400 TRANSURANIC ELEMENTS IN THE ENVIRONMENT 



season, as tlie plants matured and grew taller, emission became the principal source of 

 contamination, as indicated by a higher '^^^Pu percentage. 



2. Plutonium concentrations of the foliage of soybeans and corn grown in the South 

 Field at SRP were similar to those of tlie June wheat straw [on the order of 10^^ pCi/g 

 (dry weiglit)] collected from the same field. However, the corn foliage had higlier a % 

 ^^^Pii than did the wheat and soybean foliage, which reflects the minimal contribution 

 of resuspension to the corn canopy. Plutonium contents of the combine-harvested grain 

 of tlie three crops were basically similar. Sifting the combined grain separated about 50% 

 of the plutonium-bearing particles and/or extraneous matter from the grain and resulted 

 in plutonium concentrations a factor of 2 lower in the sifted grain than in the unsifted 

 grain. 



3. Preliminary results from the SRP glasshouse studies indicated tliat only about 3% 

 of the total contamination of field-grown crops adjacent to a reprocessing facility was 

 contributed by root uptake. Also, it appeared from glasshouse results that ■^■^^Pu was 

 more available than ^^^Pu. 



4. Cultivation of the fields at SRP before planting wheat caused the plutonium 

 concentrations in the top soil layer to become more uniform and to increase the 

 plutonium concentrations at the deeper depths (5 to 15 cm). It also caused the ^^^Pu 

 percentage for the resuspendible portion to approach the soil values. Subsequent 

 cultivations caused greater uniformity in plutonium concentration in the top soil. 



5. Concentrations of 239,240p|j ^^ ^^^ foliage of forage and vegetable crops grown at 

 the woe floodplain ranged from 0.01 to 0.33 pCi/g. This represented the amounts of 

 plutonium taken up by plants exclusively via the root pathway from soils with plutonium 

 concentrations ranging from 10 to 150 pCi/g and averaging 63 pCi/g. Plutonium 

 concentrations in the fruit of these species, however, were lower by at least an order of 

 magnitude than those in the foliage. 



6. Peeling the skins of potatoes and beets grown at the WOC floodplain removed 

 approximately 99% of the residual plutonium. 



7. Plutonium contents of soybean foliage were related to the stage of maturity and 

 were maximum when the foliage biomass was maximum. 



8. In general, the CR values of vegetative parts of crops at SRP were approximately 

 one order of magnitude higher than those at Oak Ridge, which suggests the influence of 

 aerial deposition of plutonium at the SRP site. 



Acknowledgments 



This work was supported by the U. S. Department of Energy through contract Nos. 

 EY-76-C-09-0819 (to Savannah River Ecology Laboratory, University of Georgia), 

 AT(07-2)-l (to Savannah River Laboratory, E. I. du Pont de Nemours and Co.), and 

 W-7405-eng-26 (to Oak Ridge National Laboratory, Union Carbide Corp.). 



References 



Adriano, D. C, and J. li. Pinder III, 1977, Aerial Deposition of Plutonium in Mixed Forest Stands 



from Nuclear luel Reprocessing, 7. Environ. Qual , 6: 303-307. 

 Auerbach, S. 1., 1975, Environmental Sciences Division Annual Progress Report. Part I, Plutonium in 



the Hnvironment, ERDA Report ORNL-5 193, pp. 6-7, Oak Ridge National Laboratory, NTIS. 



