Seasonal variation of the atmospheric aerosol near the top of the marine boundary layer over Spitsbergen related to the Arctic sulphur cycle

Abstract

With an emphasis on marine biogenic sulphur the first 26 months of fine particle, (<1 μm radius), aerosol data from the new air chemistry station on Zeppelinfjellet, Spitsbergen, (79°N, 12°E, 474 m asl), were evaluated to elucidate source- and transformation processes of the Arctic aerosol. Results from 2 particle counters, an integrating nephelometer, and filter samples were available for our interpretation. In winter, no more than 2% of the non-sea-salt sulphur could be attributed to the marine biological source. Rigorous air mass analyses combined with the EC data as a tracer for regional anthropogenic combustion sources showed that this regional biological source became active already in March over the Barents Sea and over the North Atlantic. In summer, the levels of the biogenic sulphur components were very similar to those measured at the southern hemispheric marine site of Cape Grim. Together with the scavenging results our data support the concept that MSA- most likely is formed by condensation onto existing particles while SO42- predominantly is formed by in-cloud oxidation of SO2. -from Authors