[On-line Measurement of Trace Elements in PM_2.5 in Winter in Urban Taiyuan, China: Levels and Source Apportionment]

In order to better identify the sources of PM_2.5 in Taiyuan, hourly concentrations of 13 trace elements (K, Ca, Ba, Cr, Mn, Fe, Cu, Ni, Zn, As, Se, Pb, and Sr) in PM_2.5 were monitored at an urban site in Taiyuan from January 1 to 29, 2022. The pollution characteristics of trace elements were analyzed and sources were apportioned using positive matrix factorization (PMF). The results showed that the average concentration of 13 total trace elements was (3901.6±2611.2) ng·m^-3, which accounted for (7.1±7.7)% of PM_2.5. The three dominant elements were Fe[(1319.5±1003.5 ng·m^-3)], Ca[(1181.0±1241.6 ng·m^-3)], and K[(883.3±357.3 ng·m^-3)]. The average concentrations of Cr(Ⅵ) (4.6 ng·m^-3) and As (11.2 ng·m^-3) exceeded the guideline values of the Chinese National Ambient Air Quality Standard (GB 3095-2012) and the World Health Organization. Fugitive dust, vehicle emissions, industry, stainless-steel production, biomass burning and waste incineration, residential coal combustion, and industrial coal combustion were identified by the PMF model, which accounted for 45.5%, 1.4%, 15.8%, 23.7%, 5.5%, and 8.1%, respectively, of the total elements.Compared with those during the stages of pollution development and dissipation, the contributions of industrial coal combustion, residential coal combustion, and biomass burning and waste incineration to the total elements during the pollution maintenance stage of the PM_2.5 pollution episode increased significantly, contributing 11.8%, 7.1%, and 28.1%, respectively, of the total elements. These results could provide scientific references for the refined source apportionment of PM_2.5 in other areas.