Seasonal variations and source apportionment of carbonaceous aerosol in PM2.5 from a coal mining city in the North China Plain

Fanli Xue,Chunmiao Wu,Jingsen Fan,Chongchong Zhang,Hongya Niu,Shujiao Li,Nana Gao,Jinxi Wang,Xiulong Ren,Wei Hu,Sihao Hu

doi:10.1177/01445987211043211

Abstract

Handan is one of the most polluted coal mining cities in the North China Plain (NCP). There is a lack of research on the pollution characteristics and sources of carbonaceous components in PM2.5 in Handan city. Atmospheric PM2.5 samples were collected from Handan City during 2018 and the organic carbon (OC) and elemental carbon (EC) in PM2.5 were analyzed with a carbon analyzer. The annual average mass concentrations of PM2.5 and total carbon (TC = OC + EC) in Handan were (101.88 ± 79.01) μg/m3 and (28.03 ± 23.28) μg/m3, respectively. The annual average ratio of TC/PM2.5 was (28.29% ± 7.95%), indicating that carbonaceous components made a major contribution to PM2.5. The seasonal variations of OC and EC concentrations in PM2.5 were consistent with PM2.5, which was higher in winter and lower in summer. The annual average OC/EC ratio was (10.33 ± 5.83), and the (OC/EC)min ratio for each season was greater than 2, suggesting that there was probably secondary organic carbon (SOC) formation all around the year. The correlations between OC and EC during spring and winter were much more significant than during summer and autumn, which indicated that the sources of OC and EC in summer and autumn were more complex. Principal component analysis (PCA) displayed that the main sources of carbonaceous components in PM2.5 were coal combustion emission, road dust and vehicle exhaust, which may be related to coal-fired power generation and steelmaking, and coal transportation in Handan city. The potential source contribution function (PSCF) analysis demonstrated that PM2.5 and carbonaceous components in Handan city were significantly influenced by both local emissions and regional transport during the observation period.

Highlights

Atmospheric aerosol pollution in the North China Plain (NCP) occurs throughout the year and is characterized by high concentrations of fine particulate matter (PM2.5) (Huang et al, 2014; Niu et al, 2021)
Handan city is located in the NCP and adjacent to Taihang Mountains to the west The high-intensity emission of air pollutants and the terrain that is adverse to the dispersal of pollutants may be the main causes of air pollution in Handan
The results indicated that the sources of organic carbon (OC) and elemental carbon (EC) were more complex in summer and autumn than in spring and winter when coalburning sources may be the main source

Summary

Introduction

Atmospheric aerosol pollution in the North China Plain (NCP) occurs throughout the year and is characterized by high concentrations of fine particulate matter (PM2.5) (Huang et al, 2014; Niu et al, 2021). Carbonaceous aerosol is one of the important chemical components of PM2.5, contributing about 10 to 70% to PM2.5 in the NCP (Huang et al, 2014, 2018; Li et al, 2019; Meng et al, 2016; Niu et al, 2021; Xue et al, 2020; Zhao et al, 2019). OC can be divided into primary OC (POC) directly emitted from pollution sources and secondary OC (SOC) mainly generated by photochemical reaction of gaseous precursors (Jones and Harrison, 2005). EC is mainly derived from incomplete combustion of biomass or fossil fuels, and only exists in primary aerosols directly emitted by pollution sources (Jacobson, 2001). EC is usually used as a tracer for anthropogenic components because of its chemical stability (Castro et al, 1999; Lim and Turpin, 2002)

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