VERTICAL DISTRIBUTION OF ORGANOCHLORINE PESTICIDES IN AN ESTUARINE SEDIMENT CORE FROM OSSAIN AT FORCADOS RIVER ESTUARY, DELTA STATE

This project work evaluates the depth distribution and source of organochlorine pesticidesin an estuarine sediment core from Ossain at Forcados River. The core sediment samples were obtained at 0-10, 10-20, 20-30, 30-40, 40-50 and 50-60 cm depths. The concentrations of organochlorine pesticides (OCPs) in the samples were determined with gas chromatography equipped mass spectrometry after extraction with a mixture of n-hexane and dichloromethane in a ratio of 1:1 by volume. The total concentration of the Σ₂₆OCPs across the sediment depth ranged from 2.25 µg/kg at depth 20-30 cm to 18.28 µg/kg at depth of 10-20 cm. The concentrations of the OCPs homologues ranged 0.41 to 12.83 µg/kg for BHC, 0.16 to 1.00 for DDT, 0.35 to 2.89 µg/kg for Chlordane, 0.32 to 2.88 µg/kg for Drins and 0.05-3.62 µg/kg for Endosulfan. The homologue profile of organochlorine pesticides (OCPs) in the sediment core followed the order: Σ4BHC > Σ5Chlordane > Σ5Drins > Σ3Endosulfan > Σ3DDT. The high concentration of the BHCs in the study area could be as result of high usage of BHCs pesticide in control of pest. The source of the organochlorine pesticides contamination in the Ossain sediment, Forcados River estuary showed majorly of past or historical usage and few recent uses of organochlorine pesticides.