Chemical Transformations Involving Carbonyls and Carboxylic Acids Within Clouds

羰基化合物是臭氧的光化学前体 而羧酸是酸性的主要来源， 因此，部分控制pH依赖性转化， 大气中的水滴 尽管公认的重要性， 大气化学中的这些化合物， 不确定性存在的过程中，其地球化学 骑自行车 拟议的调查将提供第一个 同时进行的气相和水相（云）测量 羰基化合物和有机酸。 三 每个机构都将带来特定领域的专业知识， 对云中的化学变化进行详细研究 涉及这些化合物。 这次调查将使用 各种气象和汽相和水相化学 从仪表塔（海拔1014米）测量 位于弗吉尼亚州谢南多厄国家公园。 密集 将在一个月内进行实地取样， 1990年4月至5月，后来对数据进行了解释 借助最先进的云计算建模技术， 化学和物理过程。 羰基化合物和有机酸的同时观测 将检查大气氧化的证据， 羰基化合物转化为有机酸，特别关注云中 甲醛作为甲酸来源的水相氧化 酸 观察到的单个化合物的分馏 将比较气相和云水相之间的差异 达到热力学平衡时的预期值。 两个云 将收集液滴尺寸分数，这将记录 云水浓度的大小依赖性。 结果 这项调查将大大有助于我们 对决定化学品的重要过程的了解 对流层的组成。

Carbonyl compounds are photochemical precursors of ozone while carboxylic acids are major sources of acidity and therefore control in part pH dependent transformations in atmospheric droplets. Despite the recognized importance of these classes of compounds in atmospheric chemistry, much uncertainty exists concerning processes in their biogeochemical cycling. The proposed investigation will provide the first concurrent gas-phase and aqueous-phase (cloud) measurements of carbonyls and organic acids at a rural site. Three institutions, each bringing expertise in specific fields will perform a detailed study of in-cloud chemical transformations involving these compounds. This investigation will employ various meteorological and vapor- and aqueous-phase chemical measurements from an instrumented tower (1014 m elevation) situated in the Shenandoah National Park, Virginia. Intensive field sampling will be conducted over a one month period in April-May 1990, with later interpretation of the data facilitated by state-of-the-art computer modeling of in-cloud chemical and physical processes. The concurrent observations of carbonyls and organic acids will be examined for evidence of atmospheric oxidation of carbonyls to organic acids, with special focus on the in-cloud aqueous-phase oxidation of formaldehyde as a source of formic acid. The observed fractionations of individual compounds between the gas phase and the cloudwater phase will be compared to those expected from thermodynamic equilibrium. Two cloud droplet size fractions will be collected, which will document the size dependence of cloudwater concentrations. The results of this investigation will contribute substantially to our knowledge of important processes determining the chemical composition of the troposphere.