comparison of two extractants for determination of uranium (238u) phytoavailability in sandy loam soil

abstract uranium is a radioactive heavy metal. development of nuclear industries and application of phosphate fertilizers contain uranium impurity resulted in soil contamination with uranium. a pot experiment had been conducted under controlled condition. the experiment carried out in completely randomized design with two factors, including two plants (soybean and sunflower) and six levels of uranium (0, 50,100,250,500 and 1000 mg/kg). plants harvested after 40 days of experiment and before the generative stages. soil samples were extracted by dtpa and aaacedta. uranium concentration in plant tissue increased by increasing the uranium in soil. the ratio of uranium in root:shoot was between 20-100 in sunflower and soy bean. extraction efficiency of dtpa and aaacedta increased by increasing of uranium in soil. the results of the experiment showed that aaacedta extracts more uranium in all applied uranium concentrations. both extractants had a good correlation with uranium in plants; however, extraction efficiency of aaacedta was well correlated by uranium concentration in plant tissues. the results of the experiment suggest that aaacedta is suitable extractant for uranium as phytoavailability indicator. key word: uranium, phytoavailability, laser fluorometry, sunflower and soybean