LONG-TERM VARIATION OF CHEMICAL-COMPOSITION OF ATMOSPHERIC AEROSOL ON THE OKI ISLANDS IN THE SEA OF JAPAN

Chemical composition in aerosols collected on the Oki Islands, which are located in the Sea of Japan, were measured for 4 1 2 years (1983-1988) and their variations were investigated from the viewpoints of aerosol background level and transport of aerosols from both the mainland of Japan and the Asian Continent. Kosa, which is soil dust from the Asian deserts, strongly influenced the variations of the concentration of soil-derived components in aerosol, which showed high concentrations every spring and November. Sulfate had a good correlation with V in the variation and their concentrations increased in summer as the result of the transport of the aerosol from the mainland of Japan. Whereas high Pb concentration in winter was presumed to be attributed to the contribution of lead-enriched aerosol transported from the Asian Continent by the northwest monsoon. The differences of aerosol composition between summer and winter were seen in the ratios of Pb/Zn and Sulfate/V, which may be good indicators for the characterization of aerosol in Asian region. Long-term trends of changing of aerosol composition were also studied, and only C indicated a slight increase for 4 years. © 1990.