Bioaccumulation potential of heavy metals in some commercially fish species from Cika Koshi reservoir Katsina North- western Nigeria: Threat to ecosystem and public health

Abstract

Heavy metal pollution in the aquatic ecosystem has been a problem globally, this is because of their ability to accumulate in aquatic organisms particularly in fish which is a source of diet for most humans. In the present study, the bioaccumulation of five heavy metals (Cd2+, As+5, Cr+6, Pb2+ and Hg2+) was determined in the water, sediments, and fishes (Clarias gariepinus, Bagrus bayad, and Oreochromis niloticus) using Microwave Plasma Atomic Emission Spectroscopy (MP-AES) and the potential human health risk for local consumers was evaluated using standard indices. The measured mean concentration level (mg/kg) of the metals in water and sediment from five sampling location in the reservoir were 0.64 ± 0.10, 0.56 ± 0.43, 0.39 ± 0.18, 0.51 ± 0.02, 0.31 ± 0.01 mg/L, and 1.76 ± 0.05, 1.68 ± 0.00, 2.46 ± 0.83, 1.99 ± 0.06 and 1.53 ± 0.61 mg/g for Cd2+, As+5, Hg2+, Pb2+ and Cr+6 respectively. The result of the heavy metal content in the fish depicts the highest toxicity of Arsenic in the flesh, gills, and liver as 5.04 mg/kg, 5.79 mg/kg, and 2.13 mg/kg respectively. Bioaccumulation factor (BAF) of the heavy metals in B. bayad and O. niloticus were higher than C. gariepinus. Potential human health risks related with the intake of these metals were evaluated in terms of Estimated Daily Intake (EDI), Target Hazard quotient (THQ) and hazard index (HI) assessed for repercussions suggest that the values were above the permissible limit for both adults and children as recommended by WHO/FAO. The result of this study shows the health risks associated with the consumption of heavy metals through the intake of the studied fishes, therefore, there is a need for a sustainable management approach and biomonitoring of these heavy metals in Cika Koshi reservoir. This will minimize pollution of the aquatic environment which is a health threat for human consuming fishes contaminated with heavy metals.