Atmospheric transport and deposition of trace elements onto the Greenland Ice Sheet

Airborne particles of diameter > 0.4 μm reaching Dye 3, Greenland during April-May 1983 were highly variable in size and concentration from day to day. Five-day backward air mass trajectories suggest the importance of long-range transport from more northerly latitudes on days with high concentrations; particle sizes were larger on these days. Lower concentrations and smaller particle sizes were associated with transport from the south. It is inferred that Dye 3 may receive material emitted from Eurasian sources and transported over the Pole, similar to inferences for more northern Arctic sites. Elemental analysis of individual particles showed an abundance of crustal material, with many particles also containing sulfur. Bulk chemical analyses of airborne particles and fresh snow, collected during three snowstorms where ice nucleation dominated, provided data which were used to estimate mass-basis scavenging ratios. Average scavenging ratios were in the range ~1000-2000 for the crustal elements Al, Fe, K, Mg, Mn, and Na. Similar values were observed for Cd, Cu and NO₃^-. The corresponding ratios for Pb and SO₄^2- averaged less than 200. These ratios were used with precipitation rate data to estimate wet deposition velocities in the order of ~2 cm s^-1 for the first nine species, and ~0.2 cm s^-1 for Pb and SO₄^2-. Comparing fresh and older surface snow concentrations gave an average dry deposition velocity of roughly 0.2 cm s^-1 for the crustal elements, with the small fraction of large particles (~5-10 μm) dominating deposition; much smaller values were associated with the remaining species. When used with other data in the literature, the results of this study suggest that total deposition velocities of Pb and SO₄^2- may be as small as 0.05 cm s^-1 in relatively dry regions of the Arctic.