Concentration of 137Cs, 65Zn,and 85Sr by fresh-water algae

Differences in the concentration and retention of ¹³⁷Cs by unicellular diatoms, filamentous green algae, and filamentous blue-green algae were demonstrated under both batch and continuous-flow culture conditions. ¹³⁷Cs concentration factors were generally higher by a factor of 2 in batch tests than in continuous flow tests. In retention studies, ¹³⁷Cs was desorbed more rapidly from algae under continuous-flow conditions. Studies with blue-green algae indicate that ¹³⁷Cs concentrations in the various species were more closely related to the surface-to-volume ratios of algal cells than to the systematic relationships of the three species. Continuous-flow studies indicated no differences among three species of filamentous green algae in the concentration of ¹³⁷Cs, ⁶⁵Zn, and ⁸⁵Sr. However, the average concentration factors of the radionuclides were considerably different: 3800 for ⁶⁵Zn, 460 for ¹³⁷Cs, and 230 for ⁸⁵Sr. These radionuclides were rapidly desorbed following the transfer of algae to nonradioactive media. The desorption rate was inversely related to the concentration rate.