title: Dual Carbon-Bromine Stable Isotope Analysis Allows Distinguishing Transformation Pathways of Ethylene Dibromide.
abstract: The present study investigated dual carbon-bromine isotope fractionation of the common groundwater contaminant ethylene dibromide (EDB) during chemical and biological transformations, including aerobic and anaerobic biodegradation, alkaline hydrolysis, Fenton-like degradation, debromination by Zn(0) and reduced corrinoids. Significantly different correlation of carbon and bromine isotope fractionation (ΛC/Br) was observed not only for the processes following different transformation pathways, but also for abiotic and biotic processes with, the presumed, same formal chemical degradation mechanism. The studied processes resulted in a wide range of ΛC/Br values: ΛC/Br = 30.1 was observed for hydrolysis of EDB in alkaline solution; ΛC/Br between 4.2 and 5.3 were determined for dibromoelimination pathway with reduced corrinoids and Zn(0) particles; EDB biodegradation by Ancylobacter aquaticus and Sulfurospirillum multivorans resulted in ΛC/Br = 10.7 and 2.4, respectively; Fenton-like degradation resulted in carbon isotope fractionation only, leading to ΛC/Br ∞. Calculated carbon apparent kinetic isotope effects ((13)C-AKIE) fell with 1.005 to 1.035 within expected ranges according to the theoretical KIE, however, biotic transformations resulted in weaker carbon isotope effects than respective abiotic transformations. Relatively large bromine isotope effects with (81)Br-AKIE of 1.0012-1.002 and 1.0021-1.004 were observed for nucleophilic substitution and dibromoelimination, respectively, and reveal so far underestimated strong bromine isotope effects.
authors.affiliation: Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research - UFZ , Permoserstrasse 15, 04318 Leipzig, Germany.
authors.forename: Kevin
authors.initials: K
authors.lastname: Kuntze
authors.affiliation: Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem, 95501, Israel.
authors.forename: Anna
authors.initials: A
authors.lastname: Kozell
authors.affiliation: Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research - UFZ , Permoserstrasse 15, 04318 Leipzig, Germany.
authors.forename: Hans H
authors.initials: HH
authors.lastname: Richnow
authors.affiliation: Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem, 95501, Israel.|Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw , 02-089 Warsaw, Poland.
authors.forename: Ludwik
authors.initials: L
authors.lastname: Halicz
authors.affiliation: Department of Isotope Biogeochemistry, Helmholtz-Centre for Environmental Research - UFZ , Permoserstrasse 15, 04318 Leipzig, Germany.
authors.forename: Ivonne
authors.initials: I
authors.lastname: Nijenhuis
authors.affiliation: Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem, 95501, Israel.
authors.forename: Faina
authors.initials: F
authors.lastname: Gelman
mesh_terms: D001673:Biodegradation, Environmental; D001966:Bromine; D002244:Carbon; D002247:Carbon Isotopes / Q000378:metabolism; D005591:Chemical Fractionation; D015946:Ethylene Dibromide
chemical_list: D002247:Carbon Isotopes; D015946:Ethylene Dibromide; D002244:Carbon; D001966:Bromine