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Detecting unfrozen sediments below thermokarst lakes with surface nuclear magnetic resonance

Geophysical Research Letters

By:
, , , , , , ,
DOI: 10.1002/grl.50137

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Abstract

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.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Detecting unfrozen sediments below thermokarst lakes with surface nuclear magnetic resonance
Series title:
Geophysical Research Letters
DOI:
10.1002/grl.50137
Volume
40
Issue:
3
Year Published:
2013
Language:
English
Publisher:
AGU
Publisher location:
Washington, D.C.
Contributing office(s):
Alaska Science Center
Description:
6 p.
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
535
Last page:
540