Publication Date:
2012-02-16
Description:
Despite much progress over the past years in fundamental gas hydrate research, frontiers to the unknown are the early beginning and early decomposition of gas hydrates in their natural, submarine environment: gas bubbles meeting ocean water and forming hydrate, and gas starting to escape from the surface of a hydrate grain. In this paper we report on both of these topics, and present three-dimensional microstructure results obtained by synchrotron radiation X-ray cryo-tomographic microscopy (SRXCTM). Hydrates can precipitate when hydrate-forming molecules such as methane exceed solubility, and combine with water within the gas hydrate stability zone. Here we show hydrate formation on surfaces of bubbles from different gas mixtures and seawater, based on underwater robotic in situ experiments in the deep Monterey Canyon, offshore California. Hydrate begins to form from the surrounding water on the bubble surfaces, and subsequently grows inward into the bubble, evidenced by distinct edges. Over time, the bubbles become smaller while gas is being incorporated into newly formed hydrate. In contrast, current understanding has been that hydrate decomposition starts on the outer surface of hydrate aggregates and grains. It is shown that in an early stage of decomposition, newly found tube structures connect well-preserved gas hydrate patches to areas that are dissociating, demonstrating how dissociating areas in a hydrate grain are linked through hydrate that is still intact and will likely decompose at a later stage. Figure The boundaries of a gas hydrate grain: excepting for the matrix (transparent, not shown), one can see tubular structures, pores from decomposition, and bubbles. Content Type Journal Article Category Original Pages 1-8 DOI 10.1007/s00367-012-0276-0 Authors Stephan A. Klapp, MARUM – Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Bremen, Germany Frieder Enzmann, Department of Geosciences, Johannes-Gutenberg-University of Mainz, Gutenberg, Germany Peter Walz, Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA Thomas Huthwelker, Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland Jürgen Tuckermann, Department of Geosciences, Johannes-Gutenberg-University of Mainz, Gutenberg, Germany J.-Oliver Schwarz, Department of Geosciences, Johannes-Gutenberg-University of Mainz, Gutenberg, Germany Thomas Pape, MARUM – Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Bremen, Germany Edward T. Peltzer, Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA Rajmund Mokso, Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland David Wangner, MARUM – Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Bremen, Germany Federica Marone, Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland Michael Kersten, Department of Geosciences, Johannes-Gutenberg-University of Mainz, Gutenberg, Germany Gerhard Bohrmann, MARUM – Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Bremen, Germany Werner F. Kuhs, GZG, Abt. Kristallographie, Universität Göttingen, Göttingen, Germany Marco Stampanoni, Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland Peter G. Brewer, Monterey Bay Aquarium Research Institute, Moss Landing, CA, USA Journal Geo-Marine Letters Online ISSN 1432-1157 Print ISSN 0276-0460
Print ISSN:
0276-0460
Electronic ISSN:
1432-1157
Topics:
Geosciences
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