milk from the same nuts was 135 (y/min)/gm. Ripe coconut meat from Sifo indicated 85 (y/min)/gm while a green kerne] from the pandanus fruit emitted 47 (y/min)/gm as ghown in Table 1.9. An entire coconut crab from Sifo exhibited 205 (y/min)/gm of Cs*", ce, and Ru. The separation of elements among various organisms is shown in Figures 1.1, 1.2, Ashes from the meat of severa)] Enyu coconuts are shown in Figure 1.4 to 1.$ and 1.4. contain almost exclusively Cs", The body of a brown rat from the same area, caught with @ coconut-baited trap, exhibited both Cs" and Zn". The pye concentrations of the isotopes present in the coconut meat and brown rat are presented in Table 1.11. The rat which apparently fed on coconuts and plants containing Cs’, probably also fed on marine organisms containing Zn". 1.6.8 Air~borne Radioactivity. Air was drawn through a Type AA milliporefilter at the rate of 10 liter/min for periods of 100 minutes or longer at a number of stations in the lagoons and in the open sea. During the radioactivity background survey prior to Shot Cherokee, no air-borne radioactivity was detected. 1.7 CONCLUSIONS AND RECOMMENDATIONS Radioactive contamination was detected throughout the EPG. The range of distribu- tion of radioisotopes was Cs"! in coconuts, Cs"" and Zn®* in land organisms, Ceand Ru" in soil and beach sand, Ceand Ru’ in lagoon water and suspended particulate matter, Zn® in surface fish, Co™ in mollusks, Zn** and Co®in bottom fish, Ce! and Ruin coral and calcareous algae, and Ceand Ru! in bottom sediments. The greatest concentration of radionuclides was found in clams, fish, and sediments. The least activity was detected in the oceanic water and no activity was detected in the | air. The results obtained indicated that widespread radioactive contamination, non- uniform in amount and isotopic content, existed in the proving grounds during Apri} 1956. A separation of the fission products had taken place with concentrations of specific isotopes in specific phases. Hundred to thousandfold concentrations of radiocobalt and radiozinc were observed in clams and fish. The radioactive contamination of the sea water was low, while the zooplankton showed a hundredfold increase of radioactivity over that of the water. The most predominant radionuclides detected in living organisms were Zn", Co*! and Co®, none of which are fission products. The greatest tota) mass of radioactivity was found to be the Ce™ and Ru!” distributed over the ocean and lagoon floors. The study of the water mass movements in the EPG before the test series was the primary task of the Scripps’ vessel Horizon. Samples for radioactivity studies were collected whenever possible during the water mass survey. Because of this, the radioactivity samples were not necessarily taken in the proper places for a complete survey of this type. . Also, because of the limited equipment and personnel available for radioactive sample collection and analyses, the results cannot be used to give more than an indication of the distribution of radioactivity in the proving groundsprior to the test series. It is recommended that a more thorough study be made of the separation of the fission products over a period of time in the ocean with emphasis on the final deposition of the radionuclides in the sediments and in the food chain. A study should be undertaken in the laboratory and in the field to determine the metabolic pathway of the long-lived nuclides through the food chain. In order to determine oceanic fallout contours, it is necessary to perform numerous Ps a