Explicit modeling of volatile organic compounds partitioning in the atmospheric aqueous phase
Explicit modeling of volatile organic compounds partitioning in the atmospheric aqueous phase
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DOI：
10.5194/acp-13-1023-2013
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发表时间：
2012-09
影响因子：
6.3
通讯作者：
C. Mouchel-Vallon;P. Bräuer;M. Camredon;R. Valorso;S. Madronich;H. Herrmann;B. Aumont
中科院分区：
文献类型：
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作者：
C. Mouchel-Vallon;P. Bräuer;M. Camredon;R. Valorso;S. Madronich;H. Herrmann;B. Aumont
抽象的。有机物的气相氧化是一个涉及大量二次化合物的多世代过程。大多数次生有机物种是水溶性的多官能团含氧分子。完全显式化学机理Gecko-A(大气中有机物显式化学和动力学产生器)被用来描述有机物在气相中的氧化和它们向水相的传质。研究了在不同NOx条件下，大气中三种碳氢化合物(异戊二烯、辛烷和α-蒎烯)的氧化反应。模拟的氧化轨迹是在一个由平均氧化态和溶解度定义的新的二维空间中检验的。在潮解气溶胶的典型水分含量下，发现溶解有机物的量非常低(按碳原子计算，产率不到2%)。对于云水含量，在低NOx条件下，脱除母体烃后，水相中碳原子的比例为50%(异戊二烯氧化)~70%(辛烷氧化)。对于高NOx条件，在异戊二烯氧化情况下，这一比例仅为5%，但在α-蒎烯和辛烷氧化情况下，这一比例仍然很大(分别为40%和60%)。尽管该模型还不包括水相中的化学反应，但这些溶解的有机物中的大部分应该在云滴中处理，并修改氧化速率和有机物种的形态。
Abstract. The gas phase oxidation of organic species is a multigenerational process involving a large number of secondary compounds. Most secondary organic species are water-soluble multifunctional oxygenated molecules. The fully explicit chemical mechanism GECKO-A (Generator of Explicit Chemistry and Kinetics of Organics in the Atmosphere) is used to describe the oxidation of organics in the gas phase and their mass transfer to the aqueous phase. The oxidation of three hydrocarbons of atmospheric interest (isoprene, octane and α-pinene) is investigated for various NO x conditions. The simulated oxidative trajectories are examined in a new two dimensional space defined by the mean oxidation state and the solubility. The amount of dissolved organic matter was found to be very low (yield less than 2% on carbon atom basis) under a water content typical of deliquescent aerosols. For cloud water content, 50% (isoprene oxidation) to 70% (octane oxidation) of the carbon atoms are found in the aqueous phase after the removal of the parent hydrocarbons for low NO x conditions. For high NO x conditions, this ratio is only 5% in the isoprene oxidation case, but remains large for α-pinene and octane oxidation cases (40% and 60%, respectively). Although the model does not yet include chemical reactions in the aqueous phase, much of this dissolved organic matter should be processed in cloud drops and modify both oxidation rates and the speciation of organic species.