中国典型酸雨区大气湿沉降化学特性

Ions distributional characteristics of wet precipitation in typical acid rain areas of China

以湖南蔡家塘、贵州雷公山和重庆铁山坪3个小流域长年大气降水及森林穿透水的监测数据为基础,对三地的大气降水和森林林冠穿透水的化学成分的分布特征进行分析研究。研究结果表明:3个地区大气降水都已出现严重的酸化现象,大气降水多年平均pH从大至小的顺序为雷公山(4.96)、蔡家塘(4.62)和铁山坪(4.12);蔡家塘与铁山坪大气降水和森林穿透水中的阴离子均以SO42-为主,阳离子以NH4+为主;蔡家塘大气降水和森林穿透水中SO42-占总离子量的26.67%和24.14%,NH4+占总离子量的31.67%和23.69%;铁山坪大气降水和森林穿透水中SO42-占总离子量的54.73%和12.26%,NH4+占到总离子量的8.92%和59.14%;雷公山大气降水中的阴离子以Cl-为主,占总离子量的16.59%;阳离子以NH4+为主,占总离子量的20.99%;森林穿透水中的阴离子以SO42-为主,占总离子量的19.83%,阳离子以K+为主,占总离子量的16.73%;3个地区森林穿透水与大气降水相比,森林穿透水中的各种离子组分都发生了富集现象,蔡家塘、雷公山、铁山坪离子总量增加量分别为2.75倍、1.79倍和4.63倍。

Based on the long term monitoring data of the three catchments,i.e.,Caijiatang,Leigongshan and Tieshanping in typical acid areas of China,the chemical compositions characteristics of wet precipitation were studied.The results show that three catchments are serious precipitation acidification,and the multi-year average precipitation pH in the order from big to small is Leigongshan（4.96）,Caijiatang（4.62） and Tieshanping（4.12）.The dominant anion is SO42- and the cation is NH4＋,which are the wet precipitation and the forested throughfall in Caijiatang and Tieshanping.In Caijiatang,SO42- accounts for 26.67% and 24.14% respectively,and NH4＋ accounts for 31.67% and 23.69%.In Tieshanping,SO42- accounts for 54.73% and 12.26% respectively,and NH4＋ accounts for 8.92% and 59.14%.The dominant anion Cl- and cation NH4＋ of the wet precipitation in Leigongshan account for 16.59% and 20.99% respectively,and the dominant anion SO42- and cation K＋ of the forested throughfall account for 19.83% and 16.73%.Compared to the wet precipitation, the ion concentrations in the forested throughfall have undergone a variety of ion enrichment,and the total ion increases of Caijiatang,Leigongshan and Tieshanping are 2.75 times,1.79 times and 4.63 times,respectively.