Zhang Yuxin, Xie Changwei, Wu Tonghua, Zhao Lin, Pang Qiangqiang, Wu Jichun, Yang Guiqian, Wang Wu, Zhu Xiaofan, Wu Xiaodong, Li Ren
Cryosphere Research Station on the Qinghai-Tibet Plateau, State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resource, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Cryosphere Research Station on the Qinghai-Tibet Plateau, State Key Laboratory of Cryospheric Science, Northwest Institute of Eco-Environment and Resource, Chinese Academy of Sciences, Lanzhou, Gansu 730000, China.
Sci Total Environ. 2022 Sep 10;838(Pt 2):156045. doi: 10.1016/j.scitotenv.2022.156045. Epub 2022 May 18.
Lakes on the Qinghai-Tibet Plateau (QTP) have notably expanded over the past 20 years. Due to lake water level rise and lake area expansion, the permafrost surrounding these lakes is increasingly becoming submerged by lake water. However, the change process of submerged permafrost remains unclear, which is not conducive to further analyzing the environmental effects of permafrost change. Yanhu Lake, a tectonic lake on the QTP, has experienced significant expansion and water level rise. Field measurement results indicate that the water level of Yanhu Lake increased by 2.87 m per year on average from 2016 to 2019. Cold permafrost, developed in the lake basin, was partially submerged by lake water at the end of 2017. Based on the water level change and permafrost thermal regime, a numerical heat conduction permafrost model was employed to predict future changes in permafrost beneath the lake bottom. The simulated results indicate that the submerged permafrost would continuously degrade because of the significant thermal impact of lake water. By 2100, the maximum talik thicknesses could reach approximately 7, 12, 16, and 19 m under lake-bottom temperatures of +2.0, +4.0, +6.0, and +8.0 °C, respectively. Approximately 291 years would be required to completely melt 47 m of submerged permafrost under the lake-bottom temperature of +4 °C. Note that the permafrost table begins to melt earlier than does the permafrost base, and the decline in the permafrost table occurs relatively fast at first, but then the process is attenuated, after which the permafrost table again rapidly declines. Compared to climate warming, the degradation of the submerged permafrost beneath the lake bottom occurred more rapidly and notably.
在过去20年里，青藏高原的湖泊显著扩张。由于湖水水位上升和湖泊面积扩大，这些湖泊周边的永久冻土越来越多地被湖水淹没。然而，被淹没永久冻土的变化过程仍不清楚，这不利于进一步分析永久冻土变化的环境影响。盐湖是青藏高原上的一个构造湖，经历了显著的扩张和水位上升。实地测量结果表明，2016年至2019年期间，盐湖的水位平均每年上升2.87米。湖盆中发育的寒冷永久冻土在2017年底部分被湖水淹没。基于水位变化和永久冻土热状态，采用数值热传导永久冻土模型预测湖底以下永久冻土的未来变化。模拟结果表明，由于湖水的显著热影响，被淹没的永久冻土将持续退化。到2100年，在湖底温度分别为+2.0、+4.0、+6.0和+8.0°C的情况下，最大融区厚度可能分别达到约7米、12米、16米和19米。在湖底温度为+4°C的情况下，完全融化47米被淹没的永久冻土大约需要291年。需要注意的是，永久冻土上限比永久冻土底部更早开始融化，永久冻土上限的下降起初相对较快，但随后过程会减弱，之后永久冻土上限再次迅速下降。与气候变暖相比，湖底以下被淹没永久冻土的退化发生得更快、更显著。
