Laboratory investigation of absorption of 54Mn, 57Co, 95Nb, 95Zr and 144Ce by plankton from ocean water

An experimental simulation in laboratory conditions of the absorption of 54Mn, 57Co, 95Nb, 95Zr, and 144Ce radionuclides by plankton and plankton detritus from ocean water (samples were taken from the Indian Ocean) was carried out. The investigated radionuclides of manganese, cobalt and cerium were introduced in ocean water in the form of solutions of their chlorides, and niobium and zirconium radionuclides - in the form of oxalates. Radionuclide concentatrations in the working solutions with plankton were < 10-9 mol/l and were close to the content of their stable isotopes in the investigated ocean water. On the basis of the obtained results a conclusion is made that radionuclides are absorbed by plankton to a different extent and due to different processes. Mn is concentrated by plankton in the process of its vital activity primarily due to the assimilation in tissues of microorganizms, and 57Co, 95Nb and 95Zr - due to the sorption on the surface of hydrobionts, and 144Ce - as a result of a simultaneous occurence of these two processes