校园大气环境不同高度PM_(2.5)的物理化学特征比较

Comparation of physicochemical characterization of PM_(2.5) collected at different heights in the air above campus

大气细颗粒物(PM2.5)已经成为影响我国大气环境质量和人们身体健康的首要污染物.作为青少年集中学习和生活的校园环境的空气质量状况已经成为多方关注的热点.为研究校园环境大气细颗粒物的空间分布状况及其物理化学特征,在不同高度(5,40 m)设立采样点,同步采集大气PM2.5样品,利用高分辨扫描电子显微镜-X射线能谱仪(scanning electron microscope-energy dispersive spectrometer,SEM-EDS)分析了不同高度和不同时间段校园大气环境中PM2.5的微观组成、化学组分,得出如下主要结论:校园环境PM2.5的微观组分主要有燃煤飞灰颗粒、矿物颗粒(原生的和新生的矿物颗粒)、烟尘集合体以及无法鉴定的颗粒物;5 m高度处采集的颗粒物的质量浓度和数浓度均高于40 m高度处,5 m高度处PM2.5的矿物颗粒相对较多,而40 m高度处PM2.5的烟尘集合体相对较多;晚上样品中颗粒物数量和种类都比白天要多.

PM2.5 has become a major air relationship with the health of young people pollutant. Air quality in campus has close This study focuses on mass concentration and physicochemical characterization of PM2.5 collected at different heights above a cam- pus. Ambient PM2.5 particles were sampled synchronously at two heights （5 m and 40 m）. Microscopic character and its chemical composition of the fine particles were character- ized using scanning electron microscope-energy dispersive spectrometer （SEM-EDS）. The following results are obtained. Mineral particles, soot aggregates and fly ash are ubiquitous in the campus PM2.5, and gypsum particles, unknown particles can also be found. Mass and number concentrations at 5 m are higher than that of PM2.5 collected at 40 m. The numbers of mineral particles in PM2.5 collected at 5 m are more than that of fine particles sampled at 40 m. Soot aggregates in the PM2.5 at 40 m are more abundant than that at 5 m. Both the particle types and the number of mineral particles collected during daytime are less than that sampled at night.