上海城区和临安本底站PM_(2.5)的物化特征及来源解析

2008年4月在上海城区(徐家汇)和浙江临安大气污染本底站2个地区同步采集PM2.5样品,利用场发射扫描电镜(FESEM/EDS)和同步辐射相关技术对两地PM2.5的微观形貌、化学元素组成及来源,以及重金属元素Zn的价态进行了分析.结果表明,徐家汇、临安的PM2.5平均质量浓度分别为(131.6±65.2),(83.5±22.9)μg/m3.徐家汇地区PM2.5主要由烟尘、飞灰、矿物质等组成;临安地区PM2.5中主要为不规则形貌颗粒物.上海城区PM2.5中重金属元素的浓度明显高于临安地区样品.同步辐射X射线吸收近边结构谱的结果显示,两地PM2.5中的Zn元素都以ZnSO4为主要存在形式.富集因子法分析19种元素中,除K、Ca外,其他元素在PM2.5中富集程度上海均高于临安地区.

Physicochemical characterization and source apportionment of PM_(2.5) collected in Shanghai urban atmosphere and at Lin'an background atmospheric monitoring station

The ambient PM_(2.5) particles were sampled synchronously at two sites,Xujiahui (a commercial center in Shanghai) and Lin'an background atmospheric monitoring station (in Zhejiang Province) in April 2008.The microscopic image of the particles were characterized by using of FESEM/EDS,while their chemical elements composition and the valence of zinc in the samples were investigated by using synchrotron radiation fluorescence technique.The average mass concentrations of PM_(2.5) in Xujiahui and Lin'an were (131.6±65.2),(83.5±22.9)μg/m~3,respectively.The Xujiahui PM_(2.5) was primarily consisted by soots,flying ash and mineral particles,while the Lin'an PM_(2.5) was mainly composed by irregular shaped fine particles.Mass concentrations of the 19 elements (P,S,Cl,K,Ca,Ti,V,Cr,Mn,Fe,Ni,Cu,Zn,As,Se,Br,Rb,Sr,Pb) were almost higher in Xujiahui PM_(2.5) than in Lin'an PM_(2.5).The result of synchrotron radiation XANES indicated that the valence of zinc was mainly in the form of zinc sulfate at the both sites.Enrichment factor analysis demonstrated all the elements except K,Ca was more enriched in Shanghai PM_(2.5) than in Lin'an PM_(2.5).