Molecular characteristics, source contributions, and exposure risks of polycyclic aromatic hydrocarbons in the core city of Central Plains Economic Region, China: Insights from the variation of haze levels

Dong, Zhe; Jiang, Nan; Zhang, Ruiqin; Xu, Qixiang; Ying, Qi; Li, Qiang; Li, Shengli

doi:10.1016/j.scitotenv.2020.143885

Cited by 12 publications

(4 citation statements)

References 70 publications

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“…These DTT m values are comparable with those for the water-soluble fractions of BB, CC, and diesel soot (1.4 ± 0.6, 2.1 ± 2.3 and 1.1 ± 0.4 pmol/min/µg) (R. Zhu et al, 2019) but were much lower than the ranges of 14-25 pmol/min/µg in Los Angeles wildfire aerosol samples, 22-68 pmol/min/µg in Atlanta PM 2.5 samples, and 0.13 ± 0.10 nmol/min/µg in Beijing PM 2.5 samples (Verma et al, 2012;Bates et al, 2019. These results suggested that the water-soluble fraction from BB and CC in this study had a weaker ROS generation capacity than ambient aerosols, which was likely due to the differences in the chemical composition of water-soluble fractions in BB and CC smoke particles and ambient aerosols Yu, 2011, 2019;Dou et al, 2015;Wong et al, 2019). In general, ambient aerosols contain various sources, and the contribution of other sources, such as vehicle emissions or anthropogenic emissions, and transition metals (e.g., Fe, Cu) could increase the ability of atmospheric water-soluble fractions to produce ROS (Ma et al, 2018;R.…”

Section: Oxidative Potentialmentioning

confidence: 68%

Chemical composition, optical properties, and oxidative potential of water- and methanol-soluble organic compounds emitted from the combustion of biomass materials and coal

Cao

Zou

et al. 2021

Atmos. Chem. Phys.

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Abstract. Biomass burning (BB) and coal combustion (CC) are important sources of brown carbon (BrC) in ambient aerosols. In this study, six biomass materials and five types of coal were combusted to generate fine smoke particles. The BrC fractions, including water-soluble organic carbon (WSOC), humic-like substance carbon (HULIS-C), and methanol-soluble organic carbon (MSOC), were subsequently fractionated, and their optical properties and chemical structures were then comprehensively investigated using UV–visible spectroscopy, proton nuclear magnetic resonance spectroscopy (1H NMR), and fluorescence excitation–emission matrix (EEM) spectroscopy combined with parallel factor (PARAFAC) analysis. In addition, the oxidative potential (OP) of BB and CC BrC was measured with the dithiothreitol (DTT) method. The results showed that WSOC, HULIS-C, and MSOC accounted for 2.3 %–22 %, 0.5 %–10 %, and 6.4 %–73 % of the total mass of combustion-derived smoke PM2.5, respectively, with MSOC extracting the highest concentrations of organic compounds. The MSOC fractions had the highest light absorption capacity (mass absorption efficiency at 365 nm (MAE365): 1.0–2.7 m2/gC) for both BB and CC smoke, indicating that MSOC contained more of the strong light-absorbing components. Therefore, MSOC may represent the total BrC better than the water-soluble fractions. Some significant differences were observed between the BrC fractions emitted from BB and CC with more water-soluble BrC fractions with higher MAE365 and lower absorption Ångström exponent values detected in smoke emitted from BB than from CC. EEM-PARAFAC identified four fluorophores: two protein-like, one humic-like, and one polyphenol-like fluorophores. The protein-like substances were the dominant components of WSOC (47 %–80 %), HULIS-C (44 %–87 %), and MSOC (42 %–70 %). The 1H-NMR results suggested that BB BrC contained more oxygenated aliphatic functional groups (H-C-O), whereas CC BrC contained more unsaturated fractions (H-C-C= and Ar−H). The DTT assays indicated that BB BrC generally had a stronger oxidative potential (DTTm, 2.6–85 pmol/min/µg) than CC BrC (DTTm, 0.4–11 pmol/min/µg), with MSOC having a stronger OP than WSOC and HULIS-C. In addition, HULIS-C contributed more than half of the DTT activity of WSOC (63.1 % ± 15.5 %), highlighting that HULIS was a major contributor of reactive oxygen species (ROS) production in WSOC. Furthermore, the principal component analysis and Pearson correlation coefficients indicated that highly oxygenated humic-like fluorophore C4 may be the important DTT active substances in BrC.

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Section: Oxidative Potentialmentioning

confidence: 68%

Chemical composition, optical properties, and oxidative potential of water- and methanol-soluble organic compounds emitted from the combustion of biomass materials and coal

Cao

Zou

et al. 2021

Atmos. Chem. Phys.

