010
Falls, W. Fred; Caldwell, Andral W.; Guimaraes, Wladmir B.; Ratliff, W. Hagan; Wellborn, John B.; Landmeyer, James E.
Soil gas and soil were assessed for organic and inorganic contaminants at the former military police range at Fort Gordon, Georgia, from May to September 2010. The assessment evaluated organic contaminants in soil-gas samplers and inorganic contaminants in soil samples. This assessment was conducted to provide environmental contamination data to Fort Gordon pursuant to requirements of the Resource Conservation and Recovery Act Part B Hazardous Waste Permit process. Soil-gas samplers deployed and collected from May 20 to 24, 2010, identified masses above method detection level for total petroleum hydrocarbons, gasoline-related and diesel-related compounds, and chloroform. Most of these detections were in the southwestern quarter of the study area and adjacent to the road on the eastern boundary of the site. Nine of the 11 chloroform detections were in the southern half of the study area. One soil-gas sampler deployed adjacent to the road on the southern boundary of the site detected a mass of tetrachloroethene greater than, but close to, the method detection level of 0.02 microgram. For soil-gas samplers deployed and collected from September 15 to 22, 2010, none of the selected organic compounds classified as chemical agents and explosives were detected above method detection levels. Inorganic concentrations in the five soil samples collected at the site did not exceed the U.S. Environmental Protection Agency regional screening levels for industrial soil and were at or below background levels for similar rocks and strata in South Carolina.
Phytoremediation of uranium-contaminated soils: Role of organic acids in triggering uranium hyperaccumulation in plants
Huang, J.W.; Blaylock, M.J.; Kapulnik, Y.; Ensley, B.D.
Uranium phytoextraction, the use of plants to extract U from contaminated soils, is an emerging technology. The authors report on the development of this technology for the cleanup of U-contaminated soils. In this research, they investigated the effects of various soil amendments on U desorption from soil to soil solution, studied the physiological characteristics of U uptake and accumulation in plants, and developed techniques to trigger U hyperaccumulation in plants. A key to the success of U phytoextraction is to increase soil U availability to plants. The authors have found that some organic acids can be added to soils to increase U desorption from soil to soil solution and to trigger a rapid U accumulation in plants. Of the organic acids (acetic acid, citric acid, and malic acid) tested, citric acid was the most effective in enhancing U accumulation in plants. Shoot U concentrations of Brassica juncea and Brassica chinensis grown in a U-contaminated soil increased from less than 5 mg kg{sup {minus}1} to more than 5,000 mg kg{sup {minus}1} in citric acid-treated soils. To their knowledge, this is the highest shoot U concentration reported for plants grown on U-contaminated soils. Using this U hyperaccumulation technique, they are now able to increase U accumulation in shoots of selected plant species grown in two U-contaminated soils by more than 1,000-fold within a few days. The results suggest that U phytoextraction may provide an environmentally friendly alternative for the cleanup of U-contaminated soils.
An analytical deterministic model for simultaneous phytoremediation of Ni and Cd from contaminated soils.
Davari, Masoud; Homaee, Mehdi; Rahnemaie, Rasoul
Soil contamination by heavy metals, due to human activities, is not often limited to a single contaminant. The objective of this study was to develop a simple model for phytoextracting separate and combined Ni and Cd from contaminated soils. The study was further aimed to study phytoextraction potential of ornamental kale and land cress grown in soils contaminated with separate and combined Ni and Cd metals. The results indicated that elevated Ni and Cd concentrations in soil inhibit growth of both ornamental kale and land cress plants. In Ni + Cd treatments, growth and development of both plants were more affected than in either Ni or Cd treatments. Further, in Ni + Cd treatments, Ni concentration in tissues of both plants was increased by increasing soil Ni concentration under various Cd concentrations. At constant Ni concentration, addition of Cd did not appreciably changed Ni content of plant tissues. Land cress demonstrated higher tolerance to soil contamination by Ni and Cd compared to ornamental kale. It also demonstrated higher phytoextraction potential for soil Cd than ornamental kale. Enhanced bioavailability of Ni and Cd ions, due to competitive adsorption and desorption reactions, had no reasonable effect on metal ion accumulation in plant tissues. This indicates that at relatively high soil contamination, metal ion adsorption is no longer a limiting factor for phytoremediation. The newly proposed model, which assumes that metal uptake rate inversely depends on total soil metal ion concentration, reasonably well predicted the cleanup time of Ni, Cd, and Ni at the presence of Cd from the contaminated soils. The model also predicts that phytoremediation process takes much longer time when soil is contaminated by multi-metal ions. PMID:25567058
Removal of uranium from uranium-contaminated soils -- Phase 1: Bench-scale testing. Uranium in Soils Integrated Demonstration
Francis, C. W.
To address the management of uranium-contaminated soils at Fernald and other DOE sites, the DOE Office of Technology Development formed the Uranium in Soils Integrated Demonstration (USID) program. The USID has five major tasks. These include the development and demonstration of technologies that are able to (1) characterize the uranium in soil, (2) decontaminate or remove uranium from the soil, (3) treat the soil and dispose of any waste, (4) establish performance assessments, and (5) meet necessary state and federal regulations. This report deals with soil decontamination or removal of uranium from contaminated soils. The report was compiled by the USID task group that addresses soil decontamination; includes data from projects under the management of four DOE facilities [Argonne National Laboratory (ANL), Los Alamos National Laboratory (LANL), Oak Ridge National Laboratory (ORNL), and the Savannah River Plant (SRP)]; and consists of four separate reports written by staff at these facilities. The fundamental goal of the soil decontamination task group has been the selective extraction/leaching or removal of uranium from soil faster, cheaper, and safer than current conventional technologies. The objective is to selectively remove uranium from soil without seriously degrading the soil`s physicochemical characteristics or generating waste forms that are difficult to manage and/or dispose of. Emphasis in research was placed more strongly on chemical extraction techniques than physical extraction techniques.
Carbon nanomaterials in clean and contaminated soils: environmental implications and applications
NASA Astrophysics Data System (ADS)
Riding, M. J.; Martin, F. L.; Jones, K. C.; Semple, K. T.
The exceptional sorptive ability of carbon nanomaterials (CNMs) for hydrophobic organic contaminants (HOCs) is driven by their characteristically large reactive surface areas and highly hydrophobic nature. Given these properties, it is possible for CNMs to impact on the persistence, mobility and bioavailability of contaminants within soils, either favourably through sorption and sequestration, hence reducing their bioavailability, or unfavourably through increasing contaminant dispersal. This review considers the complex and dynamic nature of both soil and CNM physicochemical properties to determine their fate and behaviour, together with their interaction with contaminants and the soil microflora. It is argued that assessment of CNMs within soil should be conducted on a case-by-case basis and further work to assess the long-term stability and toxicity of sorbed contaminants, as well as the toxicity of CNMs themselves, is required before their sorptive abilities can be applied to remedy environmental issues.
Soil biotransformation of thiodiglycol, the hydrolysis product of mustard gas: understanding the factors governing remediation of mustard gas contaminated soil.
Li, Hong; Muir, Robert; McFarlane, Neil R; Soilleux, Richard J; Yu, Xiaohong; Thompson, Ian P; Jackman, Simon A
Thiodiglycol (TDG) is both the precursor for chemical synthesis of mustard gas and the product of mustard gas hydrolysis. TDG can also react with intermediates of mustard gas degradation to form more toxic and/or persistent aggregates, or reverse the pathway of mustard gas degradation. The persistence of TDG have been observed in soils and in the groundwater at sites contaminated by mustard gas 60 years ago. The biotransformation of TDG has been demonstrated in three soils not previously exposed to the chemical. TDG biotransformation occurred via the oxidative pathway with an optimum rate at pH 8.25. In contrast with bacteria isolated from historically contaminated soil, which could degrade TDG individually, a consortium of three bacterial strains isolated from the soil never contaminated by mustard gas was able to grow on TDG in minimal medium and in hydrolysate derived from an historical mustard gas bomb. Exposure to TDG had little impacts on the soil microbial physiology or on community structure. Therefore, the persistency of TDG in soils historically contaminated by mustard gas might be attributed to the toxicity of mustard gas to microorganisms and the impact to soil chemistry during the hydrolysis. TDG biodegradation may form part of a remediation strategy for mustard gas contaminated sites, and may be enhanced by pH adjustment and aeration. PMID:22752796
Characterization and Low-Cost Remediation of Soils Contaminated by Timbers in Community Gardens
Heiger-Bernays, W.; Fraser, A.; Burns, V.; Diskin, K.; Pierotti, D.; Merchant-Borna, K.; McClean, M.; Brabander, D.; Hynes, H. P.
Urban community gardens worldwide provide significant health benefits to those gardening and consuming fresh produce from them. Urban gardens are most often placed in locations and on land in which soil contaminants reflect past practices and often contain elevated levels of metals and organic contaminants. Garden plot dividers made from either railroad ties or chromated copper arsenate (CCA) pressure treated lumber contribute to the soil contamination and provide a continuous source of contaminants. Elevated levels of polycyclic aromatic hydrocarbons (PAHs) derived from railroad ties and arsenic from CCA pressure treated lumber are present in the gardens studied. Using a representative garden, we 1) determined the nature and extent of urban community garden soil contaminated with PAHs and arsenic by garden timbers; 2) designed a remediation plan, based on our sampling results, with our community partner guided by public health criteria, local regulation, affordability, and replicability; 3) determined the safety and advisability of adding city compost to Boston community gardens as a soil amendment; and 4) made recommendations for community gardeners regarding healthful gardening practices. This is the first study of its kind that looks at contaminants other than lead in urban garden soil and that evaluates the effect on select soil contaminants of adding city compost to community garden soil. PMID:21804925
Characterization and Low-Cost Remediation of Soils Contaminated by Timbers in Community Gardens.
Heiger-Bernays, W; Fraser, A; Burns, V; Diskin, K; Pierotti, D; Merchant-Borna, K; McClean, M; Brabander, D; Hynes, H P
Urban community gardens worldwide provide significant health benefits to those gardening and consuming fresh produce from them. Urban gardens are most often placed in locations and on land in which soil contaminants reflect past practices and often contain elevated levels of metals and organic contaminants. Garden plot dividers made from either railroad ties or chromated copper arsenate (CCA) pressure treated lumber contribute to the soil contamination and provide a continuous source of contaminants. Elevated levels of polycyclic aromatic hydrocarbons (PAHs) derived from railroad ties and arsenic from CCA pressure treated lumber are present in the gardens studied. Using a representative garden, we 1) determined the nature and extent of urban community garden soil contaminated with PAHs and arsenic by garden timbers; 2) designed a remediation plan, based on our sampling results, with our community partner guided by public health criteria, local regulation, affordability, and replicability; 3) determined the safety and advisability of adding city compost to Boston community gardens as a soil amendment; and 4) made recommendations for community gardeners regarding healthful gardening practices. This is the first study of its kind that looks at contaminants other than lead in urban garden soil and that evaluates the effect on select soil contaminants of adding city compost to community garden soil. PMID:21804925
In-situ bioremediation: Or how to get nutrients to all the contaminated soil
Jackson, D.S.; Scovazzo, P.
Petroleum contamination is a pervasive environmental problem. Bioremediation is winning favor primarily because the soil may be treated on site and systems can be installed to operate without interfering with facility activities. Although bioremediation has been utilized for many years, its acceptance as a cost-effective approach is only now being realized. KEMRON applied in-situ bioremediation at a retired rail yard which had maintained a diesel locomotive refueling station supplied by two 20,000 gallon above ground storage tanks. Contamination originated from both spillage at the pumps and leaking fuel distribution lines. The contamination spread over a 3 acre area from the surface to a depth of up to 20 feet. Levels of diesel contamination found in the soil ranged from less than a 100 ppm to more than 25,000 ppm. The volume of soil which ultimately required treatment was more than 60,000 cubic yards. Several remedial options were examined including excavation and disposal. Excavation was rejected because it would have been cost prohibitive due to the random distribution of the contaminated soil. In-situ Bioremediation was selected as the only alternative which could successfully treat all the contaminated soils. This paper focuses on how KEMRON solved four major problems which would have prevented a successful remediation project. These problems were: soil compaction, random distribution of contaminated soils, potential free product, and extremely high levels of dissolved iron in the groundwater.
