uptake of Transuranic Nuclides from Soil 

 by Plants Grown Under Controlled 

 Environmental Conditions 



D. C. ADRIANO, A. WALLACE, and E. M. ROMNEY 



Pla7it uptake of transuranic nuclides ranges through several orders of magnitude, 

 depending on plant, environmental, and edaphic conditions. Most information presently 

 available concerns root uptake of plutonium and americium. In environments where 

 resuspension prevails, direct deposition on plant foliage may exceed root uptake. 

 Atmospheric deposition is generally short lived, however, and the long-term assessment 

 precludes that root uptake, as in the case of surface land contamination and shallow 

 burial of nuclear wastes, will exceed that obtained from atmospheric deposition. 

 Concentration ratios for ^^^Am uptake generally ranged from I0~^ to 10^ ; those for 

 ^^^Pu generally ranged from 10^'^ to 10~^ . Information for curium and neptunium is 

 scarce, but the range appeared to vary from 10^^ to I0~^ and from I0~^ to 10'^ , 

 respectively, for these radionuclides. 



Studies conducted using soils in pot culture showed that '^'^^Am uptake by crops 

 from southeastern U. S. soils was influenced by clay content and low cation exchange 

 capacity. Lime amendment suppressed ^'^^Am uptake, whereas organic matter amend- 

 ment appeared to temporarily reduce uptake from these soils. Commonly used 

 agricultural amendments generally were ineffective in altering ■^^^ Am and '^'^ Pu uptake 

 from western U. S. desert soils. However, the chelate diethylenetriamine pentaacetic acid 

 markedly and consistently increased root uptake of both plutonium and americium by 

 plants. Chelators and other chemical compounds that enhance complexation reactions 

 with transuranic elements appeared to be most effective in enhancing root uptake from 

 soils. Such compounds, which are usually present in shallow-burial waste-storage areas, 

 may accelerate plant uptake through deep-penetrating root systems. 



Numerous studies on the root uptake and translocation of the transuranic elements have 

 been conducted which contributed to the understanding of some aspects of the processes 

 involved. Many investigators have demonstrated that transuranic elements entered plant 

 roots in trace quantities and were transported to aerial parts of plants (Jacobson and 

 Overstreet, 1948; Cline, 1968; Newbould, 1963; Newbould and Mercer, 1961; Rediske 

 and Selders, 1954; Romney, Mork, and Larson, 1970; Romney and Price, 1959; Wilson 

 and Cline, 1966; Rediske, Cline, and Selders, 1955). Adams et al. (1975) found that the 

 availability of plutonium to plants was very low from 100-/L/m ^•^^Pu02 particles 

 [concentration ratio (CR) of 10"^^ to 10""^ in ash] . In general, they found that plant 

 species differed in uptake, with about 25 times more ^'* ' Am taken up than ^ ^^Pu. Bean 

 seeds contained 200 times less plutonium than bean leaves, but radish roots contained 10 

 times as much ^^^Pu as did the tops. Peeling the radish roots, however, removed 99% of 

 the radionuclide, indicating that this radionuclide was mostly contained in or on the peel. 



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