Effect of heterogeneous aerosol chemistry on SO{sub 2} oxidation in regional deposition model

A heterogeneous aerosol chemical model is developed by coupling aerosol, gas-phase and liquid-phase chemistry model, in which SO{sub 2} oxidation rate on aerosol surface is calculated and the importance of some factors is discussed. High concentration of aerosol is an important feature of air pollution in east Asia. Aerosol provides a surface for SO{sub 2} heterogeneous oxidation, so aerosol surface chemical process can not be neglected. The SO{sub 2} oxidation rate is sensitive to the mass concentration of aerosol, relative humidity, initial values of SO{sub 2}, O{sub 3}, and H{sub 2}O{sub 2}. In order to understand the role of aerosol chemical process of SO{sub 2} in regional acid deposition, this model and Euler regional deposition model are coupled. The 2-coupled model has been used to calculate concentrations of SO{sub 2} and SO{sub 4} in China. The results indicate that oxidation of SO{sub 2} on aerosol surface is found to reduce SO{sub 2} 2-levels by 2% up to 33%, to increase SO{sub 4} concentrations by 8%-50% in surface layer.