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Author(s): A.S. Uzoekwe, T.O. Ikpesu.

Volume/Issue: Volume 2 , Issue 2 (2019)

Abstract:

The levels of organochlorine pesticide (OCPs) and polychlorobiphenyl (PCBs) residues in water and sediments of Ogba River Benin, Nigeria were investigated. The water and sediments samples were collected on monthly basis from April 2017 to March 2018 and analyzed using a gas chromatograph fitted with an election capture detector. The surface water revealed the following pesticides and their ranges in (ng/l) 8.15 – 19.90 (HCH), 24.77 – 44.90 (chlordane), 7.82-20.00 (DDT), 35.87- 98.80 (endrin), 8.90 -33.60 (dieldrin), 36.55 -77.40 (endosulfan) and 150.00 – 547.00(PCBs). Seasonally, the persistent organic pollutants in the surface water were; wet season; (in ng/l), PCBs (415 ± 5.90) endrin (82 ± 2.30), endosulfan (62 ± 2.10) , chlordane (32 ± 1.90) , dieldrin (24 ± 1.12), DDTs (14.80 ± 1.40) , HCHs (15.40 ± 0.60); dry season (in ng/l), ), PCBs (398 ± 7.10) endrin (72 ± 1.40), endosulfan (46 ± 1.40) , chlordane (23 ± 1.20) , dieldrin (18 ± 0.32), DDTs (11.20 ± 0.70) , HCHs (12.10 ± 0.20). The OCPs in the bottom sediment had the following concentrations; (µg/kg) 7.62 – 39.99 (HCH), 13.62 – 149.00 (chlordane), 47.36 – 58.55 (DDT), 16.32 -112.20 (endrin), 54.93-99.20 (diedrin), 4.19 – 97.62 (endosulfan) and 440.00 – 701. 00 (PCBs) The sediments seasonal variation were; wet (in µg/kg); PCBs (645 ± 8.40 ), chlordane (132 ± 3.40), endosulfan (92 ± 0.90), dieldrin (86 ± 2.62), DDT(51± 1.50), HCHs (28 ± 0.70); dry PCBs (580 ± 9.10 ), chlordane (13 ± 1.20), endosulfan (81 ± 0.50), dieldrin (68 ± 1.02), DDT(45±0.30), HCHs (21 ± 0.20).The OCPs and PCBs were below the values established by the regulatory bodies. Though, the pesticides had low concentration in the River at that point in time it has little or no effect on the biota. Although, if not monitored over the years, it can cause harm to the environment, bioaccumulate and biomagnifies along the food chain.

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