沈阳市冬季重污染过程PM_(2.5)浓度变化及成因分析

Concentration Change and Cause Analysis of PM_(2.5) in a Heavy Pollution Process in Winter of Shenyang

利用多种污染物浓度数据、气象观测数据,结合HYSPLIT后向轨迹模式,对2015年11月6—10日发生在沈阳的一次较长时间重污染天气过程,从大气浓度变化、天气形势特征及成因机制等方面进行综合分析。结果表明,重污染期间日空气质量指数均超过重度污染限值200,首要污染物PM_(2.5)最高小时质量浓度达到1 326μg/m3,为沈阳市监测PM_(2.5)以来的历史峰值。此次空气污染是气象及人为因素共同作用的结果,重污染过程时段内高空场不利于气流上升运动的发展,地面倒槽、稳定的大气层结不利于污染物的扩散。此次重污染过程与大范围秸秆集中燃烧、大量污染物排放有一定关系。通过后向轨迹计算分析,发现颗粒物长距离输送对区域污染产生一定影响。

By using data of various pollutants concentration and meteorological observation,combined with HYSPLIT backward trajectory model,a heavy air pollution episode from November 6 thto 10 thin Shenyang was synthetically analyzed in aspects of the concentration variation of pollution components,synoptic condition and cause mechanism.The results showed that the AQI during this haze period were all above 200 and the highest hourly PM2.5 concentration was 1326 μg/m^3,creating a new record in Shenyang.This air pollution was caused by the human factor and the meteorological condition.The pressure field during the haze episode was obviously weaker,the ground inverted trough and the stable atmospheric stratification,were not conductive to the level of pollution diffusion and providing favorable weather conditions for the occurrence of heavy pollution.In addition,the heavy pollution had certain relationship with straw burning for large range.HYSPLIT backward trajectory model indicated that the long distance transport of particulate matter had a certain effect on regional pollution.