To study the effect of fireworks/firecrackers (FF) display on aerosol particles, the chemical composition and morphology of fine aerosol particles (PM2.5) collected in a rural valley of north China in the Chinese New Year's Eve (CNYE) were analyzed. The results showed that PM2.5 was much lower in the 2022 CNYE with little influence by FF due to the strict no-FF display policy for the 2022 Winter Olympic Games. In contrast, PM2.5 was significantly affected by FF display in the 2023 CNYE with the maximum hourly PM2.5 mass concentrations reaching 1200 mu g m(-3). The value was even much higher than that in near-by cities. Chemical analysis showed that organic matter (24.5 wt% of total PM2.5) was the most abundant in the CNYE, followed by K+ (15.3 wt%), SO42- (12.3 wt%), and Cl (9.9 wt%). The mass concentrations of K+, Mg2+, Cu, Sr, and Ba were as 22.0 to 41.4 times as those before the CNYE. The concentrations of elemental carbon, Cl, SO42-, and Ti were as 3.7 to 12.3 times as those before the CNYE. Further analysis by scanning electron microscope coupled with energy dispersive X-ray spectrometer revealed that carbonaceous particles in the CNYE contained more S, Cl, K and heavy metals compared with that before the CNYE. Most of the non-carbonaceous particles in the CNYE were K-rich, Mg-rich, Al-rich, and Ba-rich, with spherical and near-spherical shapes, which were much different from those before the CNYE with irregular shapes. The different morphologies of non-carbonaceous particles can have much different optical properties, which should be further evaluated. The results above suggested that the PM2.5 mass concentration in rural valleys in the CNYE was extremely high in a short time and more attention should be paid in future policy making to improve air quality.

In the spring of 2023, two severe dust events occurred in the coastal city of Qinhuangdao, North China. We investigated organic carbon (OC) and elemental carbon (EC) in PM10 using an OC/EC analyzer and identified the morphology and elemental composition of individual dust particles using a scanning electron microscope coupled with energy-dispersive X-ray (SEM-EDX). Results showed that OC mass concentrations varied significantly from 12.6 µg m−3 to 74.6 µg m−3 and showed a significant positive correlation with the PM10 mass concentration. On average, OC made up 4.6

A special dust storm characterized by high PM10 mass concentrations (921.9 +/- 632.3 mu g m(-3)) and high relative humidity (RH; 60.1 % +/- 11.1 %) was observed on March 22-24, 2023 at a coastal city of North China. Aerosol particles of PM10 were analyzed by a scanning electron microscope coupled with energy dispersive X-ray and an ion chromatograph. The results showed that individual mineral particles were dominated by clay minerals, followed by quartz, feldspar, and carbonate. Bulk water-soluble inorganic ions analysis showed that SO42- mass concentrations varied from 3.7 mu g m(-3) to 23.3 mu g m(-3) with an average value of 12.4 mu g m(-3). However, their mass ratios to PM10 were relatively stable, being 1.15-2.01 % with an average value of 1.49 % +/- 0.25 %, similar to the value near the dust sources (Tengger Desert). Although S-containing individual mineral dust varied from 5.2 % to 70.7 %, the average weight ratio of S on individual mineral dust was 2.1 %, much lower than that of non-dust periods (11.0 %). The results suggested limited sulfate formation on mineral dust surfaces even under high RH. In contrast, NO3-, which was very limited in dust sources, varied from 0.21 % to 4.11 % of the total PM10 with an average value of 1.61 % +/- 1.07 %. The research highlighted that nitrate formation has exceeded sulfate formation during severe dust storm episodes, which might because the atmospheric compositions in China have changed significantly with a high mass ratio of NO2/SO2 after the implementation of the strict emission control measures.

Dust storms are one of the largest sources of non-exhaust emissions in China, which can adversely affect air quality and human health during long-distance transportation. To study the influence of dust storms on aerosol particle composition, samples of fine aerosol (PM2.5) were collected before, during, and after the severe dust storm episodes in a coastal city of North China. Then the water-soluble inorganic ions in the filters were analyzed. The results showed that the chemical composition varied significantly in different sampling periods. Before the dust storm periods (Phase 1), the weather was characterized by high relative humidity. NO3- was the main water-soluble inorganic ion, accounting for about 1/3 of the total mass of PM2.5, which is very different from the situation a few years ago when sulfate was the dominant. The results indicated that the chemical composition of the atmosphere in China has changed significantly after the implementation of strict air pollution control measures. During the severe dust storm periods (within a few hours after the dust invasion, Phase 2), the proportion of Ca2+ in PM2.5 was high; the sulfate formation was limited due to adiabatic air mass affected by the cold front, and the sulfate content might be mainly from desert soil. However, a small amount of nitrate can be formed during their long-distance transportation. After the dust storm periods (Phase 3), dust plums and local polluted air mass mixed well. The proportion of secondary inorganic ions increased, and nitrate formation was still the main. The changes in the chemical composition from a few years ago during Phase 1 and the sharp changes in different water-soluble inorganic ions during different Phases should be carefully considered to evaluate their implications for air quality and human health.

Although numerous studies have been carried out to study haze formation in the North China Plain (NCP) and Northeastern Plain (NP), little is known about the chemical compositions and haze formations in Qinhuangdao city, which is located in the northeast edge of the NCP and adjacent to the NP. In this study, water‐soluble inorganic ions, organic carbon and elemental carbon (EC) were analysed offline during two haze periods from October 29 to November 7, 2021. The results showed that NO 3 − and organic matter (OM) accounted for 34.81% and 21.15% of total PM 2.5 mass concentration, respectively, followed by NH 4 + (14.06%) and SO 4 2− (12.33%). The sulphur oxidation ratio and nitrogen oxidation ratio as well as OM/EC ratio on haze days were higher than those on non‐haze days, suggesting both high secondary inorganic and organic aerosol formation on haze days under high relative humidity. Source apportionment results showed that marine aerosols contributed small of total aerosol particle loads, while the combustion‐related sources were the most, possibly coal combustion, biomass burning and vehicle emissions. Air masses during haze periods mainly came from southwest and west directions in this case. Further calculated meteorological data of 2018–2021 showed high PM 2.5 mass in Qinhuangdao were mainly affected by low‐speed southwest wind in autumn. The results highlighted the important role of long‐range transport of air pollutants from the NCP instead of the NP on haze formation in autumn in Qinhuangdao.