重庆市冬季PM2.5及气态污染物的分布特征与来源

Distribution Characteristics and Sources of PM_(2.5) and Gaseous Pollutants in Winter in Chongqing

利用重庆市大气污染物监测站2013年冬季(2013年11月—2014年1月)的实测数据,分析PM2.5及相关气态污染物(SO2、NO2、O3)的时空特征,并采用轨迹聚类与PSCF(潜在源贡献因子)分析污染物来源.结果表明:除ρ(O3)以外,其他3种污染物质量浓度的月际变化趋势基本一致,均呈12月升高、1月降低的特征;污染物空间分布不均,其中ρ(PM2.5)和ρ(NO2)在工业区和人口密集区较高,ρ(SO2)南高北低,ρ(O3)城区低于郊区.ρ(SO2)、ρ(NO2)与ρ(PM2.5)均呈显著正相关,其中ρ(SO2)与ρ(PM2.5)的R(相关系数)在城、郊区分别为0.71、0.65,ρ(NO2)与ρ(PM2.5)在城、效区的R分别为0.73、0.56;而ρ(O3)与ρ(PM2.5)未表现出显著相关.ρ(SO2)、ρ(NO2)与ρ(PM2.5)的相关性高低可在一定程度上说明二次气溶胶的污染程度,ρ(O3)与ρ(PM2.5)的相关性受到PM2.5来源和污染程度的影响.轨迹分析结果显示,重庆市2013年冬季主要受东北方向气流影响;聚类分析表明,重庆市11月没有表现出明显的PM2.5外来输送特征,但12月和1月的PM2.5外来输送特征明显,并且不同方向的气流污染物浓度差异也较大.PSCF分析发现,重庆市冬季PM2.5、SO2、NO2、O3主要来源于本地和周围城市局地传输,同时还受南宁、贵阳、遵义、达州等地的影响.

Based on field measurements at air pollution detection sites from November 2013 to January 2014（ winter season） in Chongqing,the temporal and spatial characteristics of air pollutants were analyzed,including PM2. 5and related gaseous pollutants（ e. g.SO2,NO2 and O3）. Moreover,orientation sources and their corresponding contributions were explored by trajectory cluster and PSCF analysis（ i. e.,potential source contribution function analysis）. The results showed that the trends of monthly variation for PM2. 5,SO2 and NO2were similar,with the concentrations of the three pollutants increasing in December then decreasing in January. The spatial distributions of the air pollutants showed uneven,different features. For example,PM2. 5and NO2 were high in the industrial and populated districts,while SO2 was high in the south and low in the north. O3 was low in the urban area but high in the suburban area. PM2. 5and SO2 were positively correlated（ in urban areas,R = 0. 71; in the suburbs,R = 0. 65）,while O3 and PM2. 5were not significantly correlated（ in urban areas,R = 0. 73; in the suburbs,R = 0. 56）. The correlation between PM2. 5and SO2 and NO2could describe the degree of the secondary pollution to some extent,as well as the correlation between PM2. 5and O3 affected by the sources and pollution extent of PM2. 5. Trajectory analysis indicated that the dominant airflow was from the northeast during the study period. Cluster analysis demonstrated that no obvious transport pathway was found in November,but was obvious in December and January,and therewas a big difference between airflows in December and January. PSCF analysis showed that the main orientation sources of PM2. 5,SO2 and NO2were local emissions and transport from surrounding cities,such as Nanning,Guiyang,Zunyi and Dazhou.