兰州市沙尘天气及其对空气质量的影响

利用1971~2000年和2001~2004年兰州市观测站资料,分析了兰州市沙尘天气的气候特征和2001~2004年沙尘天气特点及产生原因。研究表明,兰州市区的沙尘天气30年来呈明显减少趋势,但近几年明显增多。兰州市的沙尘天气以浮尘、扬沙天气为主。沙尘天气春季(3~5月)最多,4月占全年天数的24.2%。利用2002~2004年主要污染物浓度资料和2006年4月5~15日逐日的PM10浓度资料研究了沙尘天气对兰州市区主要污染物浓度的影响,结果表明,沙尘天气发生时,伴随的大风等气象条件有利于SO2和NO2的扩散,而强沙尘天气容易导致PM10日均浓度迅速升高。在分析的一次强沙尘天气个例中,兰州市区PM10日均浓度陡然升高到1.86 mg/m3,是前一日的10.4倍。

The Dust Weather and Its Influence on Air Quality in Lanzhou City

Based on the data of Lanzhou meteorological observation from 1971 to 2000 and the data from 2001 to 2004,the temporal characteristics and the cause of sand and dust weather in Lanzhou city are analyzed.The result shows that there is a decreasing trend frequency of sandy and dust weather in the last 30 years,but it increases obviously in recent years.The floating dust is the dominating phenomena,the next is blowing sand and sand storm.Sandy and dusty weather is mostly in the spring(March to May) with the highest in April accounting for about 24.2% in the days of a year.The influence of sand and dust on air pollution in Lanzhou is investigated using data of daily reports of mean concentration of SO2,NO2 and PM10 in recent 3 years and the concentration of PM10 per day in a server dust storm occurred from April 5 to 15,2006.The research results are as followings: The weather condition of sand and dust is of benefit for SO2,NO2,but a severe dust storm could cause the density of PM10 increase sharply and cause very heavy particulate pollution.One observatory station of the environment observes that the mean concentration of PM10 in Lanzhou increases to 1.86 mg/m3 in a single day,which is 10.4 times of the concentration one day before.It clearly shows that the sand storm has significant impact on the heavy air pollution of Lanzhou.