Distribution and ecological risks of polychlorinated biphenyls (PCBs) in surface sediment of the Forcados River, Niger Delta, Nigeria

Concentrations of sigma 15 PCBs in sediments of the Forcados River, Nigeria, were determined in 2012 to provide information on the profile, sources and ecotoxicological risks of PCBs in the sediment. The screening concentrations of PCBs were quantified using a gas chromatograph equipped with a Ni-63 electron capture detector. The concentrations of the sigma 15 PCBs ranged from 2.7 to 202.3 mu g kg-1 with a mean concentration of 46.5 mu g kg-1. The composition of PCB congeners was clearly dominated by octa-PCBs, hepta-PCBs and hexa-PCBs, constituting 68.1% to 93.7%, respectively, of the total amounts of PCBs. All sites had sigma 15 PCB levels below the prescribed probable effect concentrations, and therefore no adverse effects are expected for the majority of sediment-dwelling organisms of the Forcados River system.