Water and sediment properties at Polar Fox Lagoon

As the Arctic coast erodes, it drains thermokarst lakes, transforming them into lagoons, and, eventually, integrates them into subsea permafrost. Lagoons represent the first stage of a thermokarst lake transition to a marine setting and possibly more saline and colder upper boundary conditions. In t...

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Bibliographic Details
Main Authors: Angelopoulos, Michael, Overduin, Pier Paul, Westermann, Sebastian, Tronicke, Jens, Strauss, Jens, Schirrmeister, Lutz, Biskaborn, Boris K, Maximov, Georgy M, Liebner, Susanne, Grigoriev, Mikhail N, Kitte, Axel, Grosse, Guido
Format: Other/Unknown Material
Language:English
Published: PANGAEA 2019
Subjects:
AWI_Envi
AWI_Perma
electrical resistivity
Permafrost
Permafrost Research
Polar Terrestrial Environmental Systems @ AWI
sediment
submarine
subsea
Temperature
Ice
permafrost
polar fox
Thermokarst
Tiksi
Tiksi Bay
Siberia
Online Access:https://doi.pangaea.de/10.1594/PANGAEA.907479
https://doi.org/10.1594/PANGAEA.907479
Description
Summary:As the Arctic coast erodes, it drains thermokarst lakes, transforming them into lagoons, and, eventually, integrates them into subsea permafrost. Lagoons represent the first stage of a thermokarst lake transition to a marine setting and possibly more saline and colder upper boundary conditions. In this research, borehole data, electrical resistivity surveying, and modeling of heat and salt diffusion were carried out at Polar Fox Lagoon on the Bykovsky Peninsula, Siberia. Polar Fox Lagoon is a seasonally isolated water body connected to Tiksi Bay through a channel, leading to hypersaline waters under the ice cover. The boreholes in the center of the lagoon revealed floating ice and a saline cryotic bed underlain by a saline cryotic talik, a thin ice‐bearing permafrost layer, and unfrozen ground. The bathymetry showed that most of the lagoon had bedfast ice in spring. In bedfast ice areas, the electrical resistivity profiles suggested that an unfrozen saline layer was underlain by a thick layer of refrozen talik. The modeling showed that thermokarst lake taliks can refreeze when submerged in saltwater with mean annual bottom water temperatures below or slightly above 0°C. This occurs, because the top‐down chemical degradation of newly formed ice‐bearing permafrost is slower than the refreezing of the talik. Hence, lagoons may precondition taliks with a layer of ice‐bearing permafrost before encroachment by the sea, and this frozen layer may act as a cap on gas migration out of the underlying talik.

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