Phytoavailability of uranium: influence of plant species and soil characteristics

Five plants (Maize, Indian mustard, Wheat, Pea and Ryegrass) with reported differences in uranium uptake were screened in a greenhouse experiment for their uranium soil-to-plant transfer from two soils. Soils were spiked with

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U and were distinct in uranium availability characteristics. It was investigated if variability in uptake could be traced back to a different interaction of plants with the soil matrix or to different organic acid concentrations in the soils after plant growth. Clearly distinct transfer factors were obtained between soil groups which could be traced back to a difference in uranium availability between soils. However, within a soil group, there was no relation between (plant-induced changes in) soil characteristics and the transfer factors observed. The mechanisms by which the plants inhibit or promote root-shoot transfer seemed more important than soil characteristics to explain the difference in uranium transfer factor observed.