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Assessment of Soil Pollution in the Ishaqi Project Area- Salah Al-Dean Governorate, Iraq

Ten soil samples were collected from Ishaqi project area, Salah Al-Dean Governorate, and analysed for chemical elements (Fe2O3, Al2O3, CaO, K2O Na2O, Co, Zn, Cu, and Pb) to detect the pollution in the study soil using the indices of geoaccumulation (I-geo), contamination factor (CF), and pollution load index (PLI), The results of I-geo indicate that the soil of Ishaqi project area is unpolluted with Pb, Co and slightly polluted with Zn and Cu. The results of CF for Zn, Cu, and Co showed class 2 of moderate contamination and class 1 of low contamination in some samples while those for Pb demonstrated class 1 –of low contamination. The Pollution Load Index (PLI) values for Co, Zn, Cu, and Pb showed class 2 of local pollution.


Introduction
High probability of heavy elements contamination is expected from exhaust gases of vehicles, emissions from factories, regional / local sand and dust storms. Toxic heavy elements affecting the ecosystems could lead to geo-accumulation and bioaccumulation [1]. Pollutants enter the environment in many ways , such as by industrial discharge, municipal waste discharge and others; also by land runoff mainly by rivers, tributaries, agricultural canals and by the atmospheric fallout of pollutants transferred by the air mass onto the land-surface [2]. Many authors studied the heavy elements as a direct relations with Fe₂O₃ and Al₂O₃, and these relations may be attributed to the association of these metals in the clay minerals. It was found that the mean value of (CaO) was 17.18% in thestudy area. Sodium oxide: Sodium oxide content in the samples is due to its relation with clay minerals especially montmorillonite [15]. Navratilova and Kula (2000) showed that sodium element was considered as a major element in the montmorillonite minerals [16]. Also, Gregor (1976) reported that sodium element is fixed in the clay minerals by institution of potassium by sodium element. This study also mentioned the ability of sodium element to adsorb on clay minerals in the basic condition [17]. It was found that the mean value of Na₂O was 1.26% in thestudy area. Potassium oxide: It was found that the mean percent of K₂O was 1.44 % in the study area. The correlation of K₂O with the other oxides in the sediments of the study area reflected an indirect relation with Fe₂O₃, and Na₂O, due to the lack of potassium element and carbonate minerals in the clays. In this research, three soil pollution indices were selected to assess the contamination level of Co, Zn, Cu, and Pb in the soil of study area. These are the Geo accumulation index (I-geo), contamination factor (CF) and Pollution Load Index (PLI) ( Tables-2 and 3).

1-Geo-accumulation index (I-geo)
This index is used for comparing the levels of the analysed heavy elements to the background level. Igeo was determined by the following equation according to Taylor [20]. The values of this index vary from sub-zero to more than 5 having 7 grades (Table-3). The highest grade (6) reflects a 100fold enrichment and (0) reflects the background concentration according to Table-3. The values of this index have seven grades and the results reflected the following: The value for Pb was found negative in study area, ranging from -0.20 --0.9 (Table-3). The result indicates that the study area is unpolluted by Pb. I geo values of Cu in Ishaqi area ranged from 0.2 to 0.5 indicating slightly polluted sediments by Cu. the I-geo value of Zn in the study area ranged from -0.0 to 0.1, indicating that these samples are slightly polluted. I-geo value for Co were in Ishaqi area ranged from -0.0 to--1.4 and were considered as unpolluted sediments by Co.

2-Contamination factor (CF)
The contamination factor (CF) was determined according to Thomilson et al. (1980) equation. CF = Cm Sample/ Cm Background Where: CF: contamination factor. Cm Sample: metal content in the sample. Cm Background: background level of metal. The contamination factor (CF) for Co, Zn, Cu, and Pb was calculated in the Ishaqi area (Table-3). The values of pb in the ten sites ranged from 0.7 to1.2, reflecting low to moderate contamination with. Lead is known to come from the use of high lead gasoline [9]. CF for Cu in Ishaqi area ranged from 1.8to 2.2 indicating moderate contamination (class 2). Zn in the study area was classified as class 2, representing moderate contamination ranging from 1.4 to 1.9. Zn originates from toxic waste from industrial sources [21]. Cobalt (Co) in the study area is represented low to moderate contamination, as class 2, ranging from 0.5 to 1.9. (Table-3). It is believed that a considerable part of heavy elements find its way into the environment as a result of the burning of diesel oil and may be due to the disposal of heavy elements -containing wastewater.

3-Pollution load index (PLI)
The pollution load index (PLI) was determined according to Thomilson et al. (1980) [22] equation, where (PLI) is expressed as follows: PLI = n√CF1 x CF2 x CF3 x … ..xCFn Where: n = the number of analyzed metals in each site. The Pollution Load Index (PLI) for Co, Zn, Cu, and Pb was calculated, and the samples were classified as class 2 (Deterioration on-site quality), indicating local pollution. PLI values in the study area ranged from 1.1 to1.6 ( Table-3). Higher values of PLI factor may result from the effects of untreated toxic waste that discharges to the drainage from the domestic areas, along with some anthropogenic activities that contaminate the soil by heavy metals.

CONCLUSIONS
The concentrations of heavy metals (Co, Zn, Cu, and Pb) found in the study area can mainly be due to the relatively high percentages of clay contamination . Moreover, pollution with these heavy elements is thought to be due to different sources such as urban wastes, fertilizers, etc. It is clear that the pollutants affected Ishaqi area soil that have relatively high clay.