Carbon and hydrogen isotope fractionation resulting from anaerobic methane oxidation

Alperin, Marc J.; Reeburgh, William S.; Whiticar, Michael J.

doi:10.1029/gb002i003p00279

Cited by 331 publications

(228 citation statements)

References 43 publications

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“…Furthermore, aerobic and anaerobic oxidation of methane is known to be accompanied by a large hydrogen isotope fractionation with isotopic enrichment factors between -95 and -285‰ (41,42). The hydrogen isotope fractionation during benzene oxidation is smaller than that during anaerobic toluene degradation and methane oxidation.…”

Section: Discussionmentioning

confidence: 99%

Hydrogen and Carbon Isotope Fractionation during Aerobic Biodegradation of Benzene

Hunkeler

Andersen

Aravena

et al. 2001

Environ. Sci. Technol.

163

112

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The main aim of the study was to evaluate hydrogen and carbon isotope fractionation during biodegradation of benzene as a possible tool to trace the process in contaminated environments. Aerobic biodegradation of benzene by two bacterial isolates, Acinetobacter sp. and Burkholderia sp., was accompanied by significant hydrogen and carbon isotope fractionation with hydrogen isotope enrichment factors of -12.8 ( 0.7‰ and -11.2 ( 1.8‰, respectively, and average carbon isotope enrichment factors of -1.46 ( 0.06‰ and -3.53 ( 0.26‰, respectively. Inorganic carbon produced by Acinetobacter sp. was depleted in 13 C by 3.6-6.2‰ as compared to the initial δ 13 C of benzene, while the produced biomass was enriched in 13 C by 3.8‰. The secondary aim was to determine isotope ratios of benzenes from different manufacturers with regard to the use of isotopes for source differentiation. While two of the four analyzed benzenes had similar δ 13 C values, each of them had a distinct δ 2 H-δ 13 C pair and δ 2 H values spread over a range of 66.5‰. Thus, combined analyses of hydrogen and carbon isotopes may be a more promising approach to trace sources and/or biodegradation of benzene than measuring carbon isotopes only.

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Section: Discussionmentioning

confidence: 99%

Hydrogen and Carbon Isotope Fractionation during Aerobic Biodegradation of Benzene

Hunkeler

Andersen

Aravena

et al. 2001

Environ. Sci. Technol.

163

112

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“…These calculations enabled us to then determine the rates of methanogenesis at each depth by inserting these rates into the DI 12 C equation. The rates were constrained using the best fit of the d 13 C DIC profile and a fractionation factor for methanogenesis of 60% (after Nü sslein et al 2001) and one for methanotrophy of 10% (after Barker and Fritz 1981;Alperin et al 1988). Two scenarios were examined in the model: only methanogenesis throughout the sediments, and methanogenesis in the upper sediment section and methanotrophy in the lower sediment section.…”

Section: Methodsmentioning

confidence: 99%

“…In marine environments where sulfate is consumed largely through AOM, which can be tens of meters below the sediment-water interface , SO 2{ 4 has a linear diffusion profile toward the zone of AOM (Niewö hner et al 1998). Significant AOM results in 13 C-depleted DIC and slightly higher d 13 C values of the residual CH 4 due to a small fractionation of 0% to 10% during CH 4 oxidation (Alperin et al 1988;Martens et al 1999).…”

mentioning

confidence: 97%

Quantifying rates of methanogenesis and methanotrophy in Lake Kinneret sediments (Israel) using pore‐water profiles

