Carbon and chlorine isotope fractionation during microbial degradation of tetra- and trichloroethene

Charline Wiegert*, Manolis Mandalakis, Tim Knowles, Paraskevi N Polymenakou, Christoph Aeppli, Jiřina Macháčková, Henry Holmstrand, Richard P Evershed, Richard D Pancost, Orjan Gustafsson

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

49 Citations (Scopus)

Abstract

Two-dimensional compound-specific isotope analysis (2D-CSIA), combining stable carbon and chlorine isotopes, holds potential for monitoring of natural attenuation of chlorinated ethenes (CEs) in contaminated soil and groundwater. However, interpretation of 2D-CSIA data sets is challenged by a shortage of experimental Cl isotope enrichment factors. Here, isotope enrichments factors for C and Cl (i.e., εC and εCl) were determined for biodegradation of tetrachloroethene (PCE) and trichloroethene (TCE) using microbial enrichment cultures from a heavily CE-contaminated aquifer. The obtained values were εC = -5.6 ± 0.7‰ (95% CI) and εCl = -2.0 ± 0.5‰ for PCE degradation and εC = -8.8 ± 0.2‰ and εCl = -3.5 ± 0.5‰ for TCE degradation. Combining the values for both εC and εCl yielded mechanism-diagnostic εCl/εC ratios of 0.35 ± 0.11 and 0.37 ± 0.11 for the degradation of PCE and TCE, respectively. Application of the obtained εC and εCl values to a previously investigated field site gave similar estimates for the fraction of degraded contaminant as in the previous study, but with a reduced uncertainty in assessment of the natural attenuation. Furthermore, 16S rRNA gene clone library analyses were performed on three samples from the PCE degradation experiments. A species closely related to Desulfitobacterium aromaticivorans UKTL dominated the reductive dechlorination process. This study contributes to the development of 2D-CSIA as a tool for evaluating remediation strategies of CEs at contaminated sites.

Original languageEnglish
Pages (from-to)6449-6456
Number of pages8
JournalEnvironmental Science and Technology
Volume47
Issue number12
DOIs
Publication statusPublished - 18 Jun 2013

Keywords

  • REDUCTIVE DECHLORINATION
  • NATURAL ATTENUATION
  • MASS-SPECTROMETRY
  • VINYL-CHLORIDE
  • DEHALOGENATION
  • TRANSFORMATION
  • ETHENES
  • IRON
  • PCE
  • CIS-1,2-DICHLOROETHENE

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