Methane production and consumption monitored by stable H and C isotope ratios at a crude oil spill site, Bemidji, Minnesota

Révész, Kinga; Coplen, Tyler B.; Baedecker, Mary Jo; Glynn, Pierre D.; Hult, Marc F.

doi:10.1016/0883-2927(95)00021-6

Cited by 99 publications

(79 citation statements)

References 27 publications

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“…At the same time, the sulfate and sulfide concentrations in M-24 also dropped, but the decrease in sulfate was not as pronounced as in M-21. The small fractionation between the δ 34 S values of sulfate and sulfide (to <2‰) in these wells during this time period is a clear indication of sulfate limitation (17,21). This is also the time period during which the U(VI) concentrations rebounded to near background levels (Figure 2h).…”

Section: Resultsmentioning

confidence: 87%

“…Stable isotope studies have illustrated the benefit of using isotopic measurements to track the biological removal of contaminant species while separating out the effects of transport in through-flowing systems (17)(18)(19)(20). Recent studies have also demonstrated enrichment of 238 U relative to 235 U in residual U(VI) during microbial uranium reduction (21).…”

Section: Introductionmentioning

confidence: 99%

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Sulfur Isotopes as Indicators of Amended Bacterial Sulfate Reduction Processes Influencing Field Scale Uranium Bioremediation

Druhan

Conrad

Williams

et al. 2008

Environ. Sci. Technol.

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Aqueous uranium (U(VI)) concentrations in a contaminated aquifer in Rifle Colorado have been successfully lowered through electron donor amended bioreduction. Samples collected during the acetate amendment experiment were analyzed for aqueous concentrations of Fe(II), sulfate, sulfide, acetate, U(VI), and δ34S of sulfate and sulfide to explore the utility of sulfur isotopes as indicators of in situ acetate amended sulfate and uranium bioreduction processes. Enrichment of up to 7‰ in δ34S of sulfate in down-gradient monitoring wells indicates a transition to elevated bacterial sulfate reduction. A depletion in Fe(II), sulfate, and sulfide concentrations at the height of sulfate reduction, along with an increase in the δ34S of sulfide to levels approaching the δ34S values of sulfate, indicates sulfate limited conditions concurrent with a rebound in U(VI) concentrations. Upon cessation of acetate amendment, sulfate and sulfide concentrations increased, while δ34S values of sulfide returned to less than −20‰ and sulfate δ34S decreased to near-background values, indicating lower levels of sulfate reduction accompanied by a corresponding drop in U(VI). Results indicate a transition between electron donor and sulfate-limited conditions at the height of sulfate reduction and suggest stability of biogenic FeS precipitates following the end of acetate amendment.

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Section: Resultsmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Sulfur Isotopes as Indicators of Amended Bacterial Sulfate Reduction Processes Influencing Field Scale Uranium Bioremediation

Druhan

Conrad

Williams

et al. 2008

Environ. Sci. Technol.

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“…No significant carbon isotope fractionation was observed during degradation of aromatic (17) and polyaromatic (18) hydrocarbons. In contrast, a large carbon isotope fractionation occurs during production (19) and oxidation (20) of methane in aquifers. In a recent study, a small chloride isotope fractionation during oxidation of TCE has been reported (21).…”

Section: Introductionmentioning

confidence: 99%

Monitoring Microbial Dechlorination of Tetrachloroethene (PCE) in Groundwater Using Compound-Specific Stable Carbon Isotope Ratios: Microcosm and Field Studies

Hunkeler

Aravena

Butler

1999

Environ. Sci. Technol.

299

313

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The determination of compound-specific stable isotope ratios is a promising new tool to assess biodegradation of organic compounds in groundwater. In this study, the occurrence of carbon isotope fractionation during dechlorination of tetrachloroethene (PCE) to ethene was evaluated in a PCE-contaminated aquifer and in a microcosm that was based on aquifer material from the site. In the microcosm, all dechlorination steps were accompanied by carbon isotope fractionation. The largest fractionation occurred during dechlorination of cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC), resulting in a large enrichment of 13 C in the remaining cDCE and VC. Stable carbon isotope ratios (δ 13 C) of cDCE and VC increased from -25.7 to -1.5‰ and -37.0 to -2.5‰, respectively. The δ 13 C of ethene was initially -60.2‰ and approached the δ 13 C of the added PCE (-27.3‰) as dechlorination came to completion. A similar carbon isotope pattern was observed for PCE dechlorination at the field site. Strong enrichment of 13 C in cDCE and VC during microbial dechlorination may serve as a powerful tool to monitor the last two dechlorination steps, which frequently determine the rate of complete dechlorination of chlorinated ethenes at field sites undergoing intrinsic bioremediation.

