Doubly substituted isotopologues of methane hydrate (13CH3D and 12CH2D2): Implications for methane clumped isotope effects, source apportionments and global hydrate reservoirs

Zhang, Naizhong; Snyder, G. T.; Lin, Mang; Nakagawa, Mayuko; Gilbert, Alexis; Yoshida, Naohiro; Matsumoto, Ryo; Sekine, Yasuhito

doi:10.1016/j.gca.2021.08.027

Cited by 26 publications

(23 citation statements)

References 119 publications

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“…S10). Recent reevaluations of slowly forming biogenic methane sources such as marine sediments, coal beds, or shale gas deposits revealed that apparent CH 4 -CO 2 and CH 4 -H 2 O isotopic equilibrium is common (20,41,43,(63)(64)(65). We used our model to study the isotopic effects in these settings by adopting enzyme kinetic parameters obtained from methanogens grown under energy limitation.…”

Section: Isotopic Fractionation In Energy-limited Environmentsmentioning

confidence: 99%

Controls on the isotopic composition of microbial methane

2022

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Microbial methane production (methanogenesis) is responsible for more than half of the annual emissions of this major greenhouse gas to the atmosphere. Although the stable isotopic composition of methane is often used to characterize its sources and sinks, strictly empirical descriptions of the isotopic signature of methanogenesis currently limit these attempts. We developed a metabolic-isotopic model of methanogenesis by carbon dioxide reduction, which predicts carbon and hydrogen isotopic fractionations, and clumped isotopologue distributions, as functions of the cell’s environment. We mechanistically explain multiple isotopic patterns in laboratory and natural settings and show that these patterns constrain the in situ energetics of methanogenesis. Combining our model with data from environments in which methanogenic activity is energy-limited, we provide predictions for the biomass-specific methanogenesis rates and the associated isotopic effects.

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Section: Isotopic Fractionation In Energy-limited Environmentsmentioning

confidence: 99%

Controls on the isotopic composition of microbial methane

2022

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“…Further studies should include culture experiments with different substrates and electron acceptors as well as the analysis of the ion concentrations in the samples (especially sulfate, nitrate and iron species) to determine their role in hydrocarbon production and consumption. Finally, the study should be pursued including newly developed isotopologue measurements such as the 13 C− 13 C isotopologue of ethane [ 17 , 18 , 47 ] and the 13 CH 3 D and CH 2 D 2 isotopologues of methane [ 14 , 15 , 34 , 48 ]. These new tracers are currently used to understand the sources and sinks of hydrocarbons.…”

Section: Discussionmentioning

confidence: 99%

“…The bulk δD isotope values of CH 4 were analyzed using a Thermo 253 Ultra Isotope Ratio Mass Spectrometer (Ultra-IRMS; Thermo Fisher Scientific Inc.) at Tokyo Institute of Technology. Sample preparation and analytical protocols followed the exact same procedures as described in [ 34 ], which is briefly listed here. Approximately 4–6 mL mud volcano sample was purified using a gas chromatograph (GC-4000, GL-Science) with He as the carrier gas.…”

Section: Methodsmentioning

confidence: 99%

Hydrocarbon Cycling in the Tokamachi Mud Volcano (Japan): Insights from Isotopologue and Metataxonomic Analyses

et al. 2022

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Understanding hydrocarbon cycling in the subsurface is important in various disciplines including climate science, energy resources and astrobiology. Mud volcanoes provide insights into biogeochemical processes occurring in the subsurface. They are usually associated with natural gas reservoirs consisting mainly of methane and other hydrocarbons as well as CO2. Stable isotopes have been used to decipher the sources and sinks of hydrocarbons in the subsurface, although the interpretation can be ambiguous due to the numerous processes involved. Here we report new data for hydrocarbon isotope analysis, including position-specific isotope composition of propane, for samples from the Tokamachi mud volcano area, Japan. The data suggest that C2+ hydrocarbons are being biodegraded, with indirect production of methane (“secondary methanogenesis”). Data from chemical and isotopic composition are discussed with regard to 16S rRNA analysis, which exhibits the presence of hydrogenotrophic and acetoclastic methoanogens. Overall, the combination of isotopologue analysis with 16S rRNA gene data allows refining of our understanding of hydrocarbon cycling in subsurface environments.

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“…S9). Recent reevaluations of slowly forming biogenic methane sources such as marine sediments, coalbeds or shale gas deposits, revealed that apparent CH 4 -CO 2 and CH 4 -H 2 O isotopic equilibrium is common (8,25,(37)(38)(39)(40). There are currently no laboratory cultures that reproduce the isotopic effects associated with these conditions.…”

Section: Isotopic Fractionation In Energy-limited Environmentsmentioning

confidence: 99%

Controls on the isotopic composition of microbial methane

Gropp

Jin

Halevy

2021

Preprint

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Microbial methane production (methanogenesis) is responsible for more than half of the annual emission of this major greenhouse gas to the atmosphere. Though the stable isotopic composition of methane is often used to characterize its sources and sinks, empirical descriptions of the isotopic signature of methanogenesis currently limit such attempts. We developed a biochemical-isotopic model of methanogenesis by CO2 reduction, which predicts carbon and hydrogen isotopic fractionations, and clumped isotopologue distributions, as functions of the cell's environment. We mechanistically explain multiple-isotopic patterns in laboratory and natural settings and show that such patterns constrain the in-situ energetics of methanogenesis. Combining our model with environmental data, we infer that in almost all marine environments and gas deposits, energy-limited methanogenesis operates close to chemical and isotopic equilibrium.

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Doubly substituted isotopologues of methane hydrate (13CH3D and 12CH2D2): Implications for methane clumped isotope effects, source apportionments and global hydrate reservoirs

Cited by 26 publications

References 119 publications

Controls on the isotopic composition of microbial methane

Controls on the isotopic composition of microbial methane

Hydrocarbon Cycling in the Tokamachi Mud Volcano (Japan): Insights from Isotopologue and Metataxonomic Analyses

Controls on the isotopic composition of microbial methane

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