Summary of analytical results for hydrologic studies of wells open through large intervals of the Snake River plain aquifer at the Idaho National Engineering Laboratory, project 1

This report summarizes results of groundwater analyses for samples collected from wells USGS-44, -45, -46 and -59 in conjunction with the INEL Oversight Program straddle-packer project between 1992 and 1995. The purpose of this project was to develop and deploy a high-quality straddle-packer system for characterization of the three-dimensional geometry of solute plumes and aquifer hydrology near the Idaho Chemical Processing Plant (ICPP). Principle objectives included (1) characterizing vertical variations in aquifer chemistry; (2) documenting deviations in aquifer chemistry from that monitored by the existing network, and (3) making recommendations for improving monitoring efforts

Amino Acid Synthesis in a Supercritical Carbon Dioxide - Water System

Mars is a CO2-abundant planet, whereas early Earth is thought to be also CO2-abundant. In addition, water was also discovered on Mars in 2008. From the facts and theory, we assumed that soda fountains were present on both planets, and this affected amino acid synthesis. Here, using a supercritical CO2/liquid H2O (10:1) system which mimicked crust soda fountains, we demonstrate production of amino acids from hydroxylamine (nitrogen source) and keto acids (oxylic acid sources). In this research, several amino acids were detected with an amino acid analyzer. Moreover, alanine polymers were detected with LC-MS. Our research lights up a new pathway in the study of life’s origin

A note on the fluxes of abiogenic methane and hydrogen from mid-ocean ridges

The concentrations of methane and hydrogen in hydrothermal vent fluids issuing from mid-ocean ridges tend to fall into two groups, one with high concentrations of these gases in ultramafic-hosted vent fields and a second group with relatively lower concentrations in basalt-hosted vent fluids. Ultramafic-hosted systems, however, appear to be restricted to slow-spreading ridges and constitute only a fraction of the hydrothermal systems found there. In this note, the hydrothermal fluxes of methane and hydrogen have been calculated by estimating the percentages of the total subsurface hydrothermal circulation that circulate through each type of host rock. Even though the percentage of the total subsurface flow that is affected by serpentinization appears to be rather small (8%), it still appears that this process produces about 70% of the total mid-ocean flux of these gases. The total production of methane and hydrogen is calculated to be about 20 x 10(9) mol yr(-1) and 190 x 10(9) mol yr(-1), respectively. The hydrogen flux is comparable to that most recently calculated on the basis of the rate of hydration of mantle rock in newly formed crust and the stoichiometry of the serpentinization reaction. This suggests that, except for the production of methane, a major portion of the hydrogen produced in the subsurface is not consumed before venting

Experimental investigation of single carbon compounds under hydrothermal conditions

Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 70 (2006): 446-460, doi:10.1016/j.gca.2005.09.002.The speciation of carbon in subseafloor hydrothermal systems has direct implications for the maintenance of life in present day vent ecosystems and possibly the origin of life on early Earth. Carbon monoxide is of particular interest because it represents a key reactant during the abiotic synthesis of reduced carbon compounds via Fischer-Tropsch-type processes. Laboratory experiments were conducted to constrain reactions that regulate the speciation of aqueous single carbon species under hydrothermal conditions and determine kinetic parameters for the oxidation of CO according to the water water-gas shift reaction (CO2 + H2 = CO + H2O). Aqueous fluids containing added CO2, CO, HCOOH, NaHCO3, NaHCOO, and H2 were heated at 150, 200, and 300°C and 350 bar in flexible cell hydrothermal apparatus, and the abundance of carbon compounds were monitored as a function of time. Variations in fluid chemistry suggest that the reduction of CO2 to CH3OH under aqueous conditions occurs via a stepwise process that involves the formation of HCOOH, CO, and possibly CH2O, as reaction intermediaries. Kinetic barriers that inhibit the reduction of CH3OH to CH4 allow the accumulation of reaction intermediaries in solution at high concentrations regulated by metastable equilibrium. Reaction of CO2 to form CO involves a two-step process in which CO2 initially undergoes a reduction step to HCOOH which subsequently dehydrates to form CO. Both reactions proceed readily in either direction. A preexponential factor of 1.35 x 106 s-1 and an activation energy of 102 KJ mol-1 were retrieved from the experimental results for the oxidation of CO to CO2. Reactions rates amongst single carbon compounds during the experiments suggests SCO2 (CO2 + HCO3- + CO3=), CO, SHCOOH (HCOOH + HCOO-), and CH3OH may reach states of redox-dependent metastable thermodynamic equilibrium in subseafloor and other hydrothermal systems. The abundance of CO under equilibrium conditions, which in turn may influence the likelihood for abiotic synthesis via Fischer-Tropsch-type processes, is strongly dependent on temperature, the total carbon content of the fluid, and host-rock lithology. If crustal residence times following the mixing of high-temperature hydrothermal fluids with cool seawater are sufficiently long, reequilibration of aqueous carbon can result in the generation of additional reduced carbon species such as HCOOH and CH3OH and the consumption of H2. The present study suggests that abiotic reactions involving aqueous carbon compounds in hydrothermal systems are sufficiently rapid to influence metabolic pathways utilized by organisms that inhabit vent environments.This study was supported by the National Science Foundation grant #OCE-0136954, the Office of Basic Energy Sciences, U.S. Department of Energy grant #DEFG0297ER14746, and by NASA Exobiology grant #NAG5-7696 and Origins grant #NNG04GG23G

Nitrate-Dependent Iron Oxidation: A Potential Mars Metabolism

This work considers the hypothetical viability of microbial nitrate-dependent Fe2+ oxidation (NDFO) for supporting simple life in the context of the early Mars environment. This draws on knowledge built up over several decades of remote and in situ observation, as well as recent discoveries that have shaped current understanding of early Mars. Our current understanding is that certain early martian environments fulfill several of the key requirements for microbes with NDFO metabolism. First, abundant Fe2+ has been identified on Mars and provides evidence of an accessible electron donor; evidence of anoxia suggests that abiotic Fe2+ oxidation by molecular oxygen would not have interfered and competed with microbial iron metabolism in these environments. Second, nitrate, which can be used by some iron oxidizing microorganisms as an electron acceptor, has also been confirmed in modern aeolian and ancient sediment deposits on Mars. In addition to redox substrates, reservoirs of both organic and inorganic carbon are available for biosynthesis, and geochemical evidence suggests that lacustrine systems during the hydrologically active Noachian period (4.1–3.7 Ga) match the circumneutral pH requirements of nitrate-dependent iron-oxidizing microorganisms. As well as potentially acting as a primary producer in early martian lakes and fluvial systems, the light-independent nature of NDFO suggests that such microbes could have persisted in sub-surface aquifers long after the desiccation of the surface, provided that adequate carbon and nitrates sources were prevalent. Traces of NDFO microorganisms may be preserved in the rock record by biomineralization and cellular encrustation in zones of high Fe2+ concentrations. These processes could produce morphological biosignatures, preserve distinctive Fe-isotope variation patterns, and enhance preservation of biological organic compounds. Such biosignatures could be detectable by future missions to Mars with appropriate instrumentation

Isotope fractionation and mixing in methane plumes from the Logatchev hydrothermal field