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“…In the model, all CO 2 and CH 4 produced from the biodegradation of BEX, toluene, and NVDOC enter the aqueous solution, unlike from n-alkane biodegradation in the oil body, which generates direct outgassing. However, aqueous plumes of CO 2 and CH 4 are strongly controlled by their outgassing, which has been found to occur based on dissolved gas measurements [Revesz et al, 1995;Amos et al, 2005]. Following the degassing batch model implemented in Amos et al [2005], we allow outgassing to occur in the model once the sum of the partial pressures of CO 2 , CH 4 , and N 2 reaches 0.93 atm, the average atmospheric pressure at 425 m elevation.…”

Section: Direct Outgassing Adjacent To the Oil Bodymentioning

confidence: 99%

“…Amos et al [2005] required 4 times more CO 2 input than CH 4 to match observed partial pressure values in their degassing batch model. Revesz et al [1995] calculated from isotopic fractionation measurements an unexplained 2.4 times more CO 2 produced than CH 4 consumed by oxidation. Excess ratios of CO 2 to CH 4 can occur if methanogenic degradation is partially stalled at intermediary stages, although site data supporting this mechanism are not available.…”

Section: Direct Outgassing Adjacent To the Oil Bodymentioning

confidence: 99%

Reactive transport modeling of geochemical controls on secondary water quality impacts at a crude oil spill site near Bemidji, MN

Bekins

Cozzarelli

et al. 2015

Water Resources Research

131

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Anaerobic biodegradation of organic amendments and contaminants in aquifers can trigger secondary water quality impacts that impair groundwater resources. Reactive transport models help elucidate how diverse geochemical reactions control the spatiotemporal evolution of these impacts. Using extensive monitoring data from a crude oil spill site near Bemidji, Minnesota (USA), we implemented a comprehensive model that simulates secondary plumes of depleted dissolved O 2 and elevated concentrations of Mn 21 , Fe 21 , CH 4 , and Ca 21 over a two-dimensional cross section for 30 years following the spill. The model produces observed changes by representing multiple oil constituents and coupled carbonate and hydroxide chemistry. The model includes reactions with carbonates and Fe and Mn mineral phases, outgassing of CH 4 and CO 2 gas phases, and sorption of Fe, Mn, and H 1 . Model results demonstrate that most of the carbon loss from the oil (70%) occurs through direct outgassing from the oil source zone, greatly limiting the amount of CH 4 cycled down-gradient. The vast majority of reduced Fe is strongly attenuated on sediments, with most (91%) in the sorbed form in the model. Ferrous carbonates constitute a small fraction of the reduced Fe in simulations, but may be important for furthering the reduction of ferric oxides. The combined effect of concomitant redox reactions, sorption, and dissolved CO 2 inputs from source-zone degradation successfully reproduced observed pH. The model demonstrates that secondary water quality impacts may depend strongly on organic carbon properties, and impacts may decrease due to sorption and direct outgassing from the source zone.

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Methane production and consumption monitored by stable H and C isotope ratios at a crude oil spill site, Bemidji, Minnesota

Cited by 99 publications

References 27 publications

Sulfur Isotopes as Indicators of Amended Bacterial Sulfate Reduction Processes Influencing Field Scale Uranium Bioremediation

Sulfur Isotopes as Indicators of Amended Bacterial Sulfate Reduction Processes Influencing Field Scale Uranium Bioremediation

Monitoring Microbial Dechlorination of Tetrachloroethene (PCE) in Groundwater Using Compound-Specific Stable Carbon Isotope Ratios: Microcosm and Field Studies

Reactive transport modeling of geochemical controls on secondary water quality impacts at a crude oil spill site near Bemidji, MN

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