Evaluation of polybrominated diphenyl ethers in sediment of Lagos Lagoon, Nigeria

Abstract

Certain pollutants, particularly synthetic organic compounds have given rise to important environmental concerns. New organic pollutants especially polybrominated diphenyl ether (PBDEs) employed in electronic equipment and in some household items as flame retardants are now finding their way into the aquatic environment as components of waste discharge into the water body. These highly hazardous organic pollutants of concern are persistent, can bioaccumulate and biomagnify in aquatic organism especially fish, and there appears to be no clear strategy for managing them. In this study, levels of polybrominated diphenyl ethers were determined in sediments collected from Lagos lagoon with the aim of generating a database which can be employed for management options. Sediment samples were collected using Van Veen grab for a period of one year from randomly selected sites in Lagos lagoon. The samples were soxhlet extracted with dichloromethane to obtain PBDEs extracts which were later cleaned up in a column of silica gel using hexane as eluant. The cleaned extracts were analyzed using gas chromatography coupled with electron capture detector. The total concentrations of PBDEs in sediments ranged from 0.11 to 23.33 mg/kg. In all the studied locations, BDE-28, BDE-153, BDE-154 and BDE 205 were detected in all sediment samples at concentration range of 0.22 to 23.33 mg/kg. Among the PBDEs congeners, sum of tri to hepta BDEs contributed 61.32%, while BDE-205 contributed 38.68% to the total PBDE in the sediment samples. Brominated congeners BDE-47, BDE-153 and BDE-154 (tetra and hepta BDEs) were abundant which contributed 18.31, 12.06 and 34.75%, respectively to the sum of tri to hepta BDE in the sediment. The composition patterns of PBDEs in Lagos Lagoon sediment samples revealed that technical deca-BDE mixture was the major pollutant sources with a minor contribution of penta-BDE mixture. Key words : Gas chromatograph, polybrominated diphenyl ether (PBDEs), sediment, Lagos Lagoon.