| Summary: | Arctic aerosols at Barrow AK from 16 March to 7 May 1986 were sampled and studied for natural aerosols or natural aerosol components as well as pollutants using ion chromatography and proton induced X-ray emission analyses, and a modified principal component analysis receptor model, absolute principal component analysis (APCA). Natural organic acids were found in the aerosols at high concentrations and were likely due to low temperature condensation of acid vapors. By APCA, 20% of non-sea salt sulfate was found to come from oxidation of marine emitted organo-sulfur compounds by means of the tracer methanesulfonate. 80% of sulfate was found in the form of NH$\sb4$HSO$\sb4$. Pollutant coal combustion aerosols, determined from their chemical composition as condensate from gaseous precursors, were found and were traced back to northern Europe during a major haze event by synoptic meteorological studies. Similarly, sea salt aerosols were present and were traced back to either the Beaufort Sea or the remote North Pacific. Dust particles were present in the Arctic throughout the sampling period. Bromine was found to exist in aerosol particles not related to these aerosol components. The size distributions of these aerosol components were obtained by applying APCA to 8 cascade impactor stages, and indicated (1) the sea salt particles were aged and were consistently enriched in chlorine; (2) the dust particles were probably due to long range transport of eolian dust and had absorbed sulfur gases; (3) the coal combustion pollutants were due to gaseous phase condensation; and (4) bromine on particles was due to absorption of bromine gases. Aerosol bromine was found to vary inversely with ozone concentration changes during both day and night time, but only when very low aerosol nitrate was present. When nitrate levels were high, ozone followed the variation in nitrate, indicating a pollution origin. Movements of ozone-depleted air and ozone-rich air apparently caused very large in situ ozone concentration fluctuations, ...
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