Reducing the bioavailability of cadmium in contaminated soil by dithiocarbamate chitosan as a new remediation.
Yin, Zheng; Cao, Jingjing; Li, Zhen; Qiu, Dong
Dithiocarbamate chitosan (DTC-CTS) was used as a new amendment for remediation of cadmium (Cd)-contaminated soils to reduce the Cd bioavailability. Arabidopsis thaliana was chosen as a model plant to evaluate its efficiency. It was found that DTC-CTS could effectively improve the growth of A. thaliana. The amount of Cd up-taken by A. thaliana could be decreased by as much as 50% compared with that grown in untreated Cd-contaminated soil samples. The chlorophyll content and the aerial biomass of Arabidopsis also increased substantially and eventually returned to a level comparable to plants grown in non-contaminated soils, with the addition of DTC-CTS. These findings suggested that DTC-CTS amendment could be effective in immobilizing Cd and mitigating its accumulation in plants grown in Cd-contaminated soils, with potential application as an in situ remediation of Cd-polluted soils. PMID:25628112
Influence of indian mustard (Brassica juncea) on rhizosphere soil solution chemistry in long-term contaminated soils: a rhizobox study.
Kim, Kwon-Rae; Owens, Gary; Kwon, Soon-lk
This study investigated the influence of Indian mustard (Brassica juncea) root exudation on soil solution properties (pH, dissolved organic carbon (DOC), metal solubility) in the rhizosphere using a rhizobox. Measurement was conducted following the cultivation of Indian mustard in the rhizobox filled four different types of heavy metal contaminated soils (two alkaline soils and two acidic soils). The growth of Indian mustard resulted in a significant increase (by 0.6 pH units) in rhizosphere soil solution pH of acidic soils and only a slight increase (< 0.1 pH units) in alkaline soils. Furthermore, the DOC concentration increased by 17-156 mg/L in the rhizosphere regardless of soil type and the extent of contamination, demonstrating the exudation of DOC from root. Ion chromatographic determination showed a marked increase in the total dissolved organic acids (OAs) in rhizosphere. While root exudates were observed in all soils, the amount of DOC and OAs in soil solution varied considerably amongst different soils, resulting in significant changes to soil solution metals in the rhizosphere. For example, the soil solution Cd, Cu, Pb, and Zn concentrations increased in the rhizosphere of alkaline soils compared to bulk soil following plant cultivation. In contrast, the soluble concentrations of Cd, Pb, and Zn in acidic soils decreased in rhizosphere soil when compared to bulk soils. Besides the influence of pH and DOC on metal solubility, the increase of heavy metal concentration having high stability constant such as Cu and Pb resulted in a release of Cd and Zn from solid phase to liquid phase. PMID:20397393
Time-dependent performance of soil mix technology stabilized/solidified contaminated site soils.
Wang, Fei; Wang, Hailing; Al-Tabbaa, Abir
This paper presents the strength and leaching performance of stabilized/solidified organic and inorganic contaminated site soil as a function of time and the effectiveness of modified clays applied in this project. Field trials of deep soil mixing application of stabilization/solidification (S/S) were performed at a site in Castleford in 2011. A number of binders and addictives were applied in this project including Portland cement (PC), ground granulated blastfurnace slag (GGBS), pulverised fuel ash (PFA), MgO and modified clays. Field trial samples were subjected to unconfined compressive strength (UCS), BS CN 12457 batch leaching test and the extraction of total organics at 28 days and 1.5 years after treatment. The results of UCS test show that the average strength values of mixes increased from 0-3250 kPa at 28 days to 250-4250 kPa at 1.5 years curing time. The BS EN 12457 leachate concentrations of all metals were well below their drinking water standard, except Ni in some mixes exceed its drinking water standard at 0.02 mg/l, suggesting that due to varied nature of binders, not all of them have the same efficiency in treating contaminated soil. The average leachate concentrations of total organics were in the range of 20-160 mg/l at 28 days after treatment and reduced to 18-140 mg/l at 1.5 years. In addition, organo clay (OC)/inorgano-organo clay (IOC) slurries used in this field trial were found to have a negative effect on the strength development, but were very effective in immobilizing heavy metals. The study also illustrates that the surfactants used to modify bentonite in this field trail were not suitable for the major organic pollutants exist in the site soil in this project. PMID:25603299
Soil application of biochar produced from biomass grown on trace element contaminated land.
Evangelou, Michael W H; Brem, Anette; Ugolini, Fabio; Abiven, Samuel; Schulin, Rainer
Trace element (TE) contamination of soils is a worldwide problem. However, although not considered safe anymore for food production without clean-up, many of these soils may still be used to produce biomass for non-food purposes such as biochar. Exploring the suitability of such biochar for the amendment of low-fertility soil, we investigated growth and metal accumulation of ryegrass (Lolium perenne, var. Calibra) as well as soil microbial abundance on a non-contaminated soil after amendment with biochar from birch (Betula pendula) wood produced on TE contaminated soil in comparison to a treatment with birch wood biochar originating from non-contaminated soil. Biochars were produced from both feedstocks by pyrolysis at two temperatures: 450 and 700 °C. During the pyrolysis, in contrast to Cu, Fe, Mg, K, Mn and P, the elements Cd, Pb, S and Na volatilized. The root biomass of the biochar treated plants was lower than that of the non-amended plants, while that of the shoot was higher. Plant shoot K and Zn concentrations were increased significantly by up to 7- and 3.3-fold respectively. For P, Mg, Mn, Fe and Cu no significant increase in shoot concentration could be detected. Neither the TE-contaminated biochar, nor the non-contaminated biochar had adverse effect on the bacterial community of the soil. PMID:25163600
Remediation aspect of microbial changes of plant rhizosphere in mercury contaminated soil.
Sas-Nowosielska, Aleksandra; Galimska-Stypa, Regina; Kucharski, Rafał; Zielonka, Urszula; Małkowski, Eugeniusz; Gray, Laymon
Phytoremediation, an approach that uses plants to remediate contaminated soil through degradation, stabilization or accumulation, may provide an efficient solution to some mercury contamination problems. This paper presents growth chamber experiments that tested the ability of plant species to stabilize mercury in soil. Several indigenous herbaceous species and Salix viminalis were grown in soil collected from a mercury-contaminated site in southern Poland. The uptake and distribution of mercury by these plants were investigated, and the growth and vitality of the plants through a part of one vegetative cycle were assessed. The highest concentrations of mercury were found at the roots, but translocation to the aerial part also occurred. Most of the plant species tested displayed good growth on mercury contaminated soil and sustained a rich microbial population in the rhizosphere. The microbial populations of root-free soil and rhizosphere soil from all species were also examined. An inverse correlation between the number of sulfur amino acid decomposing bacteria and root mercury content was observed. These results indicate the potential for using some species of plants to treat mercury contaminated soil through stabilization rather than extraction. The present investigation proposes a practical cost-effective temporary solution for phytostabilization of soil with moderate mercury contamination as well as the basis for plant selection. PMID:17492484
Soil amendments reduce trace element solubility in a contaminated soil and allow regrowth of natural vegetation.
Madejón, Engracia; de Mora, Alfredo Pérez; Felipe, Efraín; Burgos, Pilar; Cabrera, Francisco
We tested the effects of three amendments (a biosolid compost, a sugar beet lime, and a combination of leonardite plus sugar beet lime) on trace element stabilisation and spontaneous revegetation of a trace element contaminated soil. Soil properties were analysed before and after amendment application. Spontaneous vegetation growing on the experimental plot was studied by three surveys in terms of number of taxa colonising, percentage vegetation cover and plant biomass. Macronutrients and trace element concentrations of the five most frequent species were analysed. The results showed a positive effect of the amendments both on soil chemical properties and vegetation. All amendments increased soil pH and TOC content and reduced CaCl(2)-soluble-trace element concentrations. Colonisation by wild plants was enhanced in all amended treatments. The nutritional status of the five species studied was improved in some cases, while a general reduction in trace element concentrations of the aboveground parts was observed in all treated plots. The results obtained show that natural assisted remediation has potential for success on a field scale reducing trace element entry in the food chain. PMID:16005126
Electrokinetically enhanced bioremediation of creosote-contaminated soil: laboratory and field studies.
Suni, Sonja; Malinen, Essi; Kosonen, Jarmo; Silvennoinen, Hannu; Romantschuk, Martin
Creosote is a toxic and carcinogenic substance used in wood impregnation. Approximately 1,200 sites in Finland are contaminated with creosote. This study examined the possibility of enhancing bioremediation of creosote-contaminated soil with a combination of electric heating and infiltration and electrokinetic introduction of oxygenated, nutrient-rich liquid. Preliminary tests were performed in the laboratory, and a pilot test was conducted in situ at a creosote-contaminated former wood impregnation plant in Eastern Finland. Wood preservation practices at the plant were discontinued in 1989, but the soil and the groundwater in the area are still highly contaminated. The laboratory tests were mainly performed as a methodological test aiming for upscaling. The soils used in these tests were a highly polluted soil from a marsh next to the impregnation plant and a less polluted soil near the base of the impregnation building. The laboratory test showed that the relative degradation was significantly higher in high initial contaminant concentrations than with low initial concentrations. During the first 7 weeks, PAH-concentrations decreased by 68% in the marsh soil compared with a 51% reduction in the building soil. The field test was performed to a ca. 100 m3 soil section next to the former impregnation building. Nutrient and oxygen levels in the soils were elevated by hydraulic and electrokinetic pumping of urea and phosphate amended, aerated water into the soil. The DC current introduced into the soil raised the temperature from the ambient ca. 6 degrees C up to between 16 and 50 degrees C. Total PAH concentrations decreased by 50-80% during 3 months of treatment while mineral oil concentrations decreased approximately 30%. Electrokinetically enhanced in situ - bioremediation, which also significantly raised the soil temperature, proved to be a promising method to remediate creosote-contaminated soils. PMID:17365294
Delineation of Hydrocarbon Contamination of Soils and Sediments With Environmental Magnetic Methods: Laboratory and Field Studies
NASA Astrophysics Data System (ADS)
Rijal, M. L.; Appel, E.; Porsch, K.; Kappler, A.; Blaha, U.; Petrovsky, E.
Hydrocarbon contamination of soils and sediments is a worldwide environmental problem. The present research focuses on the study of magnetic properties of hydrocarbon contaminated soils and sediments using environmental magnetic methods both on field sites as well as in laboratory batch experiments. The main objectives of this research are i) to determine a possible application of magnetic proxies for the delineation of organic contamination in soils and sediments and ii) to examine the role of bacteria in changing soil magnetic properties after hydrocarbon contamination. A former oil field and a former military site which are heavily contaminated with hydrocarbons were studied. Additionally, three different types of natural clean soils were investigated in laboratory experiments by simulating hydrocarbon contamination in sterile and microbial active setups. Magnetic properties, soil properties, iron bioavailability, iron redox state and hydrocarbon content of samples were measured. Additionally, magnetic susceptibility (MS) was monitored weekly in laboratory batch set-ups during several months. Results from the field sites showed that there is an increase of MS and a good correlation between MS and hydrocarbon content. A weekly monitored MS result from the laboratory study clearly indicated~~10% change (increase as well as decrease) of initial MS of respective soils only in microbial active set-ups with saturation after a few weeks of experimental period. This depicts that there is a change of MS caused by microbial iron mineral transformation in presence of hydrocarbon contamination in soils. The results from the field study demonstrate that magnetic proxies can be used to localize hydrocarbon contamination. However, more field sites with hydrocarbon contaminated soils and sediments need to be investigated by using environmental magnetic methods for better understanding the factors driving such changes in magnetic properties.
A partition-limited model for the plant uptake of organic contaminants from soil and water
Chiou, C.T.; Sheng, G.; Manes, M.
