Download and their direct dependency upon fluid

Initial Geochemical and Microbiological Characterization
of Henderson Fluids
Tom Kieft (New Mexico Tech)
for
Alexis Templeton (University of Colorado – Boulder)
• 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?
BIOSCIENCE SAMPLING TEAM
Templeton: Henderson DUSEL Capstone Workshop May 4-7th
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)
D1
D2
D3
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+
O2 levels drop 1000x within 1 hour of packer-insertion
Natural Fracture Surface: Degassing CO2
Can also detect N2O (6-18 microM), only low CH4 (sub-microM), and H2 not measured yet.
CO2 Movie:
High CO2 important for autotrophic growth
What’s the disequilibrium between the fluids and the surface?
Oxic-Anoxic Interface
Fe2+ rapidly oxidizes and oxide and sulfate minerals precipitate
Fe-oxides
2.70 C
4.21 C
25000
3.37 S
2.08 C
1.71 C
1.5 S
2.47 C
20000
1.90 S
Counts
15000
Sulfates
10000
5000
3.03 M 2.29 S 1.85 S
3.85 M 2.56 C
1.6 S
0
10
20
30
40
Q-space (nm-1)
New minerals hard to structurally identify – relatively amorphous
50
60
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
First assessement:
Microbial Diversity in the Ancient Fluids
10%
Surprising abundance of
Eukaryotic fungal sequences..
10%
14%
17%
3%
3%
Fungus; Ascomycota
Green Non-Sulfur or Chlorofexi
Delta-Proteobacterium
Beta-Proteobacterium
Alpha-Proteobacterium
Spirochete
Actinobacterium
Firmicutes; Clostridium
29%
14%
Data from John Spear, CSM
Second assessment:
Microbial Diversity in fluids of varying chemistry
(samples only separated by meters….)
More dilute fluids
(7025-D1), pre-packer:
Fluids with high Fe, Mn, sulfate, NH4+, N2O
(7025-D4) post-packer:
Dominated by uncultured beta-Proteobacteria
(e.g. Japanese Gold Mine): 80%
Abundant delta-Proteobacteria (SRB)
Abundant Nitrospira
Remarkable diversity (~27 other groups)
•See John Spear talk on Friday…
Thermophilic Metal-oxidizing bacteria?
DNA-labeled cells
Water and Mat samples:
Fe-oxide particles
 Fe-oxidizing bacteria
 Mn-oxidizing bacteria
Establish enrichments:
*site-specific Henderson medium*
Microbes more abundant in the Fe-oxide mats
with and without organics
near-neutral pH
stabilized on mineral surfaces
culture at 40°C-55°C
Growth on
Fe-media also
successful…
Rapid growth on Mn-media at 50°C using D4 mineral mat! First 3 isolates being sequenced
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
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 Feoxide 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