Abstract
The potential of using Xβray computed tomography (CT) to (i) analyse individual biogenic gas bubbles entrapped within peats and (ii) produce reliable descriptors of peat structure is examined. Existing approaches used to study biogenic gas bubbles measure the gas content of volumes of peat many orders of magnitude larger than most bubbles, and are, therefore, of little use in helping to understand bubble dynamics. In many peatland studies, the description of peat structures is derived from only a few relatively basic metrics; principally the porosity, the bulk density, and the von Post humification scale. CT is applied to identify and quantitatively analyse the size, location and shape of individual gas bubbles entrapped during the saturation of a 200 cm^3^ sample of S. fuscum. 3421 gas bubbles were identified, ranging in size from 0Β·1 mm^3^ to 99Β·9 mm^3^. These gas bubbles were nonβrandomly distributed, clustered predominantly in the vertical plane. When analysing the peat structure, Sphagnum peat and water are shown to be indistinguishable within CT scans. Peat samples were therefore prepared prior to scanning by flushing the peat with lead (II) nitrate solution to increase the linear attenuation of the Sphagnum. Sphagnum stems and branches were analysed, producing metrics of the peat structure; including stem and branch lengths, radii and orientation. In a 100 cm^3^ sample of S. magellanicum, the length of all Sphagnum stems totalled 1Β·82 m, with an average radius of 0Β·65 mm. The Sphagnum stems and branches were both preferentially orientated in the horizontal direction. Copyright Β© 2008 John Wiley & Sons, Ltd.