Particulate matters (PMs) were collected in stacks from two types of ultralow emission coal-fired power plants by a heated electrical low-pressure impactor (HT-ELPI⁺), including ultralow emission pulverized combustion technology boilers (ULPCBs) and ultralow emission circulating fluidized bed boilers (ULCFBs). The characteristics of organic carbon (OC) and elemental carbon (EC) in size-resolved particles were analyzed. The ultralow emission technologies significantly decreased the mass concentrations of the carbonaceous content, and the emission concentrations of OC and EC ranged from 5.64 to 17.9 μg/m³ for ULPCBs and from 0.57 to 1.85 μg/m³ for ULCFBs. However, the number concentration of particles was not significantly decreased in the four ultralow emission power plants. The OC in the particle emission of ULPCBs presents a bimodal size distribution with the particle size, while three successive unimodal distributions were observed in the ULCFB emission. Compared to ULPCBs, much more char-EC and soot-EC condensed in the particles, which were collected from ULCFBs. Furthermore, the char-EC/soot-EC in the particle fractions of ULPCBs characterized by the “V” type with the sequence of PM_1.0 > PM_2.5–10 > PM_1.0–2.5, differing from the PM_1.0 > PM_1.0–2.5 > PM_2.5–10 of ULCFBs. The ratios of OC/EC in the stacks from two types of boilers did not show obvious variations in particle size distributions, and the mean OC/EC was far higher than those for non-ultralow emission power plants. Considering the impact of OC₁, OC₄, and EC₁, the ratio of high-temperature organic carbon (HTOC, defined as OC₂ + OC₃) and soot-EC was studied. The HTOC/soot-EC increased with the increase of RH in the stack, and the highest HTOC/soot-EC values were obtained from ULPCBs (33.0% (PM_1.0), 11.4% (PM_1.0–2.5), and 23.9% (PM_2.5–10)). Meanwhile, strong correlations (0.69–0.85, p < 0.001) between HTOC and soot-EC were obtained, implying that HTOC and soot-EC probably simultaneously condensed in the purification equipment.

This study investigates the impact of fireworks on air quality during the Spring Festival in Nanchang City, utilizing high-resolution monitoring data from February 7th to 15th, 2021. Significant variations in K⁺ concentrations were observed, indicating severe air quality impacts. During the most intense discharge event A, K⁺ concentrations were 20.7 times higher than background levels, with PM_2.5 and PM₁₀ levels rising to 3.63 and 3.32 times above the background, respectively. The contribution of fireworks to PM_2.5 was determined to be 72.5 ± 25.6%. Sulfate (SO₄ ^2-) and nitrate (NO₃ ^-) concentrations also increased significantly, with Δ[SO₄ ^2- ] and Δ[NO₃ ^- ] accounting for 15.4 ± 18.7% and 10.9 ± 12.3% of PM_2.5, respectively. The study highlights the necessity for effective emission control strategies to mitigate the adverse effects of fireworks on urban air quality and public health. Future research should focus on the detailed chemical pathways and long-term impacts of these episodic emissions.