Seasonal variations and source apportionment of carbonaceous aerosol in PM_2.5 from a coal mining city in the North China Plain

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.

Chemical compositions and possible transportation of PM2.5 during two haze periods in a coastal city of the North China Plain

“…OM can be primary OM and secondary OM, while EC are mainly from primary emissions (Dong et al, 2023; Xue et al, 2022). When OC/EC ratio is greater than 2, secondary organic aerosol formation is believed to occur (Xue et al, 2022). OM was also well correlated with PM 2.5 , as shown in Figure 4.…”

“…In addition, the CCs of Cl − and Na + , Cl − and K + , and Na + and K + were 0.95, 0.92, and 0.96, respectively, as shown in Table 1. The OC/EC ratios can reflect the possible sources of carbonaceous aerosols, with vehicle emissions ranging from 1.0 to 4.2, coal combustion ranging from 2.5–10, and biomass burning ranging from 16.8 to 40.0 (Dong et al, 2023; Xue et al, 2022). OC/EC ratios ranged from 6.28 to 25.28 in this study, which were close to those particles emitted from coal combustion and biomass burning.…”

“…Our results confirmed that combustion‐related sources played significant roles in haze formation in Qinhuangdao, and haze formation was mainly affected by the air masses from the west and south‐west. Indeed, there are some heavily polluted industrial cities on the border of Hebei, Shandong and Henan Provinces, which are located south‐west of Qinhuangdao city (Li et al, 2019; Xue et al, 2022). Qinhuangdao is bordered by a mountain to the north.…”

“…The North China Plain (NCP) including Beijing–Tianjin–Hebei region has a large area of around 3,000,000 km 2 and is one of the most polluted areas in China (Du et al, 2020; Song et al, 2022). Many studies have reported the chemical compositions and corresponding source apportionment to reveal haze formation in the NCP, such as Beijing (Ma et al, 2017), Tianjin (Yao et al, 2020), Shijiazhuang (Wang et al, 2020), Handan (Xue et al, 2022), Taiyuan (Li et al, 2012) and Zhengzhou (Song et al, 2022).…”

“…The results showed that water‐soluble inorganic ions and carbonaceous components are the main anthropogenic aerosol components, which have significant effects on haze formation in the NCP (Dong et al, 2023; Huang et al, 2014; Wang et al, 2016; Xue et al, 2022). For example, water‐soluble inorganic ions and carbonaceous component accounted for about 14%–49% and 11%–35% of PM 2.5 in Beijing (Shao et al, 2018).…”