Study on the Water Quality of Urban Forest Ecogystem in the Pearl River Delta

Based on stationary observation and chemical analysis in the subtropical evergreen broad-leaved forest ecosystem at Daling Mountain in Daliang town of Shunde from 2002 to 2003, the hydrochemical cycles in the ecosystem was studied combined with their hydrologic process. The distribution of rainfall was 1 628.9 mm. The amount of rainfall from May to Sep. represented as about 82.4% of total precipitation.The amount of throughfall took 85.01%,the amount of stemflow took 3.17%,and 11.82% of annual rainfall was intercepted by the forest canopy.The average of pH of rainfall was 5.27 and the frequency of acid rain was 67.8% in industrial estate of Daling town.The average of pH of rainfall was respectively 5.84 and 5.72 and the frequency of acid rain was 27.1% in residential area of Daliang town and Longjiang town. The average of pH of rainfall was 6.31 and the frequency of acid rain was 6.5% in forest.By analyzing the water quality and the throughfall,it showed that the content of most ions in throughfall increased, the concentrations of TPKZnPb in throughfall were higher than that of those in rainfall by 4 times1 times2 times7 times1 times respectively,and the concentrations of AlCaCu were less than that of those by 89.8%40.7%30.5% respectively.