Biogeochemical consequences of non‐vertical methane transport in sediment offshore northwestern Svalbard

Treude, Tina, Krause, Stefan, Steinle, L., Burwicz, Ewa B., Hamdan, L. J., Niemann, H., Feseker, T., Liebetrau, Volker, Krastel, Sebastian and Berndt, Christian (2020) Biogeochemical consequences of non‐vertical methane transport in sediment offshore northwestern Svalbard Journal of Geophysical Research: Biogeosciences . DOI 10.1029/2019JG005371.

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Abstract

A site at the gas hydrate stability limit was investigated offshore northwestern Svalbard to study methane transport in sediment. The site was characterized by chemosynthetic communities (sulfur bacteria mats, tubeworms) and gas venting. Sediments were sampled with in‐situ porewater collectors and by gravity coring followed by analyses of porewater constituents, sediment and carbonate geochemistry, and microbial activity, taxonomy, and lipid biomarkers. Sulfide and alkalinity concentrations showed concentration maxima in near‐surface sediments at the bacterial mat and deeper maxima at the gas vent site. Sediments at the periphery of the chemosynthetic field were characterized by two sulfate‐methane transition zones (SMTZ) at ~204 and 45 cm depth, where activity maxima of microbial anaerobic oxidation of methane (AOM) with sulfate were found. Amplicon sequencing and lipid biomarker indicate that AOM at the SMTZs was mediated by ANME‐1 archaea. A 1D numerical transport reaction model suggests that the deeper SMTZ‐1 formed on centennial scale by vertical advection of methane, while the shallower SMTZ‐2 could only be reproduced by non‐vertical methane injections starting on decadal scale. Model results were supported by age distribution of authigenic carbonates, showing youngest carbonates within SMTZ‐2. We propose that non‐vertical methane injection was induced by increasing blockage of vertical transport or formation of sediment fractures. Our study further suggests that the methanotrophic response to the non‐vertical methane injection was commensurate with new methane supply. This finding provides new information about for the response time and efficiency of the benthic methane filter in environments with fluctuating methane transport.

Document Type: Article
Additional Information: Genetic datasets are accessible through the BioProject database (ID: PRJNA591650). Datasets from the gravity corer (https://doi.pangaea.de/10.1594/PANGAEA.909703) and the peeper sampling (https://doi.pangaea.de/10.1594/PANGAEA.909702) are accessible through the PANGAEA database.
Keywords: sulfate‐methane transition zone, carbonates, ANME, cold seep, sulfate reduction, methane oxidation
Research affiliation: MARUM
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
NIOZ
Kiel University
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Refereed: Yes
DOI etc.: 10.1029/2019JG005371
ISSN: 2169-8953
Related URLs:
Projects: PERGAMON, Future Ocean
Expeditions/Models:
Date Deposited: 09 Mar 2020 11:14
Last Modified: 09 Mar 2020 11:22
URI: http://eprints.uni-kiel.de/id/eprint/49197

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