University of Cambridge > Talks.cam > Scott Polar Research Institute - Physical Sciences Seminar > Microbial activity beneath the Antarctic Ice Sheet: impacts beyond the ice margin?

Microbial activity beneath the Antarctic Ice Sheet: impacts beyond the ice margin?

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Once thought to be devoid of life, the Antarctic Ice Sheet is now known to be a dynamic reservoir of organic carbon and metabolically active microbial cells. At the ice-bed interface, subglacial lake environments and till are believed to support low diversity microbial populations, adapted to perennial cold, anoxia and lack of light. The dynamic exchange of water between these shallow environments sustains nutrient and organic carbon supply to the subglacial zone, and ultimately conveys meltwaters and sediments into the coastal ocean. The latter may be important for fertilizing the Southern Ocean with N, P and Fe, with potential implications for marine productivity and associated CO2 drawdown. Beyond the subglacial lakes and the subglacial till complex are deep sedimentary basins up to 14km thick located largely around the Antarctic periphery. Here, sustained microbial activity over Myr timescales is likely to be important for the cycling of organic carbon and elements in the deep sub-surface. These sedimentary basins may be hydrologically decoupled from shallower lake and till environments by the presence of highly consolidated sediments which limit the penetration of glacial meltwaters to depth. Organic carbon buried in these basins (e.g. marine sediments) during ice sheet formation is thought to be microbially cycled to methane gas, which is stored as hydrate within sediments, stabilized by the high pressure/low temperature conditions. It has been demonstrated via numerical modeling that this methane store could be of a similar order of magnitude to that present as hydrate in other globally significant reserves. In summary, microbial activity beneath the Antarctic ice sheet is likely to have far reaching impacts beyond the ice margin and may be important to consider in future global models of biogeochemical cycling.

This talk is part of the Scott Polar Research Institute - Physical Sciences Seminar series.

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