The sluggish speed of making abiotic methane

Bradley, Alexander S.

doi:10.1073/pnas.1617103113

Cited by 14 publications

(12 citation statements)

References 23 publications

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“…The debate on detecting and interpreting methane on Mars illustrates the difficulty of remote life detection in and beyond the Solar System (Seager and Bains, 2015 ). The knowledge of abiotic sources and sinks remains incomplete even for methane on Earth (Bradley, 2016 ; McCollom, 2016 ). These may be distinguished from biology by measuring isotopes (Krasnopolsky et al, 2004; Young et al, 2017 ) and abundance patterns among hydrocarbon gases (Allen et al, 2006).…”

Section: Application To Past Attempts At Life Detectionmentioning

confidence: 99%

The Ladder of Life Detection

Neveu

Hays

Voytek³

et al. 2018

Astrobiology

194

158

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We describe the history and features of the Ladder of Life Detection, a tool intended to guide the design of investigations to detect microbial life within the practical constraints of robotic space missions. To build the Ladder, we have drawn from lessons learned from previous attempts at detecting life and derived criteria for a measurement (or suite of measurements) to constitute convincing evidence for indigenous life. We summarize features of life as we know it, how specific they are to life, and how they can be measured, and sort these features in a general sense based on their likelihood of indicating life. Because indigenous life is the hypothesis of last resort in interpreting life-detection measurements, we propose a small but expandable set of decision rules determining whether the abiotic hypothesis is disproved. In light of these rules, we evaluate past and upcoming attempts at life detection. The Ladder of Life Detection is not intended to endorse specific biosignatures or instruments for life-detection measurements, and is by no means a definitive, final product. It is intended as a starting point to stimulate discussion, debate, and further research on the characteristics of life, what constitutes a biosignature, and the means to measure them.

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Section: Application To Past Attempts At Life Detectionmentioning

confidence: 99%

The Ladder of Life Detection

Neveu

Hays

Voytek³

et al. 2018

Astrobiology

194

158

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“…Although exactly where in the system and how it is produced remains a matter of ongoing debate [74,75,94,95]. In the absence of catalysis, reduction of dissolved CO 2 is extremely slow even at temperatures up to 350 °C [33,68,96].…”

Section: Serpentinization: Methanementioning

confidence: 99%

Serpentinization: Connecting Geochemistry, Ancient Metabolism and Industrial Hydrogenation

Preiner

Xavier

Sousa

et al. 2018

Life

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Rock–water–carbon interactions germane to serpentinization in hydrothermal vents have occurred for over 4 billion years, ever since there was liquid water on Earth. Serpentinization converts iron(II) containing minerals and water to magnetite (Fe3O4) plus H2. The hydrogen can generate native metals such as awaruite (Ni3Fe), a common serpentinization product. Awaruite catalyzes the synthesis of methane from H2 and CO2 under hydrothermal conditions. Native iron and nickel catalyze the synthesis of formate, methanol, acetate, and pyruvate—intermediates of the acetyl-CoA pathway, the most ancient pathway of CO2 fixation. Carbon monoxide dehydrogenase (CODH) is central to the pathway and employs Ni0 in its catalytic mechanism. CODH has been conserved during 4 billion years of evolution as a relic of the natural CO2-reducing catalyst at the onset of biochemistry. The carbide-containing active site of nitrogenase—the only enzyme on Earth that reduces N2—is probably also a relic, a biological reconstruction of the naturally occurring inorganic catalyst that generated primordial organic nitrogen. Serpentinization generates Fe3O4 and H2, the catalyst and reductant for industrial CO2 hydrogenation and for N2 reduction via the Haber–Bosch process. In both industrial processes, an Fe3O4 catalyst is matured via H2-dependent reduction to generate Fe5C2 and Fe2N respectively. Whether serpentinization entails similar catalyst maturation is not known. We suggest that at the onset of life, essential reactions leading to reduced carbon and reduced nitrogen occurred with catalysts that were synthesized during the serpentinization process, connecting the chemistry of life and Earth to industrial chemistry in unexpected ways.

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“…In addition, serpentinization, a water-rock interaction, has been regarded as the major H 2supplying and thus CH 4 -supplying process [32]. However, as the reaction rate of serpentinization was recently revised to be slower than previously expected [33], its significance in abiotic methanogenesis has been subject to reevaluation [29,34].…”

Section: Abiogenic Methane Of Inorganic Origin: Fischer-tropsch Procementioning

confidence: 99%

Geo-Biological Coupling of Authigenic Carbonate Formation and Autotrophic Faunal Colonization at Deep-Sea Methane Seeps I: Geo-Biological Settings

Naganuma¹

2018

Marine Ecology - Biotic and Abiotic Interactions

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Methane (CH 4) in sub-seafloor sediment is generated both biologically and non-biologically from organic and inorganic sources. A major part of the sub-seafloor methane is oxidized before leakage via "anaerobic oxidation of methane" (AOM) in the subsurface. The AOM-survivor methane, which is relatively minor part of the subsurface methane, leaches to the overlying water column and is eventually subject to thorough anaerobic and aerobic oxidation in the water column. The AOM with sulfate results in the generation of carbon dioxide and sulfide; the former (CO 2) is incorporated into authigenic carbonate and autotrophic biomass, and the autotrophy is energetically driven by oxidation of the latter (H 2 S). These processes are typically observed at focused sites that are generally known as "methane seeps" or hydrocarbon seeps, or occasionally called as cold seeps in comparison with hydrothermal vents. Methane seeps are typically formed in passive and active continental margins, occasionally with unique features such as exposed methane hydrates, mud volcanoes, asphalt volcanoes, salt diapirs, and brine pools. Accordingly, authigenic carbonates and unique biological communities are shaped at respective methane seeps. This chapter overviews geological and biological setting for the formation of methane seeps associated with unique landscapes of carbonates and biomes.

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The sluggish speed of making abiotic methane

Cited by 14 publications

References 23 publications

The Ladder of Life Detection

The Ladder of Life Detection

Serpentinization: Connecting Geochemistry, Ancient Metabolism and Industrial Hydrogenation

Geo-Biological Coupling of Authigenic Carbonate Formation and Autotrophic Faunal Colonization at Deep-Sea Methane Seeps I: Geo-Biological Settings

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