HR: 0800h
AN: B31A-0201    [Abstracts]
TI: Microbiological and Biogeochemical Investigations of the Accreted Ice Above Subglacial Lake Vostok, Antarctica
AU: * Christner, B C
EM: bchristner@montana.edu
AF: Montana State University, Department of Land Resources and Environmental Sciences, 334 Leon Johnson Hall, Bozeman, MT 59717 United States
AU: Foreman, C F
EM: cforeman@montana.edu
AF: Montana State University, Department of Land Resources and Environmental Sciences, 334 Leon Johnson Hall, Bozeman, MT 59717 United States
AU: Arnold, B R
EM: briannaa@montana.edu
AF: Montana State University, Department of Land Resources and Environmental Sciences, 334 Leon Johnson Hall, Bozeman, MT 59717 United States
AU: Welch, K A
EM: welch.189@osu.edu
AF: The Ohio State University, Byrd Polar Research Center, Department of Geological Sciences, 1090 Carmack Road, Columbus, OH 43210-1002 United States
AU: Lyons, W B
EM: lyons.142@osu.edu
AF: The Ohio State University, Byrd Polar Research Center, Department of Geological Sciences, 1090 Carmack Road, Columbus, OH 43210-1002 United States
AU: Priscu, J C
EM: jpriscu@montana.edu
AF: Montana State University, Department of Land Resources and Environmental Sciences, 334 Leon Johnson Hall, Bozeman, MT 59717 United States
AB: Subglacial Lake Vostok is located ~4 km beneath the surface of the East Antarctic ice sheet and has been isolated from the atmosphere for at least 15 million years. The lake has a surface area near 14,000 km$^{2}$ and a depth exceeding 1000 m. While the nature of the environment within Subglacial Lake Vostok remains uncertain, if a sustained microbial ecosystem is present, life in this subsurface environment operates under arguably the most extreme conditions in the biosphere (i.e., high pressure, constant cold, high oxygen concentrations, and no light). The lake represents an analogue for ecosystems that may exist in Europa's ice-covered ocean and also provides an Earthly-based model for the evaluation of technology to search for life in icy extraterrestrial subsurface environments. Concerns for environmental protection have prevented direct sampling of the lake water thus far, as a prudent sampling plan that will not contaminate this pristine environment has yet to be developed and tested. However, an ice core has been retrieved at Vostok Station in which the bottom ~85 meters consists of lake water that has accreted to the bottom of the ice sheet, providing frozen samples of water from the lakes' surface. The ice from 3539 to 3609 mbs (accretion ice I) contains visible inclusions due to accretion in the shallow embayment or western grounding line, whereas ice from 3610-3623 mbs (accretion ice II) is very clean, forming above the deep eastern basin of the main lake. Using a multifaceted protocol to monitor cellular and molecular decontamination of ice cores, we show that the microbiology and geochemistry (i.e., dissolve organic carbon, nutrients, and ions) of accretion ice is very different from the overlying glacial ice. The numbers of cells are 2- to 7-fold higher in accretion ice I than in the overlying glacial ice, and decrease with increasing depth in accretion ice II. Cell viability in accretion ice samples has been confirmed by the measurable respiration of $^{14}$C-glucose at 10$^{o}$C and recovery of bacterial isolates by enrichment culturing. Direct amplification and phylogenetic analysis of 16S rDNA sequences related to $\beta$-, $\gamma$-, and $\delta$-proteobacterial species from samples originating from the open lake basin (i.e., accretion ice II) suggest dissimilatory metal oxidation/reduction and methylotrophic metabolic lifestyles may exist. Together, these data imply a priori that Subglacial Lake Vostok is a viable ecosystem.
UR: http://www.brent.xner.net/
DE: 1827 Glaciology (1863)
DE: 1615 Biogeochemical processes (4805)
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting