@article {Larson2015,
	title = {{Stealth export of hydrogen and methane from a low temperature serpentinization system}},
	journal = {Deep-Sea Research Part II: Topical Studies in Oceanography},
	volume = {121},
	year = {2015},
	pages = {233{\textendash}245},
	abstract = {Chemical input to the deep sea from hydrothermal systems is a globally distributed phenomenon. Hydrothermal discharge is one of the primary mechanisms by which the Earth{\textquoteright}s interior processes manifest themselves at the Earth{\textquoteright}s surface, and it provides a source of energy for autotrophic processes by microbes that are too deep to capitalize on sunlight. Much is known about the water-column signature of this discharge from high-temperature mid-ocean Ridge (MOR) environments and their neighboring low-temperature counterparts. Hydrothermal discharge farther away from the ridge, however, has garnered less attention, owing in part to the difficulty in finding this style of venting, which eludes methods of detection that work well for high-temperature {\textquoteleft}black smoker{\textquoteright}-type venting. Here we present a case study of the plume from one such {\textquoteleft}invisible{\textquoteright} off-axis environment, The Lost City, with an emphasis on the dissolved volatile content of the hydrothermal plume. Serpentinization and abiotic organic synthesis generate significant concentrations of H2 and CH4 in vent fluid, but these species are unevenly transported to the overlying plume, which itself appears to be a composite of two different sources. A concentrated vent cluster on the talus slope channels fluid through at least eight chimneys, producing a water-column plume with the highest observed concentrations of CH4 in the field. In contrast, a saddle in the topography leading up to a carbonate cap hosts broadly distributed, nearly invisible venting apparent only in its water-column signals of redox potential and dissolved gas content, including the highest observed plume H2. After normalizing H2 and CH4 to the 3He background-corrected anomaly (3He$Δ$) to account for mixing and relative amount of mantle input, it appears that, while a minimum of 60{\%} of CH4 is transported out of the system, greater than 90{\%} of the H2 is consumed in the subsurface prior to venting. The exception to this pattern occurs in the plume originating from the area dubbed Chaff Beach, in which somewhat more than 10{\%} of the original H2 remains, indicating that this otherwise unremarkable plume, and others like it, may represent a significant source of H2 to the deep sea.},
	keywords = {AUV ABE (Autonomous Benthic Explorer), HOV Alvin (Human Occupied Vehicle)},
	doi = {10.1016/j.dsr2.2015.05.007},
	author = {Larson, B I and Lang, S Q and Lilley, M D and Olson, E J and Lupton, J E and Nakamura, K and Buck, N J}
}
@article {Lang2012,
	title = {{Microbial utilization of abiogenic carbon and hydrogen in a serpentinite-hosted system}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {92},
	year = {2012},
	pages = {82{\textendash}99},
	abstract = {Mantle rocks exposed on the seafloor constitute a highly reactive chemical and thermal system, in which interaction with seawater to produce serpentinite has major consequences for lithospheric cooling, global geochemical cycles, and microbial activity. Serpentinite-hosted hydrothermal activity is exemplified by the Lost City Hydrothermal Field (30{\textdegree}N, Mid-Atlantic Ridge) where fluid{\textendash}rock reactions in the underlying ultramafic rocks result in high concentrations of abiotic hydrogen, methane, C2+ alkanes, and formate. Such systems have been proposed as possible analogs to the Early Earth environments that gave rise to the first biochemical pathways. Thus, characterizing the local microbial communities and their potential link with abiogenic compounds is of particular significance. Here we demonstrate that in active carbonate chimneys where microbial sulfate reduction is important, up to 50{\%} of the microbial biomass is synthesized from mantle carbon. Conversely, mantle carbon contributes only \~{}10{\%} of the biomass in areas with minimal sulfate reduction. We attribute this difference to greater incorporation of formate or methane by the dominant microbial species, the Lost City Methanosarcinales, in locations where sulfate reducers are able to facilitate this assimilation. The ability of autotrophic communities at Lost City to capitalize on the steady stream of chemical products resulting from serpentinization reactions and to utilize abiogenic mantle carbon lend credence to the hypothesis that early biosynthetic pathways could have developed in similar environments.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	doi = {10.1016/j.gca.2012.06.006},
	url = {http://dx.doi.org/10.1016/j.gca.2012.06.006},
	author = {Lang, S Q and Fruh-Green, G L and Bernasconi, S M and Lilley, M D and Proskurowski, G and Mehay, S and Butterfield, D A}
}
@article {Lang2010,
	title = {{Elevated concentrations of formate, acetate and dissolved organic carbon found at the Lost City Hydrothermal Field}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {74},
	number = {3},
	year = {2010},
	pages = {941{\textendash}942},
	abstract = {Fluids from the ultramafic-hosted Lost City hydrothermal field were analyzed for total dissolved organic carbon and dissolved organic acids. Formate (36{\textendash}158 $μ$mol/kg) and acetate (1{\textendash}35 $μ$mol/kg) concentrations are higher than in other fluids from unsedimented hydrothermal vents, and are a higher ratio of the total dissolved organic carbon than has been found in most marine geothermal systems. Isotopic evidence is consistent with an abiotic formation mechanism for formate, perhaps during serpentinization processes in the sub-surface. Further support comes from previous studies where the abiological formation of low molecular weight organic acids has been shown to be thermodynamically favorable during hydrothermal alteration of olivine, and laboratory studies in which the reduction of carbon dioxide to formate has been confirmed. As the second most prevalent carbon species after methane, formate may be an important substrate to microbial communities in an environment where dissolved inorganic carbon is limited. Acetate is found in locations where sulfate reduction is believed to be important and is likely to be a microbial by-product, formed either directly by autotrophic metabolic activity or indirectly during the fermentative degradation of larger organic molecules. Given the common occurrence of exposed ultramafic rocks and active serpentinization within the worlds ocean basins, the abiotic formation of formate may be an important process supporting life in these high pH environments and may have critical implications to understanding the organic precursors from which life evolved.},
	keywords = {HOV Alvin (Human Occupied Vehicle)},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2009.10.045},
	url = {http://dx.doi.org/10.1016/j.gca.2009.10.045},
	author = {Lang, S Q and Butterfield, D A and Schulte, M and Kelley, D S and Lilley, M D}
}
@article {Lang2006,
	title = {{Dissolved organic carbon in ridge-axis and ridge-flank hydrothermal systems}},
	journal = {Geochimica et Cosmochimica Acta},
	volume = {70},
	number = {15},
	year = {2006},
	pages = {3830{\textendash}3842},
	keywords = {ROV Jason (Remotely Operated Vehicle)},
	issn = {0016-7037},
	doi = {10.1016/j.gca.2006.04.031},
	url = {http://dx.doi.org/10.1016/j.gca.2006.04.031},
	author = {Lang, S Q and Butterfield, D A and Lilley, M D and Johnson, H P and Hedges, J I}
}
