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Initial Geochemical and Microbiological Characterization of Henderson Fluids

Initial Geochemical and Microbiological Characterization of Henderson Fluids. How does knowledge of the site-specific chemistry at Henderson enhance our ability to identify subsurface microbial organisms (phylogentically and functionally)

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Initial Geochemical and Microbiological Characterization of Henderson Fluids

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  1. Initial Geochemical and Microbiological Characterizationof Henderson Fluids • How does knowledge of the site-specific chemistry at Henderson enhance our ability to identify subsurface microbial organisms (phylogentically and functionally) -- and their direct dependency upon fluid-rock interaction? Tom Kieft (New Mexico Tech) for Alexis Templeton (University of Colorado – Boulder) BIOSCIENCE SAMPLING TEAM Templeton: Henderson DUSEL Capstone Workshop May 4-7th

  2. Establishing the basic chemistry, nutrient levels and cell numbers in deeply-sourced, hot fluids: Flowing boreholes variably mixed with oxygen Fluid Chemistry: 7025 level Warm, ~40C; pH 5.9 to 6.2 Dissolved O2: 0.3 to 3.8 mg/L High DIC (~30 mM) High Mn2+, Fe2+ (1 to 20 mM) High SO42- (4 to 48 mM) Trace metals: Zn > Ni > Mo Low (but detectable) organics (50 mM) Abundant nitrogen species: includes NO3-, NO2- ,N2O, NH4+ D1 D2 D3 O2 concentrations increase as borehole flow-rate decreases From D1  D3 O2 levels drop 1000x within 1 hour of packer-insertion

  3. CO2 Movie: High CO2 important for autotrophic growth Natural Fracture Surface: Degassing CO2 Can also detect N2O (6-18 microM), only low CH4 (sub-microM), and H2 not measured yet.

  4. What’s the disequilibrium between the fluids and the surface? Oxic-Anoxic Interface Fe2+ rapidly oxidizes and oxide and sulfate minerals precipitate Fe-oxides Sulfates New minerals hard to structurally identify – relatively amorphous

  5. Adjacent to the Fracture: Abundant Mn(IV)-oxides form black mineral coatings on the tunnel walls. LBB-test Shows Mn(IV) In minerals; Mn(II) in fluids

  6. First assessement: Microbial Diversity in the Ancient Fluids Surprising abundance of Eukaryotic fungal sequences.. Data from John Spear, CSM

  7. More dilute fluids (7025-D1), pre-packer: Dominated by uncultured beta-Proteobacteria (e.g. Japanese Gold Mine): 80% Fluids with high Fe, Mn, sulfate, NH4+, N2O (7025-D4) post-packer: Abundant delta-Proteobacteria (SRB) Abundant Nitrospira Remarkable diversity (~27 other groups) Second assessment: Microbial Diversity in fluids of varying chemistry(samples only separated by meters….) • See John Spear talk on Friday…

  8. DNA-labeled cells Fe-oxide particles Thermophilic Metal-oxidizing bacteria? Water and Mat samples:  Fe-oxidizing bacteria  Mn-oxidizing bacteria Establish enrichments: *site-specific Henderson medium* with and without organics near-neutral pH stabilized on mineral surfaces culture at 40°C-55°C Microbes more abundant in the Fe-oxide mats Growth on Fe-media also successful… Rapid growth on Mn-media at 50°C using D4 mineral mat! First 3 isolates being sequenced

  9. Dissolved Oxygen now below detection Now target anaerobic enrichments: Isolates for biochemical and proteomic studies Anaerobic Fe-oxidizers Mn-reducers Fe-reducers Sulfate-reducers In-situ biofilms recently extracted for analysis

  10. Summary to-date • Yes, microorganisms are present in the fluids, at low cell numbers. • The fluid chemistry at Henderson is unique due to water-rock interaction, which has implications for the likely modes of metabolism and enzymatic activities. • CO2 and sulfate concentrations are very high • N and C nutrient levels are above detection limits, but not P • Millimolar concentrations of Mn, Fe and Zn • Fluid chemistry will vary significantly depending upon location inside vs. outside mineralized rock. • The microbial diversity is high and includes unexpected fungal sequences • There exists unexpected potential for a subsurface microbial N-cycle NH4+, NO2-, NO3- and N2O all abundant (naturally or not?) • Microbial organisms are more abundant at the oxic-anoxic interface, where the Fe-oxide mineral mats are forming. • Initial culturing efforts targeting Fe and Mn-oxidizing bacteria appear to be successful: sequenced isolates anticipated in the near-term, to be compared to clone libraries. • Noble gas & stable-isotope geochemistry will constrain the age & source of the fluids. • Preliminary 14C data shows 26,000 years

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