Variation of chemical constituents in aerosol particles during kosa events in Toyama, Japan

Abstract

Kosa (Asian dust) events were observed by the Japan Meteorological Agency in western Japan from April 12 to 17, 2003, and in Toyama from April 14 to 15. Atmospheric aerosol samples were collected in Toyama using a high-volume air sampler during the period from April 12 to 19, 2003. The dominant ionic species in the aerosol samples were SO₄^2- anions. The dominant cation was Ca²⁺ before April 15 and NH₄⁺ after April 15. The concentrations of non-sea-salt (nss) Ca²⁺, NO₃^-, nssMg²⁺, and Sr in aerosols were high from April 14 to 15 and decreased afterwards. Calcium concentrations in the aerosol samples showed good correlation with those of nssMg²⁺ and Sr. The average molar ratios of nssMg²⁺/nssCa²⁺ (0.15) and Sr/Ca (0.0022) in the aerosol samples were similar to the ratios found in Chinese desert soils, suggesting that the aerosols collected in Toyama were continuously affected by mineral dust from the Asian continent during this period, although the concentrations varied.