THE ORIGIN OF ARCTIC AIR-POLLUTANTS - LESSONS LEARNED AND FUTURE-RESEARCH

Results of various studies on the origin of Arctic air pollution are r eviewed, focusing on what is known about its physical characteristics and chemical composition, as well, as on emission sources and major pa thways of pollutant transport to the region. Emissions from anthropoge nic sources in Eurasia have been found to be a major contributor to Ar ctic air pollution measured at altitudes of up to 2-3 km in the atmosp here during winter. During sporadic summer transport of pollutants to the region, emissions from sources in Europe seem to be more important than those from other sources. Polluted air masses, carrying a mixtur e of anthropogenic and natural air pollutants from a variety of source s in different geographical regions, have been identified in the Arcti c at altitudes of 4-5 km during both summer and winter. Long-range tra nsport of airborne loess from deserts in Asia and Africa to the Arctic at these altitudes was suggested. Model calculations indicate that <1 0% of pollutants emitted in the major source regions is deposited in t he Arctic, although our knowledge on wet and dry removal processes in this region is very incomplete. Maximum concentrations of sulfates and fine particles in the Arctic were observed at the beginning of the 19 80s. No major changes in concentrations were observed during the 1980s and some decrease was measured at selected stations at the end of tha t period. This decrease, particularly in lead and fine particle concen trations, was related to the decrease in their emissions in some sourc e regions. A meteorological shift was also suggested as a possible cau se of the decrease in concentration. Major gaps in information on sour ces, pathways and behavior of pollutants in the Arctic are identified. Current research programs that should improve our understanding of th e origins and environmental effects of Arctic air pollution are presen ted.