カメルーン・ニオス湖ガス災害と地球化学  [in Japanese] Geochemistry of the1986 Lake Nyos gas disaster, Cameroon  [in Japanese]

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Abstract

The sudden release of carbon dioxide gas (CO<sub>2</sub>) from Lake Nyos in 1986 resulted in the loss of 1,746 lives. A similar event killed 37 people at Lake Monoun in 1984. Geochemistry of these gassy lakes in Cameroon has shown that carbon dioxide gas was accumulated in the deep layer of the lakes prior to the gas explosion. Carbon and helium isotopic ratios of dissolved gases indicate that the carbon dioxide was of mantle origin and carried up to the earth's surface by basaltic volcanism. Follow up geochemical surveys since the 1986 disaster suggested that CO<sub>2</sub> leaked into the lakes in the form of CO<sub>2</sub>-rich spring and that CO<sub>2</sub> concentration in the lakes is returning to dangerous levels. Thus, the sudden release of gas from these lakes may be repeated. The situation at Nyos and Monoun is unique in that we can make these potentially dangerous lakes safe by artificial removal of the dissolved gases. It can be stressed that the geochemistry of these lakes has given a basis for the degassing operation. Supported by the U. S. Office of Foreign Disaster Assistance (USAID-OFDA), a 203 m long degassing pipe was set up at Lake Nyos in January 2001. The degassing is based on a self-sustaining gas lift principle. With this apparatus, the dissolved gas is currently being removed at a rate approximately 9 times greater than the natural recharge at the bottom of the lake. More degassing systems need to be installed at Lakes Nyos and Monoun to make them safe in a reasonable period of time. Our efforts to this end are discussed briefly.

Journal

  • Chikyukagaku

    Chikyukagaku 36(3), 137-147, 2002

    The Geochemical Society of Japan

References:  32

Cited by:  1

Codes

  • NII Article ID (NAID)
    110008680041
  • NII NACSIS-CAT ID (NCID)
    AN00141280
  • Text Lang
    JPN
  • Article Type
    Journal Article
  • ISSN
    0386-4073
  • NDL Article ID
    6264001
  • NDL Source Classification
    ZM41(科学技術--地球科学)
  • NDL Call No.
    Z15-645
  • Data Source
    CJP  CJPref  NDL  NII-ELS  J-STAGE 
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