Chemical Characteristics of Organic Aerosols in Shanghai: A Study by Ultrahigh‐Performance Liquid Chromatography Coupled With Orbitrap Mass Spectrometry
Chemical Characteristics of Organic Aerosols in Shanghai: A Study by Ultrahigh‐Performance Liquid Chromatography Coupled With Orbitrap Mass Spectrometry
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DOI：
10.1002/2017jd026930
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发表时间：
2017-11
期刊：
影响因子：
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通讯作者：
Xinke Wang;N. Hayeck;M. Brüggemann;L. Yao;Hangfei Chen;Ci Zhang;C. Emmelin;Jianmin Chen;
中科院分区：
文献类型：
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作者：
Xinke Wang;N. Hayeck;M. Brüggemann;L. Yao;Hangfei Chen;Ci Zhang;C. Emmelin;Jianmin Chen;
于2014年7月和10月以及2015年1月和4月在上海市区采集了颗粒物2.5(PM2.5)的过滤样品，并使用超高效液相色谱与Orbitrap质谱仪联用进行了分析。通过非目标筛选方法对测量的色谱质谱图进行处理，以识别有意义的信号。共确定了810-1,510个负极性有机化合物的化学式(负电喷雾电离−)和860-1,790个正极性有机化合物的化学式(ESI+)。上海地区有机气溶胶(OAS)的化学特征在不同月份和昼夜之间有所不同。在1月份的样本中，有机物的数量和丰度通常都较丰富，而7月份的样本中的有机物数量和丰度都要低得多。白天样品中含有较多的CHO−(只含碳、氢和氧的化合物)和CHOS−(含硫有机物)，表明存在光化学来源，而夜间样品中CHONS−(含氮和含硫有机物)含量较高，这是由于夜间样品中存在硝酸根化学。在所有样品中都检测到大量的单环和多环芳香族化合物，以及含氮和含硫的杂环化合物，表明生物质燃烧和化石燃料燃烧对上海城市大气污染具有重要的贡献。此外，前体-产物对分析表明，环氧化物途径是上海地区观察到的有机硫酸盐的重要形成途径。此外，一项类似的分析表明，在ESI+中检测到的含氮化合物中有35%-57%可能是通过氨和羰基之间的反应形成的。本研究对上海市区办公自动化系统进行了全面的概述，有助于了解其特点和来源。
Particulate matter 2.5 (PM2.5) filter samples were collected in July and October 2014 and January and April 2015 in urban Shanghai and analyzed using ultrahigh‐performance liquid chromatography coupled to Orbitrap mass spectrometry. The measured chromatogram‐mass spectra were processed by a nontarget screening approach to identify significant signals. In total, 810–1,510 chemical formulas of organic compounds in the negative polarity (negative electrospray ionization (ESI−)) and 860–1,790 in the positive polarity (ESI+), respectively, were determined. The chemical characteristics of organic aerosols (OAs) in Shanghai varied among different months and between daytime and nighttime. In the January samples, organics were generally richer in terms of both number and abundance, whereas those in the July samples were far lower. More CHO− (compounds containing only carbon, hydrogen, and oxygen and detected in ESI−) and CHOS− (sulfur‐containing organics) were found in the daytime samples, suggesting a photochemical source, whereas CHONS− (nitrogen‐ and sulfur‐containing organics) were more abundant in the nighttime samples, due to nocturnal nitrate radical chemistry. A significant number of monocyclic and polycyclic aromatic compounds, and nitrogen‐ and sulfur‐containing heterocyclic compounds, were detected in all samples, indicating that biomass burning and fossil fuel combustion made important contributions to the OAs in urban Shanghai. Additionally, precursor‐product pair analysis indicates that the epoxide pathway is an important formation route for organosulfates observed in Shanghai. Moreover, a similar analysis suggests that 35–57% of nitrogen‐containing compounds detected in ESI+ could be formed through reactions between ammonia and carbonyls. Our study presents a comprehensive overview of OAs in urban Shanghai, which helps to understand their characteristics and sources.