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

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RADIOLOGICAL RESURVEY OF AT BIKINI ATOLL, 1969 University of Washington College of Fisheries Laboratory of Radiation Ecology Work dcne under Contract AT(26-1)-269 with the United States Atom.i.cEnergy Commission

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The results of radiometric and radiochemical analyses of s~mples, exclusive of land plants, collected at Bikini Atoll in 1969 are presented and discussed. Average values for radionuclides in food items in pCi/g wet are: reef fish, 60co-2ti6, Average concentrations of 90Sr in the muscle of coconut crabs from Bikini and Enyu Islands were 12 pCi/g wet and .05 pCi/g wet, respective ly. There the 1967 and 1969 average origin, including the sea undisturbed soils in 1969 are no striking differences between values for edible foods of marine 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 60Co and 207Bi is being transported eastward by the bottom current in the lagoon. Silver-108m, previoub ly 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 Average Values of Radionuclides in Food Items Other than Land Plants Radionuclides in Eviscerated Whole Fish, Average Gamma-Emitting Radionuclides in Viscera of Reef Fish, Average Vslues Gamma-Emitting Radionuclides in Coconut Crabs, Gamma-Emitting Radionuclides in Spiny Lobsters, Gamma-Emitting Radionuclides in Giant Clams, Radionuclides in the Surface One-Inch of Soil Radionuclides in Soil Collected from the Most Radioactive Part of Eneman Islet Radionuclide”s in Soil Collected on the Seaward Shore of Eneman Islet 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 Eviscerated whole Reef Fish Viscera of Reef Fish Coconut Crabs from Bikini Island Coconut Crabs from Enyu Island Coconut Crabs from Oroken Island 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

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RADIOLOGICAL RESURVEY OF AN:XALS, SOILS AND 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, then to Kwajalein Atoll; in November, 1948, a final move was made to Kili Isla~d. that at Bikini Atoll to Kili is difficult, The land area at Kili is about one–tenth and there is no lagoon. Therefore, access often impossible, and sea foods are scarce. The results of a radiological resurvey of 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 the Atomic Energy Commission’s Health and Safety Division of Biology and Medicine, the U. S. Naval Radiological

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/“““Defense Laboratory, the Trust The data were summarized panel of experts assembled by Territory, and the University by DBM and were presented to a DBM for evaluation of potential radiological hazards. Most of the participants in the 1967 “survey attended the presentation to provide details not included in the summary. The panel concluded that Bikini co’uld be safely reoccupied, but recorrunendedsome restrictions and suggested things to be done to rehabilitate the atoll. These included restriction of coconut crabs from the diet, because they contain high concen90~rtrations of , 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 and Enyu Islets, especially, made it impractical to survey more than a few transects across the The panel’s recommendations were made to the Atomic Energy Commission who informed 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 This report presents the results of the 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. 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 three feeding habits: the mullet,* a plankton feeder; the convict surgeonfish, a grazing goatfish, a bottom-feeding carnivore. The found in fish and their concentrations are herbivore; and the 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 as representative 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 caught in or near Enyu Pass. Bikinians who were clean-up crew cut filets from the yellowfin tuna them by salting. They said tuna is one and, presumably, would fish for tuna if The invertebrates sampled were the tuna. All were part of the they return to Bikini. hippopus) . Some of the species centimeters in length, * For a list of common of Tridacna never exceed a few species were found

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h the vicinity of Nam (&arlie) Islet. The larger species were found near Bikini Island. In response to a special request to check the levels of radioactivity at Aeroko-j Islet, received during the survey, the land hermit crab, a Since coconut crabs known concentrator of 90Sr, was collected. 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 Both the birds and their eggs will be used as 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 radionucl’ides 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 was collected by driving half-inch pipe with the soil. The well point sites on Bikini and

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Eneman Islands were in areas found to be the most by the U. S. Public Health Service personnel. On well point was driven in a low area near the center of the island. Existing wells were sampled at Enyu. 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(Tl) 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

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resulting in a density of 1.0. Small 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”u resolution was done by Schonfeld’s (1965) method of least squares. A set of previously prepared reference spectra for the different geometries and radionuclides was used. All “ values were corrected for decay to the date of collection. The error given for individual values is the 9570 error. Strontium-90 was determined by measuring the equilibrium 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 was done by X-ray spectroscopy with a exceeded goyo. Counting proportional counter in con-junction with a multichannel analyzer.

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The solvent extraction techniques of Sill and Willis (1965) used as a yield determinant. Plutonium-238,239 was separated by a combination of solvent extraction and anion exchange techniques (McCowan and Larsen, the final step in Waterbury, 1962), with electrodepcsition as the separation. Plutonium-236* was used to A quantitative separation of plutonium from the coraline soils and sediments is exceptionally difficult and 236it is therefore essential that Pu 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. RESULTS AND DISCUSSION The predominant radionuclides in the terrestrial organisms are 137CS and ‘0 Sr, whereas the marine organisms contain mainly * Provided by the USAEC Health and Safety Laboratory, New York. ., I

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co and . The concentrations of these radionuclides in I edible portions of organisms range from undetectable amounts to the following maximum values: 137CS - 2260 pCi/g dry in the muscle tissues of a curlew 90Sr - 204 pCi/g dry in the hepatopancreas of a coconut crab from Bikini I. 60C0 - 219 pCi/g dry in muscle and mantle tissue of a giant clam near Bikini 1.

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The mean values for , f diet items at Bikini Atoll in 1967 were given in the Report on Bikini Atoll by Gustafson in 1968, and are Table 1 with the average values determined from the 1968 samples. omitted from Table 1 because no detectable amounts of these radionuclides were found in the 1969 samples, and Fe has been added, by using values for 1967 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

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clams were available in 1967, but the maximum value for 60Co in the edible portion of clams in 1964 was 73 pCi/g The land crabs are listed separately for Bikini I. 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 1. in 1969 were analyzed for 90Sr 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 birds 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 and 1969 average values of radionuclides for edible portions of foods of marine origin, including the sea birds. The differences tend to show a decline in radionuclide content in 1969, but there are not sufficient reasonable estimate of rates data to provide a basis for a of decline because of the large variability in the data and the many poorly defined factors involved in the uptake and retention of radionuclides by organ– isms in the natural environment of Bikini. Some basic biological information such as rates of growth and life spans of the

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fishes is not known and the chemical form nuclides are present in the lagoon waters We do not even know, for example, whether in which the radioand their stable isotopes are present in the Furthermore, there are no incontestable data can only be surmised. same chemical form. on the trace element content of lagoon waters and probably will not be until the techniques of sampling and processing seawater samples is greatly improved. However, some hypotheses can be made can”be drawn from certain data. All of the fallout radionuclides at Bikini are found in the surface of undisturbed soils. The predominant radionuclides In the crater sediments only four predominate: 55Fe 60C0 90Sr and 207Bi, although many more are present in smaller quantities. The soils and sediments are now the principal reservoirs of radionuclides at Bikini. The radionuclides are available to the land animals through the vegetation, or other animalsl where there is selection of specific radionuclides, or …