Causes of PM2.5 pollution in an air pollution transport channel city of northern China

Xueyan Zhao; Jing Wang; Bo Xu; Ruojie Zhao; Guangjie Zhao; Jian Wang; Yinhong Ma; Handong Liang; Xianqing Li; Wen Yang

doi:10.1007/s11356-021-17431-4

Causes of PM_2.5 pollution in an air pollution transport channel city of northern China

Environ Sci Pollut Res Int. 2022 Apr;29(16):23994-24009. doi: 10.1007/s11356-021-17431-4. Epub 2021 Nov 24.

Authors

Xueyan Zhao^{1

2}, Jing Wang^{1

2}, Bo Xu³, Ruojie Zhao², Guangjie Zhao¹, Jian Wang², Yinhong Ma², Handong Liang¹, Xianqing Li⁴, Wen Yang⁵

Affiliations

¹ State Key Laboratory of Coal Resources and Safe Mining, College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China.
² Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
³ Zibo Eco-Environmental Monitoring Center of Shandong Province, Zibo, 255000, China.
⁴ State Key Laboratory of Coal Resources and Safe Mining, College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing, 100083, China. Lixq@cumtb.edu.cn.
⁵ Chinese Research Academy of Environmental Sciences, Beijing, 100012, China. yangwen@craes.org.cn.

PMID: 34820758
DOI: 10.1007/s11356-021-17431-4

Abstract

To develop effective mitigation policies, a comprehensive understanding of the evolution of the chemical composition, formation mechanisms, and the contribution of sources at different pollution levels is required. PM_2.5 samples were collected for 1 year from August 2016 to August 2017 at an urban site in Zibo, then chemical compositions were analyzed. Secondary inorganic aerosols (SNA), anthropogenic minerals (MIN), and organic matter (OM) were the most abundant components of PM_2.5, but only the mass fraction of SNA increased as the pollution evolved, implying that PM_2.5 pollution was caused by the formation of secondary aerosols, especially nitrate. A more intense secondary transformation was found in the heating season (from November 15, 2016, to March 14, 2017), and a faster secondary conversion of nitrate than sulfate was discovered as the pollution level increased. The formation of sulfate was dominated by heterogeneous reactions. High relative humidity (RH) in polluted periods accelerated the formation of sulfate, and high temperature in the non-heating season also promoted the formation of sulfate. Zibo city was under ammonium-rich conditions during polluted periods in both seasons; therefore, nitrate was mainly formed through homogeneous reactions. The liquid water content increased significantly as the pollution levels increased when the RH was above 80%, indicating that the hygroscopic growth of aerosol aggravated the PM_2.5 pollution. Source apportionment showed that PM_2.5 was mainly from secondary aerosol formation, road dust, coal combustion, and vehicle emissions, contributing 36.6%, 16.5%, 14.7%, and 13.1% of PM_2.5 mass, respectively. The contribution of secondary aerosol formation increased remarkably with the deterioration of air quality, especially in the heating season.

Keywords: Formation mechanisms; Heterogeneous reactions; Liquid water content; PM2.5; Pollution levels; Secondary inorganic aerosols; Source apportionment.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Air Pollution* / analysis
China
Environmental Monitoring
Particulate Matter / analysis
Seasons
Vehicle Emissions / analysis

Substances

Aerosols
Air Pollutants
Particulate Matter
Vehicle Emissions

Abstract

MeSH terms

Substances

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