Distribution of polychlorinated biphenyl congeners in Bear Lake sediment

Contamination of the Bear Lake sediment with polychlorinated biphenyls (PCBs) and the distribution of PCB congeners as a function of core depths were determined using a freeze corer sampling technique. The; maximum level of PCBs was found in the 15 - 25 cm core section from the surface, then decreased with the depth of core section to the bottom. Congeners #105 and 118 showed a considerable dechlorination pattern compared with the Aroclor mixture which was initially introduced to the environments. However, congeners #101, 138, and 180 exhibited very small or almost no alterations in relative amount. The PCB concentrations were very homogeneous in three studied sites along Bear Lake, which suggests that the contamination of Bear Lake with PCBs is probably due to the atmospheric deposition. This study would provide very useful information for envorinmental and biomonitoring activities in west Michigan.