|Assessing the Response of Methane Hydrates to Environmental Change at the Svalbard Continental Margin
||Last Reviewed November 2016
The project goal is to study the biogeochemical response of gas hydrates to environmental change at the Svalbard Continental Margin.
Oregon State University, Corvallis, OR 97339-1086
More research is needed to better understand the role gas hydrates play in the global carbon cycle and their potential as a future energy resource. This includes determining
- the residence time of gas hydrates near the seafloor and deeper within the sediment column,
- the sources and pathways of methane transport,
- the nature and driving mechanisms for flow,
- methane distribution in the water column, and
- the changes in the (above) variables over time.
Characterizing carbon cycling in the critical zone on the upper continental slope will increase our knowledge of the hydrate stability transition at/near the seafloor. The upper edge of gas hydrate stability defines one of the most climate-sensitive boundaries and represents a potential “window” to fluid and gas migration from below the seaward-deepening bottom simulating reflector. Hydrate transformations can be documented through analyses of geochemical data, modeling efforts to quantify each process and its associated rate, and obtaining ground truth data of these geochemically-derived inferences through analyses of microbial communities.
German and Norwegian colleagues have ongoing programs focusing on characterizing gas hydrate abundance, distribution, and the effect of environmental changes on gas hydrate stability at the western Spitsbergen continental margin. In cooperation with those programs, Oregon State researchers will explore the role of biogeochemical processes in the region via pore water and sediment geochemical analyses, microbiological analyses, and kinetic modeling. The roles of microbial methane generation and oxidation will be constrained at and below the sulfate-methane transition zone, enabling researchers to quantify the amount of methane as it escapes, moves, or is consumed. These fundamental data are needed in order to constrain models for assessing the residence time of carbon in various methane-rich reservoirs as well as the dynamic response of these systems to environmental change and the resulting effect in the overlying water column. The proposed research has the potential to increase our understanding of the response and impact of gas hydrates to changing environmental conditions.
Accomplishments (most recent listed first)
- Researchers participated in two research cruises off Svalbard where they collaborated with Norwegian scientists to collect samples for geochemical and microbiological analyses. In addition, researchers participated in another DOE-funded cruise to the Cascadia margin, where they collected additional samples for microbiological analyses, which will complement the principal investigator’s geochemistry data.
- Modeling of methane dynamics and evaluation against data collected at seep sites in the Ulleung Basins (DOE co-funded project off Korea) was completed, and two papers have been published in Transport in Porous Media. The results were also presented at a methane gas conference in Taiwan in September 2014.
- Results from the recent cruises off Svalbard document: 1) the significance of methane release at the upper limit of gas hydrate stability relative to additional sources on the shelf; 2) evidence for the presence of gas hydrate pavements near the seafloor in a pockmark location on Vestnesa Ridge; and 3) presence of gas hydrate mounds in Storfjordrenna, west Barents Sea that may reflect ongoing methane venting in the region.
Current Status (May 2016)
Geochemical and microbiological samples from the past expeditions are being analyzed. The researchers have demonstrated the ability to extract DNA using two Svalbard cores from the past October expedition (GC-09 and GC-12) from depths ranging from 0 to 220 cm below seafloor, as well as amplification of the 16S rRNA. The research team established collaboration with Fengping Wang (State Key Laboratory of Microbial Metabolism at Shanghai Jiao Tong University in Shanghai, China) and funding for Scott Klassec (via a National Science Foundation summer fellowship) to use samples collected from the most recent Svalbard expedition for incubation experiments at high pressures to elucidate microbial response to changes in methane content. Building on the experience from the visit to Shanghai, Klassec has implemented sediment incubations for time-series experiments at situ temperatures and pressures under different methane concentrations. Methane consumption, sulfate reduction, and sulfide and dissolved inorganic carbon production will be measured. In addition to microbial community analysis, the team plans to quantify cell abundances and functional genes and transcripts associated with anaerobic methane oxidation and sulfate reduction. This work is partially supported by a Deep Carbon Observatory Deep Life Cultivation Internship grant to enrich or cultivate carbon-cycling microbes from subsurface environments. Preliminary results from these studies were presented at the AGU Fall Meeting in San Francisco, CA (Dec 2015), and at the Gordon Research Conference on Gas Hydrates in Galveston, TX (Feb-March 2016).
Geochemical characterization of samples recovered from the various expeditions is underway. A manuscript is in preparation describing the gas hydrate dynamics and associated geochemical response at newly discovered Pingo-Like features off the shore of Svalbard. A 1-D numerical model provides a first order estimate for the timing of the methane supply increase that can be best explained by dissociation of gas hydrate at depth. The manuscript will be submitted for publication in December 2016. Results were presented at the Gordon Research Conference on Gas Hydrates in Galveston, TX (Feb-March 2016).
Samples for the water column component of the research were obtained during the most recent expedition, which document extensive methane seepage not only at the upper edge of hydrate stability but also associated with shelf seeps. The seeps are possibly being fed by methane trapped beneath gas hydrates in the slope, which then migrate along glaciogenic deposits towards the shelf. Preliminary results were presented at the 2016 Gordon Research Conference on Natural Gas Hydrate (Galveston, TX, March 2016), and a manuscript has been submitted for publication to “Scientific Reports,” also published by the Nature consortium with an impact factor of ~5. The paper is now under revision. An abstract detailing these results was submitted to the upcoming International Conference on Gas Hydrates to be held in Denver, June 2017.
Project Start: November 1, 2013
Project End: October 31, 2016
DOE Contribution: $645,724
Performer Contribution: $180,000
NETL – Joseph Renk (Joseph.Renk@netl.doe.gov or 412-386-6406)
Oregon State University – Marta Torres (firstname.lastname@example.org or 541-737-2901)
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