Neutralization of soil aerosol and its impact on the distribution of acid rain over East Asia: observed evidence and simulation

Zifa Wang, I. Uno, H. Akimoto

Journal of Geophysical Research, 107 (D19), 4389, doi:10.1029/2001JD001040, 2002.


A comprehensive Air Quality Prediction Modeling System (AQPMS)is applied to simulate the pH value in precipitation and to investigate neutralization by soil aerosols and its influence on the distribution of acid rain over East Asia. A modified deflation module is designed to provide explicit information on the soil aerosolloading. Numerical simulation was performed for one year, from December 15, 1998 to December 31, 1999. Wet deposition monitoring data at 17 sites of EANET (the Acid Deposition Monitoring Network in East Asia) was used to evaluate the model and a reasonable agreement was obtained. Observed evidence clearly shows that in northern China acid deposition is heavily influenced and buffered by natural soil dust from desert and semi-arid areas. The simulation results for 1999 exhibited strong neutralization ofprecipitation by soil aerosols over Northeast Asia and the distribution pattern of acid rain was also changed. The annual mean pH values in northern China and Korea show a remarkable increase of 0.8-2.5, while the increase in the mean pH values over southern China and Japan are lesser than 0.1. The neutralization effects vary for each season, for example, in spring the pH values increased 0.1-0.4 in Japan, 0.8-1.4 in Korea, and more than 2 in North China.