ISSN:
1573-515X
Keywords:
hexachlorobenzene
;
microbial dechlorination
;
Rhine River
;
sediment pollution
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Geosciences
Notes:
Abstract In sedimentation areas of polluted rivers, microbial dechlorination of chlorinated aromatics may be of great environmental significance. This reaction may take place in the deeper, anaerobic sediment layers and involves replacement of a chlorine in the pollutant molecule by hydrogen. In this study, the microbial dechlorination of hexachlorobenzene in a sedimentation area of the Rhine River is evaluated by using Rhine water pollution data, concentrations in historical sediment samples and in recent sediment cores, and the results of anaerobic laboratory incubations with Lake Ketelmeer sediment. The various data support the conclusion that microbial dechlorination of hexachlorobenzene has occurred in the anaerobic sediment. Up to 80% of the hexachlorobenzene deposited in the early 1970s has been dechlorinated. The maximum half-life of hexachlorobenzene in the sediment is found to be 7 years. Two limitations of microbially mediated dechlorination in the natural environment have become clear. In the first place, a residual concentration of about 40 μg/kg remains unaltered in the sediment or transformation rates of this fraction are at least extremely low. Secondly, the lower chlorinated benzenes that are produced from hexachlorobenzene appear to accumulate in the anaerobic sediment.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00000796
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