HR: 0800h
AN: B21A-1020    [Abstracts]
TI: Taylor Glacier basal ice, Antarctica; a biogeochemical hot-spot in a glacial environment
AU: * Skidmore, M
EM: skidmore@montana.edu
AF: Montana State University, Department of Earth Sciences, 200 Traphagen Hall, Montana State University, Bozeman, MT 59717 United States
AU: Christner, B
EM: bchristner@montana.edu
AF: Montana State University, Land Resources and Environmental Sciences, 334 Leon Johnson Hall, Montana State University, Bozeman, MT 59717 United States
AU: Samyn, D
EM: desamyn@ulb.ac.be
AF: Universite Libre de Bruxelles, Departement des Sciences de la Terre et de l'Environnement (DSTE), CP 160/03, Universite Libre de Bruxelles (ULB), Avenue F.D. Roosevelt 50, Brussels, B-1050 Belgium
AU: Lorrain, R
EM: rlorrain@ulb.ac.be
AF: Universite Libre de Bruxelles, Departement des Sciences de la Terre et de l'Environnement (DSTE), CP 160/03, Universite Libre de Bruxelles (ULB), Avenue F.D. Roosevelt 50, Brussels, B-1050 Belgium
AB: Increasing evidence points to a significant role for microbes in mediating the dissolution and oxidation of minerals in sediments beneath ice masses (i.e., subglacial weathering). Subglacial microbial ecosystems are local hotspots of microbial activity relative to the glacial ice overlying them due to the presence of liquid water and finely comminuted rock debris, providing nutrients and chemical energy sources. Eight different ice units from a 4 m basal ice sequence (ice temperature, -17°C) at the Taylor Glacier, McMurdo Dry Valleys, Antarctica, were identified and sampled for microbiological and geochemical analysis. The vertical profile of cell and gas concentration in basal ice from Taylor Glacier indicates that the debris-rich ice layers have higher CO₂ and cell concentrations relative to the glacier ice, but are depleted in O₂ relative to atmospheric values. Acetate mineralization experiments were undertaken on a subset of glacial and basal ice samples with varying debris content, CO₂ concentration, and cell biomass to assess heterotrophic activity at 2°C. Our results show that ¹⁴C-acetate was respired to CO₂ in all the melted debris-rich ice samples analyzed, but little activity was observed in glacial ice samples of meteoric origin. Together, these data suggest that microorganisms entrapped within the debris-rich basal ice may be metabolically active in situ.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0448 Geomicrobiology
DE: 0716 Cryobiology (0475)
DE: 1827 Glaciology (0736, 0776, 1863)
SC: Biogeosciences [B]
MN: Fall Meeting 2005