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Characterization of peat structure using X-ray computed tomography and its control on the ebullition of biogenic gas bubbles

Kettridge, Nicholas and Binley, Andrew (2011) Characterization of peat structure using X-ray computed tomography and its control on the ebullition of biogenic gas bubbles. Journal of Geophysical Research: Biogeosciences, 116 (G1). ISSN 2169-8961

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Abstract

The structural arrangement of peat constituents controls the hydrological and thermal properties of peat. However, the importance of these structural characteristics on other physical processes within a peatland has not been fully assessed. Here, we evaluate the importance of peat structure on its ability to entrain biogenic gas bubbles and control ebullition, an important transport mechanism for methane. X-ray computed tomography (CT) was applied to characterize the structure of a range of peats at varying levels of decomposition. The structural properties of the peat were quantified from a vector representation of the CT images, and the potential of each sample to entrain biogenic gas bubbles was quantified using a rule-based Monte Carlo model that calculates the tortuosity of bubbles pathways through the peat. Sixty-six percent of the variability in the trapping potential of the peat results from porosity variations and 34% from structural variations between samples. A metric that represents this structural control was not identified for all peat types because of difficulties adequately representing some peats as a vector network. However, for S. magellanicum peat we were able to establish that the influence of peat structure on the entrainment of gas bubbles is characterized by (L) over bar (v), the average vector length of the stems and branches. Peat characterized by longer structural components (larger (L) over bar (v)) enhances the entrainment of gas bubbles. Our findings demonstrate the need to incorporate some representation of the peat structure in numerical models of biogenic gas transport in peat.

Item Type: Article
Journal or Publication Title: Journal of Geophysical Research: Biogeosciences
Additional Information: Copyright 2011 by the American Geophysical Union.
Uncontrolled Keywords: BOG ; WATER ; HYDRAULIC CONDUCTIVITY ; FLOW ; HYDROLOGY ; PORE-SIZE
Subjects: Q Science > QH Natural history
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 50323
Deposited By: ep_importer_pure
Deposited On: 11 Oct 2011 17:00
Refereed?: Yes
Published?: Published
Last Modified: 24 Sep 2013 11:24
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/50323

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