CHEMICAL COMPOSITION OF PRECIPITATION, THROUGHFALL AND SOIL SOLUTIONS AT TWO FORESTED SITES IN GUANGZHOU, SOUTH CHINA

摘要

Rain water at two forested sites in Guangzhou (south China) show high concentrations of SO_4~(2-), NO_3~- and Ca~(2+) and display a remarkable seasonal variation, with acid rain being more important during the spring and summer than during the autumn and winter. The amount of acid rain represents about 95% of total precipitation. The sources of pollutants from which acid rain developed includes both locally derived and long-middle distance transferred atmosphere pollutants. The seasonal variation in precipitation chemistry was largely related to the increasing neutralizing capacity of base cations in rainwater in winter. Soil acidification is highlighted by high H~+ and A1~(3+) concentrations in soil solutions. The variation in elemental concentration in soil solution was related to nitrification (H~+, NH_4~+ and NO_3~-) and cation exchange reaction (H~+, A1) in soil. The negative effect of soil acidification is partly dampened by substantial deposition of base cations (Ca~(2+), Mg~(2+) and K~+) in this area.