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General Session 4: Marine environment, ecosystem & sustainability |
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Stereoisomer-specific distribution of 1,2,5,6,9,10-hexabromocyclododecane and 1,2-dibromo-4-(1,2-dibromoethyl) cyclohexane in sediment and marine organisms from the South China Sea
Monday 9th @ 1055-1115
Room 1
Yuefei Ruan* , State Key Laboratory in Marine Pollution, Department of Biology and Chemistry, City University of Hong Kong
Xiaohua Zhang, State Key Laboratory in Marine Pollution, City University of Hong Kong
James C.W. Lam, State Key Laboratory in Marine Pollution, City University of Hong Kong; Department of Science and Environmental Studies, The Education University of Hong Kong
Bingqing Zhu, State Key Laboratory in Marine Pollution, Department of Biology and Chemistry, City University of Hong Kong
Paul K.S. Lam, State Key Laboratory in Marine Pollution, Department of Biology and Chemistry, City University of Hong Kong
Presenter Email: yruan8-c@my.cityu.edu.hk
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| Due to the worldwide phase-out of polybrominated diphenyl ethers (PBDEs), several brominated flame retardants (BFRs), such as 1,2,5,6,9,10-hexabromocyclododecane (HBCD) and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (DBE-DBCH), have been mainly used as replacements for PBDEs in insulation products. Information on occurrence of these emerging BFRs in the environment, especially DBE-DBCH, is very limited. Little is known about the distribtuion and fate of HBCD and DBE-DBCH in marine environment of South China. The present study aims to investigate the stereo-selective behaviours of HBCD and BDE-DBCH in sediment, fish, and marine mammal, from the Pearl River Estuary in South China Sea. Using specific columns for chiral separation, coupled with GC-MS and UPLC-MS/MS for quantification of α-, β-, γ- and δ-DBE-DBCH enantiomers, as well as α-, β- and γ-HBCD enantiomers and δ- and ε-HBCD meso-stereoisomers, were analyzed in these samples. Temporal changes in concentrations of HBCD and BDE-DBCH stereoisomers in marine mammals were also examined in the study. Concentrations of ΣHBCD (sum of all isomers) and ΣDBE-DBCH in dolphins (Sousa chinensis) ranged from 445 to 45,762 ng/g lipid weight (lw), and from below limits of detection (LOD) (< 0.3) to 378 ng/g lw, respectively, while those in porpoises (Neophocaena phocaenoides) ranged from 97 to 6,261 ng/g lw, and from below LOD to 125 ng/g lw, respectively. A significant increasing trend of ΣHBCD levels, was found in dolphins collected between 2005 to 2015 with an estimated annual rate of ~8%. This is the first study to report the isomeric composition of meso forms of HBCD and DBE-DBCH stereoisomers in marine mammals. The α-diastereomers of both HBCD and DBE-DBCH were the predominant isomers in the cetaceans, and the proportions of α-diastereomer in ΣHBCD and (α+β)-diastereomers in ΣDBE-DBCH was significantly higher in dolphins than those in porpoises. Moreover, selective enrichment was observed in all (−)-enantiomers of HBCD and DBE-DBCH in both species, except for γ-DBE-DBCH, whose (+)-enantiomer was more accumulative than its (−)-antipode in either cases. Interestingly, the body lengths of porpoises showed a significant negative correlation with enantiomer fractions (EFs) of α-HBCD (r = −0.72). Results of HBCD and BDE-DBCH stereoisomers in fish samples (preys of cetaceans) and sediment from the same investigated area will also be evaluated for the bioaccumulation of these chemicals in the estuarine food web. |
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