Seasonal characteristics and provenance of organic aerosols in the urban atmosphere of Liaocheng in the North China Plain: Significant effect of biomass burning--颗粒学报PARTICUOLOGY

Li, Y., Chen, M., Wang, Y., Huang, T., Wang, G., Li, Z., . . . Hou, Z. (2023). Seasonal characteristics and provenance of organic aerosols in the urban atmosphere of Liaocheng in the North China Plain: Significant effect of biomass burning. Particuology, 75, 185-198. https://doi.org/10.1016/j.partic.2022.07.012

Seasonal characteristics and provenance of organic aerosols in the urban atmosphere of Liaocheng in the North China Plain: Significant effect of biomass burning

Yuanyuan Li ^a, Min Chen ^a, Yachen Wang ^a, Tonglin Huang ^a, Gehui Wang ^b, Zheng Li ^a ^b, Jianjun Li ^c, Jingjing Meng ^a, Zhanfang Hou ^a *

a School of Geography and the Environment, Liaocheng University, Liaocheng, 252000, China
b Key Lab of Geographic Information Science of the Ministry of Education, School of Geographic Sciences, East China Normal University, Shanghai, 200241, China
c State Key Laboratory of Loess and Quaternary Geology, Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, 710075, China

10.1016/j.partic.2022.07.012

Volume 75, April 2023, Pages 185-198

Received 14 June 2022, Revised 24 July 2022, Accepted 24 July 2022, Available online 7 August 2022, Version of Record 26 August 2022.

E-mail: houzhanfang@lcu.edu.cn

Highlights

• Primary organic markers exhibit the highest concentrations in winter.

• Biogenic secondary organic aerosol (BSOA) present the highest value in summer.

• Combustion sources contributed more to organic aerosol (OA) in cold seasons.

• The secondary oxidation made up more in the warm seasons.

• Biomass burning was an important contributor to OA in winter.

Abstract

To better understand the seasonal characteristics of urban organic aerosol (OA) in the North China Plain (NCP), PM_2.5 samples in the urban atmosphere of Liaocheng were collected and analyzed. The molecular distribution of the organic markers in the urban atmosphere of Liaocheng reveals that n-alkanes (39.3%) was the most abundant species all year round, followed by saccharides (28.2%), phthalic acids (Ph, 20.8%), biogenic secondary organic aerosol (BSOA) tracers (9.4%), and polycyclic aromatic hydrocarbon (PAHs, 2.3%). PM_2.5, organic carbon (OC), elemental carbon (EC), and primary organic markers exhibit the highest concentrations in winter, due largely to the increased biomass burning and coal combustion for house heating in local and surrounding regions. However, the concentration and relative abundance of BSOA are significantly higher in summer than other seasons, induced by the more favorable meteorological conditions that would promote the emissions of biogenic volatile organic compounds (BVOCs) and the secondary production of BSOA. The ratios of OC/EC and 3-methyl-1,2,3-butanetricarboxylic acid to cis-pinic acid plus cis-pinonic acid (MBTCA/(PA + PNA) are higher in the warm seasons than those in the cold seasons, indicating that the oxidation of OA is sensitive to air temperature. Compared to 2017, the concentration level of PAHs during wintertime decreased by 40.8%, confirming that the stringent regulation of coal burning is effective. The highest concentration of high molecular weight (HMW) n-alkanes and three anhydrosugars in winter, and the close correlation of levoglucosan with HMW n-alkanes suggests that the impact of biomass burning was more significant in winter. The same seasonal characteristic of the ratios of high-/low-NO_x products with NO_x and the strong correlation of high-/low-NO_x products with levoglucosan indicate that the formation of isoprene SOA (SOA_I) tracers was significantly influenced by anthropogenic emissions. The molecular compositions, the distributions of fire spots, backward trajectories of air masses, and correlation analysis suggest that air pollution events in spring were primarily resulted from biomass burning and secondary oxidation, while pollution events in winter were largely driven by the increased combustion sources, and promoted aqueous secondary formation. Our results suggest that the reduction of biomass and coal combustion should be taken into account to improve the urban air quality in the NCP.

Graphical abstract

Keywords

Organic aerosol (OA) markers; Seasonal variations; Pollution periods; Biomass burning; The north China Plain (NCP)

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