Initial geochemical and microbiological characterization of henderson fluids
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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
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


Initial geochemical and microbiological characterization of henderson fluids

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


Initial geochemical and microbiological characterization of henderson fluids

CO numbers 2 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.


Initial geochemical and microbiological characterization of henderson fluids

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


Initial geochemical and microbiological characterization of henderson fluids

Adjacent to the Fracture: surface?

Abundant Mn(IV)-oxides form black mineral coatings on the tunnel walls.

LBB-test

Shows Mn(IV)

In minerals;

Mn(II) in fluids


First assessement microbial diversity in the ancient fluids
First assessement: surface? Microbial Diversity in the Ancient Fluids

Surprising abundance of

Eukaryotic fungal sequences..

Data from John Spear, CSM


Initial geochemical and microbiological characterization of henderson fluids

More dilute fluids surface?

(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…


Initial geochemical and microbiological characterization of henderson fluids

DNA-labeled cells surface?

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


Initial geochemical and microbiological characterization of henderson fluids

Dissolved Oxygen now below detection surface?

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


Summary to date
Summary to-date surface?

  • 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