In dealing with the passive transport of organic contaminants from soils to plants (including crops), a partition-limited model is proposed in which (i) the maximum (equilibrium) concentration of a contaminant in any location in the plant is determined by partition equilibrium with its concentration in the soil interstitial water, which in turn is determined essentially by the concentration in the soil organic matter (SOM) and (ii) the extent of approach to partition equilibrium, as measured by the ratio of the contaminant concentrations in plant water and soil interstitial water, ??pt (??? 1), depends on the transport rate of the contaminant in soil water into the plant and the volume of soil water solution that is required for the plant contaminant level to reach equilibrium with the external soil-water phase. Through reasonable estimates of plant organic-water compositions and of contaminant partition coefficients with various plant components, the model accounts for calculated values of ??pt in several published crop-contamination studies, including near-equilibrium values (i.e., ??pt ??? 1) for relatively water-soluble contaminants and lower values for much less soluble contaminants; the differences are attributed to the much higher partition coefficients of the less soluble compounds between plant lipids and plant water, which necessitates much larger volumes of the plant water transport for achieving the equilibrium capacities. The model analysis indicates that for plants with high water contents the plant-water phase acts as the major reservoir for highly water-soluble contaminants. By contrast, the lipid in a plant, even at small amounts, is usually the major reservoir for highly water-insoluble contaminants.
Assessing the biological activity of oil-contaminated soddy-podzolic soils with different textures
NASA Astrophysics Data System (ADS)
Vershinin, A. A.; Petrov, A. M.; Akaikin, D. V.; Ignat'ev, Yu. A.
The respiratory activity features in oil-contaminated soddy-podzolic soils of different textures have been studied. Unidirectional processes occur in contaminated loamy and loamy sandy soddy-podzolic soils; their intensities depend on the soil parameters. The mineralization rates of the oil products and the activity of the microflora in loamy soils exceed the corresponding parameters for loamy sandy soils. The long-term impact of oil and its transformation products results in more important disturbances of the microbial community in light soils. It has been shown that light soils containing 9% oil require longer time periods or more intensive remediation measures for the restoration of soil microbial cenoses disturbed by the pollutant.
Physicochemical and biological quality of soil in hexavalent chromium-contaminated soils as affected by chemical and microbial remediation.
Liao, Yingping; Min, Xiaobo; Yang, Zhihui; Chai, Liyuan; Zhang, Shujuan; Wang, Yangyang
Chemical and microbial methods are the main remediation technologies for chromium-contaminated soil. These technologies have progressed rapidly in recent years; however, there is still a lack of methods for evaluating the chemical and biological quality of soil after different remediation technologies have been applied. In this paper, microbial remediation with indigenous bacteria and chemical remediation with ferrous sulphate were used for the remediation of soils contaminated with Cr(VI) at two levels (80 and 1,276 mg kg(-1)) through a column leaching experiment. After microbial remediation with indigenous bacteria, the average concentration of water-soluble Cr(VI) in the soils was reduced to less than 5.0 mg kg(-1). Soil quality was evaluated based on 11 soil properties and the fuzzy comprehensive assessment method, including fuzzy mathematics and correlative analysis. The chemical fertility quality index was improved by one grade using microbial remediation with indigenous bacteria, and the biological fertility quality index increased by at least a factor of 6. Chemical remediation with ferrous sulphate, however, resulted in lower levels of available phosphorus, dehydrogenase, catalase and polyphenol oxidase. The result showed that microbial remediation with indigenous bacteria was more effective for remedying Cr(VI)-contaminated soils with high pH value than chemical remediation with ferrous sulphate. In addition, the fuzzy comprehensive evaluation method was proven to be a useful tool for monitoring the quality change in chromium-contaminated soils. PMID:23784058
Microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants in lead contaminated soil.
Gattai, Graziella S; Pereira, Sônia V; Costa, Cynthia M C; Lima, Cláudia E P; Maia, Leonor C
The goals of this study were to evaluate the microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants (Caesalpinia ferrea, Mimosa tenuiflora and Erythrina velutina) in lead contaminated soil from the semi-arid region of northeastern of Brazil (Belo Jardim, Pernambuco). Dilutions were prepared by adding lead contaminated soil (270 mg Kg(-1)) to uncontaminated soil (37 mg Pb Kg soil(-1)) in the proportions of 7.5%, 15%, and 30% (v:v). The increase of lead contamination in the soil negatively influenced the amount of carbon in the microbial biomass of the samples from both the dry and rainy seasons and the metabolic quotient only differed between the collection seasons in the 30% contaminated soil. The average value of the acid phosphatase activity in the dry season was 2.3 times higher than observed during the rainy season. There was no significant difference in the number of glomerospores observed between soils and periods studied. The most probable number of infective propagules was reduced for both seasons due to the excess lead in soil. The mycorrhizal colonization rate was reduced for the three plant species assayed. The inoculation with arbuscular mycorrhizal fungi benefited the growth of Erythrina velutina in lead contaminated soil. PMID:24031701
Microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants in lead contaminated soil
Gattai, Graziella S.; Pereira, Sônia V.; Costa, Cynthia M. C.; Lima, Cláudia E. P.; Maia, Leonor C.
The goals of this study were to evaluate the microbial activity, arbuscular mycorrhizal fungi and inoculation of woody plants (Caesalpinia ferrea, Mimosa tenuiflora and Erythrina velutina) in lead contaminated soil from the semi-arid region of northeastern of Brazil (Belo Jardim, Pernambuco). Dilutions were prepared by adding lead contaminated soil (270 mg Kg-1) to uncontaminated soil (37 mg Pb Kg soil-1) in the proportions of 7.5%, 15%, and 30% (v:v). The increase of lead contamination in the soil negatively influenced the amount of carbon in the microbial biomass of the samples from both the dry and rainy seasons and the metabolic quotient only differed between the collection seasons in the 30% contaminated soil. The average value of the acid phosphatase activity in the dry season was 2.3 times higher than observed during the rainy season. There was no significant difference in the number of glomerospores observed between soils and periods studied. The most probable number of infective propagules was reduced for both seasons due to the excess lead in soil. The mycorrhizal colonization rate was reduced for the three plant species assayed. The inoculation with arbuscular mycorrhizal fungi benefited the growth of Erythrina velutina in lead contaminated soil. PMID:24031701
Feasibility of supercritical CO{sub 2} extraction as a remediation technology for Hanford contaminated soils
Moody, T.E.; Krukonis, V.J.
A technology used by the petroleum industry for separation and purification and the coffee industry for caffeine removal is being used by a Hanford scientist with the prospect of remediating organic contaminated Hanford soil. The process is known as Supercritical Fluid Extraction or SFE. Dr. Timothy Moody of the Westinghouse Hanford Company and the Phasex Corporation of Lawrence, Mass., have conducted successful bench-scale experiments at the 50g, 500g, and 5kg levels showing that SFE can remove various chemicals from large volumes of contaminated soil. The results indicate that organic contaminant removal from soil is much more efficient than the current industrial uses of SFE.
Presence of Actinobacterial and Fungal Communities in Clean and Petroleum Hydrocarbon Contaminated Subsurface Soil
Björklöf, Katarina; Karlsson, Sanja; Frostegård, Åsa; Jørgensen, Kirsten S
Relatively little is known about the microbial communities adapted to soil environments contaminated with aged complex hydrocarbon mixtures, especially in the subsurface soil layers. In this work we studied the microbial communities in two different soil profiles down to the depth of 7 m which originated from a 30-year-old site contaminated with petroleum hydrocarbons (PHCs) and from a clean site next to the contaminated site. The concentration of oxygen in the contaminated soil profile was strongly reduced in soil layers below 1 m depth but not in the clean soil profile. Total microbial biomass and community composition was analyzed by phospholipid fatty acid (PLFA) measurements. The diversity of fungi and actinobacteria was investigated more in detail by construction of rDNA-based clone libraries. The results revealed that there was a significant and diverse microbial community in subsoils at depth below 2 m, also in conditions where oxygen was limiting. The diversity of actinobacteria was different in the two soil profiles; the contaminated soil profile was dominated by Mycobacterium -related sequences whereas sequences from the clean soil samples were related to other, generally uncultured organisms, some of which may represent two new subclasses of actinobacteria. One dominating fungal sequence which matched with the ascomycotes Acremonium sp. and Paecilomyces sp. was identified both in clean and in contaminated soil profiles. Thus, although the relative amounts of fungi and actinobacteria in these microbial communities were highest in the upper soil layers, many representatives from these groups were found in hydrocarbon contaminated subsoils even under oxygen limited conditions. PMID:19543551
Comparison of germination and seed vigor of sunflower in two contaminated soils of different texture
NASA Astrophysics Data System (ADS)
Zhao, Xin; Han, Jaemaro; Lee, Jong Keun; Kim, Jae Young
Phytoremediation as an emerging low-cost and ecologically friendly alternative to the conventional soil remediation technologies has gained a great deal of attention and into lots of research. As a kind of the methods that use of green plants to remediate heavy metals contaminated soils, the early growth status of plant seeds in the contaminated environmental directly affects the effect of phytoremediation. Germination test in the water (aqueous solution of heavy metal) is generally used for assessing heavy metal phytotoxicity and possibility of plant growth, but there is a limit. Because soil is commonly main target of phytoremediation, not the water. The bioavailability of heavy metals in the soil also depends on the texture. So soil texture is an important factor of phytoremediation effect. Sunflower is the representative species which have good tolerance to various heavy metals; furthermore, the seeds of sunflower can be used as the raw-material for producing bio-diesel. The objectives of this research were to investigate germination rate of sunflowers in various heavy metal contaminated soils and to compare the seedling vigor index (SVI) of sunflower in two contaminated soils of different texture. Sunflower (Helianthusannuus L.) seeds were obtained from a commercial market. In order to prove the soil texture effect on heavy metal contaminated soil, germination tests in soil were conducted with two different types of soil texture (i.e., loam soil and sandy loam soil) classified by soil textural triangle (defined by USDA) including representative soil texture of Korea. Germination tests in soil were conducted using KS I ISO 11260-1 (2005) for reference that sunflower seeds were incubated for 7 days in dark at 25 ± 1 Celsius degree. The target heavy metals are Nickel (Ni) and Zinc (Zn). The Ni and Zn concentrations were 0, 10, 50, 100, 200, 300, 500 mg-Ni/kg-dry soil, and 0, 10, 50, 100, 300, 500, 900 mg-Zn/kg-dry soil, respectively. After germination test for 7
Electrokinetic remediation and microbial community shift of β-cyclodextrin-dissolved petroleum hydrocarbon-contaminated soil.
Wan, Chunli; Du, Maoan; Lee, Duu-Jong; Yang, Xue; Ma, Wencheng; Zheng, Lina
Electrokinetic (EK) migration of β-cyclodextrin (β-CD), which is inclusive of total petroleum hydrocarbon (TPH), is an economically beneficial and environmentally friendly remediation process for oil-contaminated soils. Remediation studies of oil-contaminated soils generally prepared samples using particular TPHs. This study investigates the removal of TPHs from, and electromigration of microbial cells in field samples via EK remediation. Both TPH content and soil respiration declined after the EK remediation process. The strains in the original soil sample included Bacillus sp., Sporosarcina sp., Beta proteobacterium, Streptomyces sp., Pontibacter sp., Azorhizobium sp., Taxeobacter sp., and Williamsia sp. Electromigration of microbial cells reduced the biodiversity of the microbial community in soil following EK remediation. At 200 V m(-1) for 10 days, 36% TPH was removed, with a small population of microbial cells flushed out, demonstrating that EK remediation is effective for the present oil-contaminated soils collected in field. PMID:21052991
Biochar and compost amendments enhance copper immobilisation and support plant growth in contaminated soils.
Jones, Sarah; Bardos, R Paul; Kidd, Petra S; Mench, Michel; de Leij, Frans; Hutchings, Tony; Cundy, Andrew; Joyce, Chris; Soja, Gerhard; Friesl-Hanl, Wolfgang; Herzig, Rolf; Menger, Pierre
Contamination of soil with trace elements, such as Cu, is an important risk management issue. A pot experiment was conducted to determine the effects of three biochars and compost on plant growth and the immobilisation of Cu in a contaminated soil from a site formerly used for wood preservation. To assess Cu mobility, amended soils were analysed using leaching tests pre- and post-incubation, and post-growth. Amended and unamended soils were planted with sunflower, and the resulting plant material was assessed for yield and Cu concentration. All amendments significantly reduced leachable Cu compared to the unamended soil, however, the greatest reductions in leachable Cu were associated with the higher biochar application rate. The greatest improvements in plant yields were obtained with the higher application rate of biochar in combination with compost. The results suggest joint biochar and compost amendment reduces Cu mobility and can support biomass production on Cu-contaminated soils. PMID:26850677
Characterization and solubility measurements of uranium-contaminated soils to support risk assessment
Elless, M.P.; Armstrong, A.Q.; Lee, S.Y.
