Distribution of heavy metals and pesticides residues in sediments of some rivers in Ekiti state, Southwest Nigeria

Sediments are habitats and major sources of nutrients for benthic organisms. High concentration of pollutants can impact negatively on the lives of such organisms and ultimately on the lives of human beings who may feed on them. This study was carried out in order to evaluate some environmental pollutants’ load: heavy metals and pesticide residues in Irintan, Omi-Eye and Egbigbu river sediments in Ekiti State, Southwest Nigeria. Sediment samples were taken at upper, middle and lower courses of each river relative to the farm used for the study. The samples were air-dried in the laboratory, disaggregated, sieved and analysed for heavy metals and organochlorine pesticides (OCP) residues using standard methods. The heavy metal range at floodplains (mg/kg) was: Cr (0.25-2.08), Cu (0.19-14.28), Zn (BDL-2.53), Cd (BDL-0.87), Pb (BDL-0.32), Fe (0.38-22.35) while for OCP residues, the range (µg/kg) was α-BHC (0.15-0.33), β-BHC (0.19-14.28), ẟ-BHC (0.25-1.09), lindane (BDL-1.23), chlorothalonil (0.87-1.44), heptachlor (BDL-1.04), heptachlor epoxide (BDL-1.96), endosulfan I (0.20-1.98), endosulfan II (BDL-0.67), aldrin (BDL-1.93), endrin (BDL-0.37), dieldrin (BDL-0.42), p,p-DDE (BDL-0.52), p,p-DDT (BDL-1.20), methoxychlor (0.21-0.88). The pollutants’ concentrations in the sediments were generally low at all the sites when compared with international guidelines for each pollutant. Governments in Nigeria should checkmate indiscriminate dumping of refuse most of which end in our rivers in order to reduce pollutants’ concentration in rivers/sediments so as to protect the lives of benthic organisms.