川南城市群冬季大气细颗粒物中金属元素特征及其来源解析

Characterization of Metal Elements in Atmospheric Fine Particulate Matter and Their Sources in Winter in the Southern Sichuan Urban Agglomeration

为探究川南城市群(自贡、泸州、内江和宜宾)冬季大气重污染过程中PM_(2.5)中金属元素的浓度特征和来源,在2018年12月30日至2019年1月14日,使用膜采样方法对PM_(2.5)中的金属元素进行测定,并运用富集因子法(EF)和正定矩阵因子分解法(PMF)对金属元素来源进行解析.同时采用自贡市在2015年同期金属元素观测数据,探究自贡市在“大气十条”实施中期与实施结束后的金属元素污染与富集程度变化情况.结果表明:①不同城市细颗粒物中各金属元素浓度与占比差异不大,4个城市中浓度与占比较高的元素呈现相似性,Al、Sb和Fe元素占比位于前列.从自贡市不同观测期对比来看,除Tl外各元素浓度均有变化.②富集因子计算结果表明,城市群中Cr(自贡与宜宾)、Ni、Cu、As、Se、Ag、Cd、Sb、Tl和Pb元素的富集程度较高.自贡市不同观测期的元素富集程度对比显示,除Cu元素外,2018年冬季观测期各元素富集程度均有减小趋势.③PMF源解析结果表明,各城市中金属元素主要来源为扬尘源、燃煤源、工业源与交通源,同时各污染源之间存在混合贡献.各城市主要污染源贡献不同,自贡以交通扬尘源与混合源为主;泸州以工业源为主;内江市各污染源贡献占比相近;而宜宾市则以交通源为主导.

To investigate the concentration characteristics and sources of metal elements in PM_(2.5) during winter heavy pollution in the southern Sichuan urban agglomeration(Zigong,Luzhou,Neijiang,and Yibin),the metal elements in PM_(2.5) were measured using membrane sampling methods from December 30,2018 to January 14,2019,and the enrichment factor method(EF)and positive matrix factorization(PMF)were applied to investigate the sources of metal elements.The metal element observation data of Zigong in the same period of 2015 were also used to investigate the changes in metal element pollution and enrichment in Zigong in the middle and end of the implementation of China’s Air Pollution Prevention and Control Action Plan.The main findings were as follows:①The concentrations and percentages of metal elements in particulate matter in different cities did not differ significantly.The elements with higher concentrations in the four cities showed similarities,with Al,Sb,and Fe at the top.From the comparison of different observation periods in Zigong,the concentrations of all elements except Tl changed.②The results of the enrichment factor calculation showed that the enrichment of the elements Cr(Zigong and Yibin),Ni,Cu,As,Se,Ag,Cd,Sb,Tl,and Pb in the urban agglomeration was high.The comparison of the enrichment levels of elements in Zigong for different observation periods showed that the enrichment levels of all elements,except Cu,tended to decrease in the winter observation period of 2018.③The results of PMF source analysis showed that the metal elements in each city mainly originated from dust sources,coal-fired sources,industrial sources,and traffic sources,whereas there was a mixed contribution among the sources.The contribution of the main sources differed among cities,in which Zigong was dominated by traffic dust sources and mixed sources,Luzhou was dominated by industrial sources,Neijiang had a similar contribution from different sources,and Yibin was dominated by traffic sources.