沙尘天气过程对中国北方城市空气质量的影响

Effect of Dust Process on Air Quality in Cities of Northern China

2014年4月23—25日中国北方地区经历了一次大范围的强沙尘天气过程。利用13个城市的空气质量和气象数据结合后向轨迹模式和MODIS deep-blue气溶胶光学厚度数据,研究沙尘天气过程对中国北方城市空气质量的影响,特别是对PM2.5质量浓度的贡献。结果表明:来源于塔克拉玛干沙漠及其周边地区的沙尘途经甘肃西北部和内蒙古中西部的沙漠区进而影响下游城市。MODIS deep-blue气溶胶光学厚度的空间分布能够较好地反映出沙尘的水平运动特征。沙尘天气过程可以使中国北方城市PM2.5和PM10质量浓度分别增加7.5%~1 141.2%和344.0%~2 562.1%,可以有效地降低SO2、NO2和CO气体污染物的浓度,而对O3的浓度影响较小。银川、大同和库尔勒沙尘天气过程期间平均SO2、NO2和CO浓度较非沙尘天气过程期间降低最明显,分别降低约80.0%、78.7%和62.1%。

In order to investigate effect of dust process on air quality in cities of Northern China,the particulate concentration(PM2.5and PM10)and gaseous pollutant concentration(SO2,NO2,O3 and CO)and meteorological data were measured in 13 cities of Northern China during a serious regional dust process occurred on April 23-25,2014.Sources of dust were identified using backward trajectory model and spatial distributions of MODIS deep-blue AOD(Aerosol Optical Depth).The dust particles originated from the Taklimakan Desert and its outer edge,passed through desert areas in northwestern Gansu,western and central Inner Mongolia,and affected downstream cities.The horizontal movement characteristics of dust particles could be seen from spatial distributions of MODIS deep-blue AOD.The PM2.5and PM10 mass concentrations increased by7.5%-1 141.2% and 344.0%-2 562.1%in northern cities of China during the dust process,respectively.In addition,the dust process alleviated gaseous pollutants concentrations effectively such as SO2,NO2 and CO,but it had a less effect on O3 concentration.The decreases of mean concentrations of SO2,NO2 and CO were more significant in Yinchuan,Datong and Korla during the dust process than during non-dust event,which were 80.0%,78.7% and 62.1%lower,respectively.