Bismuth-207 Analyses The solvent extraction techniques of Sill and Willis were used for separating and purifying 207 54. (1965) Bismuth-212 was used as a yield determinant. Plutonium-238, 239 Analyses Plutonium-238,239 was separated by a combination of solvent extraction and anion exchange techniques 1960; Kressin and Waterbury, 1962), with electrodeposition as the final step in the separation. determine yield. (McCowan and Larsen, Plutonium-236* was used to A quantitative separation of plutonium from the coraline soils and sediments is exceptionally difficult and it is therefore essential that 236 Pu be used as a yield determi- nant and that counting be done by alpha spectrometry. Tritium Analyses r Well water samples were measured for tritium content by a liquid scintillation technique with a minimum level of detection of 200 tritium units. RESULTS AND DISCUSSION The predominant radionuclides in the terrestrial organisms 3 are 1 Tos and 90 : . . Sr, whereas the marine organisms contain mainly * Provided by the USAEC Health and Safety Laboratory, New York.