Some factors influencing the uptake of plutonium-239 by pea plants

An increase in plant uptake of 239Pu over time, observed by previous investigators, could indicate that this radionuclide is a long-term hazard in the terrestrial food chain. To consider properly this possible hazard, three of the hypotheses which have been advanced to explain this observed increase in uptake (chelation, increasing colloid size and depth of plutonium in the soil) were tested experimentally. Pea plants were grown in sand contaminated with plutonium. Various levels of the factors being considered (0 or 100 ppm of DTPA chelating agent; 0.2 to 0.6, 0.6 to 1.0 or greater than 1.0 micron, equivalent spherical diameter, plutonium colloid size; and 2 or 8 cm burial) were used, and their influence on plutonium uptake by plants compared, to determine statistically significant effects. Increases in uptake due to chelation were of the order of 103, and lesser effects due to colloid size and depth of burial were observed. (author)