Polybrominated diphenyl ethers (PBDEs) and decabromodiphenyl ethane (DBDPE) were determined in water, sediment, and three fish species from the Dongjiang River, a highly polluted river by brominated flame retardants in South China due to the intensive industry activities. The stable isotope analysis was used to compare differences between the feeding ecology of the fish species. The bioaccumulations of PBDEs and DBDPE were evaluated by calculation of bioaccumulation factors (BAFs) and biota-sediment accumulation factors (BSAFs). Two potential debromination products of DBDPE were detected in sediment. The occurrence of these two compounds probably ascribed to the thermal degradation during instrumental analysis but degradation in the environment cannot be ruled out. Three fish species showed two quite different PBDE congener profiles. Two carp species were dominated by BDE47 while plecostomus were dominated by both BDE47 and BDE99. The contributions of higher brominated congeners were higher in plecostomus than in two carp species. This different PBDE congener profile can be attributed to the difference in metabolism and feeding habits among fish species. The calculated BAFs for PBDE congeners follow a bioaccumulation model. The BSAFs for all PBDE congeners except for BDE47 and BDE100 were less than unit, implying that bioavailability of PBDEs in sediments is low. Contrary to expectation, the BAFs value of DBDPE was one order of magnitude higher than that of BDE209 in fish, which can partly attributed to the absence of debromination of DBDPE in fish. The calculated BAFs for DBDPE indicated that this compound can significantly accumulate in fish.
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