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Variability of acoustically evidenced methane bubble emissions offshore western Svalbar

Variability of acoustically evidenced methane bubble emissions offshore western Svalbar
Variability of acoustically evidenced methane bubble emissions offshore western Svalbar
Large reservoirs of methane present in Arctic marine sediments are susceptible to rapid warming, promoting increasing methane emissions. Gas bubbles in the water-column can be detected and flow-rates can be quantified using hydroacoustic survey methods, making it possible to monitor spatiotemporal variability. We present methane (CH4) bubble flow-rates derived from hydroacoustic datasets acquired during 11 research expeditions to the western Svalbard continental margin (2008-2014). Three seepage areas emit in total 725–1125 t CH4 y-1 and bubble fluxes are up to 2 kg m-2 y-1. Bubble fluxes vary between different surveys but no clear trend can be identified. Flux variability analyses suggest that two areas are geologically interconnected, displaying alternating flow changes. Spatial migration of bubble-seepage was observed to follow seasonal changes in the theoretical landward limit of the hydrate stability zone, suggesting that formation/dissociation of shallow hydrates, modulated by bottom water temperatures, influences seafloor bubble release.
0094-8276
9072-9081
Veloso-Alarcó, Mario E.
623121cf-44d7-41a7-9058-7666f3fb2132
Jansson, Pär
e304bcb1-f630-4a8a-a5e6-c61fcaeca229
De Batist, Marc
c4d103c4-2ba7-46fe-ac7f-fa9e62949537
Minshull, Timothy
bf413fb5-849e-4389-acd7-0cb0d644e6b8
Westbrook, Graham K.
ccd95de7-a1a1-4fc9-be37-f1a487bb65ca
Palike, Heiko
b9bf7798-ad8c-479b-8487-dd9a30a61fa5
Bünz, Stefan
23aa04cd-7a71-4550-b218-d857af41be49
Wright, Ian
c18c3700-3f72-4f8f-805a-70adcd8ca34d
Greinert, Jens
4e3d5578-8e20-402e-bb76-6742df96f8db
Veloso-Alarcó, Mario E.
623121cf-44d7-41a7-9058-7666f3fb2132
Jansson, Pär
e304bcb1-f630-4a8a-a5e6-c61fcaeca229
De Batist, Marc
c4d103c4-2ba7-46fe-ac7f-fa9e62949537
Minshull, Timothy
bf413fb5-849e-4389-acd7-0cb0d644e6b8
Westbrook, Graham K.
ccd95de7-a1a1-4fc9-be37-f1a487bb65ca
Palike, Heiko
b9bf7798-ad8c-479b-8487-dd9a30a61fa5
Bünz, Stefan
23aa04cd-7a71-4550-b218-d857af41be49
Wright, Ian
c18c3700-3f72-4f8f-805a-70adcd8ca34d
Greinert, Jens
4e3d5578-8e20-402e-bb76-6742df96f8db

Veloso-Alarcó, Mario E., Jansson, Pär, De Batist, Marc, Minshull, Timothy, Westbrook, Graham K., Palike, Heiko, Bünz, Stefan, Wright, Ian and Greinert, Jens (2019) Variability of acoustically evidenced methane bubble emissions offshore western Svalbar. Geophysical Research Letters, 46 (15), 9072-9081. (doi:10.1029/2019GL082750).

Record type: Article

Abstract

Large reservoirs of methane present in Arctic marine sediments are susceptible to rapid warming, promoting increasing methane emissions. Gas bubbles in the water-column can be detected and flow-rates can be quantified using hydroacoustic survey methods, making it possible to monitor spatiotemporal variability. We present methane (CH4) bubble flow-rates derived from hydroacoustic datasets acquired during 11 research expeditions to the western Svalbard continental margin (2008-2014). Three seepage areas emit in total 725–1125 t CH4 y-1 and bubble fluxes are up to 2 kg m-2 y-1. Bubble fluxes vary between different surveys but no clear trend can be identified. Flux variability analyses suggest that two areas are geologically interconnected, displaying alternating flow changes. Spatial migration of bubble-seepage was observed to follow seasonal changes in the theoretical landward limit of the hydrate stability zone, suggesting that formation/dissociation of shallow hydrates, modulated by bottom water temperatures, influences seafloor bubble release.

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More information

Submitted date: May 2019
Accepted/In Press date: 5 June 2019
e-pub ahead of print date: 22 July 2019
Published date: 16 August 2019

Identifiers

Local EPrints ID: 431729
URI: https://eprints.soton.ac.uk/id/eprint/431729
ISSN: 0094-8276
PURE UUID: fa8a50b9-4f5e-4116-b06f-b9f9c4f55c6d
ORCID for Timothy Minshull: ORCID iD orcid.org/0000-0002-8202-1379

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Date deposited: 14 Jun 2019 16:30
Last modified: 10 Dec 2019 01:49

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