Origin of Short-Chain Organic Acids in Serpentinite Mud Volcanoes of the Mariana Convergent Margin
説明
Serpentinitic systems are potential habitats for microbial life due to frequently high concentrations of microbial energy substrates, such as hydrogen (H2), methane (CH4), and short-chain organic acids (SCOAs). Yet, many serpentinitic systems are also physiologically challenging environments due to highly alkaline conditions (pH > 10) and elevated temperatures (>80°C). To elucidate the possibility of microbial life in deep serpentinitic crustal environments, International Ocean Discovery Program (IODP) Expedition 366 drilled into the Yinazao, Fantangisña, and Asùt Tesoru serpentinite mud volcanoes on the Mariana Forearc. These mud volcanoes differ in temperature (80, 150, 250°C, respectively) of the underlying subducting slab, and in the porewater pH (11.0, 11.2, 12.5, respectively) of the serpentinite mud. Increases in formate and acetate concentrations across the three mud volcanoes, which are positively correlated with temperature in the subducting slab and coincide with strong increases in H2 concentrations, indicate a serpentinization-related origin. Thermodynamic calculations suggest that formate is produced by equilibrium reactions with dissolved inorganic carbon (DIC) + H2, and that equilibration continues during fluid ascent at temperatures below 80°C. By contrast, the mechanism(s) of acetate production are not clear. Besides formate, acetate, and H2 data, we present concentrations of other SCOAs, methane, carbon monoxide, and sulfate, δ13C-data on bulk carbon pools, and microbial cell counts. Even though calculations indicate a wide range of microbial catabolic reactions to be thermodynamically favorable, concentration profiles of potential energy substrates, and very low cell numbers suggest that microbial life is scarce or absent. We discuss the potential roles of temperature, pH, pressure, and dispersal in limiting the occurrence of microbial life in deep serpentinitic environments.
Frontiers in Microbiology, 10
ISSN:1664-302X
収録刊行物
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- Frontiers in Microbiology
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Frontiers in Microbiology 10 1729-, 2019-07-26
Frontiers Media SA
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キーワード
- Microbiology (medical)
- International Ocean Discovery Program
- 550
- THERMOCHEMICAL SULFATE REDUCTION
- [SDU.STU]Sciences of the Universe [physics]/Earth Sciences
- serpentinization
- International Ocean Discovery Program (IODP)
- R Medicine
- Microbiology
- HYDROGEN GENERATION
- REDUCING BACTERIA
- formate
- ANAEROBIC-BACTERIA
- deep biosphere
- ACTIVITY-COEFFICIENTS
- NERC UK IODP Phase 2 Moratorium Award
- MICROBIAL COMMUNITIES
- Limits of life
- [SDU.OCEAN]Sciences of the Universe [physics]/Ocean, Atmosphere
- [SDU.OCEAN]Sciences of the Universe [physics]/Ocean
- Atmosphere
- Acetate
- Natural Environment Research Council (NERC)
- HYDROTHERMAL REACTIVITY
- Limits of life; Deep biosphere; Serpentinization; Abiotic synthesis; Formate; Acetate; Methane; International Ocean Discovery Program (IODP)
- methane
- Serpentinization
- R
- Formate
- QR1-502
- abiotic synthesis
- Abiotic synthesis
- DEEP SUBSEAFLOOR SEDIMENTS
- Deep biosphere
- FORE-ARC
- VOLATILE FATTY-ACIDS
- limits of life
- [SDE]Environmental Sciences
- International ocean discovery program
- acetate
- Methane
- NE/P020909/1
詳細情報 詳細情報について
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- CRID
- 1360290617424651904
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- ISSN
- 1664302X
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- HANDLE
- 20.500.11850/355178
- 2164/13121
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- データソース種別
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- Crossref
- KAKEN
- OpenAIRE