Studies on the Uptake of Plutonium from Major Indian Soils and Its Distribution in Plants

Abstract

AbstractPot experiments were conducted to study the plant uptake of Pu from major Indian soil types and its distribution in plants.It was observed that, irrespective of plant species, highest amount of Pu was absorbed from acidic laterite soil baying predominantly kaolinite clay mineral and low cation exchange capacity followed by alluvial soil and was lowest in medium black alkaline soil with predominantly montmorillonite clay and high cation exchange capacity. ‘Plutonium Concentration Ratios’ for beans (Phaseolus vulgaris L.) and maize (Zea mays L.) ranged from 1.5 × 10−4 to 9.6 × 10−4 for the aerial tissues and from 13.9 × 10−4 to 15.3 × 10−4 for roots; the values for beans were higher than those for maize over identical durations of plant growth.The distribution pattern of Pu in bean plants grown to maturity in labelled nutrient solutions indicated maximum concentration of Pu in roots and a marked acropetal gradient in the aerial tissues. Further, split‐root studies indicated that Pu absorbed by roots from the soil was not subsequently released into the nutrient solution.Fractionation of Pu in freshly harvested bean pods indicated maximum amount of Pu (39.11%) to be associated with ionic forms extractable by HClO4. The levels of Pu associated with ethanol fraction (13.00%), HCl fraction (11.44%), acetone insoluble fraction (7.58%), soda fraction (11.39%), and lignin and cellulose fraction (12.24%) were next in significance. The nucleic acid fraction was found to contain the lowest levels (5.18%) of the radionuclide.