2017年兰州市大气污染物输送来源及传输特征模拟分析

利用HYSPLIT后向轨迹模式，结合兰州市AQI（空气质量指数）及常规大气污染物质量浓度数据，模拟研究了2017年1月1日-12月31日以兰州市为受点的大气污染物输送特征.通过聚类分析确定了抵达兰州市气团的主要输送途径和每类路径所对应的污染物质量浓度特征，并利用受体模型PSCF（潜在源贡献因子分析法）和CWT（权重浓度轨迹分析法），分析了大气污染区域传输对兰州市空气质量的影响，探讨了影响兰州市空气质量的污染物输送来源和可能的潜在源区.结果表明，在影响兰州市的气流轨迹中，污染轨迹多来自兰州市以西和以北方向，污染轨迹约占总轨迹的39.52%，说明外部污染物的输入对兰州市空气质量具有重要影响.其中，第3类轨迹（对应来向为西）的气团对兰州市的空气质量有较大的影响，该类轨迹虽仅占总轨迹的15.21%，但其中污染轨迹数占56.76%，是影响兰州市空气质量的主要传输路径；第4类轨迹（对应来向为东南）的气团最为清洁.研究显示，对兰州市空气质量影响最大的强潜在源区主要分布在青海共和盆地、兰州市本地及周边区域，中等强度潜在源区为内蒙古自治区南部、宁夏回族自治区及甘肃省河西走廊等地区. 

Simulation Analysis of Sources and Transmission Characteristics of Air Pollutants in Lanzhou City in 2017

The characteristics of air pollutant transmission in Lanzhou City from January 1^st to December 31^st, 2017 were simulated and studied by using the HYSPLIT backward trajectory mode combined with air quality index (AQI) and the quality concentration data of conventional air pollutant index. The main transmission routes of air masses arriving in Lanzhou City and the characteristics of pollutant quality and concentration corresponding to each type of path were determined by cluster analyses, and the receptor model potential source contribution function (PSCF) and concentration weighted trajectory (CWT) were analyzed. This paper discusses the impact of the regional air pollution transmission on the air quality in Lanzhou City and possible potential source area. The results show that the pollution track that affects the air flow track of Lanzhou City is mostly from the west and north of Lanzhou City, and the pollution track accounts for about 39.52% of the total trajectory, indicating that the input of external pollutants has an important influence on the air quality of Lanzhou City. The air mass of the third kind of trajectory (corresponding direction to the air mass is west) has a great influence on the air quality of Lanzhou City. Although this type of trajectory only accounts for 15.21% of the total trajectory, 56.76% of the third type of trajectory belongs to the pollution trajectory, which is the main transmission path affecting the air quality of Lanzhou City. The air mass under the fourth type of trajectory (corresponding direction to the air mass is southeast) is the cleanest. The strong potential source areas that have the greatest impact on air quality in Lanzhou City are mainly distributed in Qinghai Gonghe basin, Lanzhou City and surrounding areas. The potential sources of moderate strength are the southern Inner Mongolia Autonomous Region, Ningxia Hui Autonomous Region and Gansu Hexi Corridor Areas.