Kling George W, Evans William C, Tanyileke Greg, Kusakabe Minoru, Ohba Takeshi, Yoshida Yutaka, Hell Joseph V
Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.
Proc Natl Acad Sci U S A. 2005 Oct 4;102(40):14185-90. doi: 10.1073/pnas.0502274102. Epub 2005 Sep 26.
Since the catastrophic releases of CO(2) in the 1980s, Lakes Nyos and Monoun in Cameroon experienced CO(2) recharge at alarming rates of up to 80 mol/m(2) per yr. Total gas pressures reached 8.3 and 15.6 bar in Monoun (2003) and Nyos (2001), respectively, resulting in gas saturation levels up to 97%. These natural hazards are distinguished by the potential for mitigation to prevent future disasters. Controlled degassing was initiated at Nyos (2001) and Monoun (2003) amid speculation it could inadvertently destabilize the lakes and trigger another gas burst. Our measurements indicate that water column structure has not been compromised by the degassing and local stability is increasing in the zones of degassing. Furthermore, gas content has been reduced in the lakes approximately 12-14%. However, as gas is removed, the pressure at pipe inlets is reduced, and the removal rate will decrease over time. Based on 12 years of limnological measurements we developed a model of future removal rates and gas inventory, which predicts that in Monoun the current pipe will remove approximately 30% of the gas remaining before the natural gas recharge balances the removal rate. In Nyos the single pipe will remove approximately 25% of the gas remaining by 2015; this slow removal extends the present risk to local populations. More pipes and continued vigilance are required to reduce the risk of repeat disasters. Our model indicates that 75-99% of the gas remaining would be removed by 2010 with two pipes in Monoun and five pipes in Nyos, substantially reducing the risks.
自20世纪80年代发生灾难性的二氧化碳释放事件以来，喀麦隆的尼奥斯湖和莫诺恩湖经历了二氧化碳以高达每年80摩尔/平方米的惊人速度补给。2003年莫诺恩湖和2001年尼奥斯湖的总气压分别达到8.3巴和15.6巴，导致气体饱和度高达97%。这些自然灾害的特点是有可能通过缓解措施来预防未来的灾难。2001年在尼奥斯湖和2003年在莫诺恩湖开始了受控排气，当时有人猜测这可能会无意中破坏湖泊的稳定性并引发另一次气体喷发。我们的测量表明，水柱结构并未因排气而受到损害，排气区域的局部稳定性正在增强。此外，湖泊中的气体含量已减少了约12% - 14%。然而，随着气体被移除，管道入口处的压力降低，移除速率会随着时间下降。基于12年的湖沼学测量，我们建立了一个未来移除速率和气体存量的模型，该模型预测，在莫诺恩湖，当前的管道将移除天然气补给与移除速率平衡之前剩余气体的约30%。在尼奥斯湖，到2015年单根管道将移除剩余气体的约25%；这种缓慢的移除将当前对当地居民的风险延长了。需要更多的管道和持续的警惕来降低再次发生灾难的风险。我们的模型表明，在莫诺恩湖安装两根管道、在尼奥斯湖安装五根管道，到2010年将移除剩余气体的75% - 99%，从而大幅降低风险。
