Geochemical evidence for seabed fluid flow linked to the subsea permafrost outer border in the South Kara Sea
Driven by rising bottom water temperatures, the thawing of subsea permafrost leads to an increase in fluid flow intensity in shallow marine sediments and results in the emission of methane into the water column. Limiting the release of permafrost-related gas hydrates and permafrost- sequestered meth...
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Online Access: | https://hdl.handle.net/10037/18472 https://doi.org/10.1016/j.chemer.2019.04.005 |
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ftunivtroemsoe:oai:munin.uit.no:10037/18472 2023-05-15T14:26:58+02:00 Geochemical evidence for seabed fluid flow linked to the subsea permafrost outer border in the South Kara Sea Semenov, Petr Portnov, Aleksei D Krylov, Alexey Egorov, Alexander V Vanshtein, Boris 2019-04-16 https://hdl.handle.net/10037/18472 https://doi.org/10.1016/j.chemer.2019.04.005 eng eng Elsevier Chemie der Erde info:eu-repo/grantAgreement/RCN/SFF/223259/Norway/Centre for Arctic Gas Hydrate, Environment and Climate/CAGE/ Semenov, Portnov AD, Krylov A, Egorov AV, Vanshtein B. Geochemical evidence for seabed fluid flow linked to the subsea permafrost outer border in the South Kara Sea. Chemie der Erde. 2019 FRIDAID 1693578 doi:10.1016/j.chemer.2019.04.005 0009-2819 1611-5864 https://hdl.handle.net/10037/18472 openAccess VDP::Mathematics and natural science: 400::Geosciences: 450::Sedimentology: 456 VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Sedimentologi: 456 Journal article Tidsskriftartikkel Peer reviewed acceptedVersion 2019 ftunivtroemsoe https://doi.org/10.1016/j.chemer.2019.04.005 2021-06-25T17:56:47Z Driven by rising bottom water temperatures, the thawing of subsea permafrost leads to an increase in fluid flow intensity in shallow marine sediments and results in the emission of methane into the water column. Limiting the release of permafrost-related gas hydrates and permafrost- sequestered methane into the global carbon cycle are of primary importance to the prevention of future Arctic Ocean acidification. Previous studies in the South Kara Sea showed that abundant hydro-acoustic anomalies (gas flares) induced by seafloor gas discharge into the water column occur in water whose depth is ≥20 m. This distribution of gas flares could indicate the outer extent to which continuous permafrost restricts upward fluid flow. This paper reports on a geochemical analysis of a 1.1 m long sediment core located in an area of shallow fluid flow off of the Yamal Peninsula coast (South Kara Sea) using high-resolution seismic data. Our results reveal a thin zone of Anaerobic Oxidation of Methane (AOM), a sharp shallow sulfate-methane transition (SMT) located at a sub-bottom depth of 0.3 m, and significant temporal variation in methane discharge confirmed by the pyrite (FeS2) distribution in the core sample. A concave up pore water chloride profile depicts upward fresh/brakish water advection in subsurface sediments. The terrestrial/fresh water genesis of methane from the sampled core is deduced from the stable isotopic signatures (δ13 C and δD). We propose two mechanisms for the observed fluid flow: i) convection of thaw water from subsea permafrost; and/or ii) lateral sub-permafrost ground water discharge marking the outer extent of continuous permafrost off of the central Yamal Peninsula coast at ˜45 m water depth. Article in Journal/Newspaper Arctic Arctic Arctic Ocean Arctic Ocean Acidification Kara Sea Ocean acidification permafrost Yamal Peninsula University of Tromsø: Munin Open Research Archive Arctic Arctic Ocean Kara Sea Yamal Peninsula ENVELOPE(69.873,69.873,70.816,70.816) Geochemistry 80 3 125509 |
institution |
Open Polar |
collection |
University of Tromsø: Munin Open Research Archive |
op_collection_id |
ftunivtroemsoe |
language |
English |
topic |
VDP::Mathematics and natural science: 400::Geosciences: 450::Sedimentology: 456 VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Sedimentologi: 456 |
spellingShingle |
VDP::Mathematics and natural science: 400::Geosciences: 450::Sedimentology: 456 VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Sedimentologi: 456 Semenov, Petr Portnov, Aleksei D Krylov, Alexey Egorov, Alexander V Vanshtein, Boris Geochemical evidence for seabed fluid flow linked to the subsea permafrost outer border in the South Kara Sea |
