Autori: Silviu-Laurentiu Badea, Carsten Vogt, Stefanie Weber, Hans - Hermann Richnow, Andrei-Florin Danet
Editorial: Dr. Joseph M. Suflita, Environmental Science and Technology , 2009.
Carbon isotope fractionation factors were determined with the dichloro elimination of γ-hexachlorocyclohexane (γ-HCH) by the sulfate-reducing bacteria Desulfococcus multivorans DSM 2059 and Desulfovibrio gigas DSM 1382. Both strains are known for cometabolic HCH dechlorination. Degradation experiments with γ-HCH in concentrations of 22−25 μM were carried out using benzoate (for D. multivorans) and lactate (for D. gigas) as electron donors, respectively. γ-HCH was dechlorinated by both bacterial strains within four weeks, and the metabolites γ-3,4,5,6-tetrachlorocyclohexene (γ-TCCH), chlorobenzene (CB), and benzene were formed. The carbon isotope fractionation of γ-HCH dechlorination was quantified by the Rayleigh model, using a bulk enrichment factor (εC) of −3.9 ± 0.6 for D. gigas and −3.4 ± 0.5 for D. multivorans, which correspond to apparent kinetic isotope effect (AKIEC) values of 1.023 ± 0.004 or 1.02 ± 0.003 for stepwise Cl−C bond cleavage. The extent and range of isotope fractionation suggest that γ-HCH dechlorination can be monitored in anoxic environments by compound-specific isotope analysis (CSIA).
Cuvinte cheie: Stable Isotope Fractionation, Lindane