Radiological Resurvey of Animals, Soils and Groundwater at Bikini Atoll, 1969

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University of Washington College of Fisheries Laboratory of Radiation Ecology Work done ur,der Contract AT(26-l)-269 with the United States Atomic Energy Cm-mission

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The results of radiometric and radiochemical analyses of samples, exclusive of land plants, collected at BikinL Atoll in 1969 are presented and discussed. Average values for radionuclides in food items in pCi/g wet are: reef fish, 6oCo-2.6, ea.. Average concentrations of gOSr in the muscle of coconut crabs from Bikini and Enyu Islands were 12 pCi/g wet and -05 pCi/g wet, respectively. There are no striking differences between the 1967 and 1969 average values for edible foods of marine origin, including the sea birds. Predominant radionuclides in _ 207Bi predominate. There are quantitative and qualitative differences in radionuclide content associated with the feeding habit of fish and there appears to be an increasing concentration of some radionuclides with increasing age of fish and clams, The radionuclide content of bird species presents a sharp contrast, both qualitatively and quantitatively, associated with feeding habit. It appears that some 6oCo and 207 Bi is being transported eastward by the bottom current in the lagoon. Silver-108m, previously unreported in fallout, was found in the hepatopancreas of the spiny lobster, The present levels of radionuclides and their distribution at Bikini are not likely to change significantly except for decrease in amounts, due to physical decay.

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Selection of Samples and Sampling Sites 3 Results and Discussion 8 1. Average Values of Radionuclides in Food Items Other than Land Plants 21 2. Radionuclides in Eviscerated Whole Fish, Average Fish, Average Vslues Viscera of Reef Radionuclides in the Surface One-Inch of Soil Radionuclides in Soil Collected from the Most Radioactive Part of Eneman Islet 30 Radionuclides in Soil Collected on the Seaward Shore of Eneman Islet 31 Strontium-90 in Samples Collected at Bikini Atoll, March, June, August 1969 (see also Table 2 for

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Bismuth-207 in Soils and Sediment Collected at Plutonium in Soil, Sediment and Fish Collected. at Bikini Atoll, 1969 . Tritium and Cesium-137 in Well Water ,Samples Collected at Bikini Atoll, June 1969 Iron-55 in Biological Samples Collected at Bikini Atoll, June 1969. Average Values Gamma-Ray Spectrum of Sediment from Opposite Bravo Crater, Collected at a Water Depth of 160 Feet, August, 1969 pancreas From Bikini Atoll, 1969 Opposite Eviscerated Whole Reef Fish Viscera of Reef Fish Coconut Crabs from Bikini Island Coconut Crabs from Enyu Island Coconut Crabs from Oroken Island Giant Clams Oepartment of EnmY Eviscerated Whole Reef Fish Coconut Crabs from Bikini Island Coconut Crabs from Enyu Island Coconut Crabs from Oroken Island Iron-55 in Samples Collected at Bikini Atoll, 1969 List of Common and Scientific Names of Organisms Sampled at Bikini, 1969

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.RADIOLOGICAL RESURVEY OF ANIMALS, SOILS AND GROUNDWATER AT BIKINI ATOLL, 1969 Bikini Atoll was a site for atmospheric tests of nuclear devices from 1946 to 1958. The population of 166 Bikinians was moved from the atoll in March, 1946, first to Rongerik Atoll,IL then to Kwajalein Atoll; in November, 1948, a final move was made to Kili Island. The land area at Kili is about one-tenth that at Bikini Atoll and there is no lagoon. Therefore,. access to Kili is difficult, often impossible, and sea foods are scarce. The results of a radiological resurvey o'f Bikini in 1964 by of Washington's Laboratory of Radiation Biology Bikini might be radiologically safe for permanent request from the High Commissioner of the Trust the Pacific to the Atomic Energy Commission in 1966 to rehabilitate Bikini resulted in an extensive survey of the atoll in the spring of 1967. This survey emphasized external radiation measurements, including in situ gamma-ray spectrometry,-- although some food items were collected to supplement data from the 1964 survey.- The 1967 survey party included personnel from the Atomic Energy Commission's Health and Safety Laboratory, the Division of Biology and Medicine, the U. S.

