Atmospheric aerosol over Alaska: 2. Elemental composition and sources

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Abstract
The fine particle (+, and K identified as forest fire smoke was obtained for all data sets except at Katmai. Factors with high concentrations of S, BC‐Na‐S, and Zn‐Cu were obtained at all sites. At three sites, the solutions also contained a factor with high Pb and Br values. The factors with the high S, Pb, and BC‐Na‐S values at most sites show an annual cycle with maxima during the winter‐spring season and minima in the summer. The seasonal variations and elemental compositions of these factors suggest anthropogenic origins with the spatial pattern suggesting that the sources are distant from the receptor sites. The seasonal maxima/minima ratios of these factors were higher for more northerly locations. Four main sources contribute to the observed concentrations at these locations: long‐range transported anthropogenic aerosol (Arctic haze aerosol), sea‐salt aerosol, local soil dust, and aerosol with high BC concentrations from regional forest fires or local wood smoke. A northwest to southeast negative gradient suggesting long‐range transport of air masses from regions north or northwest of Alaska dominated the spatial distribution of the high S factor concentrations.