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Absence of ice-bonded permafrost beneath an Arctic lagoon revealed by electrical geophysics.

ABSTRACT: Relict permafrost is ubiquitous throughout the Arctic coastal shelf, but little is known about it near shore. The presence and thawing of subsea permafrost are vital information because permafrost stores an atmosphere's worth of carbon and protects against coastal erosion. Through electrical resistivity imaging across a lagoon on the Alaska Beaufort Sea coast in summer, we found that the subsurface is not ice-bonded down to ~20 m continually from within the lagoon, across the beach, and underneath an ice-wedge polygon on the tundra. This contrasts with the broadly held idea of a gently sloping ice-bonded permafrost table extending from land to offshore. The extensive unfrozen zone is a marine talik connected to on-land cryopeg. This zone is a potential source and conduit for water and dissolved organic matter, is vulnerable to physical degradation, and is liable to changes in biogeochemical processes that affect carbon cycling and climate feedbacks.

SUBMITTER: Pedrazas MN

PROVIDER: S-EPMC7608830 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature

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Absence of ice-bonded permafrost beneath an Arctic lagoon revealed by electrical geophysics.

Pedrazas Micaela N MN Cardenas M Bayani MB Demir Cansu C Watson Jeffery A JA Connolly Craig T CT McClelland James W JW

Science advances 20201023 43

Relict permafrost is ubiquitous throughout the Arctic coastal shelf, but little is known about it near shore. The presence and thawing of subsea permafrost are vital information because permafrost stores an atmosphere's worth of carbon and protects against coastal erosion. Through electrical resistivity imaging across a lagoon on the Alaska Beaufort Sea coast in summer, we found that the subsurface is not ice-bonded down to ~20 m continually from within the lagoon, across the beach, and undernea ...[more]

PMID: 33097537

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Project description:Significant progress is being made in the development of the next generation of low cost life detection instrumentation with much smaller size, mass and energy requirements. Here, we describe in situ life detection and sequencing in the field in soils over laying ice wedges in polygonal permafrost terrain on Axel Heiberg Island, located in the Canadian high Arctic (79°26'N), an analog to the polygonal permafrost terrain observed on Mars. The life detection methods used here include (1) the cryo-iPlate for culturing microorganisms using diffusion of in situ nutrients into semi-solid media (2) a Microbial Activity Microassay (MAM) plate (BIOLOG Ecoplate) for detecting viable extant microorganisms through a colourimetric assay, and (3) the Oxford Nanopore MinION for nucleic acid detection and sequencing of environmental samples and the products of MAM plate and cryo-iPlate. We obtained 39 microbial isolates using the cryo-iPlate, which included several putatively novel strains based on the 16S rRNA gene, including a Pedobacter sp. (96% closest similarity in GenBank) which we partially genome sequenced using the MinION. The MAM plate successfully identified an active community capable of L-serine metabolism, which was used for metagenomic sequencing with the MinION to identify the active and enriched community. A metagenome on environmental ice wedge soil samples was completed, with base calling and uplink/downlink carried out via satellite internet. Validation of MinION sequencing using the Illumina MiSeq platform was consistent with the results obtained with the MinION. The instrumentation and technology utilized here is pre-existing, low cost, low mass, low volume, and offers the prospect of equipping micro-rovers and micro-penetrators with aggressive astrobiological capabilities. Since potentially habitable astrobiology targets have been identified (RSLs on Mars, near subsurface water ice on Mars, the plumes and oceans of Europa and Enceladus), future astrobiology missions will certainly target these areas and there is a need for direct life detection instrumentation.

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Absence of ice-bonded permafrost beneath an Arctic lagoon revealed by electrical geophysics.

Publications

Absence of ice-bonded permafrost beneath an Arctic lagoon revealed by electrical geophysics.

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