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首页> 外文期刊>Atmospheric chemistry and physics >Urban organic aerosol composition in eastern China differs from north to south: molecular insight from a liquid chromatography–mass spectrometry (Orbitrap) study
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Urban organic aerosol composition in eastern China differs from north to south: molecular insight from a liquid chromatography–mass spectrometry (Orbitrap) study

机译：中国东部的都市有机气溶胶组合物与北部到南方不同：来自液相色谱 - 质谱（Orbitrap）研究的分子洞察力

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Air pollution by particulate matter in China affects human health, the ecosystem and the climate. However, the chemical composition of particulate aerosol, especially of the organic fraction, is still not well understood. In this study, particulate aerosol samples with a diameter of ≤2.5 ? μ m ( PM 2.5 ) were collected in January 2014 in three cities located in northeast, east and southeast China, namely Changchun, Shanghai and Guangzhou. Organic aerosol (OA) in the PM 2.5 samples was analyzed by an ultrahigh-performance liquid chromatograph (UHPLC) coupled to a high-resolution Orbitrap mass spectrometer in both negative mode (ESI-) and positive mode electrospray ionization (ESI+). After non-target screening including the assignment of molecular formulas, the compounds were classified into five groups based on their elemental composition, i.e., CHO, CHON, CHN, CHOS and CHONS. The CHO, CHON and CHN groups present the dominant signal abundances of 81?%–99.7?% in the mass spectra and the majority of these compounds were assigned to mono- and polyaromatics, suggesting that anthropogenic emissions are a major source of urban OA in all three cities. However, the chemical characteristics of these compounds varied between the different cities. The degree of aromaticity and the number of polyaromatic compounds were substantially higher in samples from Changchun, which could be attributed to the large emissions from residential heating (i.e., coal combustion) during wintertime in northeast China. Moreover, the ESI- analysis showed higher H / C and O / C ratios for organic compounds in Shanghai and Guangzhou compared to samples from Changchun, indicating that OA undergoes more intense photochemical oxidation processes in lower-latitude regions of China and/or is affected to a larger degree by biogenic sources. The majority of sulfur-containing compounds (CHOS and CHONS) in all cities were assigned to aliphatic compounds with low degrees of unsaturation and aromaticity. Here again, samples from Shanghai and Guangzhou show a greater chemical similarity but differ largely from those from Changchun. It should be noted that the conclusions drawn in this study are mainly based on comparison of molecular formulas weighted by peak abundance and thus are associated with inherent uncertainties due to different ionization efficiencies for different organic species.
机译：中国颗粒物质的空气污染影响人类健康，生态系统和气候。然而，颗粒气溶胶的化学成分，尤其是有机级分，仍然不太了解。在本研究中，颗粒气溶胶样品的直径≤2.5？ μM（2.5）于2014年1月，位于东北，东南，东南，中国东南，中国，上海和广州的三个城市收集。 PM 2.5样品中的有机气溶胶（OA）通过耦合到负模式（ESI-）和正模式电喷雾电离（ESI +）中的高分辨率型液相色谱仪（UHPLC）分析了PM 2.5样品中的液相色谱仪（UHPLC）。在包括分子式的分配的非靶筛选后，将化合物分为五组，基于其元素组合物，即Cho，Chon，CHN，CHOS和CHONS。 CHO，CHON和CHN组在质谱中呈现81μm-99.7？％的主导信号丰度，其中大多数化合物分配给单和聚芳基，表明人为排放是城市OA的主要来源所有三个城市。然而，这些化合物的化学特性在不同的城市之间变化。长春的样品中的芳香度和多芳族化合物的数量基本上高于，这可能归因于中国东北冬季冬季住宅供热（即煤炭燃烧）的大排放。此外，与来自长春的样品相比，ESI分析显示了上海和广州的有机化合物的H / C和O / C比率，表明OA在中国下纬度地区进行了更强烈的光化学氧化过程和/或受到影响通过生物来源进行更大程度。将所有城市的含硫含硫化合物（CHOS和官部）分配给具有低不饱和度和芳香性的脂族化合物。在这里，来自上海和广州的样品均具有更大的化学相似性，但主要来自长春的化学相似性。应注意，本研究中得出的结论主要是基于峰值加权的分子型的比较，因此由于不同有机物种的不同电离效率而与固有的不确定性相关。

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