苏锡常地区PM2.5污染特征及其潜在源区分析

利用2014年12月—2015年11月苏锡常地区国控大气环境质量监测站发布的逐时数据,分析了研究区PM_(2.5)浓度的季节变化和空间分布特征,并利用HYSPLIT模型分析了大气污染物的输送路径及苏锡常地区PM_(2.5)的潜在源区.结果表明,苏锡常地区PM_(2.5)浓度日均值变化趋势基本一致,均呈现冬季高、夏季低的规律.PM_(2.5)浓度四季空间差异显著,不同监测站之间的差异较小.四季PM_(2.5)浓度与其它污染物之间相关性显著.单位面积污染物排放量与空气质量分布的空间错位,表明该地区PM_(2.5)污染与区域性污染物迁移有较大关系.苏锡常地区气流后向轨迹季节变化特征明显,冬、春、秋季的气流主要来自西北内陆地区,夏季气流以东南和西南方向输入居多.聚类分析表明,来自内陆的污染气流和来自海洋的清洁气流是苏锡常地区两种主要输送类型,外源污染气流不仅直接输送颗粒物,还贡献了大量的气态污染物.山东南部、江苏西部、安徽东部、浙江北部及江西西北地区对苏锡常冬季PM_(2.5)浓度贡献较大,春、夏、秋季的潜在源区主要分布在苏锡常本地和周边城市.

Pollution characteristics and potential sources of PM2.5 in Su-Xi-Chang region

The seasonal and spatial distribution of PM_2.5 in Su-Xi-Chang area from December 2014 to November 2015 was analyzed using hourly air pollutants data from the state-controlled atmospheric environmental monitoring stations, and the transport trajectories of air pollutants and potential source regions of PM_2.5 in Su-Xi-Chang area was investigated with HYSPLIT model. The results showed that the daily mean PM_2.5 concentration values of three cities demonstrated same trend of higher in winter and lower in summer. The spatial difference of PM_2.5 concentration was small while seasonal difference was large. The PM_2.5 concentration of Su-Xi-Chang area in different seasons was significantly correlated with other air pollutants. The spatial differences between air pollutant emissions per unit area and air quality was obvious, therefore it was concluded that PM_2.5 pollution was significantly correlated with regional transport. The seasonal variations of backward trajectory were significant in Su-Xi-Chang area. The air flow mainly came from northwest inland area in winter, spring and autumn, while from the southeast and southwest direction in summer. Cluster analysis showed that they were the two main types of air flow transport in Su-Xi-Chang area. The external air flow contributed not only particulate matter, but also large amount of gaseous pollutants. South Shandong, west Jiangsu, east Anhui, north Zhejiang and northwest Jiangxi contributed greatly to PM_2.5 concentration in Su-Xi-Chang area in winter, and the local and surrounding cities were the potential source area in the other three seasons.