Grain size effect on PBDE and PCB concentrations in sediments from the intertidal zone of Bohai Bay, China

Polybrominated diphenyl ethers (PBDEs) are of great environmental concern because their concentrations in the environment are increasing exponentially, and polychlorinated biphenyls (PCBs) are ubiquitous contaminants, although their usage ceased in most industrialized countries in the mid-1970s. This research provides particle-scale understanding of PBDE and PCB distribution in sediments obtained from the three intertidal flats of Bohai Bay, China. The sediments were fractionated into three size groups (<31, 31-63, and >63 μm diameter). The PBDE, PCB, and total organic matter contents were not associated with grain size, and the lowest total organic matter was found in the 31-63 μm fraction at all three sites. The PCBs and PBDEs were distributed differently among the various fractions from the three sites. The highest level of PCBs and PBDEs occurred in the 31-63 μm fraction of the Dagukou sediments, and their lowest levels were found in Lujuhe sediments. In the Qikou sediments, the lowest PCB level occurred in the 31-63 μm fraction and the lowest PBDE level was found in the <31 μm fraction. These results indicate that the environmental behavior of PBDEs and PCBs are affected by the texture and organic matter content of sediments.