Detecting unfrozen sediments below thermokarst lakes with surface nuclear magnetic resonance
Detecting unfrozen sediments below thermokarst lakes with surface nuclear magnetic resonance
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DOI：
10.1002/grl.50137
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发表时间：
2013-02
影响因子：
5.2
通讯作者：
A. Parsekian;G. Grosse;J. Walbrecker;M. Müller‐Petke;K. Keating;Lin Liu;B. Jones;R. Knight
中科院分区：
文献类型：
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作者：
A. Parsekian;G. Grosse;J. Walbrecker;M. Müller‐Petke;K. Keating;Lin Liu;B. Jones;R. Knight
冻土层是由于热、水文或水化学条件的异常而出现在永久冻土中的一层或一团未冻结的地面。有关talik几何信息是重要的了解区域地表水和地下水的相互作用，以及湖底甲烷生产热岩溶湖泊。由于可以直接测量未冻水含量，地面核磁共振（NMR）是一种很有前途的非侵入性估算地层厚度的地球物理方法。我们对阿拉斯加州费尔班克斯附近的热岩溶湖泊和陆地永久冻土进行了表面核磁共振测量，并使用有限的直接测量证实了我们的结果。在一个8米深的湖泊，我们观察到解冻球至少22米以下的表面;在一个1.4米深的湖泊，我们检测到一个talik延伸5和6米以下的表面。我们的研究表明，表面核磁共振可能在冻土层的热岩溶湖泊水文学及其在碳循环中的相关作用的研究的价值。
A talik is a layer or body of unfrozen ground that occurs in permafrost due to an anomaly in thermal, hydrological, or hydrochemical conditions. Information about talik geometry is important for understanding regional surface water and groundwater interactions as well as sublacustrine methane production in thermokarst lakes. Due to the direct measurement of unfrozen water content, surface nuclear magnetic resonance (NMR) is a promising geophysical method for noninvasively estimating talik dimensions. We made surface NMR measurements on thermokarst lakes and terrestrial permafrost near Fairbanks, Alaska, and confirmed our results using limited direct measurements. At an 8 m deep lake, we observed thaw bulb at least 22 m below the surface; at a 1.4 m deep lake, we detected a talik extending between 5 and 6 m below the surface. Our study demonstrates the value that surface NMR may have in the cryosphere for studies of thermokarst lake hydrology and their related role in the carbon cycle.