Emission control priority of PM2.5-bound heavy metals in different seasons: A comprehensive analysis from health risk perspective

Characteristics and Sources of Hourly Trace Elements in Airborne Fine Particles in Urban Beijing, China

“…Because certain TEs are tracers for specific pollution sources, the decrease in their concentrations suggests that the emissions from those sources declined as a result of the execution of the air pollution control measures. For example, Cr and Mn mainly originate from industrial activities (Liu et al, ; Tian et al, ; Zhu et al, ); Cu and Zn are normally from vehicle emissions in the urban environment (Lin et al, ; Wang, Qiao, Zhang, et al, ); and As and Se in PM 2.5 are closely associated with coal combustion (Liu et al, ; Tian et al, ; Zhu et al, ). The decline in the As, Cr, Mn, Ni, Cu, Zn, and Pb concentrations is consistent with the gradual improvement in air quality in Beijing for the past five years, suggesting that the APPCAP put in place since 2013 was effective.…”

“…The concentration differences of K, Cr, Mn, Fe, Cu, and Pb during HP days and MP days were statistically significant ( p < 0.05) based on the Mann‐Whitney U test, while the differences of Ni, As, Se, and Zn during these two periods were not statistically significant. It is known that the local emissions of industrial activities, coal combustion, and biomass burning are lower in urban Beijing than in the areas outside Beijing in the BTH (Gao et al, ; Liu et al, ; Zhu et al, ); this is because a series of the strictest air pollution control measures were taken in the Beijing Municipality, including phasing out and/or relocation of highly polluting industries, reduction in coal consumption, and usage of clean energy. Consequently, during the highest polluted days, there was some decline in the concentrations of K, Cr, Mn, Fe, Ni, Zn, and Pb, which are closely associated with industrial emission and coal combustion.…”

“…Factor 2, characterized by high loadings of Cr and Mn and moderate loadings of Fe, Ni, Cu, Zn, and Ba, was identified as industrial activities. Cr mainly originates from fuel combustion and metallurgical industry such as chrome plating and steel production (Liu et al, ; Zhu et al, ), and Mn is mainly released by ferrous metal smelting (Duan & Tan, ; Tian et al, ; Zhu et al, ). This source contributed 10.7% of the total TE mass, and it contributed 20%, 19.8%, 15.2%, 12%, and 17.8% of the total Fe, Ni, Cu, Zn, and Ba mass concentrations, respectively.…”

“…Factor 5, characterized by high loadings of As, Se, Pb, and Zn, seems to be coal combustion; it contributed 7.6% of the total TE mass. As and Se have been found to be associated with coal combustion (Liu et al, ; Wang, Qiao, Zhou, et al, ; Zhu et al, ). As shown in Figure S6, the diurnal variations in this factor show a lower contribution during the daytime, and they present high values from November to March when substantial amounts of coal are used for domestic heating in Beijing.…”

“…Factor 6 was considered as oil combustion because of the high loadings of V and Ni (Liu et al, ); it was responsible for 4.6% of the total elements mass. As indicated in section , V and Ni are typical tracers of oil combustion.…”