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Title (Primary) Carbon isotope fractionation during dechlorination of 1,2,3,4-tetrachlorodibenzo-p-dioxin by a Dehalococcoides-containing culture
Author Liu, F.; Cichocka, D.; Nijenhuis, I.; Richnow, H.H.; Fennell, D.E.;
Journal Chemosphere
Year 2010
Department ISOBIO;
Volume 80
Issue 10
Language englisch;
Keywords Dechlorination; Dioxin; Dehalococcoides; Compound specific isotope analysis
Abstract Carbon isotope fractionation was observed during dechlorination of 1,2,3,4-tetrachlorodibenzo-p-dioxin (1,2,3,4-TeCDD) by a mixed culture containing Dehalococcoides ethenogenes strain 195. Fractionation was examined when 1,2,3,4-TeCDD was added as the only chlorinated compound and when 1,2,3,4-TeCDD was added with a known growth substrate, tetrachloroethene (PCE). The 1,2,3,4-TeCDD was dechlorinated to 1,2,4-trichlorodibenzo-p-dioxin (1,2,4-TrCDD) which was enriched in 13C relative to 1,2,3,4-TeCDD with isotope separation factors, eC, of 1.3 ± 0.2? and 1.7 ± 0.4? (average ± 95% confidence interval (CI)) in cultures with and without PCE, respectively. The 1,2,4-TrCDD was further dechlorinated to 1,3-dichlorodibenzo-p-dioxin (1,3-DCDD) which was depleted in 13C relative to 1,2,4-TrCDD with eC of -2.4 ± 0.4? and -2.9 ± 0.8? (average ± 95% CI) in cultures with and without PCE, respectively. This demonstrates carbon isotope fractionation during sequential reductive dechlorination of PCDDs, where isotope fractionation during dechlorination of the intermediate was substantial and a 13C depleted lightly chlorinated PCDD congener was ultimately formed during dechlorination of more highly chlorinated PCDD congeners. Despite reproducible, statistically significant differences between isotope compositions of the parent, 1,2,3,4-TeCDD and daughter, 1,2,4-TrCDD and 1,3-DCDD congeners in triplicate bottles of both treatments, fractionation factors for 1,2,3,4-TeCDD could not be determined for all replicates by regression analysis of the plot of the Rayleigh equation. It is possible that dissolution of 1,2,3,4-TeCDD imposed a kinetic limitation on dechlorination, thus masking isotope fractionation during its dechlorination.
ID 10261
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=10261
Liu, F., Cichocka, D., Nijenhuis, I., Richnow, H.H., Fennell, D.E. (2010):
Carbon isotope fractionation during dechlorination of 1,2,3,4-tetrachlorodibenzo-p-dioxin by a Dehalococcoides-containing culture
Chemosphere 80 (10), 1113 - 1119