Real Scale Cloud Experiments in a Long Vertical Shaft -A Study on the Oxidation Process of Sulfur Dioxide

在岩手县釜石矿430米长的竖井中，利用设置在竖井顶部的电风扇，以约1米/秒的速度产生潮湿的上升气流，形成人工云，并进行了以下实验：1.为了研究二氧化硫溶解成云滴和随后的氧化，将这种气体排放到竖井底部的空气流中。然后利用升降机，通过多级撞击器分别对云滴和气溶胶粒子进行采样。二氧化硫也被碳酸钠浸渍的过滤器收集。作为收集介质的冲击器，用甲醛浸渍的滤纸被用来抑制氧化的亚硫酸，这个程序使一个量化S（IV）和S（VI）分别。主要结果有：（1）云底正上方;液滴中的S（IV）被发现已经与气相二氧化硫平衡。这意味着， 关于我们 （2）在上升气流中，液滴中S（VI）/S（IV）的浓度比基本保持不变。结果表明，SO2被溶解氧热氧化的反应是缓慢的，云化学的一个显著特征是反应点（即液滴）的出现和消失是不确定的。因此，了解液滴的形成过程至关重要。意外的是，在这个项目的第二年，电梯的停止使得无法追踪云中的反应。在这种情况下。这项研究的重点是云滴的形成和增长。沿着这条路线，获得了以下结果：2.利用激光测距仪对云底高度进行了观测，发现云底高度在100 m和10 s的空间尺度和时间尺度上有波动.无机盐如氯化钠和氯化锂的水溶液在竖井底部雾化。结果，观察到液滴的数量浓度显著增加，并且发现它们的尺寸膨胀。然而，尺寸分布的模式保持不变。有人还发现，雾化的开始和浓度增加的发病之间的时间依赖于液滴的大小，和液滴的增长速率估计从这种依赖性。少

In a 430m-long vertical shaft of Kamaishi Mine, Iwate Prefecture, artificial clouds were formed by raising a humid updraft of about 1m/s using an electric fan placed at the top of the shaft, and the following experiments were carried out :1. In order to investigate the dissolution of sulfur dioxide into cloud droplets and subsequent oxidation, this gas was emitted into the air stream at the bottom of the shaft. Then by utilizing an elevator, cloud droplets and aerosol particles were separately sampled through multistage impactors. Sulfur dioxide was also collected by sodium carbonate impregnated filters. As the collection media for the impactor, filter paper impregnated with formaldehyde was used to suppress the oxidation of sulfurous acid ; this procedure enabled one to quantify S (IV) and S (VI) separately. Main results are (1) Immediately above the cloud base. S (IV) in droplets was found to be already in equilibrium with the gas-phase sulfur dioxide. This implies that the rainout o … More f sulfur dioxide is a rapid process, and (2) The concentration ratio S (VI)/S (IV) in droplets stayed almost constant through the updraft. From this result it is concluded that the thermal oxidation reaction of sulfur dioxide by dissolved oxygen is slow.A distinct feature of cloud chemistry is that the reaction sites (i.e droplets) are appearing and disappearing elusively. Therefore it is essential to understand the droplet formation processes. Accidentally, in the second year of this project, the stoppage of the elevator made it impossible to trace the in-cloud reactions. In these circumstances. the study was turned to focus on the formation and growth of cloud droplets. Along this line, the following results were obtained :2. By means of a laser ranging device, the cloud base height was observed, and it was found to fluctuate with the spacial and temporal scales of 100m and 10s, respectively.3. Aqueous solutions of inorganic salts such as sodium chloride and lithium chloride were atomized at the bottom of the shaft. As a result, conspicuous increase was observed in the number concentration of droplets and their sizes were found to be inflated. However, the mode of the size distribution remained constant. It was also found that the time between the start of the atomization and the onset of the concentration increase depended on the droplet size, and the droplet growth rate was estimated from this dependence. Less