Plutonium Contents of Field Crops 

 in the Southeastern United States 



D. C. ADRIANO, J. C. COREY, and R. C. DAHLMAN 



Agricultural crops were grown at the U. S. Department of Energy Savannah River Plant 

 (SRP) and at Oak Ridge National Laboratory (ORNL) on soils at field sites containing 

 Plutonium concentrations above background levels from nuclear weapon tests. Major 

 U. S. grain crops were grown adjacent to a reprocessing faciUty at SRP, which releases low 

 chronic levels of plutonium through an emission stack. Major vegetable crops were grown 

 at the ORNL White Oak Creek floodplain, which received plutonium effluent wastes in 

 1944 from the Manliattan Project weapon development. 



The plutonium contents of grain crops (wheat, soybeans, and corn) at SRP were 

 affected by distance from the emission stack, plant height, and grain-processing method. 

 In general, vegetative materials growing close to the stack liad higher plutonium 

 concentrations than those growing in an adjacent field. Plutonium concentrations of 

 portions of plants, such as wheat and corn, collected highest from the ground level 

 indicate tliat plutonium contamination of these plant parts from soil resuspendible matter 

 was minimal. The plutonium content of the grain when harvested by combine was 

 elevated because the grain was mixed with extraneous matter and straw, which had 

 relatively higher plutonium concentrations. Results from glasshouse studies using the 

 same field-grown crops indicate tliat root uptake contributed insignificantly to the total 

 plutonium contents of the field-grown crops. 



Plutonium contents of vegetable crops grown at the ORNL White Oak Creek 

 floodplain were influenced by part of plant, stage of maturity, and method of processing 

 for the edible portions of the subterranean crops. Plutonium concentrations of fruits were 

 at least one order of magnitude lower than those of the foliage. The plutonium content of 

 the vegetable foliage was maximum when the foliage biomass was at maximum. Peeling 

 the skins from potatoes and beets removed approximately 99% of the residual plutonium. 



In general, the concentration ratios of vegetative parts of crops at SRP were 

 approximately one order of magnitude higher than those at ORNL, which indicates the 

 influence of aerial deposition of plutonium at the SRP site. 



Research on transuranic nuclides in the environment has gained momentum in recent 

 years as a result of proposed increases in production and use of plutonium in the nuclear 

 fuel cycle. Because of the toxicity and long half-life of plutonium (specifically 

 2 3 9,2 4 0p|j^^ its health hazard to man is being evaluated. Although inhalation has been 

 considered the major pathway by which plutonium reaches man (Bennett, 1976), 

 ingestion of plutonium-contaminated foodstuff through the soil-to-plant pathway should 

 be critically evaluated because of the long persistence and general immobility of 

 plutonium in the environment (Francis, 1973). Numerous studies have been conducted to 



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