Chemical composition, sources and formation mechanism of urban PM 2.5 in Southwest China: a case study at the beginning of 2023

作者：Junke Zhang, Yunfei Su, Chunying Chen, Wenkai Guo, Qinwen Tan, Miao Feng, Danlin Song, Tao Jiang, Qiang Chen, Yuan Li, Wei Li, Yizhi Wang, Xiaojuan Huang, Lin Han, Wanqing Wu, Gehui Wang · 发表于：Atmospheric chemistry and physics · 年份：2024 · DOI：10.5194/acp-24-2803-2024 · 被引用次数：28 · 研究领域：Atmospheric chemistry and aerosols、Air Quality and Health Impacts、Air Quality Monitoring and Forecasting

Abstract. Despite significant improvements in air quality in recent years, the Sichuan Basin (SCB) is still facing frequent haze pollution in winter, and the causes of severe haze formation have not yet been fully investigated. In this study, the chemical components of PM2.5 (i.e., particulate matter with an aerodynamic diameter of less than 2.5 µm) in a typical pollution period at the beginning of 2023 in Chengdu, a megacity in the SCB, were characterized by bulk-chemical and single-particle analysis, and the PM2.5 sources and formation mechanism of pollution were analyzed. The average mass concentration of PM2.5 during the study period was 95.6 ± 28.7 µg m−3. Organic matter (OM) was the most abundant component (35.3 %), followed by nitrate (22.0 %), sulfate (9.2 %) and ammonium (7.8 %). The individual aerosol particles were classified into five categories, i.e., mineral, OM, secondary inorganic aerosol (SIA), soot and fly ash/metal particles, and most of them were in the state of being internally mixed. The entire observation period could be divided into two non-pollution periods (NP-1 and NP-2) and two haze periods (Haze-1 and Haze-2). With the evolution of pollution, the bulk-chemical and single-particle analysis exhibited similar characteristics, suggesting that Haze-1 was mainly caused by pollutants related to fossil fuel combustion, especially local mobile sources, while Haze-2 was triggered by the rapidly increasing secondary pollutants, which mainly came from regiona...