Abstract
This paper proposed a method to estimate the chemical composition of calcium compounds in the KOSA particles according to the carbonate equilibrium system in an acidic solution. The calcium compounds in the KOSA aerosols were classified into two categories in terms of the neutralizing capacity of acidic substances in the atmosphere, i.e. the portion that contributes to neutralization and the portion that does not. It was shown that the former might consist of carbonates and that the latter might consist of neutral salts such as sulfate and nitrate. The ratio of carbonate content to total soluble cation content in the KOSA aerosol collected in Toyama, Japan, which was also estimated by a chemical equilibrium established in this study, implied that fairly large portion of the calcium carbonate in KOSA aerosols could be regarded as having reacted with acidic pollutants in the atmosphere.