沙尘天气对西安市环境空气质量的影响

Influence of dust storm on atmospheric environment quality in Xi’an,China

利用2013—2018年陕西省环境空气质量自动站监测数据,分析沙尘天气对西安市环境空气质量的影响。结果表明:(1)大气颗粒物是影响西安市空气质量的首要污染物。(2)西安市沙尘天污染主要在春季和冬季,期间可吸入颗粒物(PM10)的污染强度明显增加。(3)2013—2018年,西安市冬季PM2.5/PM10比值(0.48~0.66)最高,春季最低(0.43~0.49)且细颗粒物(PM2.5)和PM10浓度相关性最弱;西安市空气质量在春季受沙尘污染影响大于冬季。(4)不同沙尘源的远距离传输对西安市空气质量的影响程度不同,提前采取防沙抑尘措施能有效削减沙尘过境时本地颗粒物源的叠加污染。(5)尽管沙尘天气导致了颗粒物浓度升高,但与之伴随的大风气象条件,有利于城市区域累积污染物的扩散清除,从而降低SO2和NO2等气态污染物浓度。在采暖期,沙尘天气除了降低气态污染物浓度之外,还有利于扩散稀释雾霾污染累积的高浓度PM2.5。

The influence of dust storm on atmospheric environment quality in Xi’an was analyzed based on the air quality data collected during 2013-2018. The main conclusions include:(1)The particulate materials were the dominant pollutant in Xi’an.(2)The dust storm happened frequently in spring and winter,during which the pollution intensity of PM10 increased significantly.(3)The average PM2.5/PM10 ratio was the highest in winter(range of 0. 48-0. 66)and the lowest in spring(range of 0. 43-0. 49). The correlation between PM2.5 and PM10 was the worst in spring. The air quality of Xi’an was more affected by dust pollution in spring than in winter.(4)We analyzed typical dust pollution episode during 2017-2018 and found that the long-distance transmission of different dust sources affected the air quality of Xi’an in variable degrees,suggesting that taking measure in advance to suppress dust can effectively reduce the superposition pollution of local particulate matter sources during the dust storm.(5)Although the dust storm carried high concentration particulate matter,the accompanying windy weather was effective to diffuse and reduce the accumulated pollutants such as SO2 and NO2. In heating season,the dust storm could reduce not only the concentration of gaseous pollutants but also the accumulated PM2.5 during haze pollution.