Electrical Resistivity Imaging Reveals Thawed Substrate Beneath and Across an Entire Arctic Lagoon within Continuous Permafrost
Abstract
Rapid warming's concomitant changes to Arctic coastal environments are incompletely documented and seldom monitored, particularly relating to the degradation of subsea permafrost. Permafrost degradation accelerates coastal erosion and releases formerly frozen and trapped stores of organic carbon, which directly impact local communities and ecosystems and constitute a positive feedback to Arctic warming. Yet the depth and extent of subsea permafrost is still unknown, making it challenging to determine its role in the exchange of water and nutrients with lagoon waters as well as its degradation. Electrical resistivity imaging (ERI) is a promising but largely untested method for acquiring this information. Here we tested ERI by using boat-towed floating electrodes, fixed submerged, and on-land electrodes within a shallow lagoon system in northeastern Alaska to detect and map coastal subsea permafrost. We interpreted the observations through synthetic forward modeling. The analyses show that the lagoon substrate is ice-free down to the full depth of the profiles − 7.5 m in the lagoon and 18 m along and across the shoreline. This coastal talik or thaw bulb suggests that the beach and lagoon substrate are an active component of the Arctic coastal system and that the exchange of water and released nutrients and organic matter from sediments are significant for the biogeochemistry of the lagoons.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.C13E1384P
- Keywords:
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- 0702 Permafrost;
- CRYOSPHERE;
- 0708 Thermokarst;
- CRYOSPHERE;
- 0768 Thermal regime;
- CRYOSPHERE;
- 0774 Dynamics;
- CRYOSPHERE