Molecular characteristics, sources and environmental risk of aromatic compounds in particulate matter during COVID-2019: Nontarget screening by ultra-high resolution mass spectrometry and comprehensive two-dimensional gas chromatography

• Published in: Environment international 2022-09, Vol.167, p.107421-107421, Article 107421
• Main Authors: Xu, Chi, Gao, Lirong, Lyu, Yibing, Qiao, Lin, Huang, Di, Liu, Yang, Li, Da, Zheng, Minghui
• Format: Article
• Language: English
• Subjects: Aromatic compound; Comprehensive two-dimensional gas chromatography; COVID-19; Fourier transform ion cyclotron resonance; Nontarget screening; Particulate matter
• ISSN: 0160-4120; 1873-6750
• DOI: 10.1016/j.envint.2022.107421

[Display omitted] •Aromatics besides 16 PAHs were nontarget screened by FT-ICR MS and GC × GC-TOF MS.•The PAH characteristics before and during COVID were significantly different.•Four class and 75 compounds were identified in particulate matter during COVID.•The sources, environmental behavior and risk of aromatics were explored. Aromatic compounds, including many polycyclic aromatic hydrocarbons (PAHs), are suspected carcinogens and may originate from different sources. To investigate the impact of anthropogenic emission reductions on unknown aromatic compounds in particulate matter, we collected samples during the pre-COVID period in 2020, the COVID-19 lockdown period in 2020, and the same period as the lockdown in 2019. Besides the 16 PAHs, other aromatic compounds were analyzed by Fourier transform ion cyclotron resonance mass spectrometry and comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry. Four main compound classes were identified: CH, CHO, CHNO, and CHOS. Hierarchical cluster analysis showed the aromatic compounds varied during the different periods. Compared with before the pandemic, the relative abundances of aromatic compounds with low degrees of unsaturation and long alkyl chains (e.g., alkylbenzenes) increased. These compounds probably mainly arose from fossil fuel combustion and petrochemical industry emissions. The CHO compounds, which were dominated by those with high degrees of oxidation, might originate from secondary organic aerosols. Aromatic aldehydes (e.g., cyclamen aldehyde) and benzoates (e.g., 2-ethylhexyl benzoate) probably with high toxicity deserve more attention. During lockdown, nitro derivatives of condensed PAHs were the main CHNO compounds, and the numbers of homologs decreased perhaps because of significant reductions in NOx and PAHs. CHOS compounds with long carbon chains and low degrees of unsaturation were predominant and the numbers of homologs increased. Five compounds (e.g. 1,3-dimethyl pyrene) were predicted to possibly exhibit persistent and bio-accumulated by EPI Suite model, which need further research. The results provide insight on aromatic compounds and their source appointment in atmospheric particulate matter.