Uranium accumulation in the lichen Cladonia rangiferina. Part I. Uptake of cationic, neutral, and anionic forms of the uranyl ion

Evidence from published work is first reviewed to show that cationic, neutral, and anionic complexes of the uranyl ion are available to plants growing in uranium-enriched environments. The results of a study on the uptake of uranyl ions by the lichen Cladonia rangiferina L. Wigg. are then presented. Uptake was examined from three different uranyl solutions each predominantly containing a single species: namely, the cation [Formula: see text] (in distilled water), the neutral 1:1 complex with phthalate (UO 2 L), and the anionic complex of oxalate [Formula: see text]. Uptake decreased along the chemical speciation series: cation [Formula: see text] neutral species [Formula: see text] anion. Maximum observable capacities for this series were, respectively, 49, 17, and 1.6 μmol/g for 1-g samples in 100 mL containing 840 μmol of total uranium. The [Formula: see text] uptake curve was observed to be monophasic, while biphasic patterns appeared to apply for the phthalate and oxalate buffers. Heat-killed tissues showed marginally higher uptake capacities than live material.