@article {ISI:000356731300054,
	title = {{Pathways for abiotic organic synthesis at submarine hydrothermal fields}},
	journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA},
	volume = {112},
	number = {25},
	year = {2015},
	month = {jun},
	pages = {7668{\textendash}7672},
	type = {Article},
	abstract = {Arguments for an abiotic origin of low-molecular weight organic compounds in deep-sea hot springs are compelling owing to implications for the sustenance of deep biosphere microbial communities and their potential role in the origin of life. Theory predicts that warm H-2-rich fluids, like those emanating from serpentinizing hydrothermal systems, create a favorable thermodynamic drive for the abiotic generation of organic compounds from inorganic precursors. Here, we constrain two distinct reaction pathways for abiotic organic synthesis in the natural environment at the Von Damm hydrothermal field and delineate spatially where inorganic carbon is converted into bioavailable reduced carbon. We reveal that carbon transformation reactions in a single system can progress over hours, days, and up to thousands of years. Previous studies have suggested that CH4 and higher hydrocarbons in ultramafic hydrothermal systems were dependent on H-2 generation during active serpentinization. Rather, our results indicate that CH4 found in vent fluids is formed in H-2-rich fluid inclusions, and higher n-alkanes may likely be derived from the same source. This finding implies that, in contrast with current paradigms, these compounds may form independently of actively circulating serpentinizing fluids in ultramafic-influenced systems. Conversely, widespread production of formate by SCO2 reduction at Von Damm occurs rapidly during shallow subsurface mixing of the same fluids, which may support anaerobic methanogenesis. Our finding of abiogenic formate in deep-sea hot springs has significant implications for microbial life strategies in the present- day deep biosphere as well as early life on Earth and beyond.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0027-8424},
	doi = {10.1073/pnas.1506295112},
	author = {McDermott, Jill M and Seewald, Jeffrey S and German, Christopher R and Sylva, Sean P}
}
@article {ISI:000334288600024,
	title = {{The origin of methanethiol in midocean ridge hydrothermal fluids}},
	journal = {PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA},
	volume = {111},
	number = {15},
	year = {2014},
	month = {apr},
	pages = {5474{\textendash}5479},
	type = {Article},
	abstract = {Simple alkyl thiols such as methanethiol (CH3SH) are widely speculated to form in seafloor hot spring fluids. Putative CH3SH synthesis by abiotic (nonbiological) reduction of inorganic carbon (CO2 or CO) has been invoked as an initiation reaction for the emergence of protometabolism and microbial life in primordial hydrothermal settings. Thiols are also presumptive ligands for hydrothermal trace metals and potential fuels for associated microbial communities. In an effort to constrain sources and sinks of CH3SH in seafloor hydrothermal systems, we determined for the first time its abundance in diverse hydrothermal fluids emanating from ultramafic, mafic, and sediment-covered midocean ridge settings. Our data demonstrate that the distribution of CH3SH is inconsistent with meta-stable equilibrium with inorganic carbon, indicating that production by abiotic carbon reduction is more limited than previously proposed. CH3SH concentrations are uniformly low (similar to 10(-8) M) in high-temperature fluids ({\textgreater}200 degrees C) from all unsedimented systems and, in many cases, suggestive of meta-stable equilibrium with CH4 instead. Associated low-temperature fluids ({\textless}200 degrees C) formed by admixing of seawater, however, are invariably enriched in CH3SH (up to similar to 10-6 M) along with NH4+ and low-molecular-weight hydrocarbons relative to high-temperature source fluids, resembling our observations from a sediment-hosted system. This strongly implicates thermogenic interactions between upwelling fluids and microbial biomass or associated dissolved organic matter during subsurface mixing in crustal aquifers. Widespread thermal degradation of subsurface organic matter may be an important source of organic production in unsedimented hydrothermal systems and may influence microbial metabolic strategies in cooler near-sea-floor and plume habitats.},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0027-8424},
	doi = {10.1073/pnas.1400643111},
	author = {Reeves, Eoghan P and McDermott, Jill M and Seewald, Jeffrey S}
}
