Diastereoisomer- and enantiomer-specific profiles of hexabromocyclododecane in the sediment of Dongjiang River, South China

Abstract

Environmental contextHexabromocyclododecanes are widely used as additive brominated flame retardants in thermal insulation building materials, upholstery textiles and electronic products. Dongjiang River is located at the Pearl River Delta, one of the most highly industrialised regions in China, which was seriously polluted by hexabromocyclododecanes. Higher levels of hexabromocyclododecanes in Dongjiang River will pose a serious threat to ecological health in this region. AbstractThe objective of this study was to investigate the levels, diastereoisomer profiles and enantiomeric fractions of hexabromocyclododecanes (HBCDs) in the sediment of the Dongjiang River, China. The results showed that the total HBCD concentrations in the sediment ranged from below 2.5 to 424.16 ng g–1, which is similar to levels downstream of point source discharges in Europe and significantly higher than HBCD levels in sediments from rivers in the USA. The diastereoisomeric pattern showed the predominance of the γ-isomer, with low contributions of the α- and β-isomers. This diastereoisomer profile of the HBCDs was similar to that of commercial formulations. No uniform enantioselective enrichment was observed for α- and β-HBCD in sediments, which suggested that different stereoselective biotransformations occurred for these two isomers at different sites. However, (–)-γ-HBCD was apparently enriched in the sediment, which suggested that HBCDs in these studied sites were selectively biodegraded by microorganisms in the sediment.