ANALYTICAL METHODS Gamma-Ray Spectrometry All of the samples were analyzed by gamma-ray spectrometry. They were counted for at least 100 minutes with a 3 x 3-inch NAI(TI) crystal used in conjunction with a 256-channel analyzer. Selected samples were counted for 1,000 minutes, either with a 3 x 3-inch detector or a detector system consisting of two opposing 5 x 5-inch crystals operating as a summing spectrometer. Most of the biological samples were oven dried, ground and compressed in polyvinyl chloride (PVC) pipe to a volume resulting in a density of 1.0. Small samples, spiny lobster hepatopancreas for example, were ashed, dis-— solved in hydrochloric acid, and sealed in PVC pipe. Oven-dried soil samples were compressed to a density of 1.35 in PVC pipe. Spectrum resolution was done by Schonfeld's (1965) method of least squares. A set of previously prepared reference spectra for the different geometries and radionuclides were used. All values were corrected for decay to the date of collection. The error given for individual values is the two-sigma, propagated counting error. Strontium-90 Analyses Strontium-90 was determined by measuring the equilibrium concentration of its 2°y daughter. Yttrium-90 was separated by solvent extraction and precipitation techniques (Petrow, 1965), with stable yttrium serving as both a carrier and a yield determinant. Recoveries ranged from 80% to 100%. Iron-55 Analyses Iron-55 was separated and purified by a combination of solvent extraction and electrodeposition techniques (Palmer and Beasley, 1967). Recoveries generally exceeded 90%. Counting was done by x-ray spectroscopy with a proportional counter in conjunction with a multichannel analyzer. Bismuth-207 Analyses The solvent extraction techniques of Sill and Willis (1965) were used for separating and purifying 207Bi. 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 (McCowan and Larsen, 1960; Kressin and Waterbury, 1962), with electrodeposition as the final step in the separation. Plutonium-236* was used to determine yield. A quantitative separation of plutonium from the coralline soils and sediments is exceptionally difficult and it is therefore essential that 7°°Pu be used as a yield determinant and that counting be done by alpha spectrometry. SHOT OL a ae * Provided by the USAEC Health and Safety Laboratory, New York. =a wee See eee oe eeese 3.