太原市城区大气PM_(2.5)中元素污染特征及其来源解析

Characteristics and Sources Analysis of Element in Ambient PM_(2.5) in Taiyuan City

为了解2017年—2018年非采暖季、采暖季PM_(2.5)污染较轻时期和采暖季PM_(2.5)污染较重时期太原市城区大气PM_(2.5)及其附着的15种金属及类金属元素(铝、砷、钙、镉、铬、铜、铁、钾、镁、锰、钠、镍、铅、钒和锌)的分布特征及主要来源,在太原市城区的尖草坪区解放北路、迎泽区新建南路和双塔寺街三个监测点使用中流量颗粒物采样器连续采集6 d且每天不少于20 h的大气PM_(2.5)滤膜样品。PM_(2.5)滤膜样品用微波消解法进行前处理后,使用电感耦合等离子体质谱(ICP-MS)检测其中15种金属及类金属元素的含量。通过描述性统计方法分析和比较三个监测点大气PM_(2.5)及其附着的15种金属及类金属元素日均浓度在时间和空间上分布的差异,进一步采用富集因子法和主成分分析法分析其聚集特征和主要来源。结果发现各采样点大气PM_(2.5)及其附着的15种金属及类金属元素的日均浓度在整体上呈现的趋势为:采暖季污染较重时期>采暖季污染较轻时期>非采暖季;各监测期大气中PM_(2.5)及其附着的大多数金属及类金属元素的日均浓度在3个监测点间无显著性差异(p<0.01); PM_(2.5)上附着的15种金属及类金属元素的主要来源在非采暖季是土壤扬尘、建筑扬尘和冶金工业,其贡献率分别为32.03%, 30.52%和18.26%,在采暖期污染较轻时,主要来源是建筑、土壤和冶金工业的混合源、建筑和生物质燃烧混合源以及土壤,其贡献率分别为37.98%, 37.05%和16.55%,在采暖期污染较重时,主要来源是建筑和生物质燃烧混合源,建筑、土壤和冶金工业的混合源以及土壤,其贡献率分别为40.62%, 35.52%和13.96%。与往年的相关研究结果相比,虽然近年来太原市对PM_(2.5)的污染源如冶金工业、机动车和燃煤等的污染物排放控制有所成效,但还应进一步加强对生物质燃烧、土壤扬尘、建筑扬尘和冶金工业污染源的管控措施。

In2017-2018,the concentrations and sources of ambient fine particulate matter (PM2.5 ) and its15 elements (Al,As,Ca,Cd,Cr,Cu,Fe,K,Mg,Mn,Na,Ni,Pb,V,Zn) in three sampling points (Jiefang North Road Jiancaoping District,Xinjian South Road and Shuangtasi Street Yingze District) in Taiyuan city were investigated during the non-heating season,the light pollution period in heating season and the heavy pollution period in heating season.The samples were collected continuously by medium flow particle samplers in 6 days with more than20 hours each day,and the concentrations of the15 elements were determined by ICP-MS after pretreatment of microwave digestion.The spatial and temporal distribution characteristics were analyzed by descriptive statistical method.The main sources of PM2.5 were analyzed by enrichment factor method (EF) and the principal component analysis method (PCA).The concentrations of PM2.5 and its15 elements showed the tendency of the heavy pollution period in heating season > the light pollution period in heating season > the non-heating season.There were no significant differences in concentrations of PM2.5 and most of the15 elements between the 3 sampling points ( p <0.01).The main sources of the15 elements in the non-heating season was soil,construction and metallurgical industry with the contribution of 32.03%,30.52% and18.26%.The main sources in the light pollution period in heating season was the mixed source of construction,soil and metallurgical industry,the mixed source of construction and biomass combustion and soil with the contribution of 37.98%,37.05% and16.55%.The main sources in the heavy pollution period in heating season was the mixed source of construction and biomass combustion,the mixed source of construction,soil and metallurgical industry and soil with the contribution of 40.62%,35.52% and13.96%.Compared with previous studies,the results of this research showed that although the control measures of PM2.5 in Taiyuan had been effective in recent years,the management and control of pollution sources such as metallurgical industry,motor vehicles and coal burning should be further strengthened.