[Variation Characteristics and Potential Sources of the Mt. Haituo Aerosol Chemical Composition in Different Pollution Processes During Winter in Beijing, China].

In order to investigate the chemical composition and source apportionment of aerosols during winter in the Beijing-Tianjin-Heibei region, the particular matter (PM) and aerosol chemical composition at Mt. Haituo were observed by using a GRIMM 180, a single-particle soot photometer (SP2), and a high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS) from December 28, 2020 to February 3, 2021. Combining these observations with meteorological data and the HYSPLIT model, we calculated the potential source contribution factor (PSCF) and concentration weighted trajectory (CWT) and analyzed the temporal evolution and potential sources apportionment of PM and aerosol chemical composition under different pollution processes. The results showed that the dust storm process mainly affected PM ₁₀ and PM _2.5 in Mt. Haituo during the winter and had a small impact on PM ₁ ; by contrast, haze pollution mainly affected PM ₁ . Chemical components of aerosol accounted for 85.0% and 73.4% of PM ₁ on clean and haze days, respectively, but only 47.4% of PM ₁ in dust storm processes. NO ₃ ^- was the chemical component with the largest mass concentration in haze, accounting for 25.2% of PM ₁ ; black carbon (BC) had the largest mass concentration on clean and dust storm days, accounting for 24.1% and 12.8% of PM ₁ , respectively. The median diameters of BC were 209.7, 207.5, and 204.7 nm on clean, dust storm, and haze days, respectively. D _p / D _c was 2.15 in haze pollution, which was 1.38 and 1.39 times that on dust storm and clean days, respectively. Diurnal variations in PM and aerosol chemical components were different during the different processes. PM ₁₀ and PM _2.5 had high mass concentrations at night and low mass concentrations during the daytime on clean and dust storm days and had a unimodal distribution with a peak at 14:00 in haze. Diurnal variations in chemical composition had a unimodal distribution on clean days and a bimodal distribution on dust storm and haze days. The chemical compositions of the BC coating layer were different under different processes. The coating layers of BC were mainly NH ₄ NO ₃ , (NH ₄ ) ₂ SO ₄ , and organic matter on the clean, dust storm, and haze days, respectively. The distribution of potential sources of PM ₁ and its chemical components were different under different processes. The high-value area of the potential sources was mainly concentrated in the Beijing-Baoding-Shijiazhuang-Yangquan area in the southwestern portion of the site during dust storms and was mainly concentrated in Yanqing, Huailai, and Changping in the areas around the site during haze.