Evaluation of Organochlorine Pesticide Residues in Fish and Water from Lake Geriyo in Yola North Local Government Area of Adamawa State, Nigeria

Pesticides usage in agricultural fields to control pests is extremely toxic to non-target organisms like fish and affects fish health through deterioration of metabolism, and sometimes leading to death. The present study was carried out to determine the level of organochlorine (OC) pesticide residues in, water and fish (Catfish and Tilapia) from Lake Geriyo, in Adamawa State, Nigeria, in order to find out the extent of pesticide contamination and accumulation in the lake. Soxhlet extraction process was used for the extraction of fish using a mixture of hexane and acetone, while water sample was extracted using dichloromethane liquid- liquid extraction method. The extracts were cleaned-up and analyzed using a gas chromatograph mass spectrometer (GC-MS). The result shows that organochlorine pesticides residues such as endrin, aldrin, dieldrin, heptachlor were detected in the water and the fish samples of the study area. Dieldrin was the predominant residue in all the fish samples analysed, at the concentration range of 0.36mg/kg to 0.57mg/kg and 0. 051mg/kg to 0.047mg/kg in Tilapia and catfish respectively, while Lindane was of  higher concentration in water samples, (0.33mg/L) in point p1 upstream and 0.27mg/L in point p2 downstream.  The lowest levels of OC pesticides were related to Endrin, Aldrin and Heptachlor in which Endrin and Heptachor were not found in water samples. The result of the investigation shows that matured fish contain higher concentration of the OC pesticide residues than the immature fish. Dieldrin and Lindane were found to be the predominant pesticide residues in all the analysed water and fish samples. Therefore the result indicates that Lake Gariyo is contaminated by pesticide from the nearby vegetable gardens which affects the water quality and non target organisms like fishes thereof. Keywords: Organochlorine, Pesticides, Lake Geriyo, Adamawa State, Fish and Water DOI : 10.7176/CMR/11-2-03