Chemical Composition and Source of PM2.5 during Winter Heating Period in Guanzhong Basin

• Published in: Atmosphere 2023-11, Vol.14 (11), p.1640
• Main Authors: Cao, Lei, Tao, Yanan, Zheng, Hao, Wang, Mei, Li, Shiying, Xu, Yongjiang, Li, Mei
• Format: Article
• Language: English
• Subjects: Aerosols; Air pollution; Atmospheric particulates; Biomass burning; Carbon; Chemical composition; Chemical industry; Cities; Coal; Coal combustion; Combustion; Dust; emission sources; Emissions; Guanzhong Basin; Heating; Industrial emissions; Industrial plant emissions; Meteorological parameters; Outdoor air quality; Particulate matter; Particulate matter sources; PM2.5; Pollutants; Pollution levels; Power plants; Relative humidity; River basins; Seasons; Urban areas; Vehicle emissions; Vehicles; VOCs; Volatile organic compounds; Wind; Wind speed; Winter
• ISSN: 2073-4433; 2073-4433
• DOI: 10.3390/atmos14111640

An intensive field campaign was carried out from December 2022 to March 2023 at six different sites across five major cities (Xi’an, Baoji, Xianyang, Weinan, and Hancheng) in the Guanzhong Basin, China, covering most of the heating period there, which is characterized by high PM2.5 pollution levels. During the campaign, the mean PM2.5 concentrations at these sites exceeded the 24 h PM2.5 standard (75 μg m−3), except the site at Hancheng, with mean PM2.5 concentrations of 57.8 ± 32.3 μg m−3. The source apportionment of PM2.5 varied significantly across sites, with vehicle exhaust being the dominant source at urban sites located in Xi’an and Baoji, coal combustion at suburban sites in Hancheng, and comparable contribution from coal combustion and industrial emissions at suburban sites in Xianyang and Weinan. Compared with clean condition, the contribution of vehicle exhaust and secondary inorganic sources (SIs) were largely enhanced during heavy PM2.5 pollution periods, while the contribution from biomass burning (BB) and dust decreased significantly at all sites. Combined with an analysis of meteorological parameters, the study further found that higher contributions of SIs and heavy PM2.5 pollution were generally associated with higher relative humidity (RH). In addition, higher PM2.5 concentrations at suburban sites were related to lower wind speeds, which could be explained by the stagnant condition favoring the accumulation of local emissions as well as the formation of secondary pollutants. In contrast, at urban sites (e.g., Xianyang), higher PM2.5 concentrations were more associated with the strong influence of vehicle exhaust at slightly higher wind speeds.