Concentrations and size-distributions of water-soluble inorganic and organic species on aerosols over the Arctic Ocean observed during the US GEOTRACES Western Arctic Cruise GN01

Abstract

Marine aerosols affect the climate directly and indirectly as well as serving as tracers of biogenic processes. Here we present the results from size-segregated and bulk aerosol samples collected from 2nd August to 10th October 2015 during the US GEOTRACES Arctic Ocean (GN01) expedition. Samples were analyzed for concentrations of major water-soluble organic and inorganic species, including acetate, formate, methanesulfonate (MSA), oxalate, propionate, chloride, nitrate, sulfate and major cations (Na+, K+, Mg2+, Ca2+, NH4+). Back-trajectory analysis was performed to categorize the wind patterns into three types; type 1, originating from the North Pacific and the Bering Sea, type–2, consisting entirely of marine Arctic air, and type 3, consisting of marine Arctic air mixed with air masses from the surrounding continents. Sea-salt was the major aerosol component, dominating in the coarse mode, 1.8–5.6 μm. Non-sea-salt sulfate and MSA were predominantly present in the fine mode, 0.18–0.32 μm, and MSA was associated with type 1 and type 2 air masses. The results from this study provide useful information on the origins and chemical processes involving these aerosol species over the Arctic in summer and help elucidate the significance of natural sources as contributors for the formation of cloud condensation nuclei.