Persistent Organochlorine Pesticide Residues in Water, Sediments and Fish Samples from Ogbese River

Abstract

This study considered the levels of 15 organochlorine pesticide (OCPs) residues (α-BHC, β- BHC, ϒ-BHC, lindane, chlorothalonil, heptachlor, aldrin, heptachlor epoxide, endosulfan I, endosulfan II, endrin, dieldrin, p, p'-DDD, p, p'-DDT and endosulfan sulphate in water, sediments and fish species from Ogbese river in Ekiti State, Southwestern Nigeria. Samples were extracted and cleaned-up on silica gel adsorbent. The OCPs concentrations were determined using Gas chromatograph (GC) equipped with Electron Capture Detector. The OCPs concentration in water and sediments ranged from below detection limit (BDL): BDL – 13.6 µg/L and 0.52 –450 µg/kg whilst the mean OCPs in the fish ranged from 2.64 – 66.0 µg/kg, respectively. The results indicated that all the analysed fish samples were contaminated with the studied pesticides. Endosulfan I was found to be above EU and FAO/WHO maximum residue limits (MRL) in Clarias gariepinus fish samples. The sediments and fish samples showed evidence of organochlorine pesticides enrichment and bioaccumulation. Chi-square at α = 0.05 showed there were significant differences in the levels of organochlorine pesticide residues in sediments and fish samples except α-BHC.