Uranium Contents in Plants and Mushrooms Grown on a Uranium Mining Waste Tip Site in Former Eastern Germany

There were extensive uranium mining-activities in former Eastern Germany in 1945 to 1990, with ecological consequences, like districts with U contaminated grounds. U concentrations in plants, and mushrooms, grown on a test site within a U-contaminated area in Eastern Thuringia, were analyzed. This test site is situated on the ground of a former U mine waste leaching heap. For determination of the U concentrations, the saps of the samples were squeezed out by an ultracentrifuge; after that, the U concentrations in the saps and in the remaining residues were measured by ICP-MS. The study showed that U concentrations observed in plant compartment and mushroom sap samples were always higher than in their associated solid residues. Also, it was found that the detected U concentrations in the root samples were always higher than those in their associated above ground biomass. But, the U concentrations in plants and mushrooms were always lower than in the associated surface and soil waters. This study confirmed that the amount of extracted U from plants and mushrooms is insufficient comparing to the U contaminated in soil and water. Thus these results indicated that none of the plant and mushroom species turned out to be a hyper-accumulator for U. In addition, it was found that the detected U concentrations in the sap samples, proved to be too low - in combination with the presence of fluorescence quenching substances, e.g., Fe and Mn, and/or organic quenchers - to extract a useful fluorescence signal, which could have helped to identify the uranium speciation in plants.