长江中游地区可吸入颗粒物气团输送轨迹的时空差异分析

Analysis on the Trajectory of Respirable Particulate Air Mass Delivery in the Middle Reaches of the Yangtze River

利用2015年6月至2016年5月长江中游四个中心城市(武汉、长沙、合肥、南昌)大气环境质量监测站发布的PM10、PM2.5的质量浓度数据,分析了长江中游地区PM10浓度、PM2.5浓度的逐月变化和空间分布规律;同时利用HYSPLIT模型的72 h前向轨迹聚类方法,分析了PM10、PM2.5等可吸入颗粒物的水平方向输送路径。结果表明,长江中游地区可吸入颗粒物浓度的变化趋势一致,均呈现夏季低、冬季高的规律,且冬春季节波动频繁,表明可吸入颗粒物污染与区域性污染物迁移有较大关系,武汉市各季节PM2.5浓度在四个城市中均最高,PM10浓度冬春季节低于其他城市,夏秋季节高于其他城市;水平方向轨迹聚类分析表明,长江中游地区有两种主要的气流输送类型,即近源(来自周边省区及本区域城市群间的污染)污染气流和来自远源海洋的清洁气流;气流轨迹的季节变化特征明显,春、夏、秋季的颗粒物主要来源于周边河南省、湖南省、安徽省等本地和周边区域。因此冬春季节本区受到来自偏北方向的气流影响显著,这一结论可为本区冬季治霾提供思路,为长江中游地区大气污染联防联控提供参考依据。

Based on the mass concentrations of PM10 and PM2.5 released by the atmospheric environmental quality monitoring stations in four central cities of the middle reaches of the Yangtze River (Wuhan, Changsha, Hefei and Nanchang) from June 2015 to May 2016, the monthly variation and spatial distribution of PM10 concentration and PM2.5 concentration in the middle reaches of the Yangtze River were analyzed. At the same time, using the 72 h forward trajectory clustering method of HYSPLIT model, the horizontal conveying path and the vertical conveying height of PM10, PM2.5 and other respirable particles were analyzed. The results showed that the changing trend of respirable particulate matter in the middle reaches of the Yangtze River was the same, showing the law of low summer and high winter, and the frequent fluctuations in winter and spring, which indicated that the inhalable particulate matter had a great relationship with regional pollutant migration. The concentrations of PM2.5 in Wuhan were the highest in all four cities in all seasons;the concentrations of PM10 were lower in winter and spring than in other cities, and higher in summer and autumn than in other cities. The horizontal trajectory cluster analysis shows that there are two main types of airflow transport in the middle reaches of the Yangtze River, namely the polluted air near the source (from the surrounding provinces and the urban agglomerations of this region) and the clean air from the distant ocean;The seasonal variation of the airflow trajectory is obvious, the particles in spring, summer and autumn are mainly from the surrounding areas such as Henan Province, Hunan Province and Anhui Province. Therefore, the influence of the airflow from the northerly direction in winter and spring in this area is significant. This conclusion can provide ideas for the winter haze control in this area and provide a reference for the joint control of air pollution in the middle reaches of the Yangtze River.