Variations in expression of carbon isotope fractionation of chlorinated ethenes during biologically enhanced PCE dissolution close to a source zone

Morrill, Penny L.; Sleep, Brent E.; Seepersad, David J.; McMaster, Michaye L.; Hood, E.; Lebrón, Carmen; Major, D. J.; Edwards, Elizabeth A.; Lollar, Barbara Sherwood

doi:10.1016/j.jconhyd.2009.08.006

Cited by 31 publications

(15 citation statements)

References 57 publications

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“…However, the modeled isotope values of TCE could not be reconciled with reported d 13 C TCE ranges and enrichment factors (Hunkeler et al, 2008;Meckenstock et al, 2004;Shouakar-Stash et al, 2003). Such situations e i.e., when isotope values for TCE observed in the field are more negative than expected e this is typically attributed to the mixing of a residual fraction of TCE that was exposed to degradation (more positive) with non-degraded original contaminant TCE (Hunkeler et al, 1999;Morrill et al, 2005Morrill et al, , 2009Song et al, 2002). This evidence of inflow of non-degraded TCE indicated that contaminants in the hotspot were continuously introduced from a separate phase source.…”

Section: Evidence Of Fresh Contaminant Inputmentioning

confidence: 84%

Combined isotope and enantiomer analysis to assess the fate of phenoxy acids in a heterogeneous geologic setting at an old landfill

et al. 2013

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Section: Evidence Of Fresh Contaminant Inputmentioning

confidence: 84%

Combined isotope and enantiomer analysis to assess the fate of phenoxy acids in a heterogeneous geologic setting at an old landfill

et al. 2013

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“…While isotope fractionation revealed biodegradation of benzene only in the fringe of the plume, it was also detected in the highly contaminated zone using the BAC-TRAP approach. Thus, it can be concluded that the dissolution of benzene from the source led to an underestimation of benzene biodegradation in highly contaminated zones, as also observed at other contaminated field sites (Hunkeler et al 1999;Song et al 2002;Morrill et al 2009). …”

Section: Csia Cumulated Biodegradation Approachmentioning

confidence: 52%

“…Conclusive isotopic evidence for biodegradation of chlorinated ethenes was found to be difficult to detect close to source zones (Hunkeler et al 1999;Song et al 2002;Morrill et al 2009), since the influx of newly dissolved non-isotope-fractionated contaminants leads to an observed lack of continual isotopic enrichment trends. Morrill et al (2009) reported that isotopic fractionation was not affected by dissolution within a PCE plume down-gradient from the source but was affected close to the source, where no significant isotope shift associated with reductive dechlorination was observed. Thus, practical users of CSIA have to consider that the dissolution of contaminants may lead to underestimation or even apparent absence of biodegradation near NAPL sources.…”

Section: Dissolution Of Napl Sourcesmentioning

confidence: 99%

“…Furthermore, the isotope effects associated with physical processes such as diffusion, volatilization, and sorption may in some cases not be negligible (LaBolle et al 2008;Kopinke et al 2005a;Kuder et al 2009;Bouchard et al 2008a, b). It may even be difficult to account for the impact of non-isotopefractionating processes on observed contaminant concentrations and isotope ratios in aquifers, such as dilution/dispersion/mixing and dissolution from non-aqueous phase liquid (NAPL) sources (Fischer et al 2007;Morrill et al 2009;Green et al 2010). For application of the Rayleigh equation in open field systems, the definition of a hypothetical "closed system" is of critical importance for quantification of biodegradation (Thullner et al 2012).…”

Section: Introductionmentioning

confidence: 99%

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Field applicability of Compound-Specific Isotope Analysis (CSIA) for characterization and quantification of in situ contaminant degradation in aquifers

