Abstract An automatic observation buoy (AOB) was installed at Lake Nyos in March 2014. The temperature and electrical conductivity (EC) of lake water were continuously observed from March 10, 2014 to April 15, 2016. The thermocline and chemocline located deeper than −90 m subsided 15 m in the observation period due to the bottom water removal by the CO2 degassing pipes. The velocity of subsidence was estimated quantitatively by correlating the time variation of EC obtained by AOB and the depth profile of EC. The velocity of subsidence was not constant, namely, it was fast in dry season and slow in rainy season. The time variation in the velocity of subsidence can be attributed to the seasonal variation of water flux in the degassing pipes. Considering the water balance in the deep part of lake, the flux of ground water supplied to lake was estimated to be 6.5*106 (m3/year), which is comparable to the recharge rate of ground water within the catchment area surrounding Lake Nyos. Abrupt drops in temperature and conductivity were observed at −120 m in January 2016, when the temperature at -4 m reached 21.8 °C as the lowest value. The abrupt drops are due to the sinking of surface cold water.

中文翻译：

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自动观测浮标传输的尼奥斯湖水温和电导率

摘要 2014年3月在尼奥斯湖安装了自动观测浮标（AOB）。2014年3月10日至2016年4月15日连续观测湖水温度和电导率（EC）。温跃层和趋化层位于-由于CO2脱气管去除底部水，90 m在观察期内沉降了15 m。通过将 AOB 获得的 EC 的时间变化与 EC 的深度剖面相关联，定量估计下沉速度。沉降速度不是恒定的，即旱季快，雨季慢。沉降速度的时间变化可归因于脱气管中水通量的季节性变化。考虑到湖深部分的水平衡，估计供给湖泊的地下水通量为 6.5*106（m3/年），与尼奥斯湖周围集水区地下水的补给率相当。2016 年 1 月在-120 m 处观察到温度和电导率突然下降，当时-4 m 处的温度达到 21.8 °C，为最低值。突然下降是由于表面冷水下沉。