Determination of organochlorine pesticides residues in water, fish and sediment samples from River Tella, Gassol, Taraba State, Nigeria

Abstract

The study was aimed at determining the levels of organochlorine pesticides residues in water, sediment and fish species at River Tella to find out the extent of pesticide contamination and accumulation in the river. Total of fourteen (14) organochlorine pesticide residues were analyzed which include Delta lindane, Alpha Lindane, Beta Lindane, Gamma Lindane, Heptachlor, Aldrin, Heptachlor Epoxide, Endosulfan I, Endosulfan II, P’P-DDE, P’P-DDD, P’P-DDT and Methoxychlor. The water sample was subjected to liquid-liquid extraction method while the fish and the sediment samples were subjected to soxhlet extraction. The extracts were later analyzed for organochlorine pesticide residues using Gas-Chromatography coupled with mass spectrometer (GC-MS). The study has revealed that the level of pesticides residues in water was less than that of fish and sediment which was also below the WHO/FAO values. It was also observed that high concentrations recorded were recorded in high in Gamma Lindane (24.71), follow by Alpha Lindane (23.70) and Beta Lindane (4.50). Mormyrus rume follow by Claria gariepinus while the Tilapia zilli recorded low concentration of the pesticide residues. The Aldrin recorded high concentration of 5.11 ppm in Mormyrus rume follow by Endosulfon II which recorded the concentration of 25.03 ppm also in Mormyrus rume. Endrin also recorded the concentration of 4.88 ppm in Clarias. gariepinus. The lowest pesticide residues was recorded in p,p'-DDD (0.01 ppm), p,p'-DDT (0.03 ppm), Methoxychlor (0.01 ppm). The Heptachlor epoxide and P’P-DDE were not detected in water sample. The presence of high concentration in fish may pose a great danger when these fish are being consumed over time. Regular monitoring is therefore required to control the levels of pesticide residues in the water bodies. The measurement of the fish showed that Clarias gariepinus had the average length of 15.89 cm, and average weight of 179.87 g. Mormyrus rume had the average length of 15. 18 cm, and average weight of 210. 54g. Tilapia zilli was the least species of fish sample with a length of 12.96 cm and average weight of 96.88 g. The water quality parameters of the river were also studied, which recorded the temperature of 28.89 oC was recorded, pH value of 9.01, Conductivity value of 40.11, DO value of 6.14 and TDS of 2.35.