Determination of uranium speciation in plants

The overall process of uptake of heavy elements (actinides) into plant tissues from contaminated soils has been quantified using the soil-to-plant transfer factor (TF). Considering the radionuclide transfer, it is quantified as TF(RN) = plant specific activity (Bq/kg-1) /soil specific activity (Bq/kg-1). In practice the predominant pathway of plant contamination is direct contamination by deposition and resuspension. The comparable uptake via soil-plant transfer is about 10%. But this ratio strongly depends on the real accident scenario (distribution of contaminants via aerosol in air, as soluble or colloidal species in aquifer or surface water).Up to now, the chemistry of the various actinides has not been considered along the pathway soil-plant-animal-humans. The transfer factor has to be unfolded into the basic parameters like changes in oxidation state and complexation, differences in bonding of the elements like adsorption and ion exchange processes, formation of colloids e.g.
It was our goal to obtain first results on the change of uranium speciation during the soil-to-plant transfer. X- ray absorption spectroscopy (XAS) with synchrotron radiation and the time-resolved laser-induced fluorescence spectroscopy (TRLFS) were used as tools for the determination of uranium speciation in soil, water, and different parts of the plants. The reported investigations about the distribution and speciation of uranium were focused on lupins.