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

长竖井内的真实尺度云实验——二氧化硫氧化过程的研究

基本信息

批准号：
08680564
负责人：
FUKUYAMA Tsutomu
金额：
$ 1.66万
依托单位：
National Institute for Environmental Studies
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

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

在岩手县龟石矿430m长的竖井中，利用竖井顶部放置的电风扇，将湿上升气流提升约1m/S，形成人工云，并进行了以下实验：1.为了研究二氧化硫在云滴中的溶解和随后的氧化，将这些气体排放到竖井底部的气流中。然后利用升降机，通过多级冲击器分别对云滴和气溶胶颗粒进行采样。二氧化硫也被碳酸钠浸渍的过滤器收集。用浸渍甲醛的滤纸作为冲击器的收集介质来抑制亚硫酸的氧化，使人们能够分别定量S(IV)和S(VI)。主要结果有：(1)紧靠云底上方。发现液滴中的S(IV)已经与气相二氧化硫达到平衡。这意味着…的雨停了更多的二氧化硫是一个快速的过程，(2)雾滴中S(VI)/S(IV)的浓度比在上升气流期间几乎保持不变。结果表明，二氧化硫与溶解氧的热氧化反应是缓慢的。云化学的一个显著特征是反应中心(即液滴)的出现和消失。因此，了解液滴的形成过程是至关重要的。意外的是，在这个项目的第二年，电梯的停机让人无法追踪云中的反应。在这种情况下。研究的重点转向云滴的形成和增长。利用激光测距装置对云底高度进行了观测，发现云底高度分别在100m和10s的空间尺度和时间尺度上波动。在竖井底部雾化无机盐的水溶液，如氯化钠和氯化锂。结果表明，液滴的数量和浓度明显增加，液滴的大小发生了膨胀。然而，粒度分布的模式保持不变。研究还发现，从雾化开始到浓度开始增加的时间取决于液滴的大小，并根据这种关系估计液滴的生长速度。较少