基于同步辐射技术研究上海大气细颗粒物分布特征

Characteristics of airborne fine particulate distribution in Shanghai based on synchrotron radiation techniques

用同步辐射X射线荧光分析(SRXRF)测定了上海市大气中粒径0.03–10μm的13级颗粒物的元素组分,用X射线吸收近边谱(XANES)研究了颗粒物中S的化学价态。结果发现,在生活区和郊区,超细颗粒(<0.4μm)对粒子质量浓度贡献较大,而工业区则细颗粒(1–10μm)对质量浓度贡献较大。元素浓度测定表明,吴淞工业区大气颗粒物中S、Ca、Ti、V、Cr、Fe、Ni、Cu、Zn和Pb元素浓度最高,且Ni、Mn、As和Pb等污染元素在细颗粒尤其是超细颗粒中有明显富集。化学价态测定显示,钢研所采样点不同粒径颗粒物中的S主要以硫酸盐形态存在,而在粒径<0.1μm超细颗粒中还存在着一些还原态的低价态S。

Elemental contents in particulate matters of 13 sizes from 30 nm to 10000 nm were determined by using synchrotron radiation X-ray fluorescence （SRXRF）. X-ray absorption near-edge structure （XANES） spectra of S chemical speciation in the particulate matter samples were also measured. It was found that ultra-fine particles （ 〈 400 nm） had contributed more to the total mass concentration of the particulate matter in the resident area and suburb, while fine particles （1-10 μm） had contributed more in the industrial district. The results showed that the elemental concentration of particulate matter was highest in the Wusong industrial zone, and some polluted elements, such as Ni, Mn, As and Pb, had been obviously enriched in the fine particles and in the ultra-fine particles. The results of chemical speclation determination demonstrated that S existed mainly as sulfate in particles of different sizes, but some original states of S existed as low valences in the ultra-fine particles of 〈 100 nm in Wusong industrial zone.