Microbial Aspects of the Behaviour of Chlorinated Compounds During Soil Passage

Microbial transformation of chlorinated organic contaminants in columns, packed with sediment from a dune infiltration area and from River Rhine, has been investigated under different redox conditions. Low redox potentials favour reductive dechlorination of chlorinated ethylenes and benzenes to lower or non-chlorinated compounds. Under aerobic conditions transformation of 1,2- and 1,4 dichlorobenzene, but not of 1,3-dichlorobenzene took place. Biotransformation of chlorinated organic substances under denitrifying conditions was hardly observed. Only a slight removal of 1,2dichloro,4-nitrobenzene could be detected. Results indicate that biotransformations may also occur under conditions which approach a field situation (lowered temperature, presence of extra carbon source).