ACIDIC DEPOSITION AND ITS EFFECTS IN SOUTHWESTERN CHINA

The emissions of SO2 in China correspond at present to 8-10 TgSyr(-1). The rapid industrialization has caused a dramatic increase in the emi ssions in recent years and this increase is likely to continue. This p aper describes studies of concentrations and effects of acidifying sub stances in parts of the Guizhou and the Sichuan provinces where the S- emissions are large. A small catchment about 10 km from Guiyang centre was equipped with instruments for studies of soils, soil water and st reamwater chemistry. The molar ratio Al/(Ca + Mg) is > 0.8 in soil wat er in some places. Two small streams have median pH-values about 4.6 a nd 5.1. Laboratory studies with selected Chinese soils showed that the anion adsorption was low. These studies gave also important informati on on soil sensitivity. The studies confirm that acid deposition may a ffect soils in parts of south-western China, but the sensitivity varie s dramatically and there is a strong need for more information.