Enhancing the transfer of U and Ra from soils to Brassica juncea L

In order to test the suitability of using Brassica juncea for the remediation by phytoextraction of soils contaminated with U and Ra, the transfer process to the plant was studied. A soil with high natural uranium mineralization was used for the study. When the soil was not manipulated, the transfer factor (TF) was 0.24 ± 0.02 and 1.5 ± 0.3 for U and Ra, respectively. These low values, especially for U, are due to the radionuclides being associated in the soils to fractions unavailable for the plant. For the possible use of phytoextraction for remediation of contaminated soils it is therefore necessary to enhance the availability of the radionuclides in the soil. In this sense, soil pH is a major factor influencing the availability of these elements in the soil for plant uptake through their speciation. In this work, the effect of pH on the TF of U and Ra was studied. Also, citrate was used to enhance the bioavailability of the two radionuclides in the soils, and therefore their uptake by Brassica juncea and translocation to the shoots. The effect of pH on the action of citrate was also studied.