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Defense Laboratory, the 'Trust Territory, and the University The data were summarized by DBM and were presented $0 a panel of experts assembled by DBM for evaluation of potential radiological hazards. Most of the participants in the 1967 survey attended the presentation to provide details not included Bar in the summary. The panel concluded that Bikini could be safely reoccupied, but recommended some restrictions and suggested things to be done to rehabilitate the atoll. These included restriction of coconut crabs from the diet, because they contain high concentrations of 90 Sr, and covering the village area at Bikini Island with coral gravel from the beaches, to provide a shield against radiation from the soil. The panel also recommended that old structures and other such debris from the tests be removed from the islands and beaches and that the island be further monitored during the clean-up. Additional monitoring was necessary because dense vegetation on Bikini impractical to survey more and Enyu Islets, especially, made it than a few transects across the The panel's recommendations were made to the Chairman of the Atomic Energy Commission who informed the Secretary of the Interior, the administrator for the Trust Territory of the

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The clean-up phase of the rehabilitation of Bikini Atoll was begun in February, 1969, by Joint Task Force Eight. The AEC Nevada Operations Office is responsible for certification of the clean-up portion of the rehabilitation program, which was carried out under guidelines approved by the AEC Division of Operational Safety. At the request of NVOO, the U. S. Public Health Service took the responsibility for external radiation measurements, and ,for the collection and analysis of those land plants which are food items; the U of W Laboratory of Radiation Ecology was asked to sample and analyze other biological and environmental samples. This report presents the results of the SELECTION OF SAMPLES AND SAMPLING SITES The sampling program was based on the objective of obtaining data for evaluation of potential radiological hazards to man. The samples were limited, for the most part, to things which might be eaten by returning Bikinians, except for land plants. Some additional samples, for example soils, crater sediments and ground water, were taken to provide data for estimating the future distribution and amounts of radionuclides in the biota. DepartmentofEnergy The fish collected are in two main categories: the reef fish and the pelagic, or "troll-caught" fish. "The reef fishes are usually collected by throw nets by the Marshallese and are

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important items in their diet. Of the more than 700 species of reef fishes at Bikini Atoll, we selected three species commonly eaten by.,the Marshallese and representative of three feeding habits: the mullet,* a plankton feeder; the convict surgeonfish, a grazing herbivore; and the goatfish, a bottom-feeding carnivore. The specific radionuclides - found in fish and their.concentrations are often associated with feeding habit, hence this was a necessary consideration in selecting samples representative of the kinds of fish which would be eaten when the Bikinians return. A fourth kind of reef fish, groupers, was also collected a-a resprescntative of the higher The troll-caught fishes are all high-order carnivores and fall into two broad subcategories: resident lagoon fish, ulua and dogtooth tuna: and migratory fish, yellowfin tuna. All were caught in or near Enyu Pass. Bikinians who were part of the clean-up crew cut filets from the yellowfin tuna and preserved them by salting. They said tuna is one of their favorite fish and, presumably, would fish for tuna if they return to Bikini. The invertebrates sanpled were the spiny lobsters (langouste), hippopus). Some of the species of Tridacna never exceed a few centimeters in length, and only the smaller species were found * For a list of common names and scientific names, see

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in the vicinity of Nam (Charlie) Isiet. The larger species were found near Bikini Island. In response to a special request to check the levels of radioactivity at Aerokoj Islet, received during the survey, the land hermit crab, a known concentrator of gCSr, was collected. Since coconut crabs are both an indicator organism and a food item, they would have been sampled instead of hermit crabs, but coconut crabs were not found on Aerokoj. Thousands of terns nest at Bikini Atoll, mostly on the western islets. Both the birds and their eggs will be used as 'food. The terns almost always feed at sea, outside the lagoon or reefs. On the other hand, the curlews and turnstones feed along the shores and on the reef, and the curlew also eats the seeds of an endemic shrub, Scaevola serica, or the'beach magnolia. Although the curlews and turnstones are transients and are present in small numbers, at most a few hundred, they contain the highest levels of radionuccides among the birds. Curlews, turnstones, noddy terns, and fairy terns were sampled. Rats are not used as food but they are the only mammal living on the atoll, and a few were taken to determine their collected by driving half-inch pipe with well points into the soil. The well point sites on Bikini and

