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Please use this identifier to cite or link to this item: https://hdl.handle.net/2445/163717
Carbon and chlorine isotope analysis to identify abiotic degradation pathways of 1,1,1-trichloroethane
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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 ε_bulk^C and ε_bulk^Cl 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 (Δδ13C/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, ε_bulk^C<ε_bulk^Cl 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.
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PALAU, Jordi, SHOUAKAR-STASH, O. and HUNKELER, D. Carbon and chlorine isotope analysis to identify abiotic degradation pathways of 1,1,1-trichloroethane. Environmental Science & Technology. 2014. Vol. 48, num. 24, pags. 14400-14408. ISSN 0013-936X. [consulted: 8 of June of 2026]. Available at: https://hdl.handle.net/2445/163717