大气颗粒物吸湿性研究

大气颗粒物吸湿性是反映颗粒物理化性质的重要指标,吸湿性研究对深入了解颗粒物的环境和健康效应具有重要意义. 总结了国外近年来大气颗粒物吸湿性研究进展:①典型的大气颗粒物吸湿性分析方法为H-TDMA(吸湿性串联差分电迁移率粒径分析仪)系统及其优化方法. ②大气颗粒物吸湿性呈单峰、双峰甚至多峰分布；根据G_f(吸湿性生长因子)随粒径变化的模式,可将大气颗粒物分为强吸湿性和弱吸湿性2类,也可分为纯不溶性、混合不溶性、混合可溶性和纯可溶性4类. ③城市背景点颗粒物的G_f比城市观测点高；城市观测点的颗粒物G_f分布呈夏季高、冬季低,白天高、晚上低的特征. ④颗粒物吸湿性与其化学组成和形态密切相关,纯可溶性盐颗粒物的G_f通常较高. ⑤柴油燃烧源新排放的颗粒物属于弱吸湿性颗粒物,G_f非常小,但在其表面老化后或随燃料中硫含量的增加G_f会明显变大. ⑥生物质燃烧排放颗粒物的G_f相对较高,但存在区域差异性. 针对国内大气颗粒物吸湿性研究现状,提出了未来重点研究方向. 

Research Progress of the Hygroscopicity of Atmospheric Particles

From the view of healthy and environmental effects of particles, it is necessary to research the hygroscopicity of atmospheric particles, since it is an important factor to reflect their physical and chemical properties. The studies about the hygroscopicity in recent years were reviewed in this study. The typical equipment for hygroscopicity was hygroscopicity tandem differential mobility analyzer (H-TDMA) or improved H-TDMA. The G_f(observed growth factor) exhibited the single peak, two peaks or even multiple peaks. According to G_f, the particles could be divided into four types including pure insoluble, mixed insoluble, mixed soluble and pure soluble particles. The G_f showed higher values for particles in urban background sites than those for urban sites. The G_f for particles in urban area was higher in summer than that in winter and was higher during the daytime than that during the nighttime. The hygroscopicity of particles mainly depended on their chemical compositions and shapes. The G_f for pure soluble salt particles was usually higher. Fresh particles from diesel combustion showed less hygroscopic with low G_f, while their G_f could be enhanced with the particle aging and the fuel sulfur content increase. The G_f for particles from biomass burning was high and had obvious spatial variation. According to the domestic hygroscopic research status of atmospheric particulate matter, a key research direction was suggested for the future.