Braeckevelt

Fischer

Kästner

2012

Appl Microbiol Biotechnol

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Microbial processes govern the fate of organic contaminants in aquifers to a major extent. Therefore, the evaluation of in situ biodegradation is essential for the implementation of Natural Attenuation (NA) concepts in groundwater management. Laboratory degradation experiments and biogeochemical approaches are often biased and provide only indirect evidence of in situ degradation potential. Compound-Specific Isotope Analysis (CSIA) is at present among the most promising tools for assessment of the in situ contaminant degradation within aquifers. One- and two-dimensional (2D) CSIA provides qualitative and quantitative information on in situ contaminant transformation; it is applicable for proving in situ degradation and characterizing degradation conditions and reaction mechanisms. However, field application of CSIA is challenging due to a number of influencing factors, namely those affecting the observed isotope fractionation during biodegradation (e.g., non-isotope-fractionating rate-limiting steps, limited bioavailability), potential isotope effects caused by processes other than biodegradation (e.g., sorption, volatilization, diffusion), as well as non-isotope-fractionating physical processes such as dispersion and dilution. This mini-review aims at guiding practical users towards the sound interpretation of CSIA field data for the characterization of in situ contaminant degradation. It focuses on the relevance of various constraints and influencing factors in CSIA field applications and provides advice on when and how to account for these constraints. We first evaluate factors that can influence isotope fractionation during biodegradation, as well as potential isotope-fractionating and non-isotope-fractionating physical processes governing observed isotope fractionation in the field. Finally, the potentials of the CSIA approach for site characterization and the proper ways to account for various constraints are illustrated by means of a comprehensive CSIA field study at the benzene, toluene, ethylbenzene, and xylene (BTEX)-contaminated site Zeitz.

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“…Due to their toxicity and suspected carcinogenic properties, monitoring the remediation of this group of contaminants has gained wide public and academic interest. In addition to the conventional methods focusing on identification and quantification of parent substrates and dehalogenated products, compound specific isotope analysis (CSIA) has been increasingly applied to monitor transformation of chlorinated contaminants (Hunkeler et al 1999;Sherwood Lollar et al 1999;Bloom et al 2000;Elsner et al 2004;Aeppli et al 2009;Morrill et al 2009;Schmidt et al 2010). Isotope ratio analysis of in situ contaminants involves the use of enrichment factors, generally obtained from lab-scale studies, to quantitatively estimate the fraction of contaminants transformed at a site (Elsner et al 2005;Van Breukelen et al 2005;VanStone et al 2005;Nijenhuis et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Impacts of microbial community composition on isotope fractionation during reductive dechlorination of tetrachloroethylene

et al. 2010

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Isotope fractionation has been used with increasing frequency as a tool to quantify degradation of chlorinated aliphatic pollutants in the environment. The objective of this research was to determine if the electron donor present in enrichment cultures prepared from uncontaminated sediments influenced the extent of isotope fractionation of tetrachloroethylene (PCE), either directly, or through its influence on microbial community composition. Two PCE-degrading enrichment cultures were prepared from Duck Pond (DP) sediment and were incubated with formate (DPF) or H(2) (DPH) as electron donor. DPF and DPH were significantly different in both product distribution and extent of isotope fractionation. Chemical and isotope analyses indicated that electron donors did not directly affect the product distribution or the extent of isotope fractionation for PCE reductive dechlorination. Instead, restriction fragment length polymorphism (RFLP) and sequence analysis of the 16S rRNA clone libraries of DPF and DPH identified distinct microbial communities in each enrichment culture, suggesting that differences in microbial communities were responsible for distinct product distributions and isotope fractionation between the two cultures. A dominant species identified only in DPH was closely related to known dehalogenating species (Sulfurospirillum multivorans and Sulfurospirillum halorespirans) and may be responsible for PCE degradation in DPH. Our study suggests that different dechlorinators exist at the same site and can be preferentially stimulated by different electron donors, especially over the long-term (i.e., years), typical of in-situ ground water remediation.

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Variations in expression of carbon isotope fractionation of chlorinated ethenes during biologically enhanced PCE dissolution close to a source zone

Cited by 31 publications

References 57 publications

Combined isotope and enantiomer analysis to assess the fate of phenoxy acids in a heterogeneous geologic setting at an old landfill

Combined isotope and enantiomer analysis to assess the fate of phenoxy acids in a heterogeneous geologic setting at an old landfill

Field applicability of Compound-Specific Isotope Analysis (CSIA) for characterization and quantification of in situ contaminant degradation in aquifers

Impacts of microbial community composition on isotope fractionation during reductive dechlorination of tetrachloroethylene

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