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Formation and photochemical investigation of brown carbon by hydroxyacetone reactions with glycine and ammonium sulfate

机译：用甘氨酸和硫酸铵的羟基丙酮反应形成和光化学研究

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摘要

Increasing attention has been paid to atmospheric brown carbon (BrC) aerosols due to their effect on the earth's climate. Aqueous BrC aerosols were formed through aqueous reactions of hydroxyacetone (HA) with nitrogen compounds such as glycine (Gly) and/or ammonium sulfate (AS). When exposed to nitrogen compounds for several days, HA, as a type of aqueous carbonyl compound, becomes absorbent and fluorescent in the blue visible and near ultraviolet regions, which have been monitored by UV/vis and fluorescence spectroscopy. In this study, we quantified absorption and excitation-emission matrix (EEM) spectra in the formation of aqueous BrCs, which was generated from HA-Gly and HA-Gly-AS mixtures, respectively. The obtained data was used to determine the base-10 absorption coefficient (), absorption Angstrom exponent (AAE), and effective quantum yield (QY). All of the related parameters provide further evidence for the formation of aqueous BrC. The absorbances of the as-obtained BrCs follow the order HA-Gly-AS > HA-Gly > HA-AS. In other words, HA-Gly-AS mixtures displayed the most intense absorbances, whereas HA-AS mixtures barely produced visible absorbance. It is reasonable to speculate that Gly promotes the formation of HA-Gly BrC mixtures. The experimental results are consistent with previous measurements reported by Powelson et al. BrCs from HA-Gly-AS and HA-Gly exhibit stronger fluorescence between 300 and 400 nm. Glycine plays a more important role in the formation of aqueous BrC than that of AS. Furthermore, we examined the mass absorption coefficient (MAC) by photolysis of aqueous BrCs, which resulted from the oxidation of HA-Gly and HA-Gly-AS mixtures by 5 mM H2O2. An effective photolysis time induced significant changes near-UV (300-400 nm) absorption intensity of HA-Gly and HA-Gly-AS mixtures. These results emphasize the dynamic nature of the corresponding atmospheric aqueous BrC. Overall, our study provides the optical properties of the corresponding atmospheric aqueous BrC and the H2O2 oxidation photolysis process of the as-obtained BrC in detail, which may contribute to the understanding of the important effects of aqueous BrC for atmospheric chemistry and climate.
机译：由于它们对地球气候的影响，由于其对地球气候的影响而增加，对大气棕色碳（BRC）气溶胶的增加。通过羟基丙酮（HA）与氮化合物如甘氨酸（Gly）和/或硫酸铵（AS），通过羟基丙酮（HA）的水性反应形成含水BRC气溶胶。当暴露于氮化合物几天时，HA作为一种含水羰基化合物的类型，在蓝色可见和近紫外区域中被吸收和荧光，其被UV / VI和荧光光谱监测。在该研究中，我们在形成含水BRC的形成中量化和激发 - 发射基质（EEM）光谱，其分别由HA-GLY和HA-GLY-作为混合物产生。所获得的数据用于确定碱基-10吸收系数（），吸收埃克斯特罗姆（AAE）和有效量子产率（QY）。所有相关参数都提供了进一步的表现，用于形成含水BRC。所获得的BRC的吸光度遵循大序Ha-Gly-As> Ha-gly> Ha-as。换句话说，HA-GLY-作为混合物显示出最强烈的吸光度，而HA-随着混合物几乎没有产生可见光吸光度。推测Gly促进Ha-Gly Brec混合物的形成是合理的。实验结果与Powelson等人报告的先前测量一致。来自HA-GLY-AS和HA-GLY的BRC在300至400nm之间表现出更强的荧光。甘氨酸在含水BRC的形成中起着更重要的作用。此外，我们通过光解的水性BRC来检查容量吸收系数（MAC），其由Ha-Gly和Ha-Gly-作为混合物的氧化产生5mM H 2 O 2。有效的光解时间诱导了Ha-Gly和Ha-Gly-作为混合物的UV（300-400nm）吸收强度的显着变化。这些结果强调了相应的大气水溶液的动态性质。总体而言，我们的研究提供了相应的大气水溶液和H2O2氧化光解过程的光学性质，详细促进了如此获得的BRC的H2O2氧化光解过程，这可能有助于了解含水BRC水性化学和气候的重要作用。

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  • 来源
    《RSC Advances》 |2018年第37期|共7页
  • 作者

    Gao Yan; Zhang Yunhong;

  • 作者单位

    Beijing Inst Technol Sch Chem &

    Chem Engn Beijing 100081 Peoples R China;

    Beijing Inst Technol Sch Chem &

    Chem Engn Beijing 100081 Peoples R China;

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  • 正文语种 eng
  • 中图分类 化学;
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