Foliar Absorption of Transuranic Elements: Influence of Physicochemical Form and Environmental Factors

Abstract

AbstractThe accumulation of plutonium (238Pu) and americium (241Am) in seeds and roots of Phaseolus vulgaris L. was investigated following foliar interception. Under controlled conditions plants were exposed to well‐characterized aerosols of fresh and aged Pu‐dioxide, fresh Am‐oxides, and Pu‐nitrate and Pu‐citrate complexes to assess the influence of chemical form and long‐term weathering on foliar absorption and subsequent translocation to other plant parts. Mean values for Pu and Am accumulated in seeds and roots 28 days after foliar exposure ranged from 9 to 427 × 10−4% of that deposited on foliage. These results and previous plant uptake studies indicate that the foliar route is potentially of equal importance to the soil‐root pathway as a route of transport. The levels of Pu and Am in seeds and roots resulting from foliar absorption and translocation from foliage were significantly affected by simulated rainfall and by the size of particles to which foliage was exposed. The influence of relative humidity and solution aging of oxides was less definitive; however, results suggest that either or both may influence foliar absorption and subsequent translocation of Pu and Am to seeds and roots.