A Comparative Study of Some Heavy Metals in Fish and Sediments of Ikpoba River, Benin City, Nigeria

A research on heavy metals in fish and sediment samples collected from Ikpoba River, Benin City, Nigeria, was analyzed and compared during the months of June and November, 2023. Heavy metals accumulations in fish is a concern as they absorbed essential and non-essential metals, storing them in their muscles, gills and liver. Atomic Absorption Spectrophotometer (AAS) analysis showed the presence of all ten selected heavy metals (Iron (Fe), Chromium (Cr), Manganese (Mn), Zinc (Zn), Lead (Pb), Copper (Cu), Arsenic (As), Cobalt (Co), Nickel (Ni), and Cadmium (Cd)) in both the fish species Coptodon zilli and sediment samples. However, sediment samples showed higher concentrations of heavy metals compared to the fish. Sediments exhibited higher levels of iron (Fe) and nickel (Ni) in June, and lower levels of cadmium (Cd) and lead (Pb) in November. The order of heavy metal concentration in sediments was as follows: June: Fe>Ni >Zn >Cr >Co >Mn>Pb> As >Cu >Cd; November: Fe >Ni >Cr >Co >Zn >Cd >As > Mg >Cu >Pb. Analysis of heavy metals in gill, liver, and muscle revealed that iron (Fe) had the highest concentration of heavy metals in the muscle, gill, and liver for both months, while copper (Cu) had the lowest concentration in these tissues, except for muscle, June, and liver, November. This analysis exceeded the maximum limits set by the World Health Organization (WHO), Food and Agricultural Organization (FAO) and National Environmental Standard and Regulation Enforcement Agency (NESREA) in both sediment and fish samples during June and November, except for Zinc (Zn) and Copper (Cu) in fish samples. Contaminated fish could cause potential damages to human. Therefore, precautionary measures and continuous monitoring of Ikpoba River is necessary.