Testen van de efficiëntie van additieven in het verhogen van de uraniumbeschikbaarheid in besmette gronden

The objective of the present research is to evaluate if it is feasible to increase the phytoextraction efficiency of uranium from soils and if phytoextraction is a feasible remediation technique to decrease the uranium concentration in soils to acceptable levels. To increase the extraction efficiency, 5 amendments mere tested, each on three soils, differing in soil characteristics and uranium contamination history. Citric acid and the mixture citric acid/ammonium citrate were the most efficient in increasing uranium availability and this for all soils. Screening the effects of amendments in increasing uranium uptake by ryegrass or mustard, it was observed that uranium uptake was highly influenced by the amendment applied and soil type. EDDS, followed by citric acid and the solution ammoniumcitrate and citric acid, was generally most effective in increasing uranium uptake. Based on the results, we must conclude that phytoextraction is not a feasible technique to decrease the uranium concentration of historically contaminated soils to acceptable levels. In the most optimal scenario, only 0.16 % of the total uranium present in the soil could be extracted with one harvest and it would hence take 239 years to reduce the initial uranium content with 10 %.