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DOI | 10.5194/acp-2022-465 |
Chromophores and chemical composition of brown carbon characterized at an urban kerbside by excitation-emission spectroscopy and mass spectrometry | |
Feng Jiang, Junwei Song, Jonas Bauer, Linyu Gao, Magdalena Vallon, Reiner Gebhardt, Thomas Leisner, Stefan Norra, and Harald Saathoff | |
2022-07-05 | |
发表期刊 | Atmospheric Chemistry and Physics
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出版年 | 2022 |
英文摘要 | Abstract. The optical properties, chemical composition, and potential chromophores of brown carbon (BrC) aerosol particles were studied during typical summer and winter time at a kerbside in downtown Karlsruhe, a city in central Europe. The average absorption coefficient and mass absorption efficiency at 365 nm (Abs365 and MAE365) of BrC were lower in the summer period (1.6 ± 0.5 Mm-1, 0.5 ± 0.2 m2 g-1) than in the winter period (2.8 ± 1.9 Mm-1, 1.1 ± 0.3 m2 g-1). Using a Parallel factor (PARAFAC) analysis to identify chromophores, two different groups of highly oxygenated humic-like substances (HO-HULIS) dominated in summer and contributed 96 ± 6 % of total fluorescence intensity. In contrast, less oxygenated-HULIS (LO-HULIS) dominated the total fluorescence intensity in winter with 57 ± 12 %, followed by HO-HULIS with 31 ± 18 %. The statistical analysis of AMS data (positive matrix factorization) and Aqualog excitation-emission spectra (parallel factor analysis) showed that the LO-HULIS chromophores are most likely emitted from biomass burning in winter. Less volatile oxygenated organic aerosol shows good correlations (r > 0.7; p < 0.01, respectively) with HO-HULIS components in summer. The LO-HULIS have a negative correlation (r = -0.6, p < 0.01) with O3, which indicates that the LO-HULIS may be depleted by reaction with ozone. In contrast, the HO-HULIS had a positive correlation (r = 0.7, p < 0.01) with O3, indicating that they may result from oxidation reactions. Five nitro-aromatic compounds (NACs) were identified by CIMS (C7H7O3N, C7H7O4N, C6H5O5N, C6H5O4N, and C6H5O3N) which contributed 0.03 ± 0.01 % to the total organic mass, but can explain 0.3 ± 0.1 % of the total absorption of methanol-extracted BrC at 365 nm in winter. Furthermore, we identified 316 potential brown carbon molecules which accounted for 2.5 ± 0.6 % of the organic aerosol mass. Using an average mass absorption efficiency (MAE365) of 9.5 m2 g-1 for these compounds, we can estimate their mean light absorption to be 1.2 ± 0.2 Mm-1, accounting for 32 ± 15 % of the total absorption of methanol-extracted BrC at 365 nm. The potential BrC molecules assigned to the LO-HULIS component had a higher average molecular weight (265 ± 2 Da) and more nitrogen-containing molecules (62 ± 1%) than the molecules assigned to the HO-HULIS components. Our analysis shows that the LO-HULIS, with a high contribution of nitrogen-containing molecules originating from biomass burning, dominate aerosol fluorescence in winter and HO-HULIS, with less nitrogen-containing molecules from less volatile oxygenated organic aerosol, dominate in summer. |
领域 | 地球科学 |
URL | 查看原文 |
引用统计 | |
文献类型 | 期刊论文 |
条目标识符 | http://119.78.100.173/C666/handle/2XK7JSWQ/352910 |
专题 | 地球科学 |
推荐引用方式 GB/T 7714 | Feng Jiang, Junwei Song, Jonas Bauer, Linyu Gao, Magdalena Vallon, Reiner Gebhardt, Thomas Leisner, Stefan Norra, and Harald Saathoff. Chromophores and chemical composition of brown carbon characterized at an urban kerbside by excitation-emission spectroscopy and mass spectrometry[J]. Atmospheric Chemistry and Physics,2022. |
APA | Feng Jiang, Junwei Song, Jonas Bauer, Linyu Gao, Magdalena Vallon, Reiner Gebhardt, Thomas Leisner, Stefan Norra, and Harald Saathoff.(2022).Chromophores and chemical composition of brown carbon characterized at an urban kerbside by excitation-emission spectroscopy and mass spectrometry.Atmospheric Chemistry and Physics. |
MLA | Feng Jiang, Junwei Song, Jonas Bauer, Linyu Gao, Magdalena Vallon, Reiner Gebhardt, Thomas Leisner, Stefan Norra, and Harald Saathoff."Chromophores and chemical composition of brown carbon characterized at an urban kerbside by excitation-emission spectroscopy and mass spectrometry".Atmospheric Chemistry and Physics (2022). |
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