Remediation of uranium-contaminated soils is considered a high priority by the US Department of Energy because these soils, if left untreated, represent a hazard to the environment and human health. Because the risk to human health is a function of the solubility of uranium in the soils, the objectives of this work are to measure the uranium solubility of two contaminated soils, before and after remedial treatment, and determine the health risk associated with these soils. Two carbonate-rich, uranium-contaminated soils from the US Department of Energy Fernald Environmental Management Project facility near Cincinnati, Ohio, as well as two nearby background soils were characterized and their uranium solubility measured in a 75-d solubility experiment using acid rain, groundwater, lung serum, and stomach acid simulants. Results show that the soluble uranium levels of each soil by each simulant are greatly influenced by their contamination source term. Risk calculations and biokinetic modeling based on the solubility data show that the risks from the soil ingestion and groundwater ingestion pathways are the predominant contributors to the total carcinogenic risk, whereas the risk from the soil inhalation pathway is the smallest contributor to this risk. However, kidney toxicity was the greater health concern of the Fernald Environmental Management Project soils, primarily from undiluted ingestion of the groundwater solution following contact with the contaminated soils. Sensitivity analyses indicate that uranium solubility is a key parameter in defining kidney toxicity; therefore, without proper consideration of the solubility of radionuclides/metals in untreated and treated soils, important factors may be overlooked which may result in soil cleanup goals or limits which are not protective of human health and the environment.
Azospirillum rugosum sp. nov., isolated from oil-contaminated soil.
Young, C C; Hupfer, H; Siering, C; Ho, M-J; Arun, A B; Lai, W-A; Rekha, P D; Shen, F-T; Hung, M-H; Chen, W-M; Yassin, A F
The taxonomic status of a light-orange-coloured bacterial isolate from an oil-contaminated soil sample was characterized by using a polyphasic taxonomic approach. Comparative analysis of 16S rRNA gene sequences demonstrated that the isolate belonged phylogenetically to the genus Azospirillum, with Azospirillum canadense, Azospirillum brasilense and Azospirillum doebereinerae as its closest phylogenetic relatives (97.3, 97.0 and 97.0 % similarity, respectively). DNA-DNA pairing studies showed that the unidentified organism displayed 25.0, 17.0 and 19.0 % relatedness to the type strains of A. brasilense, A. canadense and A. doebereinerae, respectively. The generic assignment was confirmed by chemotaxonomic data, which revealed a fatty acid profile that was characteristic of the genus Azospirillum, consisting of straight-chain saturated and unsaturated fatty acids with C18 : 1 omega 7c as the major fatty acid, and ubiquinone with ten isoprene units (Q-10) as the predominant respiratory quinone. On the basis of both the phenotypic and molecular genetic evidence, it is proposed that the unknown isolate be classified as a representative of a novel species of the genus Azospirillum, for which the name Azospirillum rugosum sp. nov. is proposed. The type strain is IMMIB AFH-6T (=CCUG 53966T=DSM 19657T). PMID:18398202
DNA microarrays detect effects of soil contamination on Arabidopsis thaliana gene expression.
Magrini, Kimberly D; Basu, Amit; Spotila, James R; Avery, Harold W; Bergman, Lawrence W; Hammond, Rachel; Anandan, Shivanthi
Soil contamination, such as heavy metals and benzene compounds, is a widespread problem on military installations. It is important to be able to determine the effects of soil contamination before any adverse effects appear in organisms in surrounding areas. We examined gene expression in Arabidopsis thaliana grown in soil from three sites at the Radford Army Ammunition Plant in Radford, Virginia, USA, using DNA microarrays. We analyzed soil, germination, and growth rate to compare with the microarray data. Soil contamination affected both external phenotype and gene expression. Plants grown in soil with high levels of contaminants were chloritic and were smaller than control plants grown in potting soil. Plants grown in soil with the highest copper concentration had the lowest growth rates and had genes up-regulated across several functional groups. Plants grown in soils with elevated lead had many genes down-regulated that were related to photosystem II, metabolism, cellular transport, and protein synthesis. Genes consistently up-regulated across most microarrays were genes related to photosystem I, genes related to water deprivation and oxidative stress response, heat shock proteins, and toxin catabolism genes such as glutathiones. DNA microarrays, in concert with a model genetic organism such as A. thaliana, were an effective assessment tool to determine the presence of toxic substances in soil at a site used for the production of military explosives. PMID:18613744
[Leaching Remediation of Copper and Lead Contaminated Lou Soil by Saponin Under Different Conditions].
Deng, Hong-xia; Yang, Ya-li; Li, Zhen; Xu, Yan; Li, Rong-hua; Meng, Zhao-fu; Yang, Ya-ti
In order to investigate the leaching remediation effect of the eco-friendly biosurfactant saponin for Cu and Pb in contaminated Lou soil, batch tests method was used to study the leaching effect of saponin solution on single Cu, Pb contaminated Lou soil and mixed Cu and Pb contaminated Lou soil under different conditions such as reaction time, mass concentration of saponin, pH, concentration of background electrolyte and leaching times. The results showed that the maximum leaching removal effect of Cu and Pb in contaminated Lou soil was achieved by complexation of the heavy metals with saponin micelle, when the mass concentration of saponin solution was 50 g x L(-1), pH was 5.0, the reaction time was 240 min, and there was no background electrolyte. In single and mixed contaminated Lou soil, the leaching percentages of Cu were 29.02% and 25.09% after a single leaching with 50 g x L(-1) saponin under optimal condition, while the single leaching percentages of Pb were 31.56% and 28.03%, respectively. The result indicated the removal efficiency of Pb was more significant than that of Cu. After 4 times of leaching, the cumulative leaching percentages of Cu reached 58.92% and 53.11%, while the cumulative leaching percentages of Pb reached 77.69% and 65.32% for single and mixed contaminated Lou soil, respectively. The fractionation results of heavy metals in soil before and after a single leaching showed that the contents of adsorbed and exchangeable Cu and Pb increased in the contaminated soil, while the carbonate-bound, organic bound and sulfide residual Cu and Pb in the contaminated Lou soil could be effectively removed by saponin. PMID:26164925
Bioavailability and mobility of organic contaminants in soil: new three-step ecotoxicological evaluation.
Prokop, Zbyněk; Nečasová, Anežka; Klánová, Jana; Čupr, Pavel
A novel approach was developed for rapid assessment of bioavailability and potential mobility of contaminants in soil. The response of the same test organism to the organic extract, water extract and solid phase of soil was recorded and compared. This approach was designed to give an initial estimate of the total organic toxicity (response to organic extractable fraction), as well as the mobile (response to water extract) and bioavailable fraction (response to solid phase) of soil samples. Eighteen soil samples with different levels of pollution and content of organic carbon were selected to validate the novel three-step ecotoxicological evaluation approach. All samples were chemically analysed for priority contaminants, including aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), hexachlorocyclohexane (HCH) and dichlordiphenyltrichloroethane (DDT). The ecotoxicological evaluation involved determination of toxicity of the organic, mobile and bioavailable fractions of soil to the test organism, bacterium Bacillus cereus. We found a good correlation between the chemical analysis and the toxicity of organic extract. The low toxicity of water extracts indicated low water solubility, and thus, low potential mobility of toxic contaminants present in the soil samples. The toxicity of the bioavailable fraction was significantly greater than the toxicity of water-soluble (mobile) fraction of the contaminants as deduced from comparing untreated samples and water extracts. The bioavailability of the contaminants decreased with increasing concentrations of organic carbon in evaluated soil samples. In conclusion, the three-step ecotoxicological evaluation utilised in this study can give a quick insight into soil contamination in context with bioavailability and mobility of the contaminants present. This information can be useful for hazard identification and risk assessment of soil-associated contaminants. Graphical Abstract New three-step ecotoxicological
Potential soil contaminant levels of polychlorinated dibenzodioxins and dibenzofurans at industrial facilities employing heat transfer operations
Korte, N.E.; Muhr, C.A.; Greene, D.W.
Certain manufacturing facilities formerly used large quantities of polychlorinated biphenyl (PCB) fluids in heat transfer operations. At many of these locations, operations have also involved PCB-containing electrical equipment. Commonly, over many years of plant operations, spills and leaks have resulted in PCB soil contamination. Dioxins and furans have been associated with PCB contamination in both the technical and popular press. Consequently, the need for analyses for dioxins and furans must be evaluated at locations where soils are contaminated with PCBs. This report presents an evaluation of potential dioxin and furan soil contamination based on heat transfer operations and spills from electrical equipment. The following five scenarios were examined for dioxin and furan contamination: (1) impurities in heat transfer fluids, (2) formation during heat transfer operations, (3) pyrolysis of heat transfer fluids, (4) impurities in dielectric fluids, and (5) pyrolysis of dielectric fluids. The potential contamination with dioxins and furans was calculated and compared with a 20 ppb guideline that has been used by the Centers for Disease Control for dioxin in subsoil. The results demonstrated that dioxins are formed only under pyrolytic conditions and only from the trichlorobenzenes present in dielectric fluids. Furans are found as impurities in PCB fluids but, as with dioxins, are not formed in significant quantities except during pyrolysis. Fortunately, pyrolytic conditions involving PCB fluids and soil contamination are unlikely; therefore, analyses for dioxin and furan contamination in soils will rarely be needed.
Modelling phytoremediation by the hyperaccumulating fern, Pteris vittata, of soils historically contaminated with arsenic.
Shelmerdine, Paula A; Black, Colin R; McGrath, Steve P; Young, Scott D
Pteris vittata plants were grown on twenty-one UK soils contaminated with arsenic (As) from a wide range of natural and anthropogenic sources. Arsenic concentration was measured in fern fronds, soil and soil pore water collected with Rhizon samplers. Isotopically exchangeable soil arsenate was determined by equilibration with (73)As(V). Removal of As from the 21 soils by three sequential crops of P. vittata ranged between 0.1 and 13% of total soil As. Ferns grown on a soil subjected to long-term sewage sludge application showed reduced uptake of As because of high available phosphate concentrations. A combined solubility-uptake model was parameterised to enable prediction of phytoremediation success from estimates of soil As, 'As-lability' and soil pH. The model was used to demonstrate the remediation potential of P. vittata under different soil conditions and with contrasting assumptions regarding re-supply of the labile As pool from unavailable forms. PMID:19171413
Ultrasonic desorption of petroleum hydrocarbons from crude oil contaminated soils.
Li, Jianbing; Song, Xinyuan; Hu, Guangji; Thring, Ronald Wallen
Ultrasonic irradiation was applied to improve the desorption of petroleum hydrocarbons (PHC) in crude oil from three types of soil. Soil A was an Ottawa sand, while soil B and soil C were fine soils that contained 27.6% and 55.3% of silt and clay contents, respectively. It was found that the ultrasonic desorption was highly related to soil types, with the highest and the lowest desorption occurring in coarse soil (i.e., soil A) and finer soil (i.e., soil C), respectively. Under the experimental conditions, the maximum ultrasonic desorption enhancement of the total petroleum hydrocarbons (TPH) reached 22% for soil A, 61% for soil B, and 49% for soil C, respectively. The maximum enhancement on the F2 (n-C10 to n-C16), F3 (n-C16 to n-C34), and F4 (n-C34 to n-C50) fractions of PHC reached 91, 44, and 51% for soil B, and 90, 38, and 31% for soil C, respectively. The desorption enhancement also illustrated an increasing trend with initial soil TPH concentration. PMID:23705614
Efficiency of soil organic and inorganic amendments on the remediation of a contaminated mine soil: II. Biological and ecotoxicological evaluation.
