Analysis of aerosol composition at Cheju Island, Korea, using a two-bin gas-aerosol equilibrium model

Aerosol chemical composition data measured at Cheju Island, Korea from March 1992 to December 1994 are analyzed with a gas-aerosol equilibrium model. The aerosol composition is divided into fine and coarse modes, with each mode assumed to be in equilibrium with the gas phase. The model represents the mean aerosol composition. The particulate ammonium is found to exist mostly in the fine mode to neutralize nss-sulfate, and the particulate nitrate and chloride are present mostly in the coarse mode and compete with each other to share sea salt and mineral cations. This means little formation of ammonium nitrate and chloride. Sensitivity analyses suggest that the aerosol in this region will be more deficit in chloride due to dechlorination and ammonium nitrate associated with the fine mode may become important.