A CHEMICAL CHARACTERIZATION OF ATMOSPHERIC AEROSOL IN SAPPORO

Monthly mean chemical composition of aerosol with diameter less than 8 μm was identified in Sapporo in 1982. The mass of aerosol was made up of nine components: elemental C, organics, SO42-, NO3-, NH4+, Cl-, Na+, soil particles and water. The concentrations of carbonaceous particles (elemental C and organics) was relatively high (12.7-16.0μ m-3) in autumn and winter (October-February) due to emission from domestic heating and comprised 36-41% of total aerosol mass. Higher concentration of soil particles was observed in spring (March-May) (9.7-13.1 μg m-3) and comprised 22-29% of total aerosol mass due to suspension by strong wind. On the other hand, the concentration of excess SO42- (non-sea salt SO42-), which ranged from 2.6-5.2 μg m-3, did not change remarkably with season, and the fraction of excess sulfate increased to 21% in summer (July-August) probably due to photochemical transformation from SO2. Nitrate concentration was far less than that of SO42- throughout the year in Sapporo. © 1990.