Chemical Characteristics and Potential Sources of PM2.5 in Shahe City during Severe Haze Pollution Episodes in the Winter

Xiaoyong Liu; Xiaole Pan; Zifa Wang; Hong He; Dawei Wang; Hang Liu; Yu Tian; Weiling Xiang; Jie Li

doi:10.4209/aaqr.2020.03.0124

Chemical Characteristics and Potential Sources of PM2.5 in Shahe City during Severe Haze Pollution Episodes in the Winter

Xiaoyong Liu^1,2,4, Xiaole Pan This email address is being protected from spambots. You need JavaScript enabled to view it.¹, Zifa Wang^1,2,5, Hong He^1,3, Dawei Wang², Hang Liu^2,4, Yu Tian^2,4, Weiling Xiang², Jie Li²

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¹ Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
² State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
³ Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
⁴University of Chinese Academy of Sciences, Beijing 100049, China
⁵ College of Earth Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China

Received: March 29, 2020
Revised: August 16, 2020
Accepted: August 16, 2020

Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

Download Citation: ||https://doi.org/10.4209/aaqr.2020.03.0124

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Cite this article:

Liu, X., Pan, X., Wang, Z., He, H., Wang, D., Liu, H., Tian, Y., Xiang, W. and Li, J. (2020). Chemical Characteristics and Potential Sources of PM_2.5 in Shahe City during Severe Haze Pollution Episodes in the Winter. Aerosol Air Qual. Res. 20: 2741–2753. https://doi.org/10.4209/aaqr.2020.03.0124

HIGHLIGHTS

SO₂ oxidation pathways changed in different RH.
Photochemical reactions were responsible for nitrate formation.
Primary aerosols emissions were enhanced during the haze.
Local emission was the largest potential source area for regional haze.

ABSTRACT

In recent years, North China has suffered from severe air pollution. Hence, this study performed a comprehensive field experiment during Dec. 2017 in Shahe (114.5°N, 36.85°E), a typical industrial city in this region that is characterized by intensive NO_x emission from the local glassmaking industry. During the study period, the mass concentration of the PM_2.5 (fine particulate matter) averaged 121.6 ± 91.8 µg m^–3, whereas the mass concentrations of the nitrate and sulfate in the PM_2.5 averaged 21.4 ± 16.3 and 15.9 ± 20.9 µg m^–3, respectively. The high sulfate mass concentration primarily resulted from the oxidation of SO₂, which was mainly due to gas-phase and heterogeneous reactions during low relative humidity (RH; < 40%) and enhanced aqueous reactions during high RH (> 40%). In addition, because the nitrogen oxidation ratio (NOR) increased as the RH decreased during the day, the nitrate was largely generated through photochemical reactions. The mass concentrations of the optical organic carbon (OC), elemental carbon (EC), and water-soluble organic compounds (WSOCs) equaled 50.4 ± 31.1, 5.8 ± 4.4, and 12.8 ± 10.1 µgC m^–3, respectively, and applying the EC tracer method revealed that primary emissions contributed approximately 72% of the total OC. Furthermore, intense industrial activities were detected in a nearby area to the northeast, which potential source contribution function (PSCF) analysis identified as the main potential source area for PM_2.5 during haze.

Keywords: Air pollution; Chemical composition; North China Plain; Potential source analysis.

Aerosol Air Qual. Res. 20 :2741 -2753 . https://doi.org/10.4209/aaqr.2020.03.0124