Radiological Resurvey of Animals, Soils and Groundwater at Bikini Atoll, 1969-1970 - Revision 1

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1 wish to thank the staff of the Laboratory of Radiation Ecology, whose work produced the data that made this report possible. I wish especially to thank Dr. Thomas Beasley, who supervised all of the radiochemical analyses and who did many of them himself. Dr. Allyn Seymour and Dr. Beasley were of great help in planning the collections and in interpreting the results of the survey. I atn grateful to Dr. Beasley, Rodney Eagle, Terrence Jokela, and Raymond Lusk for their part in the field collections. I appreciate the cooperation of personnel of Joint Task Force Eight and Holmes & Narver, Inc., and recognize that the field collections would not have been successfully completed without their help. We exchanged samples in the field with Drs. John Harshbaw= and Donald Squires of the Smithsonian Institution and thank them for samples of coconut crabs from Oroken Island and rats from Bikini Island. Dr. Jack Tobin, Trust Territory of the Pacific, made valuable suggestions regarding the collections and was instrumental in obtaining the services of two Bikini people to assist with the collections. William Moore, U.S. Public Health Service, accompanied us during most of the collections and pointed out areas giving the highest external radiation measurements; well water and soil samples were collected from The final guidelines for the survey were developed during a preliminary survey of Bikini Atoll in March, 1969 with Frank Cluff and Donald Hendricks, Nevada Operations Office, and Alan Smith, U.S. Public Health Service.

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The results of radiometric and radiochemical analyses of samples, exclusive of land plants, collected at Bikini Atoll in 1969 and 1970 are presented and discussed. Average values in pCi/g wet for radionuclides in food items collected in 1969 were: reef fish, 60C0-z.6> ‘“sr-.oas 137CS-.13; nut crabs from Bikini and Eneu Islands were 12 pCi/g wet and .05 pCi/g wet, respectively. There are no striking differences between average values for edible foods of marine origin, including the sea birds> compared with values reported in 1967. Predominant radionuclides in undisturbed soils in 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, previously unreported in fallout, was found in the hepatopancreas of the spiny lobster. Tritium levels in groundwater are within the range of values for continental surface water samples. The present levels of radionuclides and their distribution at Bikini are not likely to change significantly except for decrease in amounts, due to

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I TABLE OF CONTENTS I 2. Selection of Samples and Sampling Sites I 4. Results and Discussion [ 1. Radionuclides in the Surface One-Inch of Soil Collected at Bikini Atoll, June 1969. 18 I 2. Radionuclides in Soil Collected from the Most Radioactive Part of Eneman Islet, June 1969. 19 I 3. Radionuclides in Soil Collected on the Seaward Shore of Eneman Islet, June 1969. 20 Soils Collected June 1970, Bikini Island. 21 5. Gamma-Emitting Radionuclides in Soil from Well Point 4, Bikini Island, Collected June 1970. 26

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TABLE OF CONTENTS Plutonium and Cesium-137 in the Surface One Inch of Bikini Atoll Soils and Bravo Crater Sediment. Cesium-37 in Rat Tissues Collected at Bikini, June lected at Bikini Atoll, June 1969. Strontium-90 in Samples Collected at Bikini Atoll, March, June, August, 1969. lected at Bikini Atoll, June 1969. Radionuclides in Eviscerated Whole Reef Fish Collected at Bikini Atoll, June 1969. Gamma-Emitting Radionuclides in Viscera of Reef Fish Collected at Bikini Atoll, June 1969. Gamma-Emitting Radionuclides in Goatfish Collected at Nam Island, Bikini Atoll, May 1970. Bikini Atoll, March and June 1969. Strontium-90 in Eviscerated Whole Reef Fish Collected at Bikini Atoll, June 1969. Cobalt-60 in Tridacna and Hippopus (Giant Clams) Collected at Bikini Atoll, June 1969. Gamma-Emitting Radionuclides in Birds Collected at Iron-55 in Biological Samples Collected at Bikini Atoll, Bismuth-207 in Soils and Sediment Collected at Bikini List of Common and Scientific Names of Organisms Collected at Bikini Atoll, 1969.

