TY - JOUR
T1 - Variability of Acoustically Evidenced Methane Bubble Emissions Offshore Western Svalbard
AU - Veloso-Alarcón, Mario E.
AU - Jansson, Pär
AU - De Batist, Marc
AU - Minshull, Timothy A.
AU - Westbrook, Graham K.
AU - Pälike, Heiko
AU - Bünz, Stefan
AU - Wright, Ian
AU - Greinert, Jens
N1 - Funding Information:
We thank the crewmembers of RV Helmer Hanssen (UiT the Arctic University of Norway, N-9037 Troms?) and RRS James Clark Ross (British Antarctic Survey) for support. M.?V. and J.?G. both received support via COST Action ES0902 (PERGAMON) to join research cruises and acquire data. M.?V. thanks the ERASMUS Mundus program of the EU (grant VECCEU) and the BECAS CHILE: CONICYT PAI/INDUSTRIA 79090016? program of the Chilean government. P.?J. was supported by the Centre of Excellence: Arctic Gas Hydrate, Environment and Climate (CAGE) funded by the Norwegian Research Council (Grant 223259). T.?A.?M. was supported by a Royal Society Wolfson Research Merit award. Data acquisition on RRS James Clark Ross was supported by Natural Environment Research Council Grants NE/D005728, NE/H002732/1, and NE/H022260/1. We thank Joana Beja De Almeida E Silva for giving us technical support with data supplied by the National Oceanography Centre. We finally thank the reviewers for their valuable feedback toward improving our manuscript. EK60 data are available at PANGAEA (https://doi.org/10.1594/PANGAEA.902832). This is publication 45 of the Deep Sea Monitoring Group at GEOMAR.
Publisher Copyright:
©2019. American Geophysical Union. All Rights Reserved.
PY - 2019/8/16
Y1 - 2019/8/16
N2 - 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 data sets acquired during 11 research expeditions to the western Svalbard continental margin (2008–2014). Three seepage areas emit in total 725–1,125 t CH4/year, and bubble fluxes are up to 2 kg·m−2·year−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.
AB - 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 data sets acquired during 11 research expeditions to the western Svalbard continental margin (2008–2014). Three seepage areas emit in total 725–1,125 t CH4/year, and bubble fluxes are up to 2 kg·m−2·year−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.
KW - bubbles
KW - flux
KW - hydracoustics
KW - methane
KW - Svalbard
KW - temporal variability
UR - http://www.scopus.com/inward/record.url?scp=85070578070&partnerID=8YFLogxK
U2 - 10.1029/2019GL082750
DO - 10.1029/2019GL082750
M3 - Article
AN - SCOPUS:85070578070
VL - 46
SP - 9072
EP - 9081
JO - Geophysical Research Letters
JF - Geophysical Research Letters
SN - 0094-8276
IS - 15
ER -
