Toxic Substances Hydrology Program
History and Ecology of Chloroethene Biodegradation-A Review
USGS scientist Paul M. Bradley has written a review of the scientific community’s current understanding of biodegradation of chloroethenes such as the common industrial solvents perchloroethene (PCE) and trichloroethene (TCE). The biodegradation of chloroethene compounds has been investigated extensively since these compounds were first identified in the late 1970s as common contaminants in ground water at hazardous-waste sites. Over time, perspectives on chloroethene biodegradation and on the fate of these compounds in the environment have changed. Before 1980, chloroethene contaminants were considered to be recalcitrant (not readily biodegradable). Today, biodegradation is viewed as an essential component of remediation of chloroethene plumes, and several microbial mechanisms for biodegradation of chloroethenes have been identified.
The USGS Toxic Substances Hydrology Program has had a key role in developing the scientific community’s understanding of the microbial degradation of chloroethene contaminants. The Program’s long-term investigations have been instrumental in revealing the environmental factors that affect the natural attenuation of chloroethenes. Such investigations have recently demonstrated the potential for microbial oxidation of dichloroethene (DCE) and vinyl chloride (VC) in anoxic ground-water and surface-water environments.
Dr. Bradley’s review places the shifting perspectives on the biodegradation of chloroethene contaminants within historical and ecological contexts. Recent advances in the scientific understanding of mechanisms responsible for anaerobic and aerobic biodegradation of chloroethenes are summarized in a readily accessible format for environmental cleanup professionals.