上海梅雨季节云水和雨水的化学组分分析

1986年6—7月梅雨季节在上海进行了云水和地面雨水的pH值测量和化学组分分析，结果表明:上海酸雨属于硫酸型酸雨；雨水酸度与其化学组分有关，pH≥6的云、雨水中含有大量的Ca2+离子浓度，而pH＜5的云、雨水中有大量的SO2-4离子浓度；As雨水的酸化以云下冲刷过程为主；Ns雨水的酸度可能主要决定于云内雨除过程，NS云内云水的酸化过程，不仅受向上输送局地污染物的影响，而且受平流输送外来污染物的影响。

Analysis of Chemical Compositions of Cloud Water and Rain Water During the Plum Rains Period in Shanghai

During the plum rains period of June-July, 1986, the pH values of cloud water and surface rain water were measured in Shanghai, and their chemical compositions were also analysed. These results indicate that: (1) The acidification of rain water is caused by sulphates in Shanghai; (2) The rain acidity is related to its chemical compositions. In cloud water and rain water with higher pH values (pH≥6.00), Ca2+ content is the highest, and with pH＜5.00, SO content is the highest; (3) The acidification of altostratus (As) precipitation is mainly due to washout process below the cloud, and the rain acidity of nimbostratus (Ns) is mainly due to rainout process in the cloud. Further, the acidification of cloud water in Ns may be affected not only by the local air pollutants transported upward but also by the distant air pollutants through the advection transportation