天津不同气团来向PM2.5中组分和污染源贡献的季节变化

利用基于新型多点位三维受体模型和后轨迹所构建的来向解析技术（SDA），探讨了天津市内陆和近海点位的不同季节不同来向气团载带的颗粒物浓度、组分和源分担率特征，并定量计算了不同来向污染源对受体点位的贡献大小.整体上，渤海来向的气团相对清洁（97.1μg/m³），气团占比较大（23.7%）；内蒙-河北-北京-天津来向气团载带的PM_2.5浓度高（197μg/m³），但气团占比小（内陆点位春冬季分别为12.5%，11.9%，近海点位春冬季分别为8.6%，10.7%），对PM_2.5的综合影响较小.近海点位春夏秋冬季对PM_2.5分担率最大的污染源分别为：SSW来向地壳源（12.8%）、SE来向硫酸盐+SOC（二次有机碳）（9.8%）、WSW来向燃煤源（10.3%）、WNW来向硫酸盐+SOC（12.1%）.内陆点位分别为SSW来向地壳源（14.5%）、S来向硫酸盐+SOC（13.5%）、SSW来向机动车源（8.9%）、WNW来向硫酸盐+SOC（9.5%）.

Seasonal patterns of PM2.5 sources and chemical composition from different air mass directions in Tianjin

PM_2.5 samples were collected simultaneously at an inland and coastal sites during four seasons in Tianjin, China. A three-way receptor model and HYSPLIT model were utilized to investigate the sources of PM_2.5 at two sites, and qualitatively determine the major air mass origins, and then the source directional apportionment (SDA) was applied to quantify source contributions from different directions to the ambient PM_2.5. The results showed that PM_2.5 concentration from Bohai Sea direction was relatively low (97.1μg/m³), but the air masses percentage was high (23.7%). While PM_2.5 concentration from Inner Mongolia direction was high compared with the Bohai direction,but the air masses percentage was low. In coastal site, the largest contributors to PM_2.5 were crustal dust from SSW for spring (12.8%), sulfate and SOC (secondary organic carbon) from SE for summer (9.8%), coal combustion from WSW for autumn (10.3%), sulfate and SOC from WNW for winter (12.1%). For inland site, the largest contributors to PM_2.5 during four seasons were crustal dust from SSW (14.5%), sulfate+SOC from S (south direction, 13.5%), vehicle exhaust form SSW(8.9%), sulfate and SOC from WNW respectively (9.5%).