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Eneman Islands were in areas found to be the most radioactive by the U. 6. Public Health Service personnel. On Nam I. the well'point was driven in a low area near the center of the island. Existing wells were sampled at Bnyu. Attempts to obtain groundwater at Aerokoj were unsuccessful. Soil samples were taken by one-inch depth increments to - depths of ten inches or more near each well point. All depth increments for two sets of samples from Eneman were analyzed but only the surface one-inch of other sets of samples were analyzed. In addition to samples from soil pits at the well points, surface samples also were taken at Aomen and Oroken. Sediments from the Bravo Crater were taken by dredge from depths of 40, .120, 140; and 160 feet. 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(T1) 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 S-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

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resulting in a density of 1.0. Smal.%samples,' spiny lobster hepatopancreas for example, were ashed, dissolved in.hydrochloric acid, and sealed in PVC pipe. . Oven-dried soil samples were compressed to a density of Spectr'umresolution was done by Schonfeld's (1965) method of least squares. A set of previously prepared reference spectra for the different geometrie's and radionuclides was used. All values were corrected for decay to the date of collection. The error given for individual values is the 95% error. Strontium-90 was determined by measuring the equilibrium concentration of its 90Y 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 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.

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.- _. The solvent extraction techniques of Sill and Willis (1965)' used as a yield determinant. R Plutonium-238,239 was separated by a combination of solvent extraction and anion exchange techniques (McGowan 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 coraline soils and sediments is exceptionally difficult and it is therezore essential that 236Pu be used as a yield determinant and that counting be done by alpha spectrometry. Well water samples were measured for tritium content by a liquid scintillation technique with a minimum level of detection of 200 tritium units. I The predominant radionuclides in the terrestrial organisms are 137Cs and go Sr, whereas the marine organisms contain mainly * Provided by the USAEC Health and Safety Laboratory, New York.

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edible portions of organisms range from undetectable amounts to the following maximum values: . . - 2260 pCi/g dry In the musclk tissues of a curlew . "5, - 204 pCi/g dry in the hepatopancreas of a coconut 6oC0 - 219 pCi/g dry in muscle and mantle tissue of a giant 55Fe - 40,900 pCi/g dry in the liver of an ulua. The range in the amount of a radionuclide in the same tissue from the same species at the same islet is wide. When and maximum values and sometimes by a of radionuclides are present, the minimum often differ by factors of four or five factor of ten. The values for concentration of radionuclides in individual samples are given in Tables 1 through 15. Average values and ranges are weights were used for-the basic calculations because water content of some samples is difficult to determine. The average concentrations of radionuclides were converted to a wet-weight basis for convenience in calculating daily intake from the diet; the conversions were made by using average wet to dry weight ratios for each kind of sample.

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Report on Bikini Atoll by Gustafson in 1968, and are listed in Table 1 with.,the average values omitted from Table 1 because no radionuclides were found in the I added, by using values for 1967 determined from the 1968 samples. detectable amounts of these 1969 samples, and 55Fe has been samples from an addendum to the' The 1967 values for fish include reef fish and troll-caught fish, whereas the 1969 data in Table 1 are for reef fish only. The average values for 60Co in the muscle of.troll-caught fish Yellowfin tuna 0.15 pCi/g wet Thus, the 1969 values for fish in Table 1 are greater than if the values for troll-caught fish were included in the averages. In Table 1 the data for giant clams are for 1969 samples taken from the vicinity of Bikini I. Clams were also collected around Nam I. but they were of a small species which is rarely eaten; also, the level of 60 Co in the Nam I. clams was lower than in the Bikini I. clams, presumably because the latter were older clams which had accumulated 60Co for several years. No

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data for clams were available in 1967, but the maximum value for 6oCo in the edible portion of clams in 1964 was 73 pCi/g . The land crabs are listed separately for Bikini.1. and Enyu I. because the panel convened by the DBM in 1968 recommended, on *the basis of the data then available, that coconut crabs be omitted from the Bikini diet. Thirteen crabs collected at Enyu I. in 1969 were analyzed for 90 Sr and gamma emitters; the levels of all radionuclides are sufficiently low that a reconsideration of the restriction for Enyu I. is indicated. The species of birds are listed separately for 1969 because an average value for all bird&would be a poor estimate of the potential intake, since few curlews or turnstones are available. In general, there are no striking differences between the 1967 …