Comparative Distribution of Plutonium 

 in Contaminated Ecosystems at Oak Ridge, 

 Tennessee, and Los Alamos, New Mexico 



ROGER C. DAHLMAN, CHARLES T. GARTEN, JR., and THOMAS E. HAKONSON 



The distribution of plutonium was compared in portions of forest ecosystems at Oak 

 Ridge, Tenn., and Los Alamos, N.Mex., which were contaminated by liquid effluents. 

 Inventories of plutonium in soil at the two sites were generally similar, but a larger 

 fraction of the plutonium was associated with biota at Los Alamos than at Oak Ridge. 

 Most (99.7 to 99.9%) of the plutonium was present in the soil, and very little (0.1 to 

 0.3%) was in biotic components. Comparative differences in distributions within the two 

 ecosystems appeared to be related to individual contamination histories and greater 

 physical transport of plutonium in soil to biotic surfaces at Los Alamos. 



Currently most of the plutonium present in terrestrial ecosystems of the United States 

 originates from nuclear weapons testing and from the reentry burnup of the SNAP-9A 

 satellite power source (Hanson, 1975). In the future, however, local ecosystems will 

 receive small quantities of plutonium released from nuclear fuel reprocessing and 

 fabrication facilities. The purpose of this chapter is to compare and contrast the 

 distribution of plutonium in two contaminated ecosystems that are representative of 

 humid and semiarid environments of the United States. Current plutonium inventories for 

 ecosystems several decades after initial contamination can help ecologists forecast the fate 

 of plutonium in the environment. One important question is whether the availability of 

 this element to plants and other organisms will change after it has been subjected to 

 weathering and ecological processes of the environment. Potential radiological toxicity 

 and long physical half-lives of plutonium dictate that its behavior in ecosystems be 

 understood. 



Although the ecosystems at Oak Ridge, Tenn., and Los Alamos, N.Mex., are 

 dissimilar owing to differences in geology, climate, and ecology, there are certain similar 

 features of these contaminated environments. A forested floodplain at Oak Ridge and a 

 canyon at Los Alamos were contaminated by treated hquid waste effluents which have 

 resulted in detectable levels of plutonium in most ecosystem components. However, the 

 discharge and chemical characteristics of plutonium were not similar at Oak Ridge and 

 Los Alamos; therefore it is not possible to conduct a rigorous intercomparison of 

 plutonium behavior in the different ecosystems. Althougli many environmental variables 

 are uncontrolled, a comparative analysis of plutonium in both ecosystems provides insight 

 on patterns of plutonium behavior in the environment. 



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