Tuesday, December 05, 2017, 12:00PM - 2:00PM
SEEL room 303
Biogeochemistry, contaminant transport and atmospheric exchange in glacial cryoconite meltwater of the McMurdo Dry Valleys, Antarctica
Cryoconite holes are small melt pools on the ablation surface of glaciers created by the accumulation of aeolian sediment with a lower albedo than the surrounding ice. The energy balance in the McMurdo Dry Valleys of Antarctica often leads to the formation of dense ice lids over these pools, isolating the liquid from gas exchange while others remain open to the surface. This study analyzed the hydrology and biochemistry of open and lidded subsurface melt pools from six glaciers in the Dry Valleys throughout the initial melt, equilibrium, and refreezing periods in 2013- 2015. High solute concentrations relative to glacial ice indicate that the pools can be secluded from hydrologic connectivity for more than a decade. Vertical stratification of ice layers within the columns can be used to identify freeze/thaw cycles in the ice, and may be highly useful to indicate temporal variation and meltflow into ephemeral streams and lakes. Carbon cycling in lidded pools causes atmospheric disequilibrium and extreme pH. Solid-phase extraction and LC-MS/MS identified trace levels of perfluorinated compounds in the water. Results indicate that organic pollution transported to Antarctica by global distillation preferentially sorbs to organic matter and sediment at the bottom of the pools, and may help to indicate the magnitude of long-range atmospheric transport for anthropogenic contaminants in the Southern Hemisphere.