The origin of Arctic air pollutants: lessons learned and future research

Results of various studies on the origin of Arctic air pollution are reviewed, focusing on what is known about its physical characteristics and chemical composition, as well as on emission sources and major pathways of pollutant transport to the region. Emissions from anthropogenic sources in Eurasia have been found to be a major contributor to Arctic air pollution measured at altitudes of up to 2–3 km in the atmosphere 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 mixture of anthropogenic and natural air pollutants from a variety of sources in different geographical regions, have been identified in the Arctic at altitudes of 4–5 km during both summer and winter. Long-range transport of airborne loess from deserts in Asia and Africa to the Arctic at these altitudes was suggested. Model calculations indicate that <10% of pollutants emitted in the major source regions is deposited in the 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 1980s. No major changes in concentrations were observed during the 1980s and some decrease was measured at selected stations at the end of that period. This decrease, particularly in lead and fine particle concentrations, was related to the decrease in their emissions in some source regions. A meteorological shift was also suggested as a possible cause of the decrease in concentration. Major gaps in information on sources, pathways and behavior of pollutants in the Arctic are identified. Current research programs that should improve our understanding of the origins and environmental effects of Arctic air pollution are presented.