2011 年 26 巻 4 号 p. 315-320
Observations of atmospheric aerosols were carried out at Maebashi and Mt Akagi located in the inland Kanto plain. Fine and coarse particles were collected using a low-volume air sampler, and organic carbon (OC), water-soluble organic carbon (WSOC), elemental carbon and ionic components were measured. The highest concentration of fine particles was observed in spring, and nitrate and sulfate were the major components. Sulfate and OC were dominant in summer and fall. We found that ammonium sulfate was widely distributed in the inland Kanto plain while ammonium nitrate was localized in Maebashi. The seasonal variation of WSOC concentration rising from summer to fall was observed at Maebashi. The WSOC/OC ratio increased in summer, suggesting that organic aerosols were influenced by aging. We focused on water-soluble organic components in fine particles; dicarboxylic acids as tracers of photochemical reaction products, and levoglucosan as a tracer of biomass burning emission. The concentrations of total diacids in spring and summer were higher than in winter. WSOC concentration showed highly positive correlation with total diacids concentration in each season. Levoglucosan observed was considerably high in winter. We found that the secondary formation is the dominant source of organic aerosols, especially in the warm seasons, and that biomass burning is another important source of organic aerosol in winter.