Pardo, T; Clemente, R; Alvarenga, P; Bernal, M P
The feasibility of two organic materials (pig slurry and compost) in combination with hydrated lime for the remediation of a highly acidic trace elements (TEs) contaminated mine soil was assessed in a mesocosm experiment. The effects of the amendments on soil biochemical and ecotoxicological properties were evaluated and related with the main physicochemical characteristics of soil and soil solution. The original soil showed impaired basic ecological functions due to the high availability of TEs, its acidic pH and high salinity. The three amendments slightly reduced the direct and indirect soil toxicity to plants, invertebrates and microorganisms as a consequence of the TEs' mobility decrease in topsoil, reducing therefore the soil associated risks. The organic amendments, especially compost, thanks to the supply of essential nutrients, were able to improve soil health, as they stimulated plant growth and significantly increased enzyme activities related with the key nutrients in soil. Therefore, the use of compost or pig slurry, in combination with hydrated lime, decreased soil ecotoxicity and seems to be a suitable management strategy for the remediation of highly acidic TEs contaminated soils. PMID:24875876
Evaluation of the Infectiousness to Mice of Soil Contaminated with Yersinia pestis-Infected Blood
Boegler, Karen A.; Graham, Christine B.; Montenieri, John A.; MacMillan, Katherine; Holmes, Jennifer L.; Petersen, Jeannine M.; Gage, Kenneth L.; Eisen, Rebecca J.
Plague, an often-fatal zoonotic disease caused by Yersinia pestis, is characterized by epizootic and quiescent periods. How Y. pestis is maintained during inter-epizootic periods is poorly understood, but soil has been implicated as a potential reservoir. Although previous studies have suggested that Y. pestis is able to survive in soil for weeks or months, it is unclear whether or not it is infectious to susceptible hosts. Here we investigate the potential for Y. pestis to infect mice through close contact with contaminated soil under laboratory conditions. In an attempt to approximate the natural conditions under which animals would be exposed to Y. pestis-contaminated soil, mouse cages filled with soil from a plague-endemic region were held at temperature and humidity ranges observed in ground squirrel burrows. These laboratory "burrows" were contaminated with highly bacteremic blood (> 108 cfu/mL) to simulate the introduction of infectious material from a dying animal during an epizootic. Outbred Swiss-Webster mice with scarified skin patches were held on contaminated soil for 10 days and monitored for signs of illness. Following exposure to contaminated soil, one animal of 104 became infected with Y. pestis. None of the remaining animals seroconverted following a 21-day holding period. Under our experimental conditions, which maximized the likelihood of contact between susceptible mice and contaminated soil, transmission efficiency from soil to mice was 0.96% (95% CI 0.17, 5.25%). This suggests that although transmission of Y. pestis from contaminated soils is possible, it is not likely a major transmission route under natural conditions. PMID:22925020
Electrochemical processes for in-situ treatment of contaminated soils. 1998 annual progress report
Huang, C.P.
'This research project is to develop electrochemical processes for in-situ treatment of contaminated soils. Specifically, it is to study electrokinetic (EK) and electro-Fento (EF) processes and to integrate these processes for the treatment of soils containing mixed contaminants. The objectives are: (1) To study important parameters controlling the mobilization and the transport of selected organics and metals in soils by the electrokinetic (EK) process. Factors to be studied include field strength, pH, ionic strength, soil washing agents, types of organic and metal contaminants, and soil surface properties such as cation exchange capacity(CEC), soil organic content, soil moisture content, soil composition, and surface charge. (2) To study the important factors governing the oxidation of selected organic contaminants by the electro-Fenton (EF) process. Parameters such as pH, surface area and the configuration of working electrode, oxygen concentration, ferrous ion, and temperature that may affect the performance of the EF process will be investigated. (3) To understand the mechanism of the oxidation of selected organic contaminants by the electro-Fenton oxidation process.'
Determination of urease activity in soils by carbon dioxide release for ecotoxicological evaluation of contaminated soils.
Guettes, Ralf; Dott, Wolfgang; Eisentraeger, Adolf
A method for the quantification of urease enzyme activity has been set up, which is based on the quantification of carbon dioxide set free into the head space of gastight vessels. The method can be applied for ecotoxicological characterisation of contaminated soil samples besides other methods like soil respiration measurements or nitrification inhibition tests. The sieved soil sample can be incubated under nearly natural conditions with an adjusted water content of about 50% of the water holding capacity. Ammonia or urea do not need to be extracted, since carbon dioxide release is correlated to urease activity. Thus carbon dioxide release is a direct result of urease activity which can be measured in the head space using gastight syringes and gaschromatographic equipment. The urease activity is determined by comparing the carbon dioxide release of incubation vessels with and without urea supply. The applicability of this method has been demonstrated by experiments with N-(n-butyl)phosphoric triamide (NBPT), copper ions and zinc ions as known inhibitors of urease activity. PMID:12463682
Use of immunoassay testing and landfarming to remediate pesticide - contaminated soil at agrichemical businesses
Frank, J.F.
The recent combination of two new technologies - immunoassay and landfarming - now offers an efficient, effective and economical option in the remediation of pesticide-contaminated soil. Participation in 28 landfarming projects in Illinois - 20 with pesticide-contaminated soil and eight with fuel-contaminated soil - has convinced the author that the combination offers the best method of remediation for most agrichemical sites. The procedures are currently used in Illinois as well as several other states and are being considered in even more. This paper describes the legislative and regulatory background for landfarming; defines immunoassay testing; defines landfarming: (1) contaminated site sampling and analysis; (2) education of participants; (3) selection of cooperator and host farm; (4) soil spreading considerations; a. rates, b. techniques; host site sampling and analysis; and factors affecting cost.
In situ vitrification: Test results for a contaminated soil-melting process
Buelt, J.L.; Timmerman, C.L.; Westsik, J.H. Jr.
In situ vitrification (ISV) is being developed at Pacific Northwest Laboratory for the Department of Energy to stabilize soils and sludges that are contaminated with radioactive and hazardous chemical wastes. ISV is a process that immobilizes contaminated soil in place by converting it to a durable glass and crystalline product similar to obsidian and basalt. In June 1987, a large-scale test of the process was completed at a transuranic-contaminated soil site. The test constituted the first full-scale demonstration of ISV at an actual site. This paper summarizes the results of that test and describes the potential adaptation of the process to radioactive and hazardous chemical waste-contaminated soils. 15 refs., 9 figs., 3 tabs.
In Situ Vitrification: Recent test results for a contaminated soil melting process
Buelt, J.L.; Timmerman, C.L.; Westsik, J.H. Jr.
In Situ Vitrification (ISV) is being developed at Pacific Northwest Laboratory for the Department of Energy and other clients for the stabilization of soils and sludges contaminated with radioactive and hazardous chemical wastes. ISV is a process that immobilizes contaminated soil in place by converting it to a durable glass and crystalline product that is similar to obsidian. In June 1987, a large-scale test of the process was completed at a transuranic- contaminated soil site. This constituted the first full-scale demonstration of the ISV process at an actual site. This paper summarizes the preliminary results of this test and describes the processes' potential adaptation to radioactive and hazardous chemical waste contaminated soils. 10 refs., 10 figs.
Solubilization has profound implications for such diverse risk assessment activities as assessing sediment contaminant porewater exposures to benthic fauna, determining half lives of refractory toxicants in natural soils and sediments, and assessing the fate and transport of th...
Influences of solution chemical conditions on mobilization of TNT from contaminated soil
Dante, D.A.; Tiller, C.L.; Pennell, K.D.
2,4,6-trinitrotoluene (TNT) and its byproducts are common contaminants on US military installations. Many potential remediation processes are in part limited by the transfer of TNT from the contaminated soil into the aqueous phase. The purpose of this research is to assess the release of TNT from contaminated soil under varying solution chemical conditions. In particular, influences of pH, aquatic natural organic matter, and addition of two surfactants is investigated. Uncontaminated soil was collected from a near-surface site at the Alabama Army Ammunition Plant and was artificially contaminated with TNT prior to the mobilization experiments. Results for the pH experiments show that more TNT is mobilized at neutral pH conditions than at low pH conditions. The presence of dissolved organic matter enhances the release of TNT from soil, but not by a large amount. Surfactant addition has the most significant effect on TNT mobilization.
Biological treatment of TNT-contaminated soil. 2: Biologically induced immobilization of the contaminants and full-scale application
Lenke, H.; Daun, G.; Sieglen, U.; Knackmuss, H.J.; Warrelmann, J.; Walter, U.; Hund, K.
Anaerobic treatment of originally contaminated soil from a former ammunition plant was carried out in a laboratory slurry reactor. While fermenting glucose to ethanol, acetate, and propionate, the anaerobic bacteria completely reduced the nitro groups of 2,4,6-trinitrotoluene (TNT) and aminodinitrotoluenes, which led to a complete and irreversible binding of the reduced products to the soil. 2,4-dinitrotoluene and hexahydro-1,3,5-trinitro-1,3,5-triazine were also reduced in the soil slurry and were no longer detectable after the anaerobic treatment. To mineralize the fermentation products, a subsequent aerobic treatment was necessary to complete the bioremediation process. This bioremediation process was tested in a technical scale at Hessisch Lichtenau-Hirschhagen, Germany. A sludge reactor (Terranox system) was filled with 18 m{sup 3} of contaminated soil (main contaminants were TNT, 2,4-dinitrotoluene, hexahydro-1,3,5-trinitro-1,3,5-triazine) and 10 m{sup 3} of water. The anaerobic stage was carried out by periodical feeding of sucrose. The sludge was subsequently dewatered and treated aerobically. Chemical analysis revealed an overall reduction of more than 99% of the contaminants. Ecotoxicological tests performed with various aquatic systems (luminescent bacteria, daphnids, algae) and terrestrial systems (respiring bacteria, nitrifying bacteria, cress plants, earth worms) showed that residual toxicity could not be detected after the anaerobic/aerobic treatment.
The Biodiversity Changes in the Microbial Population of Soils Contaminated with Crude Oil.
Abbasian, Firouz; Lockington, Robin; Megharaj, Mallavarapu; Naidu, Ravi
Crude oil spills resulting from excavation, transportation and downstream processes can cause intensive damage to living organisms and result in changes in the microbial population of that environment. In this study, we used a pyrosequencing analysis to investigate changes in the microbial population of soils contaminated with crude oil. Crude oil contamination in soil resulted in the creation of a more homogenous population of microorganisms dominated by members of the Actinomycetales, Clostridiales and Bacillales (all belonging to Gram-positive bacteria) as well as Flavobacteriales, Pseudomonadales, Burkholderiales, Rhizobiales and Sphingomonadales (all belonging to Gram-negative bacteria). These changes in the biodiversity decreased the ratios of chemoheterotrophic bacteria at higher concentrations of crude oil contamination, with these being replaced by photoheterotrophic bacteria, mainly Rhodospirillales. Several of the dominant microbial orders in the crude oil contaminated soils are able to degrade crude oil hydrocarbons and therefore are potentially useful for remediation of crude oil in contaminated sites. PMID:26858133
Bioremediation of petroleum hydrocarbon contaminated soil by Rhodobacter sphaeroides biofertilizer and plants.
