2000年春季北京特大沙尘暴物理化学特性的分析

Analysis on the Chemical and Physical Properties of "2000.4.6" Super dust Storm in Beijing

２０００年春季北京频频发生沙尘天气，严重影响了北京市大气环境状况。对４月６日北京地区发生的特大沙尘暴化学元素成分的分析表明北京春季沙尘污染极为严重。沙尘暴期间，２０种元素总质量浓度高达１５３６ μｇ／ｍ３，是１９９９年同期的３１．４倍。即使沙尘暴过后，污染依然严重，元素总质量浓度仍高达 ３３８．７ μｇ／ｍ３，是１９９９年春季的 ７倍。研究还发现，沙尘暴期间来自远方的大粒子占了很大的比例，绝大多数的元素浓度在粒径大于１６μｍ处出现一个非常高值，远高于其他谱段的浓度；在沙尘暴后及其他时间，还没有观测到这种谱分布。沙尘暴期间的粗粒子（ｄ＞２μｍ）数浓度是沙尘暴后的２０倍以上，细粒子（ｄ＜ ２ μｍ）的数浓度是沙尘暴后的 ７倍。

In the spring of 2000, dust storm weather occurred frequently in Beijing, which resulted in bad effect on atmospheric environment. Analysis on the chemical composition on' 4.6' super dust storm show that the pollution caused by dust storm is very serious. In dust storm period, the total concentration of 20 elements reached 1 536 μg / m3 which is 31.4 times as that in last spring. Even after dust storm, the concentration of 20 elements reached 338.7 μg / m3, which is 7 times as that in last spring. It is found that concentrations of most elements of particles whose diameter is above 16 μm has a very high peak, while there is no such a phenomena in non-dust time. Observation by optical particles counter shows that the number concentrations of coarse particles (d> 2 μm) are more than 20 times as that after dust storm while the number concentrations of fine particles (d< 2 μm) are only 7 times as that after dust storm.