PLANT UPTAKE AND TRANSPORT OF 241Am

Abstract

We conducted several experiments with 241Am to obtain a more complete understanding of how this transuranium element is absorbed and transported in plants. In a plant species (Tamarix pentandra (Pall.) that has salt glands in the leaves excreting NaCl and other ions, 241Am was not pumped through these glands. Cyanide, which forms complexes with any metals, when applied to a calcareous soil, greatly increased the transport of 241Am into stems and leaves of bush bean plants. When a noncalcareous soil was used, the effect of cyanide was less pronounced. A less stable complex is formed at the lower pH. Radioactive cyanide (14C) was also transported to leaves and stems. When radish was grown in both calcareous and noncalcareous soils, 241Am appeared to be fixed on the peel so firmly that it was resistant to removal by HNO3 washing. The chelating agent DTPA induced increased transport of 241Am to leaves and into the fleshy roots of the radish. This effect was little dependent upon pH. Data for ‘Golden Cross' hybrid corn grown in solution culture showed at least seven times as much 241Am transport to the xylem exudate when DTPA was the external solution around roots compared with no DTPA, indicating, along with data from other plant species, that 241Am is transported in the xylem exudate.