Evidence for complex sources of persistent halogenated compounds in birds from the south China sea

Persistent halogenated compounds (PHCs), including dichlorodiphenyltrichloroethane and its metabolites (DDTs), polybrominated diphenyl ethers (PBDEs), alternative brominated flame retardants (ABFRs), and dechlorane plus (DP), were analyzed in muscle of six bird species from the South China Sea. DDTs, with concentrations up to 19,000 ng/g lipid weight (lw), were the dominant contaminants contributing to 66-99% of PHCs in birds. Concentrations of PBDEs, ABFRs, and DP ranged from 1.1 to 130, 0.73-40, and 0.21-2.5 ng/g lw, respectively. Historically pollution of DDTs and flame retardants in surrounding Asian lands were the main sources for PHCs in birds. BDE 209 was the primary PBDE congener in all birds. 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE) and decabromodiphenyl ethane (DBDPE) were the main ABFRs. Anti-DP and p,p'-DDE were the dominating compounds of DP and DDTs, respectively. Only concentrations of BDEs 153, 203, 196, and 207, p,p'-DDE, and p,p'-DDD showed significant and positive correlations with δ¹⁵N values in samples. The resident birds, red-footed booby (Sula sula), had much lower levels of p,p'-DDE and most of PBDEs than those in migratory birds from the South China Sea. Results of stable isotope ratios of carbon suggest the highly variable food items for the five migratory bird species. The abundance of DBDPE in red-footed booby might be related with the ingestion of plastic debris, which still warrants further verification.