| Abstract
| - Thallium (Tl) is a metal of great toxicological concern andits prevalence in the natural environment has steadilyincreased as a result of manufacturing and combustionpractices. Due to its low natural abundance and increasingdemand, Tl is the fourth most expensive metal, thus,recovery and reuse could be a profitable endeavor. Thehyperaccumulator Iberis intermedia was examined via invivo micro-X-ray absorption near edge (μ-XANES) and micro-X-ray fluorescence (μ-XRF) spectroscopies to determinethe speciation and distribution of Tl within leaves of the plant.I. intermedia plants were cultivated under controlledconditions in 0, 10, and 20 mg Tl kg-1 soil leading to ashoot concentration of up to 13 430 mg Tl kg-1 dry weightplant mass during 10 weeks of growth. Live plant leaveswere examined by μ-XANES and μ-XRF which determinedaqueous Tl(I) to be the model species distributed primarilythroughout the vascular network. A direct relationship ofvein size to Tl concentration was observed. The highuptake of Tl and high potential biomass of I. intermedia,combined with knowledge of Tl speciation and compartmentation within the plant, are discussed in terms ofaccumulation/tolerance mechanisms, consequences forpotential food chain contamination, and phytomining strategiesto reclaim Tl-contaminated soils, sediments, and waters.
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