太湖沿岸湿沉降的化学特性及水体酸化的趋势

通过对太湖沿岸湿沉降的实际监测，运用统计学方法研究了太湖沿岸3个测点自2002年7月至2003年6月大气降水pH值和化学离子组成，并结合文献和太湖水体的常规观测资料，分析了太湖流域大气降水酸化的趋势及地表水酸化的状况。结果表明：太湖地区的酸雨比较严重，沿岸酸沉降具有普遍现象；大气降水中主要阴离子是SO4^2-，约占全部测定阴离子的48％。Ca^2＋是主要的阳离子，约占全部阳离子的37％；太湖酸雨频率及酸雨强度近20a来有增强的趋势，但水体pH变化不大，水体有轻微酸化的迹象。

The Chemical Characteristics of Wet Deposition and Preliminary Analysis of Surface Water Acidification along the Coastal Area of Taihu Lake

This paper statistically studies the pH value and the composition of chemical ions of the atmospheric precipitation at three sites along the coastal area of Taihu Lake by using the actual monitoring data of wet deposition from July 2002 to June 2003,and analyzes the acidification trend of atmospheric precipitation and the status of surface water acidification in drainage areas according to relevant literature and the routine observed data of the water of Taihu Lake.The result shows that acid deposition is ubiquitous along the coastal area of Taihu Lake;SO_4~(2-) is the major anion of precipitation,accounting for 48% of total anions;and Ca~(2 ) is the major cation,accounting for 37% of total cations.The acid rain frequency and intensity have an enhancing trend in the latest two decades,although the pH values of water has no obvious change.The surface water has the evidence of slight acidification according to the concentration of Ca~(2 )and SO_4~(2-) in water body.