Adler

Eckert

Sivan

2011

Limnology & Oceanography

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Full seasonal sets of chemical and isotope profiles from the pore water of Lake Kinneret (Sea of Galilee, Israel) were produced to study methanogenesis and methanotrophy processes and the couplings between methane (CH 4 ), sulfur, and iron. Sulfate is depleted within the upper 10 cm of the sediment mainly by traditional bacterial sulfate reduction by organic matter. Maximum sulfate reduction rates calculated from sulfate concentration profiles are found at the water-sediment interface (0-1 cm 2 1.4 3 10 212 6 0.2 3 10 212 mol cm 23 s 21 ). CH 4 concentrations and modeling of dissolved inorganic carbon (DIC) and its stable carbon isotope (d 13 C DIC ) suggest that maximum methanogenesis rates of 2.5 3 10 213 6 1.5 3 10 213 mol cm 23 s 21 occur at 5-12-cm depth in the sediments, and that it ends at 20 cm. Of the produced CH 4 , 50-75% is converted to gas bubbles of CH 4 before it reaches the bottom water. Model results suggest the occurrence of anaerobic oxidation of CH 4 (AOM) in the deep sediments of the lake below the zone of methanogenesis.

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“…The slight enrichment in δ 13 C-CH 4 and depletion in δ 13 C-CO 2 suggest that these gases may be trapped for extended periods of time, and serve as reservoirs of methane to microbial communities performing AOM. Anaerobic oxidation of methane typically leads to an enrichment in δ 13 C of CH 4 and a depletion in δ 13 C of CO 2 (Alperin et al 1988). The observation of enriched δ 13 C-CH 4 and depleted δ 13 C-CO 2 in the trapped gas strongly suggests that these bubbles serve as a reservoir, and equilibrate with dissolved CH 4 and DIC.…”

Section: Subsurface Gas Pocketsmentioning

confidence: 99%

Gas flux and carbonate occurrence at a shallow seep of thermogenic natural gas

et al. 2010

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The Coal Oil Point seep field located offshore Santa Barbara, CA, consists of dozens of named seeps, including a peripheral ∼200 m 2 area known as Brian Seep, located in 10 m water depth. A single comprehensive survey of gas flux at Brian Seep yielded a methane release rate of ∼450 moles of CH 4 per day, originating from 68 persistent gas vents and 23 intermittent vents, with gas flux among persistent vents displaying a log normal frequency distribution. A subsequent series of 33 repeat surveys conducted over a period of 6 months tracked eight persistent vents, and revealed substantial temporal variability in gas venting, with flux from each individual vent varying by more than a factor of 4. During wintertime surveys sediment was largely absent from the site, and carbonate concretions were exposed at the seafloor. The presence of the carbonates was unexpected, as the thermogenic seep gas contains 6.7% CO 2 , which should act to dissolve carbonates. The average δ 13 C of the carbonates was −29.2±2.8‰ VPDB, compared to a range of −1.0 to +7.8‰ for CO 2 in the seep gas, indicating that CO 2 from the seep gas is quantitatively not as important as 13 Cdepleted bicarbonate derived from methane oxidation. Methane, with a δ 13 C of approximately −43‰, is oxidized and the resulting inorganic carbon precipitates as highmagnesium calcite and other carbonate minerals. This finding is supported by 13 C-depleted biomarkers typically associated with anaerobic methanotrophic archaea and their bacterial syntrophic partners in the carbonates (lipid biomarker δ 13 C ranged from −84 to −25‰). The inconsistency in δ 13 C between the carbonates and the seeping CO 2 was resolved by discovering pockets of gas trapped near the base of the sediment column with δ 13 C-CO 2 values ranging from −26.9 to −11.6‰. A mechanism of carbonate formation is proposed in which carbonates form near the sediment-bedrock interface during times of sufficient sediment coverage, in which anaerobic oxidation of methane is favored. Precipitation occurs at a sufficient distance from active venting for the molecular and isotopic composition of seep gas to be masked by the generation of carbonate alkalinity from anaerobic methane oxidation.

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Carbon and hydrogen isotope fractionation resulting from anaerobic methane oxidation

Cited by 331 publications

References 43 publications

Hydrogen and Carbon Isotope Fractionation during Aerobic Biodegradation of Benzene

Hydrogen and Carbon Isotope Fractionation during Aerobic Biodegradation of Benzene

Quantifying rates of methanogenesis and methanotrophy in Lake Kinneret sediments (Israel) using pore‐water profiles

Gas flux and carbonate occurrence at a shallow seep of thermogenic natural gas

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