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Determination Of Some Heavy Metals In The Blood , Brain , Flesh And Liver Of Catfish ( Clarias Gariepenus ) In Gyawana Ecosystem , Adamawa State , Nigeria

Heavy metals are members of loosely defined subset of elements that exhibit metallic properties. It mainly includes the transition metals, some metalloid lanthanides, and actinide. Heavy metals occur naturally in the ecosystem with large variations in their concentration (McDowell et al. 2006; Mohsen and Salisu, 2008; Salwa et al. 2012).They are metallic elements that are toxic and have high density, specific gravity or atomic weight. Heavy metals occur naturally in the soil from the pedogenetic processes of weathering of parent materials at levels that are regarded as trace (<1000 mg/g) and rarely toxic (Kabata-Pendias and Pendias, 2001; Pierzynski et al. 2000). Anthropogenic activities and acceleration of nature’s slowly occurring geochemical cycling of metals by man have caused most soils and environments to accumulate Abstract: Heavy metals occur naturally in the ecosystem, they are metallic elements that are toxic and have high density, specific gravity or atomic weight. This study was conducted in Gyawana ecosystem, Adamawa State, Nigeria to determine the concentration of heavy metals (As, Cd, Co, Cr, Cu, Ni, Pb and Zn) in the blood, brain, flesh and liver of Catfish (Clarias gariepenus). A total of four hundred and eighty (480) male and female catfish were used. The catfish were dissected separately to obtain the organs. The brain, liver and flesh of each catfish sample were dried at 105 o C and digested with tri-acid mixture (HNO3: HCO4: H2SO4). Determination of the heavy metals was done using a Buck Scientific 200A Model, Atomic Absorption Spectrophotometer (AAS). The studied metals (As, Cd, Co, Cr, Cu, Ni, Pb and Zn) were detected at different concentrations in the blood and organs of the studied birds with the exception of Cr which was not detected. Brain of catfish had the highest mean concentration of As (0.036±0.000mg/g) and the lowest was detected in the blood (0.031±0.000mg/g). The highest mean concentration of Cd was detected in the flesh of catfish 0.431±0.005mg/g and the lowest was detected in the brain of catfish which had 0.389±0.004mg/g. The highest mean concentration of Co, Ni and Pb were detected in the blood of catfish; 0.697±0.016mg/g, 0.041±0.000mg/g, 0.932±0.019mg/g in that order. Zn had the highest concentration in the catfish liver 11.734±0.118mg/g. The heavy metal concentrations in the study catfish (Clarias gariepenus) were within the permissible limit, therefore, it is safe to consume the catfish. Regular monitoring of heavy metals in the fish species of Gyawana ecosystem should be carried out to ascertain the level of toxicants.