FACTORS AFFECTING THE AVAILABILITY OF AM-241 TO THE RICE PLANT

Since there has been no published transuranic uptake data on the rice plant (Oryza sativa L.), greenhouse experiments were conducted to determine the effects of some factors on the uptake of 241 Am by this crop. Results indicate that chelated241 Am (in the form of americium-241-diethylenetriaminepentaacetic acid) applied to the flood water was markedly taken up by the rice plant, compared to the nonchelated form. However, most of the accumulation of 241 Am occurred in the vegetative parts and only trace amounts, if any, were translocated to the grain. Soil application of241 Am resulted in much lower uptake. Soil amendment with either diethylenetriaminepentaacetic acid (DTPA) or organic matter did not produce a discernible uptake pattern. A synthesis of published data on plant uptake of241 Am indicates that the concentration ratio (CR, a measure of availability of 241 Am to the plants) values for 241 Am for agricultural crops ranged from 10-6 to 101 (from lowest to highest availability). Some factors that appear to influence 241 Am uptake are as follows : plant parts (grain usually having lower CR), chelating agents (DTPA usually increasing the CR), organic matter (inconsistent effects although generally decreasing the CR), and lime (usually decreasing the CR). © 1979, American Chemical Society. All rights reserved.