Bioaccumulation and Risk Analysis of Selected Heavy Metals in Clarias Gariapinus and Tilapia Zili Fish Species of Abandoned Mining Ponds

Abstract

Heavy metals (Cd, Co, Cr, Cu, Ni and Pb) were determined in some selected fish species (Clarias gariepenus and Tilapia zili) from Bokkos abandoned mining sites. Sample matrices examined were flesh gills, kidney and liver of each fish species. Twenty (20) sample sites were selected for the sample matrices under investigation. After sample collection and treatment, heavy metals were determined using Atomic Absorption Spectrophotometer (AAS, Bulk Scientific Model 210 VGP). The concentration patterns for each of the elements in the fish species showed significant and relatively similar patterns in cat fish with Ni having the highest concentration, followed by Cr, Co, Pb Cd and Cu in that order with respective. Cumulative bioconcentration in Tilapia zili showed that Cd < Cu < Pb < Co < Cr < Ni respectively. Pearson correlation showed various interactions and relationships existing between and within sample matrices, indicating that these heavy metals have similar source, species or geochemical interaction. Only Co has a weakly positive correlation 0.58 with Pb while in Tilapia zilli, while Cu has correlation with Ni in Clarias gariepenus. Also the interactions and behaviors of the fish species suggests water and sediment for Cu, Ni and Co, Pb respectively. The relative contributions of Cr, Ni and Pb to the aggregated risk were 59.86%, 0.21%, 38.03% and 1.76% respectively. Consumption of these fish species from the study area therefore poses serious health concern upon consumption over time.