Organochlorines and Brominated Flame Retardants in Deep-Sea Ecosystem of Sagami Bay

Organochlorine compounds (OCs), brominated flame retardants (BFRs) and stable isotopes (δ15N and δ13C) were analyzed in various deep-sea organisms collected from Sagami Bay, Japan in 2004. PCBs and DDTs were the predominant contaminants detected in this study, followed by CHLs > HCB > HBCDs > PBDEs > HCHs. Concentrations of PCBs, DDTs, CHLs, HCB and PBDEs, which have high adsorptive affinities to particles and easily precipitate to sediments, were the highest in demersal fish among the organisms analyzed. Relatively high concentrations of HBCDs were found in species living in surface waters, suggesting recent input of HBCDs in the marine environment. Significant positive correlations between δ15N (‰) and concentrations of PCBs, DDTs, CHLs, HCB, PBDEs and HBCDs were found, indicating that these compounds were biomagnified in higher trophic level organisms. On the other hand, concentrations of HCHs decreased with an increase in trophic level implying dilution of this compound through the food web. The trophodynamic magnification factor (TMFs) of the analyzed PCB congeners showed an increasing trend for congeners with low log KOW (5–7), while a decreasing trend was observed for congeners with high log KOW (7–9). This phenomenon could be due to reduced bioavailability/uptake. This trend was also observed for PBDEs with some exceptions. TMF values calculated for BDE-99, -153, and -209 were lower than those of predicted TMF values. Metabolism or debromination of these congeners in the fish body is a possible reason for this difference. In addition, BDE-209 has extremely low bioavailability due to its large molecular size.