Partitioning and Bioaccumulation of PBDEs and PCBs in Lake Michigan

摘要

Streets et al. presented bioaccumulation factors (BAFs) for polybrominated diphenyl ethers (PBDEs) and also for polychlorinated biphenyls (PCBs) in an aquatic foodweb. The writer of the present correspondence has some objections about the way these BAFs were calculated and further used. The BAFs were calculated by combination of fish data that were collected during 2000, 2001, and 2002 and water data mat were sampled during 2004. This is conceptually inappropriate, especially when big differences are observed among the various sampling years. The authors reported mat there were no differences in concentrations between years, but a closer look at the "per year" data of their Table 1 suggests that this is not true. At the data from all the Great Lakes, it can be seen that the concentrations of individual and total PBDEs are substantially lower for the year 2001, comparing to 2000 and 2002 (for example, BDE-99 was ～5 times higher in 2000 than in 2001). Using annual fish data separately, the log BAF values for BDE-99 are 6.90, 6.17, and 6.69, for the years 2000, 2001, and 2002, respectively. Then, the authors compare the average value they observed (6.7) with a bibliographic log K_(OW) value (7.32) and say the fact that BAF is lower than K_(OW) suggests debromination. If someone chooses as log K_(OW) value the one of 6.81 (2), then it is seen that BAF is higher than Kow the years 2000 and 2002 and lower the year 2001. Therefore, the conclusion about debromination (at least based on the BAF/K_(OW) ratio) is not soundly extracted, both because there has been mismatching between water and fish samples and because the log K_(OW) they used might not be the correct one.