堺で観測した大気エアロゾル粒子の長期 (1986～2004) 観測結果

抄録

We have conducted daily sampling of atmospheric aerosols since 1986 at Sakai, Osaka and analyzed the ionic constituents (Cl^-, NO₃^-, SO₄^2-, Na⁺, NH₄⁺, K⁺, Mg²⁺, Ca²⁺) in the samples collected from 1986 to 2004 with ion chromatography. The daily variations of the concentrations show that the particle mass (PM) and ionic constituent concentrations have seasonal variations and yearly trends. In the ionic constituents, Cl^- and NO₃^- exhibited the most significant seasonal variations with low mean concentrations in summer and high mean concentrations in winter and autumn. Yearly mean of PM trends to decrease from 1995 to 2000 because administrative management seems to successfully control the emission of diesel particles. Cl^-, NO₃^-, NH₄⁺, K⁺ also have a decreasing trend, and among them Cl^- is decreased at a high rate since 1997. This decrease of Cl^- could be attributed to the reduction of gaseous chlorine emitted mainly from incineration plants. The decrease of NO₃^- could have been caused by the decreasing trend of NOx from which NO₃^- is produced by the photo chemical process. On contrary, SO₄^2- has an increasing trend in 1986 ∼ 1995 due to SO₂ emission increase in China. From 1995 to 1997, the reduction of sulfur in the diesel fuel contributed a slight decrease in SO₄^2- concentration, but it remains fairly constant in 1998 ∼ 2004.