The Characteristics of the Chemical Composition of PM2.5 during a Severe Haze Episode in Suzhou, China

• Published in: Atmosphere Vol. 15; no. 10; p. 1204
• Main Authors: Huang, Xiangpeng, Chen, Yusheng, Li, Yue’e, Wang, Junfeng
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 09.10.2024
• Subjects: aerosol chemical composition; Aerosol content; Aerosols; Air pollution; Air quality; Air temperature; Atmospheric aerosols; Boundary layer dynamics; Boundary layer transition; Boundary layers; Carbon; Chemical composition; Clean Air Act-US; Emissions; Environmental effects; Environmental law; Environmental protection; fine particulate matter; Haze; High humidity; Humidity; Liquid water content; Low temperature; Meteorological parameters; Moisture content; nitrate; Nitrates; Outdoor air quality; Parameter identification; Particulate matter; Planetary boundary layer; Pollutants; Pollution; PSCF; Relative humidity; Water; Water content; Beijing China; Yangtze River Delta; United States > US; China
• ISSN: 2073-4433; 2073-4433
• DOI: 10.3390/atmos15101204

During the past decade, the air quality has been greatly improved in China since the implementation of the “Clean Air Act”. However, haze events are still being reported in some regions of China, and the pollution mechanism remains unclear. In this study, we investigate the chemical characteristics of the pollution mechanism of the PM2.5 composition in Suzhou from October 18 to December 15, 2020. A notable declining trend in temperature was observed from 18 to 27 November, which indicates the seasonal transition from fall to the winter season. Four representative periods were identified based on meteorological parameters and the PM2.5 mass concentrations. The heavy pollution period had the typical characteristics of a relatively low temperature, a high relative humidity, and mass loadings of atmospheric pollutants; nitrate was the dominant contributor to the haze pollution during this period. The nitrate formation mechanism was driven by the planetary boundary layer dynamics. The potential source contribution function model (PSCF) showed that the major PM2.5 composition originated from the northwest direction of the sampling site. The aerosol liquid water content presented increasing trends with an increasing relative humidity. The pH was the highest during the heavy pollution period, which was influenced by the aerosol liquid water content and the mass loadings of NO3−, SO42−, NH4+, and Cl−. The comprehensive analysis in this paper could improve our understanding of the nitrate pollution mechanism and environmental effects in this region.