OH-Initiated Heterogeneous Aging of Highly Oxidized Organic Aerosol
OH-Initiated Heterogeneous Aging of Highly Oxidized Organic Aerosol
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DOI：
10.1021/jp212131m
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发表时间：
2012-06-21
影响因子：
2.9
通讯作者：
Kroll, Jesse H.
中科院分区：
文献类型：
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作者：
Kessler, Sean H.;Nah, Theodora;Kroll, Jesse H.
大气中有机物的氧化演化（“老化”）被认为对有机颗粒物的组成和性质有重大影响，但人们对此仍知之甚少，特别是对于气溶胶中氧化程度最高的部分。在这里，我们测量了高度氧化的有机气溶胶的非均相氧化的动力学和产物，目的是更好地限制这种大气老化过程。由模型氧化有机物（1,2,3,4-丁烷四甲酸 (C8H10O8)、柠檬酸 (C6H8O7)、酒石酸 (C4H6O6) 和 Suwannee River 黄腐酸）组成的亚微米颗粒在流动反应器中被气相 OH 氧化，并根据 OH 暴露情况监测颗粒的质量和元素组成。与我们之前对氧化较少的模型系统（角鲨烷、赤藓糖醇和左旋葡聚糖）的研究相比，颗粒质量并没有因非均相氧化而显着减少。气溶胶的碳含量总是有所下降，但这种质量损失大致通过氧含量的增加来平衡。估计反应的反应吸收系数范围为 0.37 至 0.51，表明此类转化发生的速率相当于在大气中 1-2 周，表明它们在有机颗粒物的大气生命周期中的重要性。
The oxidative evolution ("aging") of organic species in the atmosphere is thought to have a major influence on the composition and properties of organic particulate matter but remains poorly understood, particularly for the most oxidized fraction of the aerosol. Here we measure the kinetics and products of the heterogeneous oxidation of highly oxidized organic aerosol, with an aim of better constraining such atmospheric aging processes. Submicrometer particles composed of model oxidized organics-1,2,3,4-butanetetracarboxylic acid (C8H10O8), citric acid (C6H8O7), tartaric acid (C4H6O6), and Suwannee River fulvic acid-were oxidized by gas-phase OH in a flow reactor, and the masses and elemental composition of the particles were monitored as a function of OH exposure. In contrast to our previous studies of less-oxidized model systems (squalane, erythritol, and levoglucosan), particle mass did not decrease significantly with heterogeneous oxidation. Carbon content of the aerosol always decreased somewhat, but this mass loss was approximately balanced by an increase in oxygen content. The estimated reactive uptake coefficients of the reactions range from 0.37 to 0.51 and indicate that such transformations occur at rates corresponding to 1-2 weeks in the atmosphere, suggesting their importance in the atmospheric lifecycle of organic particulate matter.