DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: In situ decay of polyfluorinated benzoic acids under anaerobic conditions

Journal Article · · Journal of Contaminant Hydrology
 [1];  [2];  [2];  [3]; ORCiD logo [4]
  1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Earth and Planetary Sciences; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division
  3. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Earth and Planetary Sciences
  4. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Earth and Planetary Sciences. Dept. of Civil and Environmental Engineering. Dept. of Microbiology. Center for Environmental Biotechnology. Inst. for a Secure and Sustainable Environment; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division

Polyfluorinated benzoic acids (PBAs) can be used as non-reactive tracers to characterize reactive mass transport mechanisms in groundwater. The use of PBAs as non-reactive tracers assumes that their reactivities are negligible. If this assumption is not valid, PBAs may not be appropriate to use as non-reactive tracers. In this study, the reactivity of two PBAs, 2,6-difluorobenzoic acid (2,6-DFBA) and pentafluorobenzoic acid (PFBA), was tested in situ. A series of two single-well push-pull tests were conducted in two hydrogeologically similar, yet spatially distinct, groundwater monitoring wells. Bromide, 2,6-DFBA, and PFBA were added to the injection fluid and periodically measured in the extraction fluid along with chloride, nitrate, sulfate, and fluoride. Linear regression of the dilution-adjusted breakthrough curves of both PBAs indicated zero-order decay accompanied by nitrate and subsequent sulfate removal. The dilution-adjusted breakthrough curves of chloride, a non-reactive halide similar to bromide, showed no evidence of reactivity. These results strongly suggested that biodegradation of both PBAs occurred under anaerobic conditions. The results of this study implied that PBAs may not be appropriate to use as non-reactive tracers in certain hydrogeologic settings, presumably those where they can serve as carbon and/or electron donors to stimulate microbial activity. Future studies would benefit from using ring-14C-labeled PBAs to determine the fate of carbon combined with microbial analyses to characterize the PBA-degrading members of the microbial community.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Biological and Environmental Research (BER); Geological Society of America; USDOE
Grant/Contract Number:
AC05-00OR22725; AC02-05CH11231; 11472-16
OSTI ID:
1468668
Alternate ID(s):
OSTI ID: 1479446; OSTI ID: 1479741
Journal Information:
Journal of Contaminant Hydrology, Vol. 217; ISSN 0169-7722
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English