Real Scale Experiment of Pollution and Modification of Cloud by using a Vertical Shaft.

1999 Fiscal Year Final Research Report Summary

• Project/Area Number: 09450195
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Civil and environmental engineering
• Research Institution: Hokkaido University
• Principal Investigator: OHTA Sachio Hokkaido Univ., Grad. School of Eng. Pro., 大学院・工学研究科, 教授 (00100058)
• Co-Investigator(Kenkyū-buntansha): FUKUYAMA Tsutomu Natl. Inst. Envi. Sci., Head of Lab., 大気圏環境部, 室長(研究職) (90011642) ; YAMAGATA Sadsamu Hokkaido Univ., Grad. School of Eng., Inst., 大学院・工学研究科, 助手 (80220242) ; MURAO Naoto Hokkaido Univ., Grad. School of Eng., Asso. Pro., 大学院・工学研究科, 助教授 (00190869) ; UTIYAMA Masahiro Natl. Inst. Envir. Sci., Chief. Scientist, 大気圏環境部, 主任研究員 (20160294)
• Project Period (FY): 1997 – 1999
• Keywords: vertical shaft / cloud pollution / cloud modification / acidification to sulfate / cloud condensation nuclei / droplet size distribution / generation of particles / mineral particles

Research Abstract

The process of sulfur dioxide dissolution into cloud droplets and its successive oxidation to sulfate were studied in an artificial cloud experimental system in a vertical shaft in Kamaishi mining company, Iwate prefecture. Sulfur compounds in droplets, aerosols and gas were collected by serial samplers at several heights. The concentrations of sulfur compounds at each height indicate that the released sulfur dioxide at the bottom of the shaft was absorbed by cloud droplets, but the oxidation rate to sulfate was slow which may be due to the absence of light and oxidants in the shaft.
Sodium chloride and sodium hydrogensulfite particles were generated by humifier and injected into the base of shaft. Modal diameter of the particles is 0.1〜0.5μm. Without the particle injection, modal diameter of cloud droplets was 7 μm. With the particle injection, modal diameter of cloud droplets did not change, but the size distribution widened out to larger diameter.
By using eletron microscope with X ray analyzer, we found that more than 50 % of the droplets, which arrived at top of the shaft, contained chemical species of the injected particles. But, the other particles cintained calsium carbonate. It shows that calsium carbonate particles or mineral particles coated with calsium carbonate on the surface may act as condensation nuclei in the atmosphere.

Research Products

• [Publications] Yamagata, S., Baba, S., Murao, N., Ohta, S, Fukuyama, T., Utiyama. M., Yamada, T., Fujiyoshi. Y., Harimaya, T. and Inage, M.: "Real scale experiment of sulfur dioxide dissolution into cloud droplets generated in artificial cloud experimental system (ACE)."Journal of Global Environment Engineering. Vol.4. 53-63 (1998)
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