UPTAKE AND LOSS OF RADIONUCLIDES BY FRESHWATER CLAM LAMPSILIS RADIATA (GMEL)

The uptake and loss of radionuclides by the freshwater clam Lampsilis radiata (Gmel.) were studied under natural stream conditions at the Savannah River Plant (SRP). The species, common to the Savannah River, was found to be a good biological indicator of plant-released radionuclides. Specimens in a reactor effluent stream were exposed to very low concentrations of 144Ce, 137Cs, 90Sr, 65Zn, 60Co, 54Mn, 51Cr, and 35S for 91 days, and then transferred to a nonradioactive stream for retention studies. Except for 90Sr, all of the radionuclides studied were concentrated in the soft tissues; only 90Sr, 54Mn, and 137Cs were concentrated significantly in the shells. At apparent equilibrium, concentration factors for soft tissues were 220 for 137Cs, 240 for 35S, 440 for 51Cr, 790 for 60Co 900 for 144Ce, 2400 for 54Mn, and 4100 for 65Zn. The retention study showed that the biological half-life of each radionuclide in the soft tissues consisted of both short and long-lived components (days): 144Ce (2.0, 34), 137Cs (3.0, 38), 65Zn (3.5, 40), 35S (4.8, 44), 51Cr (5.0, 52), 54Mn (2.8, 81), and 60Co (4.8, 277). Short-lived components represented 34–61% of the radioactivity in soft tissues. © 1969 Health Physics Society.