Characterization of aerosol chemical composition and the reconstruction of light extinction coefficients during winter in Wuhan, China

Weijie Liao; Jiabin Zhou; Shengjie Zhu; Anshan Xiao; Kuan Li; James J Schauer

doi:10.1016/j.chemosphere.2019.125033

Characterization of aerosol chemical composition and the reconstruction of light extinction coefficients during winter in Wuhan, China

Chemosphere. 2020 Feb:241:125033. doi: 10.1016/j.chemosphere.2019.125033. Epub 2019 Oct 5.

Authors

Weijie Liao¹, Jiabin Zhou², Shengjie Zhu³, Anshan Xiao³, Kuan Li⁴, James J Schauer⁵

Affiliations

¹ School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, China; College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, 610500, China.
² School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, China; College of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, 610500, China. Electronic address: jbzhou@swpu.edu.cn.
³ Sinopec Research Institute of Safety Engineering, State Key Laboratory of Safety and Control for Chemicals, Qingdao, 266071, China.
⁴ School of Resources and Environmental Engineering, Wuhan University of Technology, Wuhan, 430070, China.
⁵ Environmental Chemistry and Technology Program, University of Wisconsin-Madison, 660 North Park Street, Madison, WI, 53706, USA. Electronic address: jjschauer@wisc.edu.

PMID: 31610462
DOI: 10.1016/j.chemosphere.2019.125033

Abstract

To evaluate light extinction contributions of aerosol chemical constituents and their impacts on atmospheric visibility, the PM_2.5 and its chemical components, light scattering (b_sp) and absorption (b_ap) were continuously measured in Wuhan from January to February 2018. The average of PM_2.5 concentration, b_sp and b_ap were 96.5 ± 13.7 μg m^-3, 564 ± 124 Mm^-1 and 44 ± 8 Mm^-1 during polluted days, respectively, which was about 2.0, 2.1 and 1.6 times higher than those of clean days, respectively. Compared with the clean days, the increase of the mass concentrations of SNA (SO₄^2-, NO₃^-, NH₄⁺) during polluted days was higher than those of organic (OC) and elemental (EC) carbon, indicated the increase of SNA was the main cause of air pollution. The PM_2.5 concentration threshold was 66 μg m^-3, corresponding to the visibility lower than 10 km. The revised Interagency Monitoring of Protected Visual Environments (IMPROVE) algorithm was used to reconstruct the light extinction coefficient (b_ext) in Wuhan. The sum of light extinction coefficients of (NH₄)₂SO₄, NH₄NO₃ and organic matter (OM) accounted for 70.5% and 83.9% of b_ext during clean and polluted days, respectively. The backward trajectory and potential source contribution function (PSCF) analysis revealed that regional transport accounted for 55.6% of the total airflow, which originated from south, northwest and west of Wuhan. The increases of (NH₄)₂SO₄ and NH₄NO₃ concentrations, emitted from local vehicle exhaust and coal combustion, and their hygroscopic growth in ambient were the major causes of pollution in Wuhan.

Keywords: IMPROVE formula; Light extinction; PM(2.5); PSCF analysis; Visibility.

MeSH terms

Aerosols / analysis
Aerosols / chemistry*
Air Pollutants / analysis*
Ammonium Compounds / analysis
China
Coal / analysis
Environmental Monitoring / methods*
Nitrates / analysis
Particulate Matter / analysis
Seasons*
Sulfates / analysis
Vehicle Emissions / analysis

Substances

Aerosols
Air Pollutants
Ammonium Compounds
Coal
Nitrates
Particulate Matter
Sulfates
Vehicle Emissions