Jiao, Haihua; Luo, Jinxue; Zhang, Yiming; Xu, Shengjun; Bai, Zhihui; Huang, Zhanbin
Bio-augmentation is a promising technique for remediation of polluted soils. This study aimed to evaluate the bio-augmentation effect of Rhodobacter sphaeroides biofertilizer (RBF) on the bioremediation of total petroleum hydrocarbons (TPH) contaminated soil. A greenhouse pot experiment was conducted over a period of 120 days, three methods for enhancing bio-augmentation were tested on TPH contaminated soils, including single addition RBF, planting, and combining of RBF and three crop species, such as wheat (W), cabbage (C) and spinach (S), respectively. The results demonstrated that the best removal of TPH from contaminated soil in the RBF bio-augmentation rhizosphere soils was found to be 46.2%, 65.4%, 67.5% for W+RBF, C+RBF, S+RBF rhizosphere soils respectively. RBF supply impacted on the microbial community diversity (phospholipid fatty acids, PLFA) and the activity of soil enzymes, such as dehydrogenase (DH), alkaline phosphatase (AP) and urease (UR). There were significant difference among the soil only containing crude oil (CK), W, C and S rhizosphere soils and RBF bio-augmentation soils. Moreover, the changes were significantly distinct depended on crops species. It was concluded that the RBF is a valuable material for improving effect of remediation of TPH polluted soils. PMID:26525019
Functional gene diversity of soil microbial communities from five oil-contaminated fields in China
Liang, Yuting; Van Nostrand, Joy D; Deng, Ye; He, Zhili; Wu, Liyou; Zhang, Xu; Li, Guanghe; Zhou, Jizhong
To compare microbial functional diversity in different oil-contaminated fields and to know the effects of oil contaminant and environmental factors, soil samples were taken from typical oil-contaminated fields located in five geographic regions of China. GeoChip, a high-throughput functional gene array, was used to evaluate the microbial functional genes involved in contaminant degradation and in other major biogeochemical/metabolic processes. Our results indicated that the overall microbial community structures were distinct in each oil-contaminated field, and samples were clustered by geographic locations. The organic contaminant degradation genes were most abundant in all samples and presented a similar pattern under oil contaminant stress among the five fields. In addition, alkane and aromatic hydrocarbon degradation genes such as monooxygenase and dioxygenase were detected in high abundance in the oil-contaminated fields. Canonical correspondence analysis indicated that the microbial functional patterns were highly correlated to the local environmental variables, such as oil contaminant concentration, nitrogen and phosphorus contents, salt and pH. Finally, a total of 59% of microbial community variation from GeoChip data can be explained by oil contamination, geographic location and soil geochemical parameters. This study provided insights into the in situ microbial functional structures in oil-contaminated fields and discerned the linkages between microbial communities and environmental variables, which is important to the application of bioremediation in oil-contaminated sites. PMID:20861922
Some Case Studies on Metal-Microbe Interactions to Remediate Heavy Metals- Contaminated Soils in Korea
NASA Astrophysics Data System (ADS)
Chon, Hyo-Taek
Conventional physicochemical technologies to remediate heavy metals-contaminated soil have many problems such as low efficiency, high cost and occurrence of byproducts. Recently bioremediation technology is getting more and more attention. Bioremediation is defined as the use of biological methods to remediate and/or restore the contaminated land. The objectives of bioremediation are to degrade hazardous organic contaminants and to convert hazardous inorganic contaminants to less toxic compounds of safe levels. The use of bioremediation in the treatment of heavy metals in soils is a relatively new concept. Bioremediation using microbes has been developed to remove toxic heavy metals from contaminated soils in laboratory scale to the contaminated field sites. Recently the application of cost-effective and environment-friendly bioremediation technology to the heavy metals-contaminated sites has been gradually realized in Korea. The merits of bioremediation include low cost, natural process, minimal exposure to the contaminants, and minimum amount of equipment. The limitations of bioremediation are length of remediation, long monitoring time, and, sometimes, toxicity of byproducts for especially organic contaminants. From now on, it is necessary to prove applicability of the technologies to contaminated sites and to establish highly effective, low-cost and easy bioremediation technology. Four categories of metal-microbe interactions are generally biosorption, bioreduction, biomineralization and bioleaching. In this paper, some case studies of the above metal-microbe interactions in author's lab which were published recently in domestic and international journals will be introduced and summarized.
Plant uptake of explosives from contaminated soil at the Joliet Army Ammunition Plant
Zellmer, S.D.; Schneider, J.F.; Tomczyk, N.A.; Banwart, W.L.; Chen, D.
Explosives and their degradation products may enter the animal and human food chains through plants grown on soils contaminated with explosives. Soil and plant samples were collected from the Group 61 area at the Joliet Army Ammunition Plant and analyzed to determine the extent to which 2,4,6-trinitrotoluene (TNT) and its degradation products are taken up by existing vegetation and crops growing on contaminated soils. Neither TNT nor its degradation products was detected in any of the aboveground plant organs of existing vegetation. Oat (Avena sativa L.) and perennial ryegrass (Lolium perenne L.) were planted on TNT-contaminated soils amended with three levels of chopped grass hay. Extractable TNT concentrations in hay-amended soils were monitored for almost 1 year. Crop establishment and growth improved with increased levels of hay amendment, but TNT uptake was not affected or detected in any aboveground crop organs. Evidence was found to indicate that soil manipulation and hay addition may reduce extractable TNT concentration in soils, but the wide variations in TNT concentrations in these soils prevented development of conclusive evidence regarding reduction of extractable TNT concentrations. Results from this study suggest that vegetation grown on TNT-contaminated soils is not a major health concern because TNT and its degradation products were not detected in aboveground plant organs. However, low concentrations of TNT, 4-amino-2,6-dinitrotoluene, and 2-amino-4,6-dinitrotoluene were detected in or on some existing vegetation and crop roots. 21 refs., 10 figs., 26 tabs.
Partitioning of heavy metals in a soil contaminated by slag: A redistribution study
Bunzl, K.; Trautmannsheimer, M.; Schramel, P.
In order to interpret reasonably the partitioning of heavy metals in a contaminated soil as observed from applying a sequential extraction procedure, information on possible redistribution processes of the metals during the various extraction steps is essential. For this purpose, sequential extraction was used to study the chemical partitioning of Ag, Cu, Ni, Pb, and Zn in a soil contaminated wither by a slag from coal firing or by a slag from pyrite roasting. Through additional application of sequential extraction to the pure slags as well as to the uncontaminated soil, it was shown that during the various extraction steps applied to the soil/slag mixtures, substantial redistribution processes of the metals between the slag- and soil particles can occur. In many cases, metals ions released during the extraction with acid hydroxylamine or acid hydrogen peroxide are partially readsorbed by solid constituents of the mixture and will therefore be found in the subsequent fractions extracted. As a result, one has to realize that (1) it will be difficult to predict the chemical partitioning of these metals in contaminated soils by investigating pure slags only, and (2) information on the partitioning of a metal in a slag contaminated soil will not necessarily give any relevant information on the form of this metal in the slag or in the slag/soil mixture, because the redistribution processes during sequential extraction will not be the same as those occurring in the soil solution under natural conditions.
[Peculiarities of structure-function organization of microbial groups of soil contaminated by cement dust].
Stefurak, V P
Long-term contamination of the forest soil by the cement dust leads to disturbances of stability of natural microbial groups, changes their quantitative and qualitative composition, results in substitution of some microbial associations by other ones. The intensive contamination of the soil by the effluents of cement integrated works, inhibits the intensity of nitrogen fixation processes and decay of the forest litter, development of micromycetes, results in the decrease of the length of mycelium and its biomass. PMID:11692672
Development and implementation of soil quality and cleanup criteria for contaminated sites
Siegrist, R.L.
A critical but vexing problem with contaminated land has always been assessing the significance of contamination and the degree of cleanup required for contaminated soils and sediments. Various approaches have evolved to address this difficult issue and debate continues over which is the most appropriate. With the growing number of contaminated sites, the majority of which are non-catastrophic, interest in criteria-based approaches has grown. While there are difficulties associated with the development and implementation of generic criteria, they serve a definite purpose in an overall program for contaminated land management their usage is gaining favor in a growing number of jurisdictions around the world. 29 refs., 3 tabs.
A review of biochars' potential role in the remediation, revegetation and restoration of contaminated soils.
Beesley, Luke; Moreno-Jiménez, Eduardo; Gomez-Eyles, Jose L; Harris, Eva; Robinson, Brett; Sizmur, Tom
Biochars are biological residues combusted under low oxygen conditions, resulting in a porous, low density carbon rich material. Their large surface areas and cation exchange capacities, determined to a large extent by source materials and pyrolysis temperatures, enables enhanced sorption of both organic and inorganic contaminants to their surfaces, reducing pollutant mobility when amending contaminated soils. Liming effects or release of carbon into soil solution may increase arsenic mobility, whilst low capital but enhanced retention of plant nutrients can restrict revegetation on degraded soils amended only with biochars; the combination of composts, manures and other amendments with biochars could be their most effective deployment to soils requiring stabilisation by revegetation. Specific mechanisms of contaminant-biochar retention and release over time and the environmental impact of biochar amendments on soil organisms remain somewhat unclear but must be investigated to ensure that the management of environmental pollution coincides with ecological sustainability. PMID:21855187
Local variation of soil contamination with radioactive cesium at a farm in Fukushima.
Sato, Itaru; Natsuhori, Masahiro; Sasaki, Jun; Satoh, Hiroshi; Murata, Takahisa; Nakamura, Tatsuro; Otani, Kumiko; Okada, Keiji
Radioactive cesium concentration in soil was measured at 27 sections with 5 points per section, and surface dose of ground was measured at 10 sections with 13 points per section at a farm in Fukushima to assess local variation of soil contamination with radioactive cesium. As for the cesium in soil, averages of the coefficient of variance (CV) and the maximum/minimum ratio in each section were 49% and 4.9, respectively. As for the surface dose, average of its CV in each section was 20% and the maximum/minimum ratio reached a maximum of 3.0. These findings suggest that exact evaluation of soil contamination with cesium is difficult. Small changes or differences in soil contamination may not be detected in studies of the environmental radioactivity. PMID:27348893
Pedobacter nanyangensis sp. nov., isolated from herbicide-contaminated soil.
Zhang, Hao; Zhang, Jing; Song, Man; Cheng, Ming-gen; Wu, Ya-dong; Guo, Su-hui; Li, Qiang; Hong, Qing; Huang, Xing
A Gram-stain-negative, strictly aerobic, non-spore-forming, motile, rod-shaped bacterium, designated Q-4T, was isolated from a herbicide-contaminated soil sample in Nanyang, Henan province, China. Strain Q-4T grew optimally in the LB medium without NaCl supplement at a pH range of 6.0–7.0 and a temperature of 30 °C. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain Q-4T was most closely related to 'Pedobacter zeaxanthinifaciens' TDMA-5 (97.4 % 16S rRNA gene sequence similarity), followed by Pedobacter xixiisoli S27T (95.8 %). The genomic DNA G+C content of strain Q-4T was 41.8 mol%. MK-7 was the major respiratory quinone. Phosphatidylethanolamine and phosphoaminolipid were the major polar lipids. The major fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH, C16 : 1ω6c and/or C16 : 1ω7c (summed feature 3) and C16 : 1ω7c/C16 : 1ω6c (summed feature 3). Strain Q-4T showed low DNA–DNA relatedness with 'P. zeaxanthinifaciens' TDMA-5 (21.4 ± 0.6 %). Physiological and biochemical characteristics are able to distinguish strain Q-4T from the most closely related species of the genus Pedobacter. On the basis of genotypic and phenotypic data, strain Q-4T is considered to represent a novel species of the genus Pedobacter, for which the name Pedobacter nanyangensis sp. nov. is proposed. The type strain is Q-4T ( = KCTC 42442T = ACCC 19798T). PMID:26297219
Rhizobium petrolearium sp. nov., isolated from oil-contaminated soil.
Zhang, Xiaoxia; Li, Baoming; Wang, Haisheng; Sui, Xinhua; Ma, Xiaotong; Hong, Qing; Jiang, Ruibo
Two Gram-negative, aerobic, rod-shaped bacteria, designated strains SL-1(T) and F11, which had the ability to decompose polycyclic aromatic hydrocarbons (PAHs), were isolated from soil samples contaminated by oil. The cells were motile by polar or lateral flagella. According to comparison of 16S rRNA gene sequences, strains SL-1(T) and F11 were identical and showed the greatest degree of similarity (96.8%) to both Rhizobium oryzae Alt505(T) and Rhizobium mesosinicum CCBAU 25010(T); however, only Rhizobium oryzae with SL-1(T) and F11 formed a separate clade. There were low similarities (<90%) between the atpD and recA sequences of the two strains and those of the genus of Rhizobium. The bacteria grew at temperatures of 10-40 °C with an optimum of 30 °C. The pH range for growth was 6.0-10.0 and optimum pH was 7.0-8.0. Growth occurred at NaCl concentrations up to 3.0% (w/v). They were catalase- and oxidase-positive. The main cellular fatty acids were summed feature 8 (18:1ω7c and/or 18:1ω6c) and 16:0. The DNA G+C content was 62.2 mol%. Strain SL-1(T) showed 29 and 0% DNA-DNA relatedness, respectively, with the most related strains R. oryzae Alt505(T) and R. mesosinicum CCBAU 25010(T) according to phylogenic analysis of the 16S rRNA gene. According to physiological and biochemical characteristics and genotypic data obtained in this work, the bacteria represent a novel species of the genus Rhizobium, and the name Rhizobium petrolearium is proposed. The type strain is SL-1(T) ( = ACCC 11238(T) = KCTC 23288(T)) and it could nodulate Medicago sativa in nodulation tests. PMID:21984664
Judicious use of kinetin to improve growth and yield of rice in nickel contaminated soil.
