NITRATE DEPOSITION TO THE ALASKAN SNOWPACK

Snowpack samples were collected from interior and arctic Alaska during March 1988 and analysed for pH, conductivity, NO3-, SO42- and other c onstituents. The mean snowpack NO; and SO42- concentrations in the int erior Alaska snowpack were found to be 160 and 179 ngg(-1), respective ly. The interior snowpack was observed to have concentrations and depo sition fluxes of NO3- which are approximately 1.5 and 1-3 times, respe ctively, those observed in Greenland. In the arctic samples, collected in the Sagavanirktok River Valley, wind-deposited loess substantially increases both pH and SO42- concentrations in the snowpack. Snowpack nitrate in these samples is unaffected by the windborne loess and had a mean NO3- concentration of 688 ngg(-1). The NO; deposition flux in t he Arctic is approximately two times that found in the interior snowpa ck. The most plausible explanation for the elevated NO3- deposition fl ux is that the snowpack deposition is strongly influenced by the prese nce of the ''arctic front'', a meteorological boundary which acts to c ontain the polluted, arctic air mass. Alternatively, local NOx emissio ns on Alaska's arctic coast or substantial changes in the scavenging e fficiencies may also influence the observed north-south gradient in NO 3- concentrations in the snowpack.