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Monitoring Microbial Dechlorination of Tetrachloroethene (PCE) in Groundwater Using Compound-Specific Stable Carbon Isotope Ratios: Microcosm and Field Studies
Auteur(s)
Date de parution
1999
In
Environmental Science & Technology, American Chemical Society, 1999/33//2733-2738
Résumé
The determination of compound-specific stable isotope ratios is a promising new tool to assess biodegradation of organic compounds in groundwater. In this study, the occurrence of carbon isotope fractionation during dechlorination of tetrachloroethene (PCE) to ethene was evaluated in a PCE-contaminated aquifer and in a microcosm that was based on aquifer material from the site. In the microcosm, all dechlorination steps were accompanied by carbon isotope fractionation. The largest fractionation occurred during dechlorination of <i>cis</i>-1,2-dichloroethene (cDCE) and vinyl chloride (VC), resulting in a large enrichment of <sup>13</sup>C in the remaining cDCE and VC. Stable carbon isotope ratios (δ<sup>13</sup>C) of cDCE and VC increased from -25.7 to -1.5‰ and -37.0 to -2.5‰, respectively. The δ<sup>13</sup>C of ethene was initially -60.2‰ and approached the δ<sup>13</sup>C of the added PCE (-27.3‰) as dechlorination came to completion. A similar carbon isotope pattern was observed for PCE dechlorination at the field site. Strong enrichment of <sup>13</sup>C in cDCE and VC during microbial dechlorination may serve as a powerful tool to monitor the last two dechlorination steps, which frequently determine the rate of complete dechlorination of chlorinated ethenes at field sites undergoing intrinsic bioremediation.
Identifiants
Type de publication
journal article
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