城市街道灰尘与大气细颗粒物（PM2.5）元素组成特征分析

摘要

Data sets of elements content in urban street dust and PM2.5 from Beijing,Shanghai,Lanzhou,Hong Kong,and Nanjing were collected and filed for analyzing the characteristics of elemental composition of urban street dust and PM2.5 .A log-log concentration diagram was applied to comparison of urban street dust and PM2.5 elemental composition,and coefficient of divergence (CD)was used to characterize the difference.The results show that Fe,Al,Ca,K,Na constitute most of the involved elements in both urban street dust and PM2.5 (street dust:97.48%,PM2.5:90.11%),and Ti,Mn,Zn,Pb,Cu,Cr,Ni only account for a small proportion (street dust:2.51%,PM2.5:9.60%),while As and Cd are scarce (street dust:0.01%,PM2.5:0.29%);that CDs of urban street dust and PM2.5 elemental compositions maintain a high level ranging from 0.627 to 0.801,and the average is 0.711,which means that there is obvious difference between elemental compositions of street dust and PM2.5 in the same city.Enrichment of human-related elements (Zn,Pb,Cu,Ni,As,Cd,Mn,K,Cr)is higher in PM2.5 than in urban street dust,while both correlation is significant (r =0.783,P <0.01).Among crust-related elements such as Al,Ti,Ca and Fe,only Ti is enriched in street dust,while others are either enriched in street dust or in PM2.5 ,and no evident correlation is found between these elements in urban street dust and its counterparts in PM2.5 .In addi-tion,Na is enriched in street dust of inland cities,while it is enriched in PM2.5 of coastal cities.%利用北京、上海、兰州、香港和南京5个城市街道灰尘与大气细颗粒物（PM2.5）中各元素的含量，比较分析不同城市街道灰尘与 PM2.5的元素组成特征，并利用对数浓度图和分歧系数法探究两者元素组成的差异及其与人为源元素的相关性。结果表明：5个城市街道灰尘和 PM2.5中，元素 Fe、Al、Ca、K、Na 占绝大部分（街道灰尘约占97.48％，PM2.5约占90.11％），元素Ti、Mn、Zn、Pb、Cu、Cr 和 Ni 仅占较小的比例（街道灰尘约占2.51％，PM2.5约占9.60％），元素 As 和 Cd 含量则更少（街道灰尘约占0.01％，PM2.5约占0.29％）。5个城市街道灰尘与 PM2.5元素组成的分歧系数为0.627—0.801之间，平均值为0.711，处于较高水平，即城市街道灰尘与 PM2.5的元素组成存在较大差异。人为源元素（Zn、Pb、Cu、Ni、As、Cd、Mn、K、Cr）在 PM2.5中的富集程度高于街道灰尘，城市街道灰尘和 PM2.5中人为源元素含量的相关性也较大（r ＝0.783，P ＜0.01）。Al、Ti、Ca、Fe 等典型的地壳元素中，仅 Ti 元素在街道灰尘中富集，Al、Ca 和 Fe 元素有时富集在街道灰尘中，有时富集在 PM2.5中，其含量也未呈明显相关。此外，内陆城市的 Na 元素在街道灰尘中富集，沿海城市的 Na 元素则多在 PM2.5中富集。