芳香化合物,包括许多多环芳烃(PAHs),是可疑的致癌物,可能来自不同的来源。为了研究人为减排对颗粒物中未知芳香族化合物的影响,我们在2020年的COVID前期、2020年的COVID-19封锁期以及2019年的同一时期收集了样本。除了16种PAHs,通过傅里叶变换离子回旋共振质谱和全面的二维气相色谱-飞行时间质谱分析其他芳香族化合物。确定了四个主要的化合物类别:CH,CHO,CHNO,和CHOS。分层聚类分析表明,芳香族化合物在不同时期有所不同。与大流行前相比,具有低不饱和度和长烷基链的芳族化合物的相对丰度(例如,烷基苯)增加。这些化合物可能主要来自化石燃料燃烧和石化工业排放。CHO化合物,主要是那些高度氧化的,可能源于二次有机气溶胶。芳香醛(例如,仙来醛)和苯甲酸盐(例如,苯甲酸2-乙基己酯)可能具有高毒性,值得更多关注。在封锁期间,缩合多环芳烃的硝基衍生物是主要的CHNO化合物,同系物的数量减少可能是由于NOx和PAHs的显着减少。以长碳链和低不饱和度的CHOS化合物为主,同系物数量增加。通过EPISuite模型预测五种化合物(例如1,3-二甲基芘)可能表现出持久性和生物累积性,这需要进一步的研究。结果提供了有关大气颗粒物中芳香族化合物及其来源的见解。
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.