Abstract Thallium is an extremely toxic metal which, due to its similarities to K, is readily taken up by plants grown in Tl-contaminated soils. Thallium is also a precious metal nearly as economically valuable as gold. Thallium is efficiently hyperaccu- mulated in Iberis intermedia as aqueous Tl(I) with highest concentrations within the vascular network of leaves. In this study we examine the utility of synchrotron X-ray differential absorption-edge computed microtomography (CMT) in determin- ing the distribution and compartmentalization of thallium (Tl) in Iberis intermedia. We found Tl to be distributed in solution throughout the vascular system of I. intermedia. Current laboratory experi- ments are examining the characteristics and po- tential recovery of Tl by I. intermedia with the objectives to remediate its toxic risks and to facili- tate its reclamation for reuse. However, the recov- ery and reuse of Tl from I. intermedia by way of phytomining requires knowledge on the speciation, distribution and compartmentalization of thallium. CMT shows great promise for application in a wide variety of metal-related structural issues due to its high 3D resolution and being a non-destructive analysis tool. Keywords computed microtomography (CMT) Æ Iberis intermedia Æ thallium hyperaccumulation Æ synchrotron spectroscopy Æ metal compartmentalization Introduction Hyperaccumulation of metals in plant tissue may provide both environmental and economic benefits to society if carefully managed and utilized (Baker et al. 1995; Chaney et al. 1995; Cunningham and Ow 1996). Metal uptake by hyperaccumulator plants has been studied for several decades (Cha- ney et al. 1995; Cunningham and Ow 1996; Li et al. 2000). However limited information exists in the Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s11104-006-9102-7 and is accessible for authorized users. K. G. Scheckel (&) ORD, NRMRL, LRPCD, US EPA, 5995 Center Hill Avenue, Cincinnati, OH 45224, USA e-mail: Scheckel.Kirk@epa.gov R. Hamon Æ E. Lombi CSIRO Land and Water Adelaide Laboratory, PMB2, Glen Osmond, SA 5064, Australia L. Jassogne School of Plant Biology, University of Western Australia, PMB1, PMB1, Glen Osmond, SA 5064, Australia M. Rivers GSECARS, University of Chicago, Chicago, IL 60637, USA Plant Soil (2007) 290:51–60 DOI 10.1007/s11104-006-9102-7 123 ORIGINAL PAPER Synchrotron X-ray absorption-edge computed microtomography imaging of thallium compartmentalization in Iberis intermedia Kirk G. Scheckel Æ Rebecca Hamon Æ Laurence Jassogne Æ Mark Rivers Æ Enzo Lombi Received: 7 June 2006 / Accepted: 1 August 2006 / Published online: 6 January 2007 Ó Springer Science+Business Media B.V. 2006