Document Detail

Oxygen and chlorine isotopic fractionation during perchlorate biodegradation: laboratory results and implications for forensics and natural attenuation studies.
MedLine Citation:
PMID:  17533841     Owner:  NLM     Status:  MEDLINE    
Perchlorate is a widespread environmental contaminant having both anthropogenic and natural sources. Stable isotope ratios of O and Cl in a given sample of perchlorate may be used to distinguish its source(s). Isotopic ratios may also be useful for identifying the extent of biodegradation of perchlorate, which is critical for assessing natural attenuation of this contaminant in groundwater. For this approach to be useful, however, the kinetic isotopic fractionations of O and Cl during perchlorate biodegradation must first be determined as a function of environmental variables such as temperature and bacterial species. A laboratory study was performed in which the O and Cl isotope ratios of perchlorate were monitored as a function of degradation by two separate bacterial strains (Azospira suillum JPLRND and Dechlorospirillum sp. FBR2) at both 10 degrees C and 22 degrees C with acetate as the electron donor. Perchlorate was completely reduced by both strains within 280 h at 22 degrees C and 615 h at 10 degrees C. Measured values of isotopic fractionation factors were epsilon(18)O = -36.6 to -29.0% per hundred and epsilon(37)Cl = -14.5 to -11.5% per hundred, and these showed no apparent systematic variation with either temperature or bacterial strain. An experiment using (18)O-enriched water (delta(18)O = +198% per hundred) gave results indistinguishable from those observed in the isotopically normal water (delta(18)O = -8.1% per hundred) used in the other experiments, indicating negligible isotope exchange between perchlorate and water during biodegradation. The fractionation factor ratio epsilon(18)O/epsilon(37)Cl was nearly invariant in all experiments at 2.50 +/- 0.04. These data indicate that isotope ratio analysis will be useful for documenting perchlorate biodegradation in soils and groundwater. The establishment of a microbial fractionation factor ratio (epsilon(18)O/ epsilon(37)Cl) also has significant implications for forensic studies.
Neil C Sturchio; John Karl Böhlke; Abelardo D Beloso; Sheryl H Streger; Linnea J Heraty; Paul B Hatzinger
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Environmental science & technology     Volume:  41     ISSN:  0013-936X     ISO Abbreviation:  Environ. Sci. Technol.     Publication Date:  2007 Apr 
Date Detail:
Created Date:  2007-05-30     Completed Date:  2007-06-21     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0213155     Medline TA:  Environ Sci Technol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2796-802     Citation Subset:  IM    
University of Illinois at Chicago, Chicago, Illinois 60607, USA.
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MeSH Terms
Biodegradation, Environmental*
Chlorine / chemistry*
Environmental Monitoring / methods*
Forensic Sciences / methods*
Oxygen / chemistry*
Perchloric Acid / chemistry*
Water Pollutants, Chemical / chemistry
Reg. No./Substance:
0/Isotopes; 0/Water Pollutants, Chemical; 7601-90-3/Perchloric Acid; 7782-44-7/Oxygen; 7782-50-5/Chlorine
Comment In:
Environ Sci Technol. 2007 Apr 15;41(8):2654   [PMID:  17533816 ]

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