Correlation of acid rain with the distributions of acid and alkaline elements in aerosols

Acid rain often appeared both in Guiyang city of Guizhou province and Chongqing city of Sichuan province in the southwest of China. Aerosol samples in these two cities were collected by Andersen cascade sampler during the spring and autumn of 1985 respectively. The contents of 18 elements in the aerosol particles were analyzed by PIXE. The distributions of acid elements such as S, Cl and alkaline elements such as Ca, K in the aerosol samples from these two cities were calculated. The comparison of the distributions of acid and alkaline elements in the aerosol samples was made between these two cities and Beijing where no acid rain was found. The results showed that the acid rain in the southwest of China was caused by the dominant concentration of acid elements in the aerosol particles, which mainly resulted from the coal combustion and the lower alkalinity of soil in this area.