during the Hardtack test series. Rhodium-102 was detected in the sample and the identity of the isotope was confirmed by several radiochemical techniques and by gamma energy determinations. The amount of the isotope was related to the levels of fission products in the sample. Radiochemical separations were made on samples of sea water and bottom material collected in the target area of a nuclear device detonated inside of Eniwetok lagoon. The sea water was divided into particulate and soluble fractions. Samples of bottom material were treated with eighteen different eluents over a pH range of 1 to 13 and the amounts of cobalt-60, conium-95, ruthenium-106, cerium-144, zir- and stable calcium re- moved by the different eluents were determined. Samples of plankton and water collected during the Rehoboth, Collett, and Silverstein surveys were subjected to radiochemi- cal and gamma spectrum analyses. The Rehoboth data have been published and the Collett-Silverstein paper is almost completed. The radioisotope content in the organs of the clams Tridacna and Hippopus was related to the amounts of stable elements same samples. of individual in the The effects of stable element content on uptake radioisotopes were studied by this method. A survey paper on the marine biological investigations at the Eniwetok Test Site was prepared for presentation at the Monaco

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