常德市酸雨化学特征、趋势分析及控制对策

常德市是中南地区酸雨污染最为严重的城市之一。以常德市2004年至2006年的降雨连续监测数据为基础，应用统计学相关分析的方法，对常德市158次降雨的变化特征进行了分析和研究。结果表明，常德市降雨酸度呈波动性变化，近3年的降雨pH年均值都在5．4以下，对降雨中离子含量的分析可知，酸雨主要为硫酸型，有向硫酸和硝酸混合型转化的趋势。降雨中的主要离子浓度和通量在冬、春季节高于夏、秋季节，降雨中阴阳离子极不平衡，SO4^2-]和Ca^2＋]浓度对降雨离子的平衡有较大的影响。常德市的净酸度沉积量在2004年高达199．29meq m^-2yr^-1，而从2004年-2006年，净酸度沉积量和离子沉降总通量均在逐年降低，表明常德市降雨酸化现象有所缓和．

Atmospheric Wet Deposition Chemistry and Acid Rain Control in Changde City

Changde city is one of the severest polluted cities by acid rain in Central - south China. The atmospheric wet deposition chemistry and the variation characteristics of acid rain were analyzed and studied by statistic correlated methods based on the monitoring data of 158 precipitation samples from 2004 to 2006 in Changde city. The results showed that the annual mean pH value was fewer than 5.4 in the near years in Changde city, concentrations and fluxes of major ions were larger in winter and spring than summer and autumn. The ionic balance between anion and cation in the precipitation was wondrously not balanced in the observed years and the concentration of SO4^- ] and Ca^2 ＋ ] have more effects on the ionic balance. The deposition amount of net acidity reached 199. 29 meq m^- yr^-1 in 2004 and played down largely each year from 2004 to 2006, which indicated that acid rain was tempered in Changde city.