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TABLE OF CONTENTS 3. Gamma-ray Spectrum of Sediment from Bravo Crater 4. Gamma-ray Spectrum of Spiny Lobster Hepatopancreas

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Bikini Atoll was a site for atmospheric tests 1946 to 1958. The population of 166 Bikinians March, 1946, first to Rongerik Atoll, then to 1948, the Bikini people moved to Kili Island. of nuclear devices from was moved from the Atoll in Kwajalein Atoll; in November, 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 seafoods are scarce. The results of a radiological resurvey of Bikini in 1964 by the University of Washington’s Laboratory of Radiation Biology indicated that Bikini might be radiologically safe for permanent habitation (Welander, 1967; Welander et al., 1967). A request from the High Commissioner of the Trust Territories of 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 Laborato~, the Division of Biology and Medicine, the U.S. Naval Radiological Defense Laboratory, the Trust Territory, and the University of The data were summarized by DBM and were presented to 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 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 include reduction of coconut crab population, because of high content of ‘OSr, and covering the village area at Bikini Island with coral gravel from the beaches, which is consistent with local custom and provides 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 cleanup. Additional monitoring was necessary because dense vegetation on Bikini and Eneu Islets, especially, made it impractical to survey more than a few transects across the islands in 1967. The panel’s recommendations were made to the Chairman of the Atomic Energy Commission, who informed the Secreta~ of the Interior, the administrator for the Trust Territory of the Pacific. 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 was 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 Enviro.pmental

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Protection Agency’s Western Environmental Research Laboratory (EPA/WERL, formerly USPHS/SWERL) took the responsibility for external radiation measurements, and for the collection and analysis of those land plants that are food items; the U of W Laboratory of Radiation Ecology was asked to sample and analyze other biological and environmental samples in 1969. Additional samples were collected in 1970, with the emphasis on air filters and soil samples. The former were analyzed and reported by the EPA (SWRHL-lllr). This report presents the results of the Laboratory’s 2. 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 that might be eaten by returning Bikinians, except for land plants. Additional samples, for example> soils, crater sediments and groundwater, were taken to provide data for estimating the future distribution and amounts of radionuclides in the 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 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 that would be eaten when the Bikinians return. A fourth kind of reef fish, groupers, was also collected as representative of the higher order carnivores. 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 Eneu 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, presu~bly, would fish for tuna if they return to The invertebrates samples were the spiny lobsters (langouste), coconut crab and “giant” clams (Tridacna sp., and Hipp opus hipp opus) . Some of the species of Tridacna never exceed a few centimeters in length, and only the smaller species were found in the vicinity of Nam (Charlie) Islet. The larger species were found near Bikini Island. * For a list of common names and scientific names, see Table 20.

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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 ‘“ST, 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 terms 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 radionuclides among the birds. Curlews, turnstones, noddy terns, and fairy terns Rats are not used as food but they are the only mammal living on the Atoll, and a few were taken to determine their radionuclide content. Groundwater was collected by driving half-inch pipe with well points into the soil. The well-point sites on Bikini and Eneman Islands were in areas found to be the most radioactive by the EPA/WERL personnel. On Nam I., the well point was driven in a low area near the center of the Island. Existing wells were sampled at Eneu. Attempts to obtain groundwater at Aerokoj were unsuccessful. Water samples were collected from existing wells at Eneu 1. and from the cisterns constructed at Bikini I. in 1969. In 1969, 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 anlayzed but only the surface one inch or 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 In 1970, composite soil samples were taken to a depth of one inch from undisturbed and disturbed areas along rows at Bikini I. and on representative transects east and west of the airstrip at Eneu 1. (Figs. 1 and 2). The subsamples combined in each composite sample were taken at intervals of 100 paces with coring devices of 3.5 inches diameter and one-inch depth. One north-south transect and one east-west transect were resampled and the subsamples were retained and analyzed individually to indicate the variability between subsamples. In the Base Camp area on Bikini Island, 16 samples were taken at 25-foot intervals on a 100 x 100-foot grid and combined as a composite sample. h additional 20 samples were taken and retained as individual samples for gamma-ray spectrum analysis. Samples from soil profiles were taken at well points 1, 4, and 5.

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WELL POINT & SOIL PIT LOCATIONS AIR SAMPLE STATIONS DISTURBED & UNDISTURBED SOIL COMPOSITE SAMPLES OF EACH DISTURBED SOIL– COMPOSITE SAMPLES UNDISTURBED SOIL – INDIVIDUAL CORES SCALE 1 inch = 800 feet FIGURE,1.

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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, dissolved 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 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. 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 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 236Pu be used as a yield determinant and that counting be done by alpha spectrometry. * Provided by the USAEC Health and Safety Laboratory, New York.

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Well water samples were measured for tritium content by a liquid scintillation technique with a minimum level of …