Results of integrated aerosol experiment in the continent-ocean transition zone (primorye and the Japan Sea). Part 3. Microphysical characteristics and ion composition of aerosol in the near-ground and near-water layers

Abstract

The paper discusses the results of simultaneous aerosol measurements performed in the spring 2009 in two regions: near Ussuriysk (43.7° N, 132.2° E) and in the Japan Sea onboard the Nadezhda sailing training vessel. The mass concentrations of aerosol and black carbon and the particle size distribution were measured using PhaN-type nephelometers, aethalometers, and AZ-5 and GRIMM photoelectric particle counters. Simultaneously, air samples were collected on filters to determine the ion chemical composition of aerosol. The spatiotemporal variations in chemical and microphysical composition of aerosol were studied. It is shown that the atmosphere of the Far East region in spring of 2009 was characterized by high contents of aerosol and black carbon, comparable with that over the Caspian Sea and three times larger than the level of concentrations over the White Sea. The average mass concentrations of aerosol and black carbon and the number concentration of particles were (17.5 ± 8.70) μg/m3, (0.99 ± 0.72) μg/m3, and (22.0 ± 13.6) cm−3, respectively. The high concentrations of aerosol and black carbon were due to emissions of continental aerosol of different origins (dust, anthropogenic, and smoke) and marine aerosol from regions neighboring the measurement regions. Close values of the concentrations in Primorye and the Japan Sea argue for the existence of a mean regional aerosolbackground. About 80% of the aerosol chemical composition in the region is accounted for by continental particle sources. Submicron aerosol prevailed in dust emissions, which formed the ion composition in most cases. The content of large particles (about 2 μm in radius) in the size spectrum may serve as an indicator of dust emissions. It follows from comparison with other regions that the maximum concentrations of “continentally derived” SO42−, NO3−, and NH4+ ions are observed over the Japan Sea, those of “sea-derived” Cl−, Na+, and Mg2+ ions are observed over the White Sea, and the minimum concentrations of most ions are observed near Antarctica.