Triple oxygen isotope constraints on the origin of ocean island basalts

Cao, Xiaobin; Bao, Huiming; Gao, Caihong; Liu, Yun; Huang, Fang; Peng, Yongbo; Zhang, Yining

doi:10.1007/s11631-019-00336-y

Cited by 8 publications

(1 citation statement)

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“…Strong isotopic discrimination during biological and abiotic methane formation has motivated the use of methane hydrogen and carbon isotopes to trace its production and consumption processes, construct global methane budgets and evaluate its climatic impacts (1,4,5). Current organism-level models that rely on isotopic mass balance can explain part of the observed range of microbial isotopic discrimination (6)(7)(8)(9), but to date, such models have prescribed rather than resolved the microbial biochemistry. It has been difficult, therefore, to distinguish between different methane sources, different modes and extents of environmental methane cycling, and different environmental controls on the microbial isotope discrimination as drivers of observed variations in the isotopic composition of methane.…”

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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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confidence: 99%