An assessment of heavy metals in the sediments of Ogun-Osun river basin, Oke-Odan, Yewa South local government area of Ogun State, Nigeria

This study was carried out to examine heavy metals concentrations in the sediments of upstream, middle stream and downstream sections of Ogun-Osun River Basin, Oke-Odan, Ogun State, Nigeria. Sediment samples were analyzed for selected heavy metals) Cd, Cr, Pb, Zn, Mn, Cu, Ni, As & Fe) by atomic absorption spectrophotometry method. The results revealed heavy metals concentrations ranging from 2.07mg/kg2.98mg/kg for Cd, 2.12mg/kg-4.66mg/kg for Cr, 5.15mg/kg-17.18mg/kg for Pb, 5.55mg/kg-14.04mg/kg for Zn, 174.62mg/kg-218.83mg/kg for Mn, 0.28mg/kg-1.47mg/kg for Cu, 12.22mg/kg-15.58mg/kg for Ni, 1.15mg/kg2.32mg/kg for As and 4.53mg/kg-7.38mg/kg for Fe in the three locations. The results showed that the concentrations of Zn, Pb, Cu, Cr, Ni, and as in the sediments are low but may require monitoring to prevent increase. The concentration of Mn was higher than the stipulated limit (50.0mg/kg) set by USEPA and this may constitute risk to the people as well as aquatic animals using the water. However, the river sediments are less contaminated but may increase if the water is managed well to continue to enhance its quality.