Dechlorination of Aroclor and specific congeners in marine, estuarine and freshwater sediments.

Reductive dechlorination of Aroclor 1242 and a mixture of specific PCB congeners were investigated in slurries of sediments from freshwater, estuarine and marine environments. The cultures containing Aroclor 1242 were incubated with different sulfate concentrations, none, 18 mM and 50 mM sulfate. Significant dechlorination activity of Aroclor 1242 were only found in freshwater sediments which were either subjected to continuously movement or were primed with brominated biphenyls and PCB. The dechlorination of Aroclor 1242 seemed to commence after the sulfate was depleted. Both freshwater and estuarine sediments were capable of dechlorination of single congeners when an extra matrix of autoclaved sediments were added. These results indicates that the dechlorination of Aroclor 1242 is dependent of an environment free from sulfate and that movement, the adding of an extra matrix to the samples or using single congeners instead of complex Aroclors may enhance the dechlorinating activity.