Synchrotron X-ray absorption-edge computed microtomography imaging of thallium compartmentalization in Iberis intermedia

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 hyperaccumulated 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 determining 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 experiments are examining the characteristics and potential recovery of Tl by I. intermedia with the objectives to remediate its toxic risks and to facilitate its reclamation for reuse. However, the recovery 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.