CHEMISTRY OF OH IN REMOTE CLOUDS AND ITS ROLE IN THE PRODUCTION OF FORMIC-ACID AND PEROXYMONOSULFATE
CHEMISTRY OF OH IN REMOTE CLOUDS AND ITS ROLE IN THE PRODUCTION OF FORMIC-ACID AND PEROXYMONOSULFATE
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DOI：
10.1029/jd091id09p09807
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发表时间：
1986-08-20
影响因子：
4.4
通讯作者：
JACOB, DJ
中科院分区：
文献类型：
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作者：
JACOB, DJ
用气相和水相耦合的化学模型研究了远距离非降水热带云中OH的化学性质。该模型考虑了短寿命水相物质浓度的径向依赖性，特别是O3（aq）和OH（aq）。自由基OH（aq）通过水相反应O2−+ o3和H2O2+hν快速生成，主要通过H2C(OH)2、H2O2和HCOO−氧化去除。氢氧根的气滴转移必须建模为可逆过程，也就是说，不能假设液滴是扩散受限的氢氧根(g)汇。液滴表面和内部存在很强的OH（aq）浓度梯度。OH的浓度（aq）强烈依赖于ph值，但仅弱依赖于黏附系数、液滴半径或云的液态水含量。甲酸是通过水相反应H2C(OH)2+ OH快速生成的，但HCOO−又被OH（aq）快速氧化。云中的HCOOH浓度与云水的ph值密切相关；ph值大于5的云不是有效的HCOOH源。提出了一种OH（aq）氧化S（IV）的新机理。预测主要产物为HSO5−（过氧单硫酸盐）。过氧单硫酸盐在遥远的云中似乎是稳定的，可能占云水总硫的很大一部分。
The chemistry of OH in a remote nonprecipitating tropical cloud is studied with a coupled gas‐phase and aqueous‐phase chemical model. The model takes into account the radial dependence of the concentrations of short‐lived aqueous‐phase species, in particular O3(aq) and OH(aq). The radical OH(aq) is produced rapidly by the aqueous‐phase reactions O2−+ O3and H2O2+hν and is removed primarily by oxidation of H2C(OH)2, H2O2, and HCOO−. Gas‐droplet transfer of OH must be modeled as a reversible process, that is, the droplets cannot be assumed to be diffusion‐limited OH(g) sinks. A strong OH(aq) concentration gradient exists between the surface and the interior of the droplets. The concentration of OH(aq) is strongly dependent onpH but is only weakly dependent on the sticking coefficient, the droplet radius, or the liquid water content of the cloud. Formic acid is rapidly produced by the aqueous‐phase reaction H2C(OH)2+ OH, but HCOO−is in turn rapidly oxidized by OH(aq). The HCOOH concentration in cloud is shown to be strongly dependent on cloud waterpH; clouds withpH greater than 5 are not efficient HCOOH sources. A novel mechanism is proposed for the oxidation of S(IV) by OH(aq). The main product is predicted to be HSO5−(peroxymonosulfate). Peroxymonosulfate appears to be stable in remote clouds and could contribute a large fraction of total cloud water sulfur.