Accumulation of polybrominated diphenyl ethers (PBDEs) in a marine foodweb from Åsefjorden, western Norway

Brominated flame retardants (BFRs) are a group of commercially synthesized compounds that have fire preventive abilities, and are used worldwide in the production of textiles, plastic, electric equipment and a wide variety of polymers. Polybrominated diphenyl ethers (PBDEs) are a group of BFRs that have the potential to cause harmful effects on living organisms because they are persistent, lipophilic and accumulative, and have abilities to be transported long-distance with wind and ocean currents. A fjord on the west coast of Norway, Åsefjorden, has been studied due to recent findings of biological samples heavily contaminated with organic pollutants such as PBDE, polychlorinated biphenyls (PCBs) and hexabromocyclododecane (HBCD). In the present study, a defined food web from Åsefjorden was analyzed to assess the relationship between trophic level of the organisms and their body burden of PBDEs, as well as overall PBDE levels at different sample sites. Samples from sediment, lugworm (Arenicola marina), blue mussels (Mytilus edulis), shore crab (Carcinus maenas) and eggs from common eider (Somateria mollissima) and great black-backed gull (Larus marinus) was treated and analyzed for the findings of 10 PBDE-congeners, including BDE-209. Mainly five samples of each specimen from five different areas in the fjord were analyzed using gas chromatography and mass spectrometry (GC-MS). The ratio of stable nitrogen isotopes (15N/14N) in the biological samples was analyzed using isotope ratio mass spectrometry (IRMS) for determination of trophic levels. Results so far show that the pattern of PBDE-congeners is dominated by the extremely accumulative BDE-47 along with BDE-99 and -100. There is a strong correlation between the levels and pattern of PBDE-congeners in sediment and lugworm. BDE-209 is found in sediments at concentrations ten times higher than in lugworm. So far low levels of BDE-209 in egg samples show little accumulative abilities for this congener. The highest levels of PBDEs in this study are found in great black-backed gull, with BDE-47 as the most dominant congener at levels above 900 ng/g lw. Food web levels of PBDEs increase in the order blue mussel < shore crab < common eider < great black-backed gull. Inter-comparison of the sample sites indicates differences in levels of contamination. However, primary PBDE sources are not yet determined.