成都春季气溶胶理化性质及不同时段污染特征

The physicochemical properties of aerosol and its pollution characteristics in different periods in spring in Chengdu

利用单颗粒气溶胶质谱(SPAMS)及多种在线设备于2017年春季对成都市大气污染进行了连续观测.结果表明,成都市春季PM2.5和PM10的平均浓度分别为(62±25)和(90±40)μg/m3和大气中单颗粒物可分为8类,由于排放源及老化过程的差异,各类颗粒质谱特征和粒径分布差异明显.对选取的细粒子污染、细粒子与粗粒子混合污染(混合污染)及清洁时段的污染特征对比分析发现:(1)钾与元素碳混合颗粒(KEC)的贡献在细粒子污染时段(42.8%~46.3%)明显高于其他时段(28.9%~33.7%);与清洁时段相比,源于燃烧过程的碳质颗粒在混合污染时段贡献降低,但沙尘/扬尘颗粒(DUST)的贡献为各时段最高.(2)相比清洁时段,大多数颗粒与二次无机组分的混合程度在其他两种时段均增强.(3)不同时段成都市气团来向差异明显,西南方向气团在细粒子污染时段占据绝对主导,川南重污染区域对成都市污染贡献重大.

A continuous observation of air pollution was made in Chengdu using single particle aerosol mass spectrometer(SPAMS)and a variety of online devices in spring of 2017.The results showed that the average mass concentrations of PM2.5 and PM10 were(62±25)and(90±40)μg/m3,respectively.Single particles in the atmosphere can be divided into eight classes.Due to the differences in emission sources and aging process,there were obvious differences in mass spectrum characteristics and particle size distribution among all particle classes.The comparative analysis of the selected fine particle pollution,mixed pollution of fine and coarse particles(mixed pollution)and clean periods showed that:(1)the contribution of potassium-elemental carbon(KEC)particles was the highest in the fine particle pollution periods(42.8%~46.3%).Compared with the clean period,the contribution of carbonaceous particles from combustion process decreased in the mixed pollution period,but the contribution of DUST particles reached the highest of all periods.(2)Compared with the clean period,the mixing degree of most particles with secondary inorganic components in other two types of periods enhanced.(3)The air masses from the southwest of Chengdu dominated in fine particle pollution periods,the heavily polluted areas in southern Sichuan contributed greatly to the pollution process in Chengdu.