Abstracts
SEARCH Open Science Meeting
October 27, 2003
Seattle, Washington, USA
The Chemical Composition of Snow Across Northwestern Alaska and the Potential Ramifications of a Warming Arctic
Thomas A. Douglas1, Matthew Sturm2
1Cold Regions Research and Engineering Laboratory, P.O. Box 35170, Building 4070, Fort Wainwright, AK, 99703-0170, USA, Phone 907-353-9555, Fax 907-353-5142, Thomas.A.Douglas@erdc.usace.army.mil
2Cold Regions Research and Engineering Laboratory, P.O. Box 35170, Building 4070, Fort Wainwright, AK, 99703-0170, USA, Phone 907-353-5183, Fax 907-353-5142, Msturm@crrel.usace.army.mil
Continued warming of the Arctic and the subsequent thinning and loss of Arctic Ocean sea ice will affect the deposition of aerosol contaminants in northern Alaska. In order to better understand the spatial and temporal aspects of current chemical deposition pathways we sampled three layers of snow at 16 sites along a 1200 km transect from Nome to Barrow. Samples were analyzed for major element concentrations, oxygen and hydrogen isotopes, specific conductance and pH. Samples from 5 of the sites were also analyzed for trace element concentrations.
Pb, Cd, SO42- and non-sea salt SO42- concentrations were significantly higher in layers deposited later in the winter than those deposited in early winter. This is consistent with the seasonal increase in atmospheric aerosol loading (arctic haze) that develops as the Arctic polar front expands southward in March and April. Haze contaminant concentrations in the snow pack were as high south of the Brooks Range as they were to the north, suggesting the Brooks Range is not an effective orographic barrier to aerosol transport. Elevated concentrations of Hg, Na and Cl were measured near the Arctic Ocean coast but not near the Bering Sea coast.
In an attempt to explain this asymmetrical spatial deposition pattern we introduce the idea of the “effective distance from the coast,” as inferred from prevailing wind directions and storm tracks. This distance is critical in governing whether halogen emissions from the ocean are available for photochemical reactions that result in mercury deposition to the snow pack. We speculate how current deposition patterns would change under a warmer arctic climate.
Abstract Categories: Changes on Land
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