Nazir, Hina; Asghar, Hafiz Naeem; Zahir, Zahir Ahmad; Akhtar, Muhammad Javed; Saleem, Muhammad
The present study was conducted to evaluate the effect of kinetin on growth and yield of rice in the presence and absence of nickel contamination. Rice seedlings were dipped in kinetin solution (10(-3), 10(-4) and 10 M(-5)) for 2 hours and transplanted in pots having soil contaminated with nickel sulfate @ 130 mg kg(-1). Experiment was laid out according to completely randomized design with four replications. Results revealed that kinetin significantly improved growth and yield of rice grown in nickel contamination. Kinetin @ 10(-4) M showed maximum improvement in plant height, paddy yield, 1000 grain weight, number of tillers and panicles up to 9.76, 15.72, 11.77, 11.87, and 10.90%, respectively, as compared to plants grown in contaminated soil without kinetin. Kinetin also improved the uptake of nutrients (NPK) in straw and grain of plants grown in Ni contaminated soil. Plants treated with kinetin had more concentration of Ni in shoot but less in grain compared to plants grown in Ni contaminated soil without application of kinetin. The application of kinetin can reduce stress effect on plants through improvement in the biomass of plant. This strategy could be used to increase the phytoextraction of Ni from the contaminated soil. PMID:26457741
Microbial expression profiles in the rhizosphere of willows depend on soil contamination
Yergeau, Etienne; Sanschagrin, Sylvie; Maynard, Christine; St-Arnaud, Marc; Greer, Charles W
The goal of phytoremediation is to use plants to immobilize, extract or degrade organic and inorganic pollutants. In the case of organic contaminants, plants essentially act indirectly through the stimulation of rhizosphere microorganisms. A detailed understanding of the effect plants have on the activities of rhizosphere microorganisms could help optimize phytoremediation systems and enhance their use. In this study, willows were planted in contaminated and non-contaminated soils in a greenhouse, and the active microbial communities and the expression of functional genes in the rhizosphere and bulk soil were compared. Ion Torrent sequencing of 16S rRNA and Illumina sequencing of mRNA were performed. Genes related to carbon and amino-acid uptake and utilization were upregulated in the willow rhizosphere, providing indirect evidence of the compositional content of the root exudates. Related to this increased nutrient input, several microbial taxa showed a significant increase in activity in the rhizosphere. The extent of the rhizosphere stimulation varied markedly with soil contamination levels. The combined selective pressure of contaminants and rhizosphere resulted in higher expression of genes related to competition (antibiotic resistance and biofilm formation) in the contaminated rhizosphere. Genes related to hydrocarbon degradation were generally more expressed in contaminated soils, but the exact complement of genes induced was different for bulk and rhizosphere soils. Together, these results provide an unprecedented view of microbial gene expression in the plant rhizosphere during phytoremediation. PMID:24067257
Effects of different remediation treatments on crude oil contaminated saline soil.
Gao, Yong-Chao; Guo, Shu-Hai; Wang, Jia-Ning; Li, Dan; Wang, Hui; Zeng, De-Hui
Remediation of the petroleum contaminated soil is essential to maintain the sustainable development of soil ecosystem. Bioremediation using microorganisms and plants is a promising method for the degradation of crude oil contaminants. The effects of different remediation treatments, including nitrogen addition, Suaeda salsa planting, and arbuscular mycorrhiza (AM) fungi inoculation individually or combined, on crude oil contaminated saline soil were assessed using a microcosm experiment. The results showed that different remediation treatments significantly affected the physicochemical properties, oil contaminant degradation and bacterial community structure of the oil contaminated saline soil. Nitrogen addition stimulated the degradation of total petroleum hydrocarbon significantly at the initial 30d of remediation. Coupling of different remediation techniques was more effective in degrading crude oil contaminants. Applications of nitrogen, AM fungi and their combination enhanced the phytoremediation efficiency of S. salsa significantly. The main bacterial community composition in the crude oil contaminated saline soil shifted with the remediation processes. γ-Proteobacteria, β-Proteobacteria, and Actinobacteria were the pioneer oil-degraders at the initial stage, and Firmicutes were considered to be able to degrade the recalcitrant components at the later stage. PMID:25240723
Removal of volatile and semivolatile organic contamination from soil by air and steam flushing.
Sleep, B E; McClure, P D
A soil core, obtained from a contaminated field site, contaminated with a mixture of volatile and semivolatile organic compounds (VOC and SVOC) was subjected to air and steam flushing. Removal rates of volatile and semivolatile organic compounds were monitored during flushing. Air flushing removed a significant portion of the VOC present in the soil, but a significant decline in removal rate occurred due to decreasing VOC concentrations in the soil gas phase. Application of steam flushing after air flushing produced a significant increase in contaminant removal rate for the first 4 to 5 pore volumes of steam condensate. Subsequently, contaminant concentrations decreased slowly with additional pore volumes of steam flushing. The passage of a steam volume corresponding to 11 pore volumes of steam condensate reduced the total VOC concentration in the soil gas (at 20 degrees C) by a factor of 20 to 0.07 mg/l. The corresponding total SVOC concentration in the condensate declined from 11 to 3 mg/l. Declines in contaminant removal rates during both air and steam flushing indicated rate-limited removal consistent with the persistence of a residual organic phase, rate-limited desorption, or channeling. Pressure gradients were much higher for steam flushing than for air flushing. The magnitude of the pressure gradients encountered during steam flushing for this soil indicates that, in addition to rate-limited contaminant removal, the soil permeability (2.1 x 10(-9) cm2) would be a limiting factor in the effectiveness of steam flushing. PMID:11475159
Enzymatic bioremediation of polyaromatic hydrocarbons by fungal consortia enriched from petroleum contaminated soil and oil seeds.
Balaji, V; Arulazhagan, P; Ebenezer, P
The present study focuses on fungal strains capable of secreting extracellular enzymes by utilizing hydrocarbons present in the contaminated soil. Fungal strains were enriched from petroleum hydrocarbons contaminated soil samples collected from Chennai city, India. The potential fungi were isolated and screened for their enzyme secretion such as lipase, laccase, peroxidase and protease and also evaluated fungal enzyme mediated PAHs degradation. Total, 21 potential PAHs degrading fungi were isolated from PAHs contaminated soil, which belongs to 9 genera such as Aspergillus, Curvularia, Drechslera, Fusarium, Lasiodiplodia, Mucor Penicillium, Rhizopus, Trichoderma, and two oilseed-associated fungal genera such as Colletotrichum and Lasiodiplodia were used to test their efficacy in degradation of PAHs in polluted soil. Maximum lipase production was obtained with P. chrysogenum, M. racemosus and L. theobromae VBE1 under optimized cultural condition, which utilized PAHs in contaminated soil as sole carbon source. Fungal strains, P. chrysogenum, M. racemosus and L. theobromae VBE1, as consortia, used in the present study were capable of degrading branched alkane isoprenoids such as pristine (C17) and pyrene (C18) present in PAHs contaminated soil with high lipase production. The fungal consortia acts as potential candidate for bioremediation of PAHs contaminated environments. PMID:24813008
The effects of PAH contamination on soil invertebrate communities
Snow-Ashbrook, J.L.; Erstfeld, K.M.
Soils were collected from an abandoned industrial site to study the effects of historic polycyclic aromatic hydrocarbons (PAHs) on soil invertebrate communities. Nematode abundance and diversity, microarthropod abundance (orders Collembola and Acarina) and earthworm growth were evaluated. Physical and chemical characteristics of soils may affect both invertebrate community structure and the mobility/bioavailability of pollutants in soils. Soil characteristics were measured and included with PAH data in multiple regression analyses to identify factors which influences the responses observed in the soil invertebrate community. Positive associations were observed between eight invertebrate community endpoints and soil PAH content. For all of these endpoints but one, a higher degree of variability was explained when both PAH content and soil characteristics were considered. It is theorized that the positive response to soil PAH content may be the result of an increased abundance of PAH-degrading soil microbes. Increased microbial abundance could stimulate invertebrate communities by providing a direct food source or increasing the abundance of microbially-produced nutrients. These results suggest that both PAH content and soil characteristics significantly influenced the soil invertebrate community. It is not clear whether these factors influenced the invertebrate community independently, or whether differences in soil characteristics affected the community response by influencing the mobility or bioavailability of PAHs.
Phytoremediation is an emerging cleanup technology for contaminated soils, groundwater, and wastewater that is both low-tech and low-cost. The cleanup technology is defined as the use of green plants to remove, contain, or render harmless such environmental contaminants as heavy ...
Metal contaminated biochar and wood ash negatively affect plant growth and soil quality after land application.
Jones, D L; Quilliam, R S
Pyrolysis or combustion of waste wood can provide a renewable source of energy and produce byproducts which can be recycled back to land. To be sustainable requires that these byproducts pose minimal threat to the environment or human health. Frequently, reclaimed waste wood is contaminated by preservative-treated timber containing high levels of heavy metals. We investigated the effect of feedstock contamination from copper-preservative treated wood on the behaviour of pyrolysis-derived biochar and combustion-derived ash in plant-soil systems. Biochar and wood ash were applied to soil at typical agronomic rates. The presence of preservative treated timber in the feedstock increased available soil Cu; however, critical Cu guidance limits were only exceeded at high rates of feedstock contamination. Negative effects on plant growth and soil quality were only seen at high levels of biochar contamination (>50% derived from preservative-treated wood). Negative effects of wood ash contamination were apparent at lower levels of contamination (>10% derived from preservative treated wood). Complete removal of preservative treated timber from wood recycling facilities is notoriously difficult and low levels of contamination are commonplace. We conclude that low levels of contamination from Cu-treated wood should pose minimal environmental risk to biochar and ash destined for land application. PMID:24915641
New information and treatment approaches have been developed for chromium-contaminated soil and groundwater treatment. The prupose of this report is to bring together the most current information pertaining to the science of chromium contamination and the insitu treatment and co...
Bioavailability of Fe(III) in natural soils and the impact on mobility of inorganic contaminants
Kosson, David S.; Cowan, Robert M.; Young, Lily Y.; Hacherl, Eric L.; Scala, David J.
Inorganic contaminants, such as heavy metals and radionuclides, can adhere to insoluble Fe(III) minerals resulting in decreased mobility of these contaminants through subsurface environments. Dissimilatory Fe(III)-reducing bacteria (DIRB), by reducing insoluble Fe(III) to soluble Fe(II), may enhance contaminant mobility. The Savannah River Site, South Carolina (SRS), has been subjected to both heavy metal and radionuclide contamination. The overall objective of this project is to investigate the release of inorganic contaminants such as heavy metals and radionuclides that are bound to solid phase soil Fe complexes and to elucidate the mechanisms for mobilization of these contaminants that can be associated with microbial Fe(III) reduction. This is being accomplished by (i) using uncontaminated and contaminated soils from SRS as prototype systems, (ii) evaluating the diversity of DIRBs within the samples and isolating cultures for further study, (iii) using batch microcosms to evaluate the bioavailability of Fe(III) from pure minerals and SRS soils, (iv) developing kinetic and mass transfer models that reflect the system dynamics, and (v) carrying out soil column studies to elucidate the dynamics and interactions amongst Fe(III) reduction, remineralization and contaminant mobility.
There is extensive mercury contamination of soil surrounding a chloralkali plant in Pavlodar, Kazakhstan that operated from 1970 to 1990. High-level mercury contamination exists within the confines of the plant, at nearby off-site waste storage and evaporation ponds, and in Balky...
Solidification/stabilization of contaminated soil and concrete debris with thermal-treated BTM
Hsieh, Hsin-Neng; Yu, Qing-Rui; Chang, J.
Contaminated black tarry materials was treated thermally and converted to a material with properties similar to petroleum-based asphalt. This property-improved material was then used as a binder to enclose contaminated concrete debris and soil in the solidification/stabilization process. The final product can be used for medium traffic pavement. 9 refs., 5 tabs.
There is extensive mercury contamination of soil surrounding a chloralkali plant in Pavlodar, Kazakhstan that operated from 1970 to 1990. High-level mercury contamination exists within the confines of the plant, at nearby off-site waste storage and evaporation ponds, and in Balky...
Remediation of Heavy Metal(loid)s Contaminated Soils – To Mobilize or To Immobilize?
Unlike organic contaminants, metal(loid)s do not undergo microbial or chemical degradation and persist for a long time after their introduction. Bioavailability of metal(loid)s plays a vital role in the remediation of contaminated soils. In this review, the remediation of heavy ...
