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Title: Carbon and chlorine isotope fractionation patterns associated with different engineered chloroform transformation reactions
Author: Torrentó Aguerri, Clara
Palau, Jordi
Rodríguez Fernández, Diana
Heckel, B.
Meyer, A.
Domènech Ortí, Cristina
Rosell, Mònica
Soler i Gil, Albert
Elsner, M.
Hunkeler, D.
Keywords: Geoquímica
Geologia isotòpica
Isotope geology
Issue Date: 9-May-2017
Publisher: American Chemical Society
Abstract: To use compound-specific isotope analysis for confidently assessing organic contaminant attenuation in the environment, isotope fractionation patterns associated with different transformation mechanisms must first be explored in laboratory experiments. To deliver this information for the common groundwater contaminant chloroform (CF), this study investigated for the first time both carbon and chlorine isotope fractionation for three different engineered reactions: oxidative C-H bond cleavage using heat-activated persulfate, transformation under alkaline conditions (pH ∼ 12) and reductive C-Cl bond cleavage by cast zerovalent iron, Fe(0). Carbon and chlorine isotope fractionation values were −8 ± 1 and −0.44 ± 0.06 for oxidation, −57 ± 5 and −4.4 ± 0.4 for alkaline hydrolysis (pH 11.84 ± 0.03), and −33 ± 11 and −3 ± 1 for dechlorination, respectively. Carbon and chlorine apparent kinetic isotope effects (AKIEs) were in general agreement with expected mechanisms (C-H bond cleavage in oxidation by persulfate, C-Cl bond cleavage in Fe(0)-mediated reductive dechlorination and E1CB elimination mechanism during alkaline hydrolysis) where a secondary AKIECl (1.00045 ± 0.00004) was observed for oxidation. The different dual carbon-chlorine (Δδ13C vs Δδ37Cl) isotope patterns for oxidation by thermally activated persulfate and alkaline hydrolysis (17 ± 2 and 13.0 ± 0.8, respectively) vs reductive dechlorination by Fe(0) (8 ± 2) establish a base to identify and quantify these CF degradation mechanisms in the field.
Note: Versió postprint del document publicat a:
It is part of: Environmental Science & Technology, 2017, vol. 51, num. 11, p. 6174-6184
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ISSN: 0013-936X
Appears in Collections:Articles publicats en revistes (Mineralogia, Petrologia i Geologia Aplicada)

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