Patterns of Transuranic Uptake by Aquatic 

 Organisms: Consequences and Implications 



L. D. EYMAN and J. R. TRABALKA 



Literature on the behavior of plutonium and transuranic elements in aquatic organisms is 

 reviewed. Tlie commonality of observed distribution coefficients over a wide array of 

 aquatic environments (both freshwater and marine) and the lack of biomagnification in 

 aquatic food chains from these environments are demonstrated. These findings lead to the 

 conclusion that physical processes dominate in the transfer of transuranic elements from 

 aquatic environments to man. The question of the nature of the association of plutonium 

 with aquatic biota (surface sorption vs. biological incorporation) is discussed as well as 

 the importance of short food chains in the transfer of plutonium to man. 



For years plutonium and the transuranic elements were considered to be unimportant in 

 ecological transfers and food chains because of their low solubihty and uptake when 

 ingested by mammals. It is true that the mobility and availability of plutonium are 

 limited compared with cesium or strontium, the major concerns for years. However, 

 sufficient information has been developed in the past 5 yr to indicate that plutonium and 

 americium are available to a greater extent than was shown in earlier studies. Current 

 information demonstrates, even with the greater uptake by aquatic biota, that the 

 transuranic elements are not enriched in aquatic food chains but rather are discriminated 

 against. Data on plutonium and americium concentration in aquatic organisms are 

 diftlcult to interpret owing to differing degrees of surface contamination and/or gut 

 loading. Thus true biological accumulation is often masked by these contributions, which 

 frequendy indicate a higher degree of assimilation than is actually the case. 



To assess die potential hazards of transuranic materials released to aquatic 

 environments, such as in low-level waste effluents from fuel-cycle processes and burial 

 grounds, some measure of their environmental behavior is needed, particularly as it relates 

 to the accumulation of these isotopes in man. The following review of the literature on 

 the behavior of plutonium and americium in aquatic environments is intended to provide 

 information on which such an assessment can be based. 



Literature Review 



Emery et al. (Emery, Klopfer, and Weimer, 1974; Emery and Fariand, 1974; Emery et al., 

 1975; Emery et al., 1976) have described the behavior of plutonium and americium in a 

 pond at the Hanford plant. The pond is fed by a plutonium processing plant and laundry 

 wastes with a flow of about 10 m^ of water per minute. Percolation accounts for about 

 95% of the water loss from the pond. The pond is described as an ultraeutrophic system 

 with most of the plant nutrients supplied by laundry wastes. Analyses of sediment from 



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