PLANT UPTAKE OF 239°240py anp 241am THROUGH ROOTS FROM SOILS CONTAINING AGED FALLOUT MATERIALS E. M. Romney, A. Wallace, P. A. T. Wieland, and J. E. Kinnear University of California, Los Angeles ABSTRACT Several species of plants were grown under glasshouse conditions in pot cultures containing soil from some of the aged plutonium fallout areas on the Nevada Test Site (NTS) and the Tonopah Test Range (TTR). This interim report contains results for alfalfa, barley, and soybean plants from experiments designed to test the influence of soil amendments on plant uptake of 239°240py and 24 lam through live root systems. Growth conditions were such that foliage surface contamination could be prevented with confidence. Results from an experiment with Area 13 soil showed that additions of nitrogen fertilizer and organic matter amendments did not alter the uptake of 239°249py and 41am through roots of barley and alfalfa plants. On the other hand, acidulation of this soil with agricultural grade sulfur significantly increased root uptake of these radionuclides (P = .05 level), especially when applied in combination with the chelating agent, diethylenetriaminepentaacetic acid (DTPA). A second experiment involving soil from eight of the different NAEG study sites also showed that the DTPA chelate amendment significantly increased root uptake of these radionuclides by soybean plants. In these experiments, the Pu/Am ratios for plants generally were much lower than the Pu/Am ratios for soils in which they were grown, indicating much greater uptake of 24 lam through roots in proportion to 239°240py uptake. Vegetation to soil concentration ratios (CR), which serve as an index of uptake through roots, were low for each plant species and for all soils tested. The CR values for 239°240py ranged from 1075 to 1073 for barley straw, and 10°§ to 1073 for barley fruit heads; 1075 to 107% for alfalfa forage; 10°*+ to 1073 for soybean leaves and stems; and 107& to 107* for soybean fruit pods. The effect of increasing uptake by DTPA chelate amendment was generally within one order of magnitude for Pu and Am radionuclides. The CR values for **!am ranged from 10°° to 1073 for barley straw and fruit heads; 107" to 1072 for alfalfa forage; 10-3 to 107! for soybean leaves and stems; and 10-* to 1072 for soybean fruit pods. These CR values obtained under glasshouse conditions were low compared to the vegetation to soil activity ratios of 1072 to 10° °53