CHEMICAL-CONSTITUENTS IN THE AIR AND SNOW AT DYE-3, GREENLAND .2. ANALYSIS OF EPISODES IN APRIL 1989

Detailed examination of a two-week period in April 1989 during the Dye 3 Gas and Aerosol Sampling Program shows that episodes of relatively high concentration of certain chemical constituents occur at this time of year. Airborne concentrations of crustal metals such as Al and Ca can exceed 100 ng m(-3), while concentrations of SO42- can exceed 1000 ng m(-3). Elevated concentrations of MSA, Be-7 and Pb-210 are also no ted. Consideration of synoptic maps and backward air mass trajectories suggests that the episodes are due to transport from a variety of sou rce regions, including Eurasia (transport over the Pole), North Americ a and western Europe. In addition to elevated airborne concentrations, levels of these constituents in surface snow are high during April. H owever, it is difficult to develop quantitative relationships between concentrations in air and in snow due to the difficulty in measuring a irborne concentrations at cloud-level; variations in scavenging by clo uds may also be significant. It is concluded that the springtime maxim a in airborne concentrations resulting from long-range transport from a variety of source regions are responsible for strong identifiable si gnals in ice cores and snowpits from this region.