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Carbon and chlorine isotope analysis to identify abiotic degradation pathways of 1,1,1-trichloroethane
- Source :
- Dipòsit Digital de la UB, Universidad de Barcelona
- Publication Year :
- 2014
- Publisher :
- American Chemical Society, 2014.
-
Abstract
- This study investigates dual C−Cl isotope fractionation during 1,1,1-TCA transformation by heat-activated persulfate (PS), hydrolysis/dehydrohalogenation (HY/DH) and Fe(0). Compound-specific chlorine isotope analysis of 1,1,1-TCA was performed for the first time, and transformation-associated isotope fractionation εCbulk and ε CIbulk values were −4.0 ± 0.2‰ and no chlorine isotope fractionation with PS, −1.6 ± 0.2‰ and −4.7 ± 0.1‰ for HY/DH, −7.8 ± 0.4‰ and −5.2 ± 0.2‰ with Fe(0). Distinctly different dual isotope slopes (Δ δ13C/Δδ37Cl): ∞ with PS, 0.33 ± 0.04 for HY/DH and 1.5 ± 0.1 with Fe(0) highlight the potential of this approach to identify abiotic degradation pathways of 1,1,1-TCA in the field. The trend observed with PS agreed with a C−H bond oxidation mechanism in the first reaction step. For HY/DH and Fe(0) pathways, different slopes were obtained although both pathways involve cleavage of a C−Cl bond in their initial reaction step. In contrast to the expected larger primary carbon isotope effects relative to chlorine for C−Cl bond cleavage, εCbulk < εClbulk was observed for HY/DH and in a similar range for reduction by Fe(0), suggesting the contribution of secondary chlorine isotope effects. Therefore, different magnitude of secondary chlorine isotope effects could at least be partly responsible for the distinct slopes between HY/DH and Fe(0) pathways. Following this dual isotope approach, abiotic transformation processes can unambiguously be identified and quantified.
- Subjects :
- Carbon Isotopes
Reaction step
Chemistry
Sulfates
Iron
Inorganic chemistry
Isotopes of chlorine
Clor
Carbon isotopes
General Chemistry
Fractionation
Chemical Fractionation
Persulfate
Isòtops de carboni
Hydrolysis
Isotope fractionation
Isotopes
Isotopes of carbon
Dehydrohalogenation
Environmental Chemistry
Trichloroethanes
Chlorine
Oxidation-Reduction
Subjects
Details
- Language :
- English
- Database :
- OpenAIRE
- Journal :
- Dipòsit Digital de la UB, Universidad de Barcelona
- Accession number :
- edsair.doi.dedup.....c6ed279e5c6099c91a247cac09f86a0d