Distribution and ecological risk assessment of pesticide residues in surface water, sediment and fish from Ogbesse River, Edo State, Nigeria

Abstract

The contamination of pesticides in water, sediments, Clarias gariepinus, and Tilapia zilli from Ogbesse River was investigated to evaluate the pollution status and potential hazard in river system. A total of sixteen pesticides were analyzed using Gas Chromatography (GC) equipped with Electron Capture Detector (GC-ECD). The concentration of pesticide residues ranged from ND to 0.43 µg/l for water samples, 0.82 to 2.14 µg/kg dw for sediment, 0.04 to 2.34 µg/kg/ww for C. gariepinus and 0.02 to 1.73 µg/kg/ww for T. zilli. There was a clear dominance of the organochlorine; Hexachlorocyclohexane (α HCH, γ - HCH (lindane), β- HCH) in all matrixes. Ecological risk assessment of pesticide residues in water samples using the Risk Quotient deterministic method showed the likelihood of cause adverse effects for each fish species (RQ≥1). Human health risk assessment indicated that the consumption of contaminated fishes (C. gariepinus and T. zilli) could have potential health implications. Key words: Pesticides, chromatography, risk quotient, estimated daily intake, hazard quotient, environmental exposure.