Arctic organic aerosol measurements show particles from mixed combustion in spring haze and from frost flowers in winter

Abstract

Submicron atmospheric aerosol particles were collected between 1 March 2008 and 1 March 2009 at Barrow, Alaska, to characterize the organic mass (OM) in the Arctic aerosol. Organic functional group concentrations and trace metals were measured with FTIR on submicron particles collected on Teflon filters. The OM varied from 0.07 μg m−3 in summer to 0.43 μg m−3 in winter, and 0.35 μg m−3 in spring, showing a transition in OM composition between spring and winter. Most of the OM in spring could be attributed to anthropogenic sources, consisting primarily of alkane and carboxylic acid functional groups and correlated to elemental tracers of industrial pollution, biomass burning, and shipping emissions. PMF analysis associated OM with two factors, a Mixed Combustion factor (MCF) and an Ocean‐derived factor (ODF). Back trajectory analysis revealed that the highest fractions of the MCF were associated with air masses that had originated from northeastern Asia and the shipping lanes south of the Bering Straits. The ODF consisted of organic hydroxyl groups and correlated with organic and inorganic seawater components. The ODF accounted for more than 55% of OM in winter when the sampled air masses originated along the coastal and lake regions of the Northwest Territories of Canada. Frost flowers with organic‐salt coatings that arise by brine rejection during sea ice formation may account for this large source of carbohydrate‐like OM during the ice‐covered winter season. While the anthropogenic sources contributed more than 0.3 μg m−3 of the springtime haze OM, ocean‐derived particles provided comparable OM sources in winter.