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Number concentrations of ice nucleating particles (NINP) in the Arctic were derived from ground-based filter samples. Examined samples had been collected in Alert (Nunavut, Northern Canadian Archipelago on Ellesmere Island), Utqiagvik, formerly known as Barrow (Alaska), Ny Ålesund (Svalbard) and at the Villum Research Station (VRS, North Greenland). For the former two stations, examined filters span a full yearly cycle. For VRS, 10 weekly samples, mostly from different month of one year, were included. Samples from Ny Ålesund were collected during the months from March until September of one year. At all four stations, highest concentrations were found in the summer months from roughly June to September. For those stations with sufficient data coverage, an annual cycle can be seen. The spectra of NINP observed at the highest temperatures, i.e., those obtained for summer month, showed the presence of INP that nucleate ice up to - 5°C. It is know from literature that ice activivity observed at such high temperatures indicates the presence of ice active material of biogenic origin. Spectra observed at the lowest temperatures, i.e., those derived for winter month, were on the lower end of respective values reported in literature. An analysis concerning the origin of INP that were ice active at high temperatures was carried out, using back-trajectories and satellite information. Both, terrestrial locations in the Arctic and the adjacent sea were found to be possible source areas for highly active INP. [ABSTRACT FROM AUTHOR]

The Arctic ecosystem is undergoing rapid changes including warming, wetting, loss of sea ice, and thawing of permafrost. The biogenic emissions that result from these changes have the potential to affect the regional chemistry and climate through the production of secondary organic aerosol (SOA) from biogenic volatile organic compound (BVOC) emissions, while anthropogenic emissions have the potential to increase with increased local activity. Recent studies investigating marine sources of organic aerosol in the Arctic highlight the need to understand the temporality, variability and characteristics of biogenic sources in the changing system. Terrestrial sources of biogenic aerosol in the Arctic are even less understood and may be more variable from low to high Arctic regions. The study site on the North Slope of Alaska is primarily sedge/grass, moss wetland, with more vegetation than high Arctic sites. To understand the long-term impact of these sources on carbonaceous aerosol concentration and composition in the Arctic, a multi-year view is needed. This presentation will highlight summer trends in organic aerosol sources and composition over 5 years on the North Slope of Alaska (2012-2017). Sources and composition of organic aerosol will be discussed with respect to results from isotopic analysis (radiocarbon), organic and elemental carbon, organic acids (including methanesulfonic acid), biogenic SOA tracers (including pinic acid and methyl tetrols), levoglucosan, and combustion tracers (including polycyclic aromatic hydrocarbons and hopanes). [ABSTRACT FROM AUTHOR]

The rapid decrease in Arctic sea ice is motivating development and increasing oil and gas extraction activities. However, few observations of these local Arctic emissions exist, limiting the understanding of impacts on atmospheric composition and climate. To address this knowledge gap, the chemical composition of atmospheric aerosols was measured within the North Slope of Alaska oil fields during August and September 2016 using an aerosol time-of-flight mass spectrometer (ATOFMS) and a time-of-flight aerosol chemical speciation monitor (ToF-ACSM). Plumes from oil and gas extraction activities were characterized by soot internally mixed with sulfate (matching diesel soot) and organic carbon particles containing aminium sulfate salts. Sea spray aerosol at the coastal site was frequently internally mixed with sulfate and nitrate, from multiphase chemical processing from elevated NO x and SO 2 within the oil field. Background (nonplume) air masses were characterized by aged combustion aerosol. No periods of "clean" (nonpolluted) Arctic air were observed. The composition of the nonrefractory aerosol measured with the ACSM was similar during plume and background periods and was consistent with the mass concentrations of nonrefractory particles measured by ATOFMS. Two ultrafine aerosol growth events were observed during oil field background periods and were correlated with fine mode amine-containing particles.