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“…PAHs, which originate from various emission sources, are one of the most abundant organic components contributing to PM 2.5 ( Qi et al, 2020 ). Different PAH diagnostic ratios are commonly used to investigate possible sources of PAHs, and subsequently, PM 2.5 ( Dong et al, 2021 ; Gao and Ji, 2018 ; Yan et al, 2019 ). The Flt/(Flt + Pyr), BaA/(BaA + Chr) and Ant/(Ant + Phe) ratios were mostly higher than 0.50, 0.35 and 0.10, respectively, during the COVID-19 Ⅲ period, revealing biomass and coal combustion, along with petroleum products, as the main source of PM 2.5 ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The PAH diagnostic ratio represents a semi-quantitative way to identify sources of PAHs and the usefulness of PAH isomer ratios in source identification has been extensively proved ( Dong et al, 2021 ; Le et al, 2020 ; Lu et al, 2017 ; Xu et al, 2020a ). The diagnostic ratios of Ant/(Phe + Ant), Flt/(Flt + Pyr), IcdP/(IcdP + BghiP), and BaA/(BaA + Chr) were calculated to investigate the sources of PM 2.5 -bound PAHs during COVID-19 Ⅲ to Ⅴ (Table S2).…”

Section: Methodsmentioning

confidence: 99%

Investigation of PM2.5 pollution during COVID-19 pandemic in Guangzhou, China

Wen

Yang

Liao

et al. 2022

Journal of Environmental Sciences

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The COVID-19 pandemic has raised awareness about various environmental issues, including PM 2.5 pollution. Here, PM 2.5 pollution during the COVID-19 lockdown was traced and analyzed to clarify the sources and factors influencing PM 2.5 in Guangzhou, with an emphasis on heavy pollution. The lockdown led to large reductions in industrial and traffic emissions, which significantly reduced PM 2.5 concentrations in Guangzhou. Interestingly, the trend of PM 2.5 concentrations was not consistent with traffic and industrial emissions, as minimum concentrations were observed in the fourth period (3/01-3/31, 22.45 μg•m −3 ) of the lockdown. However, the concentrations of other gaseous pollutants, e.g., SO 2 , NO 2 and CO, were correlated with industrial and traffic emissions, and the lowest values were noticed in the second period (1/24-2/03) of the lockdown. Meteorological correlation analysis revealed that the decreased PM 2.5 concentrations during COVID-19 can be mainly attributed to decreased industrial and traffic emissions rather than meteorological conditions. When meteorological factors were included in the PM 2.5 composition and backward trajectory analyses, we found that long-distance transportation and secondary pollution offset the reduction of primary emissions in the second and third stages of the pandemic. Notably, industrial PM 2.5 emissions from western, southern and southeastern Guangzhou play an important role in the formation of heavy pollution events. Our results not only verify the importance of controlling traffic and industrial emissions, but also provide targets for further improvements in PM 2.5 pollution.

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“…This is mainly contributed to the implementation of measures such as the "650" project for air pollution control, the summer ozone control action plan, the implementation plan for Chengdu to win the battle to defend the blue sky, and the Chengdu air quality compliance plan (2018-2027) (Table S2) [52][53][54][55][56][57][58][59][60]. In 2020, the "636" project of low-carbon city construction was implemented in depth [97,98]. The proportion of days with air quality up to standard in each district (city) county ranges from 72.7% to 91.8%.…”

Section: Annual Variationmentioning

confidence: 99%

Variation characteristics and coordinated emission reduction of air pollutants in megacity of Chengdu-Chongqing economic circle under dual carbon goal

Li,

Abdullah,

Sobri

et al. 2023

Environmental Engineering Research

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The air pollution process and impact mechanism of megacities located in complex terrain are particularly complex. As a typical megacity in China, Chengdu has unique topographical and meteorological conditions, and its pollution control is difficult. This study systematically elucidated the variation characteristics of six criteria air pollutants in Chengdu between 2014 and 2020. Besides, the PM2.5/PM10 and NO2/SO2 ratios were discussed. Furthermore, a detailed analysis of the correlation between air pollutants was carried out. Finally, the collaborative path of carbon reduction and air pollution control is discussed. The results indicated that SO2, PM2.5, PM10 and CO were significantly decreased by 62.9%, 50.8%, 45.5%, and 36.7%, respectively. PM2.5 and O3 compliance rates are very low, and O3 increases with fluctuations. SO2, NO2, CO, PM showed a “U-shaped” seasonal variation, and there was a “seesaw” phenomenon between O3 and PM2.5. The continuous changing trends also found in the ratios of PM2.5/PM10 and NO2/SO2. The results highlight the importance of coordinated reduction of carbon emissions and pollutants in Chengdu. This research can improve the prediction accuracy of air pollution in complex terrain areas under global warming, and improve the understanding of the formation mechanism of air pollution in special terrains around the world.

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Molecular characteristics, source contributions, and exposure risks of polycyclic aromatic hydrocarbons in the core city of Central Plains Economic Region, China: Insights from the variation of haze levels

Cited by 12 publications

References 70 publications

Chemical composition, optical properties, and oxidative potential of water- and methanol-soluble organic compounds emitted from the combustion of biomass materials and coal

Chemical composition, optical properties, and oxidative potential of water- and methanol-soluble organic compounds emitted from the combustion of biomass materials and coal

Investigation of PM2.5 pollution during COVID-19 pandemic in Guangzhou, China

Variation characteristics and coordinated emission reduction of air pollutants in megacity of Chengdu-Chongqing economic circle under dual carbon goal

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