Assessment of Levels of Some Metals in Water and Fish from Jos, Plateau State, Nigeria

Aim: This study was designed to assess the levels of chromium (Cr), manganese (Mn), cobalt (Co) and nickel (Ni) in water and fish to monitor the toxicity risk of consuming these fish. Place and Duration of Studies: The water and fish samples were obtained from Farin gada river, Liberty Dam, Dahwol-Tohort and Diye-Tohort mining ponds, all within Jos Metropolis, Plateau State, Nigeria, between March and April, 2018. Methodology: Water and six fish species samples were collected from four different locations, digested and analysed using Buck Scientific Atomic Absorption Spectrophotometer, model 210VGP. Results: Farin gada river had all the four metals studied in varying concentrations in the following order Mn>Ni>Co>Cr with Mn having the highest mean concentration of 0.4133±0.0100 mg/L. The concentrations of the metals in the other three sources were in the order of Ni>Co>Cr with Mn not detected. Cr also was not detected in Lamingo Dam. The concentrations of Mn and Ni in all the water sources were higher than the World Health Organisation (WHO) maximum permissible limits of 0.05 mg/L and 0.06 mg/L respectively. Petrocephalus bovei recorded the highest mean concentrations of Mn and Ni, while Co was highest in Clarias gariepinus species. The concentrations of these metals in the head, body and gills of the fish species showed that the head of Petrocephalus bovei species had the highest concentrations of all the metals except chromium. Fish species from other water sources exhibited the same general pattern of Head˃gill˃body except Co which was found to accumulate more in the body than in other parts of the fish. Conclusion: The results showed that there was biomagnification of these metals from water to the fish as the concentration of the metals in the fish far exceeded those of the water sources from which they were obtained and Petrocephalus bovei species has the highest potential to biomagnified all the metals.