As methane is consumed in the deep sea, its 13C/12C ratio progressively increases because of kinetic isotope fractionation. Many submarine hydrothermal vents emit methane with carbon isotope ratios that are higher than those of background methane in the surrounding ocean. Since the latter exists at low concentrations, mixing of background methane with vent fluid tends to decrease the 13C/12C ratio as concentration decreases, opposite to the trend produced by consumption. We investigated CH4 concentration and δ13C together with δ3He in plumes from the Logatchev hydrothermal field (LHF) located at 14°45′N, 45°W, which generates relatively heavy methane (δ13C ≈ −13‰) by serpentinization of ultramafic rock. The measured methane and δ3He were well correlated at high concentrations, indicating a CH4/3He ratio of 1 × 108 in the vent fluids. These tracer distributions were also simulated with an advection-diffusion model in which methane consumption only occurs above a certain threshold concentration. We utilized δ3He to calculate the methane remaining in solution after oxidation, f, and the deviation of δ13C from the value expected from mixing alone, Δδ13C. Both in the model and in the data, the entire set of Δδ13C values are not correlated with log f, which is due to continuous oxidation within the plume while mixing with background seawater. A linear relationship, however, is found in the model for methane at concentrations sufficiently above background, and many of the samples with elevated CH4 north of LHF exhibit a linear trend of Δδ13C versus log f as well. From this trend, the kinetic isotope fractionation factor in the LHF plumes appears to be about 1.015. This value is somewhat higher than found in some other deep-sea studies, but it is lower than found in laboratory incubation experiments

Metabolic flexibility of enigmatic SAR 324 revealed through metagenomics and metatranscriptomics

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102166/1/emi12165.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102166/2/emi12165-sup-0001-figure.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/102166/3/emi12165-sup-0002-table.pd

Geochemistry of low-molecular weight hydrocarbons in hydrothermal fluids from Middle Valley, northern Juan de Fuca Ridge

Author Posting. © Elsevier B.V., 2006. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 70 (2006): 2073-2092, doi:10.1016/j.gca.2006.01.015.Hydrothermal vent fluids from Middle Valley, a sediment-covered mid-ocean ridge on the northern Juan de Fuca Ridge, were sampled in July, 2000. Eight different vents with exit temperatures of 186 to 281°C were sampled from two areas of venting: the Dead Dog and ODP Mound fields. Fluids from the Dead Dog field are characterized by higher concentrations of ΣNH3 and organic compounds (C1-C4 alkanes, ethene, propene, benzene and toluene) compared with fluids from the ODP Mound field. The ODP Mound fluids, however, are characterized by higher C1/(C2+C3) and benzene:toluene ratios than those from the Dead Dog field. The aqueous organic compounds in these fluids have been derived from both bacterial processes (methanogenesis in low-temperature regions during recharge) as well as from thermogenic processes in higher-temperature portions of the subsurface reaction zone. As the sediments undergo hydrothermal alteration, carbon dioxide and hydrocarbons are released to solution as organic matter degrades via a stepwise oxidation process. Compositional and isotopic differences in the aqueous hydrocarbons indicate that maximum subsurface temperatures at the ODP Mound are greater than those at the Dead Dog field. Maximum subsurface temperatures were calculated assuming that thermodynamic equilibrium is attained between alkenes and alkanes, benzene and toluene, and carbon dioxide and methane. The calculated temperatures for alkene-alkane equilibrium are consistent with differences in the dissolved Cl concentrations in fluids from the two fields, and indicate that subsurface temperatures at the ODP Mound are hotter than those at the Dead Dog field. Temperatures calculated assuming benzene-toluene equilibrium and carbon dioxide-methane equilibrium are similar to observed exit temperatures, and do not record the hottest subsurface conditions. The difference in subsurface temperatures estimated using organic geochemical thermometers reflects subsurface cooling processes via mixing of a hot, low-salinity vapor with a cooler, seawater salinity fluid. Because of the disparate temperature dependence of alkene-alkane and benzene-toluene equilibria, the mixed fluid records both the high and low temperature equilibrium conditions. These calculations indicate that vapor-rich fluids are presently being formed in the crust beneath the ODP Mound, yet do not reach the surface due to mixing with the lower-temperature fluids.This work was funded by NSF OCE-9906752

Novel hydrocarbon monooxygenase genes in the metatranscriptome of a natural deep‐sea hydrocarbon plume

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102241/1/emi12182.pd