Assessment of Heavy Metal Content in Fish Obtained from Selected Rivers and Ponds of Nasarawa West Region, Nasarawa State

In this study, fish samples were collected from Karu, Keffi, Kokona, and Nasarawa local governments for heavy metal analysis via Atomic Absorption Spectrometry. The primary objective was to assess heavy metal concentrations (Cr, Cd, Pb, Cu, Mn, and Ni) in fish from rivers and ponds across these regions. Results exhibited substantial variations in heavy metal content. Manganese (Mn) concentrations spanned from 73.63 mg/kg to 124.60 mg/kg in Karu, 48.79 mg/kg to 99.5 mg/kg in Nasarawa, 78.52 mg/kg to 85.49 mg/kg in Keffi, and 32.07 mg/kg to 60.86 mg/kg in Kokona L.G.A. Chromium (Cr) levels ranged from 2.31 mg/kg to 6.99 mg/kg in Karu, 2.92 mg/kg to 6.86 mg/kg in Nasarawa, 5.00 mg/kg to 5.17 mg/kg in Kokona, and 2.02 mg/kg to 3.39 mg/kg in Keffi. Copper (Cu) exhibited a range of 18.82 mg/kg to 61.15 mg/kg in Karu, 14.86 mg/kg to 33.74 mg/kg in Kokona, 3.85 mg/kg to 24.52 mg/kg in Nasarawa, and 8.48 mg/kg to 16.92 mg/kg in Keffi. Cadmium (Cd) was solely detected in Kokona pond samples (0.06 mg/kg). Lead (Pb) concentrations spanned from 0.93 mg/kg to 1.93 mg/kg in Kokona, 0.01 mg/kg to 0.48 mg/kg in Karu, 0.003 mg/kg to 0.24 mg/kg in Nasarawa, and 0.08 mg/kg in Keffi. Nickel (Ni) content ranged from 2.48 mg/kg to 3.36 mg/kg in Karu, 0.78 mg/kg in Keffi, 2.67 mg/kg in Kokona pond, and 1.67 mg/kg in Nasarawa river. Manganese was consistently the most prevalent heavy metal in all locations, with Lead showing the lowest bioaccumulation index in Karu ponds. Elevated metal concentrations in these fish are likely linked to mining, pesticide usage, and local irrigation practices, particularly in Karu. Chromium, Nickel, and Lead concentrations adhered to WHO/FAO recommendations. However, some samples exceeded permissible limits for Manganese and Copper, posing potential risks to human consumption, except for Cadmium, which was solely found in Kokona pond samples.