基于HYSPLIT模型的2017年西安市首要大气污染物变化特征及潜在源区分析

Analysis of seasonal primary pollutants and their potential source areas of Xi'an in 2017 based on HYSPLIT model

利用2017年西安市13个空气质量监测站点实测数据,分析了大气污染物CO、NO2、O3、PM10、PM2.5、SO2的变化规律及特点,用空气质量分指数计算了不同季节的大气首要污染物,基于混合单粒子拉格朗日综合轨迹模型分析了2017年西安市污染物的后向轨迹和聚类轨迹,采用潜在源贡献因子法和浓度权重轨迹分析法计算了各个季节首要污染物的潜在源区分布.结果表明, 2017年西安市逐日ρ(NO2)、ρ(PM10)、ρ(PM2.5)、ρ(SO2)和ρ(CO)夏季低、冬季高,逐日ρ(O3)值夏季高、冬季低,反映了西安市春季首要污染物是PM10,夏季首要污染物是O3,秋冬季首要污染物是PM2.5.冬春季西安市气流轨迹方向以西北向为主,携带了大量的颗粒物和气体污染物.西安夏季污染主要以本地污染源为主.秋季,来自内蒙古南部、陕西延安、铜川的北向气流轨迹对应的ρ(PM2.5)值最高.

Based on the measured data of 13 air quality testing stations in Xi’an in 2017, the changes and characteristics of atmospheric pollutants CO, NO2, O3, PM10, PM2.5 and SO2 were analyzed. The primary atmospheric pollutants in different seasons were calculated from the air quality sub-index. The backward and clustering trajectories of pollutants in Xi’an in 2017 were analyzed based on the hybrid single particle Lagrangian integrated trajectory model(HYPSLIT). The potential source contribution factor method and concentration weight trajectory analysis were used to calculate the potential source distribution of the primary pollutants in each season. The results showed that the daily concentration of ρ(NO2), ρ(PM10),ρ(PM2.5), ρ(SO2) and ρ(CO) in Xi’an was low in summer and high in winter, while that of ρ(O3) was high in summer and low in winter in 2017. The primary pollutant in spring in was PM10, in summer was O3,and in autumn and winter was PM2.5. In the winter and spring seasons, the direction of the airflow trajectory in was mainly northwestward, carrying a large amount of particulate matter and gas pollutants. Summer pollution was mainly based on local pollution sources. In the autumn, the ρ(PM2.5) corresponding to the northward airflow trajectory from southern Inner Mongolia, Yan’an and Tongchuan of Shaanxi was the highest.