Individual aerosol particles in mountain Lu areas

Abstract

于2011年8月—9月期间以庐山山顶作为高山采样点对大气颗粒物进行采样,采用透射电镜及能谱分析方法获得单颗粒的形貌和化学组分特征。研究结果表明,庐山地区单颗粒主要为富硫、金属、矿物、飞灰、烟尘和有机颗粒等6种类型,其中富硫颗粒和金属颗粒占绝对主导,两者占总数量的80%以上。单颗粒的能谱结果显示细小的金属和飞灰颗粒包含的金属元素主要为Mn、Fe、Pb、Zn以及少量的Cr、Co、As、Cd等,表明这些颗粒主要来自于重工业排放如有色金属冶炼等。同时借助单颗粒图像分析技术获得了不同类型颗粒物的粒径分布特征,富硫和金属颗粒的粒径主要在0.05～2μm,均表现为单峰分布,峰值分别处在0.6～0.7μm和0.3～0.4μm之间。高空中发现的与工业源相关的金属、飞灰和烟尘等细颗粒完全内混于二次形成的富硫颗粒,这种内混的颗粒能够贡献到高空的云凝结核中。一旦成为云凝结核,这些细小颗粒很可能会加快二次硫酸盐的形成,进而加重酸雨(云)对本地区人体健康和植物生态系统的危害。 Aerosol particles were collected at Mountain Lu areas in southern China from August to September 2011.Morphology and composition of individual aerosol particles were measured by transmission electron microscopy(TEM) coupled with an energy-dispersive X-ray spectrometer(EDS).Six aerosol types inculding sulfate,metal,mineral,fly ash,soot and organic particles were indentified,among which sulfate and metal particles are dominant(> 80%) in particle number.The main compositions of metal and fly ash are Mn,Fe,Pb,Zn with minor Cr,Co,As,Cd.The result indicated that the metal particles were mainly originated from heavy industries,for example,non-ferrous metal smelting.Size distributions of aerosol particles were also measured through individual particle image analysis system method.The size distributions of sulfate and metal particles show unimodal in the 0.05-2 μm size range,with the peaks at 0.6-0.7 μm and 0.3-0.4 μm,respectively.These fine metal,fly ash and soot particles are completely internally mixed with sulfates.The internally mixed particles can significantly contribute to the CCN in the high-altitude atmosphere.Therefore,it is possible that the widespread metal particles with small sizes would possibly enhance the formation of sulfates,which aggravates the influence of acid rain(cloud) to human health and ecology system in southern China.