Arsenic contamination of soil, sediment and groundwater is a widespread problem in certain areas and has caused great public concern due to increased awareness of the health risks. Often the contamination is naturally occurring, but it can also be a result of waste generated from...
Evaluation of PCDD/PCDF Biodegration Using Bacterial Isolates from Contaminated Soils
Technology Transfer Automated Retrieval System (TEKTRAN)
There is a need to identify bacteria that can degrade environmental contaminants and a potentially fruitful place to identify such bacteria is within contaminated soil. Dioxins from adjacent to railroad tracts were isolated by sonicating in acetone/toluene followed by alumina, tri-phase silica, and ...
Three-dimensional data interpolation for environmental purpose: lead in contaminated soils in southern Brazil.
Piedade, Tales Campos; Melo, Vander Freitas; Souza, Luiz Cláudio Paula; Dieckow, Jeferson
Monitoring of heavy metal contamination plume in soils can be helpful in establishing strategies to minimize its hazardous impacts to the environment. The objective of this study was to apply a new approach of visualization, based on tridimensional (3D) images, of pseudo-total (extracted with concentrated acids) and exchangeable (extracted with 0.5 mol L(-1) Ca(NO3)2) lead (Pb) concentrations in soils of a mining and metallurgy area to determine the spatial distribution of this pollutant and to estimate the most contaminated soil volumes. Tridimensional images were obtained after interpolation of Pb concentrations of 171 soil samples (57 points × 3 depths) with regularized spline with tension in a 3D function version. The tridimensional visualization showed great potential of use in environmental studies and allowed to determine the spatial 3D distribution of Pb contamination plume in the area and to establish relationships with soil characteristics, landscape, and pollution sources. The most contaminated soil volumes (10,001 to 52,000 mg Pb kg(-1)) occurred near the metallurgy factory. The main contamination sources were attributed to atmospheric emissions of particulate Pb through chimneys. The large soil volume estimated to be removed to industrial landfills or co-processing evidenced the difficulties related to this practice as a remediation strategy. PMID:24865382
Remediation of a heavy metal-contaminated soil by means of agglomeration.
Polettini, Alessandra; Pomi, Raffaella; Valente, Mattia
The feasibility of treating a heavy metal-contaminated soil by means of a solidification/stabilization treatment consisting of a granulation process is discussed in the present article. The aim of the study was to attain contaminant immobilization within the agglomerated solid matrix. The soil under concern was characterized by varying levels of heavy metal contamination, ranging from 50 to 500 mg kg(-1) dry soil for chromium. from 300 to 2000 mg kg(-1) dry soil for lead and from 270 to 5000 mg kg(-1) dry soil for copper. An artificially contaminated soil with contaminant concentrations corresponding to the upper level of the mentioned ranges was prepared from a sample of uncontaminated soil by means of spiking experiments. Pure soluble species of chromium, copper and lead. namely CrCl3.6H2O, CuCl2.2H2O and Pb(NO3)2, were selected for the spiking experiments, which were arranged according to a 2(3) full factorial design. The solidification/stabilization treatment was based on an agglomeration process making use of hydraulic binders including Portland cement, hydrated lime and sodium methasilicate, which were selected on the basis of preliminary test runs. It was found that after 7 days of curing the applied treatment was able to efficiently immobilize the investigated heavy metals within the hydrated matrix. Good acid neutralization behavior was also observed, indicating improved matrix resistance to acid attack and decreased potential for metal leaching. PMID:15137715
Remediation of arsenic in soil by Aspergillus nidulans isolated from an arsenic-contaminated site.
Maheswari, S; Murugesan, A G
High concentrations of heavy metals, such as arsenic, in soils have potential long-term environmental and health consequences due to their persistence in the environment and their associated toxicity to biological organisms. Aspergillus nidulans isolated from arsenic-contaminated soil has the potential to remove arsenic from soil. The isolated resistant strain showed resistance up to 500 ppm and the mean weight was found to be 1.309 g. The main objective of this research was to study the improvement to the remediation of arsenic-contaminated soil by the addition of nutrient sources such as carbon (0.15-0.85 g L(-1)), nitrogen (0.25-1.05 g L(-1)) and phosphate (0.10-0.30 g L(-1)) to the medium. The effect of ionic strength on Aspergillus nidulans was optimized by NaCl at 0.12-0.30%. The biomass concentration and growth profile of Aspergillus nidulans in arsenic-contaminated soil was found to be 0.709 g after 11 days. The arsenic adsorption potential of Aspergillus nidulans from the contaminated soil was found to be 84.35% after 11 days at pH 4 and a temperature of 35 degrees C. This investigation indicated that the isolated resistant strain had an important role in adsorption of arsenic from the contaminated soil. PMID:19803330
Laboratory scale and pilot scale studies were conducted to evaluate composting to treat sediments and soils containing explosive and organic compounds. Sediment and soil from lagoons at Army ammunition plants, located in Louisiana, Wisconsin and Pennsylvania contained high...
Phytoremediation of radiocesium-contaminated soil in the vicinity of Chernobyl, Ukraine
Dushenkov, S.; Mikheev, A.; Prokhnevsky, A.; Ruchko, M.; Sorochinsky, B.
Remediation of soil contaminated with {sup 137}Cs remains one of the most challenging tasks after the Chernobyl 1986 accident. The objectives of this research were to (1) identify extractants that may be used to solubilize {sup 137}Cs in soil solution, (2) study the effect of soil amendments on {sup 137}Cs accumulation by plants, and (3) evaluate the applicability of phytoextraction for environmental restoration of soil contaminated with {sup 137}Cs. The availability of {sup 137}Cs to the plants in Chernobyl soil was limited, because this radionuclide was tightly bound to exchange sites of soil particles or incorporated into the crystalline structure of primary and secondary minerals. Out of 20 soil amendments tested to increase {sup 137}Cs desorption/solubility in the soil, ammonium salts were found to be the most practical soil amendment that can potentially increase {sup 137}Cs bioavailability. Among the screened plants, Amaranth cultivars had the highest {sup 137}Cs accumulation. Three sequential crops of Indian mustard grown in one vegetation season at the experimental plot resulted in a small decrease of {sup 137}Cs specific activity within the top 15 cm of soil. Further improvements are necessary to make phytoremediation technology a feasible option for restoration of {sup 137}Cs-contaminated territories.
Impacts of soil petroleum contamination on nutrient release during litter decomposition of Hippophae rhamnoides.
Zhang, Xiaoxi; Liu, Zengwen; Luc, Nhu Trung; Yu, Qi; Liu, Xiaobo; Liang, Xiao
Petroleum exploitation causes contamination of shrub lands close to oil wells. Soil petroleum contamination affects nutrient release during the litter decomposition of shrubs, which influences nutrient recycling and the maintenance of soil fertility. Hence, this contamination may reduce the long-term growth and stability of shrub communities and consequently, the effects of phytoremediation. Fresh foliar litter of Hippophae rhamnoides, a potential phytoremediating species, was collected for this study. The litter was placed in litterbags and then buried in different petroleum-polluted soil media (the petroleum concentrations were 15, 30, and 45 g kg(-1) dry soil, which were considered as slightly, moderately and seriously polluted soil, respectively) for a decomposition test. The impacts of petroleum contamination on the release of nutrients (including N, P, K, Cu, Zn, Fe, Mn, Ca and Mg) were assessed. The results showed that (1) after one year of decomposition, the release of all nutrients was accelerated in the slightly polluted soil. In the moderately polluted soil, P release was accelerated, while Cu, Zn and Mn release was inhibited. In the seriously polluted soil, Cu and Zn release was accelerated, while the release of the other nutrients was inhibited. (2) The effect of petroleum on nutrient release from litter differed in different periods during decomposition; this was mainly due to changes in soil microorganisms and enzymes under the stress of petroleum contamination. (3) To maintain the nutrient cycling and the soil fertility of shrub lands, H. rhamnoides is only suitable for phytoremediation of soils containing less than 30 g kg(-1) of petroleum. PMID:26911518
The purpose of this document is to provide assistance in deciding in situ treatment of contaminated soils is a potentially feasible remedial alternative. echnical considerations that affect the decision to treat soils in situ are discussed. eneral factors which influence the sele...
Investigation of the pathway of contaminated soil transported to plant surfaces by raindrop splash
Dreicer, M.; Hakonson, T.E.; Whicker, F.W.; White, G.C.
The environmental transport pathway of soil-borne radioisotopes to vegetation surfaces via raindrop splash was studied. The data show that soil can significantly contribute to the contamination found on plants. Further detailed study is needed to calculate the rate constant for the raindrop splash and retention pathways. 8 references, 1 figure. (ACR)
Emerging Technology Summary. ACID EXTRACTION TREATMENT SYSTEM FOR TREATMENT OF METAL CONTAMINATED SOILS
The Acid Extraction Treatment System (AETS) is intended to reduce the concentrations and/or teachability of heavy metals in contaminated soils so the soil can be returned to the site from which it originated. The objective of the project was to determine the effectiveness and com...
Soil contaminated by virgin petroleum products leaking from underground storage tanks is a pervasive problem In the United States. conomically feasible disposal of such soil concerns the responsible party (RP), whether the RP Ia one individual small business owner a group of owne...
Soil cores were collected from beneath an old chrome plating shop at the USCG Support Center near Elizabeth City, NC in order to determine the extent of chromium contamination in the soils and ground water. Selective extractions were used to assess the chemical speciation and di...
Soil contaminated by virgin petroleum products leaking from underground storage tanks Is a pervasive problem in the United States. Economically feasible disposal of such soil concerns the responsible party (RP), whether the RP is one individual small business owner, a group o...
Parameters which were expected to control the removal process of VOCs from contaminated soil during the SVE operation were studied by means of numerical simulations and laboratory experiments in this project. Experimental results of SVE with soil columns in the laboratory indicat...
We examined the bioremediation of soils contaminated with the munition compounds 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine, and octahydro-1, 3,5,7-tetranitro-1,3,5,7-tetraacocine by a procedure that produced anaerobic conditions in the soils and promote...
Phytotoxicity of zinc and manganese to seedlings grown in soil contaminated by zinc smelting
Technology Transfer Automated Retrieval System (TEKTRAN)
Historic emissions from two zinc smelters have damaged the forest on Blue Mountain near Palmerton, Pennsylvania, USA. Seedlings of soybeans and five tree species were grown in a greenhouse in a series of mixtures of smelter-contaminated and reference soils. As little as 10% Palmerton soil mixed wi...
Metals contamination of subsurface soils and ground water from a variety of industrial sources and uses has increasingly been discovered over the past decade. trategies are needed to efficiently and accurately characterize these types of sites to determine if soil remediation is ...
[Effect of different soil types on the remediation of copper-pyrene compound contaminated soils by EK-oxidation process].
Fan, Guang-Ping; Cang, Long; Zhou, Dong-Mei; Zhou, Li-Xiang
The effect of different soil types (red soil,yellow-brown soil and black soil) on the electrokinetic (EK)-oxidation remediation of heavy metals-organic pollutant contaminated soil was studied in laboratory-scale experiments. Copper and pyrene were chosen as model pollutant, and 12% H2O2, 10% hydroxypropyl-beta-cyclodextrin and 0.01 mol x L(-1) NaNO3 solution were added into the anode and cathode cell. The applied voltage was 1 V x cm(-1). After 15 days of EK remediation, the removal rate of pyrene and copper in red soil, yellow-brown soil and black soil were 38.5%, 46.8%, 51.3% for pyrene and 85.0%, 22.6%, 24.1% for Cu, respectively. The high pH of black soil produced high electroosmotic flow and increased the exposure of oxidants and pollutants, meanwhile the low clay content was also conducive to the desorption of pyrene. The low pH and organic matter of red soil affected the chemical species distribution of Cu and increased its removal rate. It is concluded that soil pH, clay content and heavy metal speciation in soil are the dominant factors affecting the migration and removal efficiency of pollutants. PMID:22295647
In Vitro And In Vivo Approaches For The Measurement Of Oral Bioavailability Of Lead (Pb) In Contaminated Soils: A Review
We reviewed the published evidence of lead (Pb) contamination of urban soils, soil Pb risk to children through hand-to-mouth activity, reduction of soil Pb bioavailability due to soil amendments, and methods to assess bioaccessibility which correlate with bioavailability of soil ...