Grantee Research Project Results
2001 Progress Report: Investigating Microbial Degradation of Polychlorinated Biphenyls Using Molecular Isotopes
EPA Grant Number: R828161Title: Investigating Microbial Degradation of Polychlorinated Biphenyls Using Molecular Isotopes
Investigators: Eglinton, Timothy I. , Reddy, Christopher M. , Wirsen, Carl O.
Current Investigators: Reddy, Christopher M. , Eglinton, Timothy I. , Wirsen, Carl O.
Institution: Woods Hole Oceanographic Institution
EPA Project Officer: Aja, Hayley
Project Period: July 7, 2000 through September 30, 2003
Project Period Covered by this Report: July 7, 2000 through September 30, 2001
Project Amount: $196,743
RFA: Exploratory Research - Engineering, Chemistry, and Physics) (1999) RFA Text | Recipients Lists
Research Category: Water , Air , Safer Chemicals , Land and Waste Management
Objective:
The objective of this research project is to investigate whether changes in the carbon, hydrogen, and chlorine isotopic composition of polychlorinated biphenyls (PCBs) can be used to study the microbial degradation of these compounds.Progress Summary:
In the summer of 2000, we started a laboratory culture that would reductively dechlorinate 2,3,4,5-tetrachlorobiphenyl (2,3,4,5-CB). After 3 months, approximately 90 percent of the latter congener was degraded to 2,3,5-trichlorobiphenyl (2,3,5-CB). Over the course of the experiment, we removed samples to monitor changes in the concentration as well as the isotopic composition of the products and reactants. So far, all of the samples have been analyzed for carbon isotopes, and we found that little or no isotopic fractionation of carbon occurred. Fortunately, we believe this may be a very useful tool because of systematic internal variations in the d13C values of congeners in Aroclors, which generally decrease with the number of chlorines per biphenyl. That is, the lower chlorinated PCBs are more enriched in 13C than the higher chlorinated PCBs. Thus, if these laboratory results accurately reflect what occurs in the field, then microbial reductive dechlorination will create congeners with more negative d13C values than native PCBs exhibiting the same degree of chlorination. Preliminary analysis of field samples from the Hudson River confirms this hypothesis. The chlorine and hydrogen isotopic measurements for this experiment are underway and should be available shortly.In addition, we have performed a series of dehydrochlorination reactions of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) to 2,2-bis(p-chlorophenyl)-1,1-dichloroethene (DDE). We thought this would be an excellent opportunity to compare the magnitude of isotope effects for abiotic versus biotic reactions. We found that this reaction produces a substantial chlorine isotope effect and that we may be able to trace this reaction in sediment porewater. This work was published in Environmental Science and Pollution Research.
To determine the isotopic characteristics of other semivolatile halogenated compounds (toxaphene, chlordane, mirex, etc.), we analyzed several of these different compounds for both their stable carbon and chlorine isotope ratios. We found that there were significant differences in the bulk isotopic composition of these compounds. In particular, we observed that compounds synthesized from hexachlorocyclopentadiene (chlordane, heptachlor, mirex) had the most enriched chlorine isotope ratios relative to other halogenated compounds. This work was recently accepted for publication in Organic Geochemistry.
Future Activities:
Future efforts will be focused mainly on analyzing field samples from the Hudson River, New Bedford Harbor, and Turtle River Estuary. We expect that several additional manuscripts on the field samples will result as well as publications on the chlorine and hydrogen isotope data from the incubation experiment.Journal Articles on this Report : 3 Displayed | Download in RIS Format
| Other project views: | All 6 publications | 3 publications in selected types | All 3 journal articles |
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Drenzek NJ, Eglinton TI, Wirsen CO, May HD, Wu Q, Sowers KR, Reddy CM. The absence and application of stable carbon isotopic fractionation during the reductive dechlorination of polychlorinated biphenyls. Environmental Science & Technology 2001;35(16):3310-3313. |
R828161 (2001) |
not available |
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Drenzek NJ, Tarr CH, Eglinton TI, Heraty LJ, Sturchio NC, Shiner VJ, Reddy CM. Stable chlorine and carbon isotopic compositions of selected semi-volatile organochlorine compounds. Organic Geochemistry 2002;33(4):437-444. |
R828161 (2001) |
not available |
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Reddy CM, Drenzek NJ, Eglinton TI, Heraty LJ, Sturchio NC, Shiner VJ. Stable chlorine intramolecular kinetic isotope effects from the abiotic dehydrochlorination of DDT. Environmental Science and Pollution Research International 2002;9(3):183-186, published online DOI: http://dx.doi.org/10.1065/espr2001.05.066. |
R828161 (2001) |
not available |
Supplemental Keywords:
isotopes, polychlorinated biphenyls, PCBs, microbial degradation., Air, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Water, Waste, Toxics, Fate & Transport, HAPS, Environmental Chemistry, Engineering, Chemistry, & Physics, Contaminated Sediments, EPCRA, chemical transport modeling, Chlorine, microbial degradation, stable isotope, contaminated sediment, hydrogen, chemical composition, fate and transport, carbon aerosols, chemical kinetics, reductive dehalogenation, PCBsRelevant Websites:
http://www.whoi.edu/science/MCG/people/creddy/index.html
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.