Perennially Ice Covered Antarctic Lakes: Oases for Life and Models for Other Icy Worlds

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Perennially Ice Covered Antarctic Lakes Oases
for Life and Models for Other Icy Worlds
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• OBJECTIVES
• Overview the McMurdo Dry Valley and Vostok Lake
  Ice systems
• Provide details on the detection of liquid water
  (liquid water life) in the dry valleys
• Describe their geomicrobiology (How do microbes
  exist in these habitats? Who are they?)
• Address the question Is there a deep-cold
  biosphere? (or do we remain surface chauvinists)
• Relate to Astrobiology

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Preamble (Why study Earthly ice?)

• Earths biosphere is cold!!
• 14 is polar
• 90 (by volume) is ocean lt5 oC
• 70 of Earths freshwater is ice
• 25 of soils are permafrost
• Most planets and moons in our solar system are
  cold and many are icy
• Average temperature of the Universe
• -270.5 oC

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Lake Vostok
McMurdo Dry Valleys
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TAYLOR VALLEY
Taylor Gl.
L. Bonney
Commonwealth Gl.
L. Hoare
Canada Gl.
L. Fryxell
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VOSTOK -87.9 oC (lowest recorded on Earth) Avg
-55 oC (Mean temp on Mars -53 oC)
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Lake Bonney, West Lobe
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Simulated View of Europas Landscape icy blocks
3 km wide (Pappalardo et al. 1999. The hidden
ocean of Europa. Sci. Amer.)
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Salt crystals
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LIQUID WATER?
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Sediment inclusions
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Time series of ERS-2 SAR (microwave backscatter)
images of Lake Fryxell, Taylor Valley. Data from
Dale P. Winebrenner, Applied Physics Lab, Univ.
of Washington
L. Fryxell
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5 cm
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What is the biological seed for life in dry
valley lake ice?
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SOIL POC
(Fritsen Priscu 2000)
 
 
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L. Bonney Ice Cover (2m) Cyanobacteria
16s ribosomal RNA
From Gordon, Priscu Giovannoni. 2000. Microbial
Ecology 39197
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L. Bonney ice aggregate
Scale 10 µm
Priscu et al. 1999 Science 2862141
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DRY VALLEY LAKE ICE AGGREGATES
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Aeolian Transport (1)
Accumulation Layer (2,3 4)
Ice Layer
Sediment Organic Layer
Water Column
Loss to Lakewater (5,6)
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R.E. Bell, Lamont-Doherty Earth Observatory,
Columbia Univ.
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Siegert et al. submitted
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Siegert et al. submitted
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Vostok Organic Carbon

• Vostok core 3590
• dissolved organic C 510 µg l-1
• bacterial C 0.13 µg l-1 (3.6 x 104 cell ml-1)
• Lake Vostok (predicted)
• dissolved organic C 1200 µg l-1
• bacterial C 3.6 µg l-1 (1 x 106 cell ml-1)
• (using partitioning coefficients from McMurdo
  Dry Valley lakes)

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175,000 ybp
Abyzov et al. 1998
Vostok glacial ice
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6-12 um
Price, P.B. 2000. PNAS 971247.
Gas record? (T. Sowers, JGR In press)
D 2 cm
Microbial habitat in deep ice bounded by liquid
ice veins. Two microbes are depicted as living in
the vein of diameter dvein surrounding a single
grain of diameter D.
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Where Do We Go From Here?

• Antarctic subglacial lakes (South Pole, Vostok,
  others??)
• Mars??
• Europa??

S. Pole station
Lake
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CONCLUSIONS

• The microbial world has few limits on our planet
  (and others?)
• Research on Earths icy systems will provide new
  information on the possibility for life (and
  liquid water) on other icy worlds
• The definition of Earths biosphere should be
  expanded to include deep-ice subglacial lakes
  (107 kgC in subglacial lakes alone!)
• Definition of biosphere (from NASA website)
  Part of the Earth system in which life can
  exist, between the outer portion of the geosphere
  and the inner portion of the atmosphere

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Collaborators
Physics/Engineering Microbiology E. E. Adams
J. Mikucki R. L. Brown
C. D. Takacs P. B. Price C.
F. Wolf S. Giovannoni Astrobiology
H.W. Paerl C. McKay A. Hall
Image Analysis R. Avci Geochemistry
W. Berry Lyons Geology K.
A. Welch D. Mogk
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Brittle surface ice
EUROPA
Metallic core
Convecting ice
Ice covering
Rocky interior
H2O layer
Liquid water
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Early Earth
CO2 atmosphere Warm surface temp
Volcanic CO2, water vapor, nitrogen
Atm CO2 depleted as carbonaceous rocks form
Tectonic activity recycles carbonaceous rocks
CO2 produced
Early Mars
Initial CO2 atmosphere Warm surface temp
Carbonate rocks not recycled CO2 atmosphere
lost Atmosphere gradually disappears
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Mars orbiter laser altimeter image of Mars N.
Pole. The ice cap is about 1200 km across, with a
maximum thickness of 3 km. The canyons are as
much as 1 km deep.
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A MARTIAN CHRONICLE
 
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1.Depolyment bus with sonde is lowered into ice
hole. Ice plug formed above bus-peroxide
added. 2-3. Completion drill melts through
remaining ice and moves to side. 4. Sonde is
deployed on pulley. 5. Sonde returns to
deployment bus and an ice plug is formed below
the bus sealing the system from the lake. 6.
Sampling sonde returned to surface.
Ice/water interface
Design Icefield Instruments, Canada E. Blake
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The sampling sonde consists of four main
sections (1) core sampler, (2) water samplers,
(3) instrument package, and (4) control computer.
Length is 4 m, depending on the number and
volume of Niskin bottles.
fins
Control module
3 Niskin bottles
vents
core tube
Design Icefield Instruments, Canada E. Blake
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Airborne Radar Chronograms of L. Vostok (60 mHz)
Distance (km)
0
10
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Lake Bonney Ice, 2m

0.82 µm
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CORE 3590
Declination from vertical small crystal
62o large crystal 43o
10 cm
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Designation of taxonomic affiliation (DNA
fingerprint) of PCR fragment clones from Lake
Vostok core 3590.
Clones Taxa 4 Acidovorax
1 Actinomyces 1 Afipia
1 Comamonas
NOTE Measurable metabolic activity no
respiratory suppression up to 20 0C (Karl et al.
1999)
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Vostok glacial ice
175,000 ybp
Abyzov et al. 1998