topic_facet |
VDP::Mathematics and natural science: 400::Geosciences: 450::Sedimentology: 456 VDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Sedimentologi: 456 |
description |
Driven by rising bottom water temperatures, the thawing of subsea permafrost leads to an increase in fluid flow intensity in shallow marine sediments and results in the emission of methane into the water column. Limiting the release of permafrost-related gas hydrates and permafrost- sequestered methane into the global carbon cycle are of primary importance to the prevention of future Arctic Ocean acidification. Previous studies in the South Kara Sea showed that abundant hydro-acoustic anomalies (gas flares) induced by seafloor gas discharge into the water column occur in water whose depth is ≥20 m. This distribution of gas flares could indicate the outer extent to which continuous permafrost restricts upward fluid flow. This paper reports on a geochemical analysis of a 1.1 m long sediment core located in an area of shallow fluid flow off of the Yamal Peninsula coast (South Kara Sea) using high-resolution seismic data. Our results reveal a thin zone of Anaerobic Oxidation of Methane (AOM), a sharp shallow sulfate-methane transition (SMT) located at a sub-bottom depth of 0.3 m, and significant temporal variation in methane discharge confirmed by the pyrite (FeS2) distribution in the core sample. A concave up pore water chloride profile depicts upward fresh/brakish water advection in subsurface sediments. The terrestrial/fresh water genesis of methane from the sampled core is deduced from the stable isotopic signatures (δ13 C and δD). We propose two mechanisms for the observed fluid flow: i) convection of thaw water from subsea permafrost; and/or ii) lateral sub-permafrost ground water discharge marking the outer extent of continuous permafrost off of the central Yamal Peninsula coast at ˜45 m water depth. |
format |
Article in Journal/Newspaper |
author |
Semenov, Petr Portnov, Aleksei D Krylov, Alexey Egorov, Alexander V Vanshtein, Boris |
author_facet |
Semenov, Petr Portnov, Aleksei D Krylov, Alexey Egorov, Alexander V Vanshtein, Boris |
author_sort |
Semenov, Petr |
title |
Geochemical evidence for seabed fluid flow linked to the subsea permafrost outer border in the South Kara Sea |
title_short |
Geochemical evidence for seabed fluid flow linked to the subsea permafrost outer border in the South Kara Sea |
title_full |
Geochemical evidence for seabed fluid flow linked to the subsea permafrost outer border in the South Kara Sea |
title_fullStr |
Geochemical evidence for seabed fluid flow linked to the subsea permafrost outer border in the South Kara Sea |
title_full_unstemmed |
Geochemical evidence for seabed fluid flow linked to the subsea permafrost outer border in the South Kara Sea |
title_sort |
geochemical evidence for seabed fluid flow linked to the subsea permafrost outer border in the south kara sea |
publisher |
Elsevier |
publishDate |
2019 |
url |
https://hdl.handle.net/10037/18472 https://doi.org/10.1016/j.chemer.2019.04.005 |
long_lat |
ENVELOPE(69.873,69.873,70.816,70.816) |
geographic |
Arctic Arctic Ocean Kara Sea Yamal Peninsula |
geographic_facet |
Arctic Arctic Ocean Kara Sea Yamal Peninsula |
genre |
Arctic Arctic Arctic Ocean Arctic Ocean Acidification Kara Sea Ocean acidification permafrost Yamal Peninsula |
genre_facet |
Arctic Arctic Arctic Ocean Arctic Ocean Acidification Kara Sea Ocean acidification permafrost Yamal Peninsula |
op_relation |
Chemie der Erde info:eu-repo/grantAgreement/RCN/SFF/223259/Norway/Centre for Arctic Gas Hydrate, Environment and Climate/CAGE/ Semenov, Portnov AD, Krylov A, Egorov AV, Vanshtein B. Geochemical evidence for seabed fluid flow linked to the subsea permafrost outer border in the South Kara Sea. Chemie der Erde. 2019 FRIDAID 1693578 doi:10.1016/j.chemer.2019.04.005 0009-2819 1611-5864 https://hdl.handle.net/10037/18472 |
op_rights |
openAccess |
op_doi |
https://doi.org/10.1016/j.chemer.2019.04.005 |
container_title |
Geochemistry |
container_volume |
80 |
container_issue |
3 |
container_start_page |
125509 |
_version_ |
1766300518564495360 |