ELEMENTAL CONCENTRATIONS IN FRESH SNOWFALL ACROSS A REGIONAL TRANSECTIN THE NORTHEASTERN US - APPARENT SOURCES AND CONTRIBUTION TO ACIDITY

Fresh snowfall was collected on the surface of 8 lakes across a 350 km west-east transect from northeastern New York state to the coast of M aine after a single storm. In addition, every snowfall event during th e winter of 1993 was collected on a single lake near the center of the transect. Across the transect, midwestern sources appear to dominate Pb and Cd concentrations, while Sb appears to be derived from midweste rn sources as well as local and/or industrial East Coast sources. In a ll samples, the highest Na, Cl and Mg concentrations reflect a marine influence, but at some transect sites roadspray aerosol appears to con tribute to Na and Cl concentrations. The regional pattern of Ca, K, Mn and Sr concentrations and Mn/Sr ratios indicate that woodsmoke may be an important winter source of these elements at some sites. In all sa mples, H+ is strongly correlated with NO3- (R(2) = 0.97) and mean NO3- /SO42- molar ratios of 6.4 for transect samples, and 4.7 for temporal samples, are higher than mean NO3-/SO42- reported for other precipitat ion studies in the same region. The contribution of NO3- to the snowpa ck greatly exceeds that of SO42-, and may be a major source of acidity in aquatic ecosystems during snowmelt.