ANAEROBIC DEHALOGENATION OF HALOGENATED ORGANIC COMPOUNDS: NOVEL STRATEGIES FOR BIOREMEDIATION OF CONTAMINATED SEDIMENTS

摘要

Remediation of sediments contaminated with toxic chemicals is one of the greatest challenges for restoration of estuaries. Halogenated organic compounds constitute one of the largest groups of environmental pollutants and their use has resulted in widespread dissemination and environmental contamination, with freshwater, estuarine and marine sediments as significant sinks. Consequently, the management of sediments contaminated with toxic organic compounds, including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), pesticides and brominated flame retardants, is a major problem with far-reaching economic and ecological consequences. Anaerobic dehalogenating populations appear to be abundant in estuarine and marine sediments and many chlorinated and brominated aromatic compounds are readily dehalogenated, potentially leading to complete degradation and mineralization. For example, dechlorination of chlorinated dioxins and dibenzofurans is readily promoted in sediments from several sites. The biodegradability of organohalides is affected by available electron donors and acceptors, and the dehalogenating microbial populations active in different redox zones are distinct. Co-amendment with halogenated analogues enhanced dechlorination of spiked PCDD/Fs in estuarine sediments under a variety of conditions. Enhancement of microbial dehalogenation is an attractive remediation alternative that could potentially detoxify sediments and avoid the problematic redistribution of contaminants that is associated with dredging. Microbial reductive dechlorination is an important environmental process because it has the potential of decreasing the toxicity of PCDD/Fs if lateral chlorines are removed.