Curium-244 and Americium-241 Uptake in Freshwater Fish

Laboratory experiments were performed to determine the biological uptake of the transuranium radionuclides curium-244 and americium-241 in rainbow trout, Salmo gairdneri Richardson. Uptake from water in fish was measured after 7 days. The uptake in synthetically prepared water with added natural organic matter (4 mg Dissolved Organic Carbon/1) was compared with uptake in water without organics. Accumulation of the radionuclides by the fish, measured after an uptake period of 7 days, yielded concentration factors (CF = radioactivity kg^-1 animal wet weight/radioactivity l^-l water) ranging on average from 0.12 to 0.47 for Cm and from 0.06 to 0.42 for Am. The highest CF values are measured in the gills (1.30 to 6.80 for Cm and 0.87 to 4.85 for Am) while in the liver CF values ranged from 0.14 to 1.5 for Cm and from 0.05 to 1.3 for Am. The relative distribution of both radionuclides among the tissues did not vary with the water type. But Cm and Am concentration factors were 5 to 30 times lower in tissues from animals in water with organic matter. These latter observations point to the importance of the presence of organic material in water for decreasing the bioavailability of transuranium radionuclides.