Radiological Resurvey of Animals, Soils and Groundwater at Bikini Atoll, 1969-1970 (Companion Documents Are 408257,408258)

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RADIOLOGICAL RESURVEY OF ANIMALS, SOILS AND GROUNDWATER AT BIKINI ATOLL, 1969-1970 University of Washington College of Fisheries Laboratory of Radiation Ecology Work done under Contract AT(26-1)-269 with the United States Atomic Energy Commission ,. ,

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AT BIKINI ATOLL, 1959–1970 Uriivezsity of Washington Laboratory of Radiation Ecology Work done under Contract AT(26–1)–269 with the United States Atomic Energy Commission

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respectively. Tlnere al-e no striking cliff-ererices between average compared with values reported in 1.967. :?~-edov.inant radionuclides 207 Bi predominate. There are qu.antit; ut.;.v~ and qualitative differ– ences in radionuclide cor.te,n-tassoci~r~ed ;~ith the feeding habit of fish and there appears to “be afi iricCeaSing concentration of some radi-onuclides with increasing age of fish and clams. The radionuclide content of ‘oird species presents a sharp con~raskl ~0’~h qualitatively and quantitutivel.y, associated with feeding habit. It appears that some 60 207 Co and Bi is being transported eastward by the bottom current in the lagoon. Silver–108m, previously unreported in fallout, was found in the “nepatopancreas of the spiny lobster. Tritium levels in groundwater are wit-bin 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 physical decay.

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Bikini f~tol.1;V. JS a site for atmospheric testc. of r:uclc:lr devices from 1946 to 195S. The population of 165 Bikinians ‘#iaS moved from the atoll. in Marcht 1946, first to Rongerik Atoll, then to Kwajalein Atoll; in November, 19~-8, the Eikini. people moved to Kili Isla P.d. The land area at Ki.li is about one–tent’n t’nat at 13i-k.iniAtoll and there is no l.aqosn. Therefore, dccess to Kili. is difficult, 0fkC313 impossible, and seafoods are scarce. The results of a radiological res~:rvey of ‘BilkiP.i in 1964 habitation (lJelander, 1967; Nelander et al.,1967). A request fro~l the High Commissioner of the Trust Territories of tb.e Pacific to tine 14tomic Energy Commission in 1966 to rehabilitate Bikini resulted in an extensive survey of the atoll in t-he spring of 1967. This survey emphasized external radiation measurements, including in situ gamma-ray spectrometry, alt”nough.— 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

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radiological ha:<~~rds. Mos-t of the participants in the 1967 survey attended t’he 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 included restriction of coconut cza-bs f~om the diet, because they contain high concentrations of , and. covering t-ne village acea at Bikini Island with coral gravel from the beaches, which is consistent with local custom and proy~icies a shield against radiation from the soil. The panel also recommended that old structures and other such debris from -k’hetests 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 Secretary of the Interior, the administrator for the Trust Territory of the

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the clea~]–up portion of the rehabilitation program, which was carried out under guidelines approved by the AEC Division of Operational Safety. ilt the request of NT700, the U. S. Public Health Service 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 asti.edto 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 U.S. PHS (SWRHL-lllr). This report presents the results of the Laboratory’s analyses. 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 biota. The fish collected are in two main categories: the reef

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feeder; the cGi~vict surgconfis’n, a grazing herbivore; and the goatf ish , a bottom-feeclin.g 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 be eaten when the Eikinians return. .> fourth kind of reef groupers, was also collected as representative of the higher fall into two broad subcategories: resident lagoon fish, ulua and dogtooth tuna, and migratory fish, yellor~fin 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 and, presumably, would fish for tuna if The invertebrates sampled were the of their favorite fish they return to Bikini. coconut crab and “giant” clams (Tridacna sp., and Hipp opus hippopus). Some of the species of Tridacna never exceed a few * For a list of common names and scientific names,- s,ee r

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ccnLilr[c!L(.’rsj.]~11.:n:jth,an(l only the sma l.ler species were found in tl)c vicinity of- Nam (Charlie) Tslet. The larger species In response! to a special request to check the levels of radioactivity at Aerokoj Islet, received during the survey, the land hermit crab, 90~r a known concentrator of , was collected. Since coconut crabs are botln 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, t-he curlews and turnstones feed alonq the shores and on the reef, and the curlew also eats the seeds of an endemic shrub, Scaevola serica, or the beach magnolia. Althoug-h tune 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 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 Groundwatcr was collected by driving half–inch pipe with well points into the soil. The well-point sites “on Bikini and

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Encman Is land:.;wcJ:c in areas found to be the most radioactive by the U. S. Pul~lic Health Service personnel. q On Nam 1. 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 Aeroko-j were unsuccessful. Water samples were collected from existing wells at Eneu I. and from the cisterns constructed at Bikini 1. in 1969. In 1969, soil samples were taken by one-inch depth i.ncre– ments 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 t-he surface one inch were analyzed. In addition to samples well points, surface samples also were of other sets of samples from soil pits at the taken at Aomen and Oroken. Sediments from the Bravo Crater were taken by dredge from depths of 40, 1.20, 140, 160 and 190 feet. In 1970, composite soil samples were taken to a depth of one inch from undisturbed and disturbed areas along rows shown in Fig. 1 at Bikini I. and on representative transects east and west of the air strip at Eneu I. (Fig. 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 subszimples were retained and analyzed individually to indicate the variability between subsamples. Samples from soil profiles were taken at well points 1, 4, and 5.

