UPTAKE BY AQUATIC ORGANISMS 617 



values for Lake Ontario which ranged from 2000 to 2700. Observed differences in CR 

 values for plankton reported in these two studies have not been resolved. Bowen (1974) 

 and Marshall, Waller, and Yaguchi (1974) reported that benthic feeders accumulate 

 plutonium to higher levels than limnetic feeders. Some predator species (i.e., largemouth 

 bass, rock bass, white perch, and coho salmon) deposit most of the plutonium in the 

 bone, whereas other forms (i.e., northern pike, yellow perch, and freshwater drum) 

 deposit plutonium primarily in the liver. These apparent differences in tissue distributions 

 between species have not been satisfactorily explained. 



Dahlman, Bondietti, and Eyman (1976) reported on the behavior of plutonium in the 

 biotic components of White Oak Lake. Results from analyses of various components of 

 the lake system support the finding by Marshall, Waller, and Yaguchi (1974) in Lake 

 Michigan, i.e., decreased concentrations of plutonium at higher trophic levels (Table 5). 



TABLE 5 Concentrations of ^ 3 9 ,2 4 op^ ^^^ Concentration 

 Ratios for Fishes from White Oak Lake 



Species 



Plutonium content 



Carcass* 



Gl tract 



Concentration ratiot 



pCi/g 



Standard error 



pCi/g 



Standard error CR Standard error 



Largemouth bass 2x10 " 



BluegiU 1 X 10"^ 



Goldfish 1 X 10-^ 



Shad 2x10"' 



6x 10" = 

 8 xlO-" 

 1 xlO"^ 

 3 xlO"' 



6x10-^ 

 4 xlO-" 

 8 xlO-^ 

 4 X 10-' 



4x 10-" 

 5 X 10-5 

 3 xlO-' 

 7 X 10-^ 



0.04 

 3 

 3 

 4 



0.2 

 2 

 3 

 0.1 



*Total fish minus Gl tract. 



fConcentration ratio (CR) is defined as [plutonium] in organisms (wet weight)/ [plutonium] in 

 water. Water concentration of plutonium used in the calculation of CR values is 4 x lO"" pCi/g. The 

 CR values are for carcass. 



Organisms living in or on the bottom of sediments in the White Oak Lake (filamentous 

 algae and benthic invertebrates) have plutonium concentrations that are two or three 

 orders of magnitude higlier than those in predatory fish, such as largemouth bass and 

 bluegill. Filamentous algae associated with sediments in shallow areas of White Oak Lake 

 had the highest concentration of plutonium of any biotic component measured. 

 Gastrointestinal contents of goldfish, gizzard shad, and bluegill had plutonium concentra- 

 tions intermediate between those of sediment and food organisms, which indicates the 

 importance of sediment as a dietary source of plutonium. Further evidence of sediment 

 ingestion by these fish was the fact that the ^^^Pu/^^^Pu ratio of gut contents was 

 similar to that measured in sediments. 



Long-term, chemically and/or biologically mediated transformations of plutonium 

 compounds may be expected to occur in aquatic systems. These transformations may 

 result in plutonium being complexed by naturally occurring chelating agents, such as 

 carboxyhc acids (citrate), fulvic acids, or proteins. Several laboratory experiments were 

 carried out at Oak Ridge (Eyman, Trabalka, and Case, 1976; Eyman and Trabalka, 1977; 

 Trabalka and Eyman, 1976) to determine the uptake and distribution of monomeric 

 plutonium (IV) in chelated forms both in an aquafic vertebrate, the channel catfish 

 Ictalums punctatus, and in a littoral aquafic microecosystem. A primary finding was that 

 the gastrointestinal intake by catfish was significantly higher than that reported for 



