Priscu, J. C. Montana State University,
Fritsen, C. H. Desert Research Institute,
Paerl, H. W. University of North Carolina-Chapel Hill,
Adams, E. E. Montana State University,

The McMurdo Dry Valleys of southern Victoria Land forms the largest ice-free expanse on the Antarctic continent. This area has an average annual temperature near -20 C and receives <10 cm y-1 precipitation. Many of the lakes of the region are perennially covered by 3 - 6 m of ice that contain a sand and gravel layer with associated organic matter of aeolian origin. The sediment layer often exists about 2 m below the surface of the ice and represents a dynamic equilibrium between downward movement of sediments due to melting during the summer and upward movement of ice from ablation at the surface and new ice formation at the bottom. A matrix of liquid water inclusions exists in this layer for about 150 days during the austral summer when solar radiation is continuous; liquid water can comprise up to 40% of the total ice cover volume during this period. The ice meltwater supports a viable microbial assemblage associated with the sediment layer dominated by photosynthetic cyanobacteria and heterotrophic bacteria. We will describe the vertical distribution of chemicals and organisms in the ice cover and present a budget for the transport and production of particulate organic carbon showing that the ice assemblage exists because of seasonal growth rather than purely physical processes.
Day: Tuesday, Feb. 2
Time: 02:15 - 02:30pm
Location: Sweeney Center
Code: SS27TU0215S