| Title: | Quantifying chlorinated ethene degradation during reductive dechlorination at Kelly AFB using stable carbon isotopes |
| Author(s): | Morrill PL; Lacrampe-Couloume G; Slater GF; Sleep BE; Edwards EA; McMaster ML; Major DW; Sherwood Lollar B; |
| Address: | "Stable Isotope Laboratory, University of Toronto, 22 Russell Street, Toronto Ontario, Canada M5S 3B1" |
| DOI: | 10.1016/j.jconhyd.2004.11.002 |
| ISSN/ISBN: | 0169-7722 (Print) 0169-7722 (Linking) |
| Abstract: | "Stable isotope analysis of chlorinated ethene contaminants was carried out during a bioaugmentation pilot test at Kelly Air Force Base (AFB) in San Antonio Texas. In this pilot test, cis-1,2-dichloroethene (cDCE) was the primary volatile organic compound. A mixed microbial enrichment culture, KB-1, shown in laboratory experiments to reduce chlorinated ethenes to non-toxic ethene, was added to the pilot test area. Following bioaugmentation with KB-1, perchloroethene (PCE), trichloroethene (TCE) and cDCE concentrations declined, while vinyl chloride (VC) concentrations increased and subsequently decreased as ethene became the dominant transformation product. Shifts in carbon isotopic values up to 2.7 per thousand, 6.4 per thousand, 10.9 per thousand and 10.6 per thousand were observed for PCE, TCE, cDCE and VC, respectively, after bioaugmentation, consistent with the effects of biodegradation. While a rising trend of VC concentrations and the first appearance of ethene were indicative of biodegradation by 72 days post-bioaugmentation, the most compelling evidence of biodegradation was the substantial carbon isotope enrichment (2.0 per thousand to 5.0 per thousand) in a13C(cDCE). Fractionation factors obtained in previous laboratory studies were used with isotope field measurements to estimate first-order cDCE degradation rate constants of 0.12 h(-1) and 0.17 h(-1) at 115 days post-bioaugmentation. These isotope-derived rate constants were clearly lower than, but within a factor of 2-4 of the previously published rate constant calculated in a parallel study at Kelly AFB using chlorinated ethene concentrations. Stable carbon isotopes can provide not only a sensitive means for early identification of the effects of biodegradation, but an additional means to quantify the rates of biodegradation in the field" |
| Keywords: | "Biodegradation, Environmental Carbon Isotopes Chlorine/chemistry Dichloroethylenes/*analysis/chemistry Environmental Monitoring/*methods Tetrachloroethylene/analysis Texas Trichloroethylene/analysis Vinyl Chloride/analysis Water/chemistry Water Pollutants;" |
| Notes: | "MedlineMorrill, Penny L Lacrampe-Couloume, Georges Slater, Gregory F Sleep, Brent E Edwards, Elizabeth A McMaster, Michaye L Major, David W Sherwood Lollar, Barbara eng Research Support, Non-U.S. Gov't Netherlands 2005/02/03 J Contam Hydrol. 2005 Feb; 76(3-4):279-93. doi: 10.1016/j.jconhyd.2004.11.002. Epub 2005 Jan 12" |