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They were countccl 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 consktingof two opposing “ 5 x 5-inch crys-iial~ 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 for example, were ashed, dissolved in hydrochloric 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 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 Y daughter. Yttrium-90 was separated by solvent extraction and precipitation techniques (Petrow,1965), with stable yttrium serving as both a carrie”r and a yield de-

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solvent extraction and el.ectrodeposition techniques (Palmer and Beaslcy, 1967) . Recoveries generally exceeded 90%. Counting was done by X–ray spectroscopy with a proportional counter in conjunction v;ith a multichannel analyzer. The solvent extraction techniques of Sill and Willis (1965) used for separating and purifying . Bismuth-212 was as a yield determinant. Plutonium-238, 239 was separated by a combination of solvent extraction a-nilanion exchange techniques (YlcCowan 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 corallire soils and sediments is exceptionally difficult and it is therefore essential that Pu be nant and that counting be done by alpha used as a yield Well water samples were measured for tritium content by a liquid scintillation technique with a minimum level of detection of 200 tritium units. * Provided by the USAEC Health and Safety Laboratory, New York.

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RESULTS AND DISCITSSION The predominant radionuclides in the terrestrial organisms are 1 whereas the marine orcjanisms contain mainly CO ai~d * The concentrations of these radionuclides in ed~.blc portions of organisms range from undetectable amounts to the following maximum values: 137CS 2260 pCi/g dry in the muscle tissues of a curlew 90 Sr – 204 pCi/g dry in the hepatopancreas of a coconut 60 Co – 219 pCi/g dry in muscle and mantle tissue of a giant taken near Bikini 1. 55 Fe – 40,900 pCi/g dry in the liver of an ulua. The range in the concentration of a radionuclide in the tissue from the same species at the same islet is wide. detectable amounts of radionuclides are present, the minim~ and maximum values often differ by factors of four or five and sometimes by a factor of ten. The values for concentration of radionuclides in individual samples are given in Tables 1 Dry weights were used for the basic calculations because the true water content of some smples i.s difficult to determine. The average concentrations of radionuclides were converted to a wet-weight basis for convenience in calculating daily intake

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from the d.ict; the conversions were made by using average wet to dry weiqht ratio:; for each kind of sample. 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 difier– ences tend to show a decline in radionuclide content, but there are not sufficient data to provide a basis for a reasonable estimate of rates of decline becauzs of the large variability in the data and the many poorly defined factors involved in the uptake and retenticn of radionu”clides by organisms in the natural environment of Bikini. Some basic biological information, such as rates of growth and life spans of the fishes are not known the chemical form in which the radionuclides are present in lagoon waters can only be surmised. We do not even know, example, whether the radionuclides and theit stable isotopes present in the same chemical form. Furthermore, there are no uncontestabie data on t},e 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 and conclusions can be drawn from All of the fallout radionuclides at Bikini are found in the surface of undisturbed soils. The predominant radionuclides are co, 137 Cs and 207

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In the crater seclimerits only four predominate : 55Fe 60 90~r and 1 although others are present in small quantities. The soils and sediments are the principal reservoirs of radi,o– nuclides at Bikini. The concentrations of radionuclides, other than plutonium, in surface soil samples collected in 1969 are given in Table 1. The samples were taken from areas where the highest gamma dose rates were measured and hence are maximum values. Differences in proportions of different radionuclides at the islets sampled to other radionuclides in the Eneman samples result from periodic flooding of the area by tidal water and consequent leaching away The results of gamma-ray spectrum analyses of the composite and individual samples collected in 1970 are given in Table 4. In general, radionuclide concentrations are lower in bulldozed areas than in undisturbed areas. The exceptions to this gener– ality are not surprising, since the lowest and highest values for individual samples from single transects differ by factors of more than ten. Fallout radionuclides in undisturbed atoll soils remain concentrated at the surface for many years (Held et al., 1965: Welanderr 1967). The surface ten centimeters at well-point four at Bikini Island were sampled by one–half centimeter increments in 1970, and the samples show a gradient of

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decreasing radionucl. ide content with increasing depth (Table 5) . Soil samples analyzed for plutonium were generally selected from areas containing the highest concentrat~ons of gamma– emitting radionuclides. Exceptions were samples from the camp area at Bikini I. and along the runway at Eneu I. The results of the plutonium analyses are given in Table 6; 137 Cs concentrations are included in the table because they indicate a correlation between Cs and Pu concentrations in samples from Bikini 1. The ratios of 239,240PU to 238 Pu approach 2:1 at Eneman 1. and are about 15:1 in Bravo Crater sediment. Bikini soils contained no detectable Pu, although t$.ey contained the highest concentrations of Pu of the samples analyzed. The radionuclides are available to the land animals through the vegetation, or other animals, where there is selection of specific radionuclides, or t“nrough …