沙尘对兰州市大气环境质量的影响

Characteristics of Dust Events and Their Influence on Air Quality of Lanzhou,China

利用1951—2010年甘肃省气象局地面观测站沙尘气象资料和2006—2010年兰州环保局PM10、SO2、NO2质量浓度资料,分析了兰州市沙尘天气时间变化特征及其对SO2、NO2、PM10等大气污染物浓度的影响。结果表明:近60年来兰州市沙尘天气总体上呈现振荡性减少的趋势,沙尘暴、扬沙和浮尘年变化倾向率分别为-0.15d、-0.72d和-0.97d,这与上游沙尘源区沙尘天气振荡性减少有关。沙尘对兰州地区SO2和NO2质量浓度影响不大,对PM2.5质量浓度和PM1.0数浓度的变化有一定的贡献,但对PM10质量浓度影响非常大,沙尘对春季PM10质量浓度的贡献率在18.4%~43.1%。对2007年5月10日一次强沙尘天气过程研究发现,随着沙尘天气的侵入,兰州市不同粒径气溶胶的浓度陡然上升,然后达到较高的浓度水平,之后由于沙尘天气的减弱、消退或离境,不同粒径气溶胶浓度也逐渐降低并缓慢恢复到正常水平。

Based on the dust events data from Gansu Meteorological Bureau from 1951 to 2005 and air pollutant data including PM10,SO2 and NO2 concentrations from Lanzhou Environmental Monitoring Station,the temporal distribution characteristics of dust events and the impacts of dust events on SO2,NO2 and PM10 concentrations were analyzed.The dust storm,blowing dust and floating dust generally descended from 1951 to 2000 in Lanzhou,and their change tendency rate were on average-0.15,-0.72,-0.97 days per year,respectively.The impacts of dust events on SO2 and NO2 concentrations were little,and were obvious on both PM2.5and PM1.0concentrations,but were serious on PM10 concentration,the contribute of dust events on PM10 concentration in spring were between 18.4% and 43.1%.During a severe dust event process on May 10,2007,PM10 concentration sharply increased with dust intrusion,then,it reached relatively high level,afterwards gradually dropped and recovered to the normal concentration level because of dust weakening,fading or leaving.PM2.5 and PM1.0 concentrations also somewhat increased during dust event,the characteristics of their variations were similar to PM10 concentration.