Impacts of industrial effluent and dumpsite leachate discharges on the quality of groundwater in Oyo state, Nigeria

The quality of groundwater at Oluyole and Ona Ara local government were studied to reveal the impacts of industrial effluent discharge into Ona River (Oluyole) and dumpsite leachate discharge into Eku River (Ona Ara). Considering the mean levels in the upstream and downstream regions at both locations, all the physico-chemical parameters studied on the groundwater samples fell within the ranges quoted for Ibadan, Lagos, Kaduna, and Warri groundwater, and the levels of zinc and copper were found to be below the World Health Organisation (WHO) acceptable level and WHO maximum permissible levels. A higher mean value, recorded at the downstream region for oil and grease (2.21mg/l) at Oluyole was partly due to the quality and handling of bailers used by the residents. The dumpsite leachate and industrial effluent were also analysed for the same parameters as for the groundwater samples. Comparisons made on the results obtained for some parameters inferred that the dumpsite leachate and the industrial effluent were but not only the sources of pollutants in the groundwater.