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Hunkeler, D.* ; van Breukelen, B.M.* ; Elsner, M.

Modelling chlorine isotope trends during sequential transformation of chlorinated ethenes.

Environ. Sci. Technol. 43, 6750-6756 (2009)
DOI PMC
Open Access Green as soon as Postprint is submitted to ZB.
There is increasing interest in combined carbon-chlorine compound-specific isotope analysis (CSIA) to differentiate between contaminant sources and to assess transformation processes, However, the significant abundance of polychlorinated molecules with several heavy chlorine isotopes complicates the evaluation of chlorine isotope trends. Therefore, the goal of this study was to develop a conceptual and mathematical framework that describes the expected chlorine isotope fractionation patterns during multistep transformation of chlorinated compounds. Reductive dechlorination of chlorinated ethenes served as an example. The study demonstrates that chlorine isotope trends can be simulated by reproducing the average behavior of light and heavy isotopes or by explicitly simulating molecules with different numbers of heavy isotopes (isotopologues). The calculations reveal that initial chlorine isotope ratios of products equal the isotope ratios of their parent compounds in the absence of secondary isotope effects, while steadily increasing during transformation. The slopes in dual isotope plots are linear for reactant and product during a one-step reaction. They become nonlinear for products that are degraded further but converge to characteristic slopes. Consideration of different scenarios reveals that combined carbon-chlorine isotope analysis bears high potential to differentiate between contaminant sources, to elucidate reaction mechanisms in laboratory studies, and to identify transformation processes in the field.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
Keywords reductive dechlorination; benzene biodegradation; fractionation; carbon; degradation; pathways; tetrachloroethene; trichloroethene; ratios; mtbe
ISSN (print) / ISBN 0013-936X
e-ISSN 1520-5851
Journal Environmental Science & Technology
Quellenangaben Volume: 43, Issue: 17, Pages: 6750-6756 Article Number: , Supplement: ,
Publisher ACS
Publishing Place Washington, DC
Non-patent literature Publications
Reviewing status Peer reviewed
Institute(s) Institute of Groundwater Ecology (IGOE)