Localisation of uranium in roots by chemical extractions and by a short term uptake study. Influence of phosphate.

Pea roots were exposed to nutrient solution containing 25 µmol L

−1

of uranium in presence or absence of phosphate. The uptake of U was followed during the first 90 minutes of exposure. Fifty percent of the uranium was removed after 45 minutes and after between 60–90 minutes in absence and in presence of phosphate respectively. After 24 hours exposure, root were extracted, to remove uranium from the root apoplasm. Copper extracted similar amounts of uranium than EDTA for root exposed to a solution with phospate while copper extracted only 18% of uranium extracted by EDTA for root exposed to a solution devoid of phosphate. Phosphate decreased the availability of uranium to roots of pea. The presence of phosphate decreased also the amounts of uranium extracted.