Radical‐initiated formation of organosulfates and surfactants in atmospheric aerosols
Radical‐initiated formation of organosulfates and surfactants in atmospheric aerosols
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DOI：
10.1029/2009gl041683
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发表时间：
2010-03
影响因子：
5.2
通讯作者：
B. Nozière;S. Ekström;T. Alsberg;S. Holmström
中科院分区：
文献类型：
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作者：
B. Nozière;S. Ekström;T. Alsberg;S. Holmström
许多大气气溶胶含有有机化合物和无机物质，例如硫酸盐。在这项工作中，我们表明，这些硫酸盐可以通过在暴露于紫外线（280-320 nm）时产生硫酸根SO 4 −来引发有机化合物的一些化学转化。特别是，我们通过质谱（LC/ESI-MSMS）表明，异戊二烯，甲基乙烯基酮，甲基丙烯醛和α-蒎烯在辐照硫酸盐溶液（硫酸铵和硫酸钠）中产生与以前在气溶胶中确定的相同的有机硫酸盐，甚至一些至今仍未确定。由于典型的时间常数为9小时，而不是4600天的分解，这些自由基反应将是大气中有机硫酸盐的合理来源。这些反应也产生了有效的表面活性剂，可能类似于实验中发现的长链有机硫酸盐。因此，混合硫酸盐/有机气溶胶中的光化学作用可能会增加云凝结核（CCN）的数量，这一点得到了之前大气观测的支持。
Many atmospheric aerosols contain both organic compounds and inorganic material, such as sulfate salts. In this work, we show that these sulfates could trigger some chemical transformations of the organic compounds by producing sulfate radicals, SO4−, when exposed to UV light (280–320 nm). In particular, we show by mass spectrometry (LC/ESI‐MSMS) that isoprene, methyl vinyl ketone, methacrolein, and α‐pinene in irradiated sulfate solutions (ammonium and sodium sulfate) produce the same organosulfates as previously identified in aerosols, and even some that had remained unidentified until now. With a typical time constant of 9 h instead of 4600 days for esterifications, these radical reactions would be a plausible origin for the atmospheric organosulfates. These reactions also produced efficient surfactants, possibly resembling the long‐chain organosulfates found in the experiments. Thus, photochemistry in mixed sulfate/organic aerosols could increase cloud condensation nuclei (CCN) numbers, which would be supported by previous atmospheric observations.