Letter to J N Wolfe, Subject: Sample Analysis from Bikini Atoll 1967

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UNIVKRSITY OK WASHINGTON College of Fisheries Laboratory of Radiation ZJflCSgf Ecology Environmental Sciences Branch Division of Biology and Medicine U.S. Atomic Energy Commission Enclosed is a list of tables and the tables giving results oF our analyses of samples collected at Bihini Atoll in 1967. /Some comparisons with the results from the 1964 Bihini survey and with Rongelap Atoll data are included. Following are some comments on the tables: Tables 1 and 2: The comparatively high values for cesium-137 in the curlews was expected since it is known that curlews feed on Scaevola seeds which contain cesium-137. The high cesium-137 values for the turnstones was not expected. Com parison of the relative amounts of cesium-137 and cobalt-60 in the turnstone and curlew livers suggests that the two radio nuclides were obtained from a common source by the turnstones— possibly direct ingestion of soil particles. The birds most frequently eaten by the Marshallese are the fairy and noddy terns because they are the most numerous. The curlew is a preferred species for food but is. seldom caught. Tables 3 and 4: The predominance of cobalt-60 and zinc-65 in the fish and the relatively high concentration of these radio nuclides in liver is as expected. The presence of bismuth-207 in fish might be of particular interest regarding transfer through the food web and redistribu tion of the radionuclide in the atoll. Bravo Crater, near Namu Island is the main, if not the sole, source of bismuth-207. Tables 7 and 8: These data will be (or have been) supplemented with data from additional analyses performed by the HASL, with

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The high levels of strontium-90 in the coconut crabs were expected Furthermore, it is expected that the strontium-90 levels in the coconut crabs will not change appreciably with time except for the effect of physical decay of the radionuclide. An exception might be at Bikini Island. If the Island is replanted to coco-, nuts, a considerable drop in strontium-90 levels in coconut crabs would be expected when the palms begin to produce fruit. Coconut contains the least relative amount of strontium-90 of any plants sampled at the atolls in the past. Incidentally, if Bikini is rehabilitated, the potential exists for a field experiment with coconut crabs at the neighboring islets of Chieerete and Rukoji. These islets are of similar size and configuration and have the same type of vegetative cover. There is a large population of coconut crabs on each island and no coconuts. One islet could be supplied with an abundance of copra and the resultant differences in radionuclide levels in the crabs and their population structure at the two islets Tables 9, 10 and 11: We cannot explain the high value of 560 pCi/g dry of cesium-137 for the muscle tissue of one of these coconut crabs collected at Enyu Island. Cesium-137 levels in plants from Enyu and the gamma dose rates measured there suggest that there is an error in the value given. The only possible explanation we can offer is that the specimen was mislabeled when the samples were packed aboard ship. Values for cesium-137 in skeleton are not given in Table 9 because the bremsstrahlung from strontium-90 contributed a major portion of the counts in the gamma spectrum. The correction for bremsstrahlung was not adequate. Table 10 gives cesium-137 after separation of the nuclide from strontium-90. Table 11 compares the values obtained before and after separation from muscle Tables 12 and 13: The old coconut husk is one that Tommy McCraw picked up as being especially "hot" as determined with a survey meter. The comparatively large amount of cobalt-60 in this sample indicates that the radioactivity is largely due to external contamination. The same is true of the Fimbrystilis collected at Aomen Island. In considering the cesium-137 content of Tacca in relation to possible hazard, it must be remembered that the processing to remove oxalic acid also removes most if not all of the radio Department of Energy

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The high value for cesium-137 in Cordia leave's from pit 5, Bikini Island, is higher in relation to values for other plants than we would have guessed on the basis of past experience, but is within the range of differences that have been found between different species. The comparatively low value for cesium-137 in Guettarda is as expected. The lesser amounts of cesium-137 in litter than in leaves is as expected since there is translocation of cesium-137 from older to younger leaves. Tables 17-20: We will reserve comment until there has been an opportunity to compare these results with those of HASL. The identical samples counted here v;ere sent to HASL. gamma emitters and their daughters are present in the soils and possibly in other samples. Values have not been given in the above tables because these nuclides are present in relatively small amounts and the accuracy of the determinations is highly There are also enclosed figures of gamma spectra of soils from Eninman, Enirikku, and Rukoji Islets. The samples contain volunteered to analyze two of these samples with their germanium diode systems. The results are expected to be available within the next two weeks. Department of Energy

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List of Tables Giving Results of Analyses of Samples collected at eikini Atoll, April - May 1967 Coconut Crabs, Rukoji Island, .. Sr, comparison of analyses by ‘ Coconut Crabs, Cs in filtrates from strontium precipitates Coconut Crabs, comparison of Cs values determined from whole dry tissue and from strontium precipitates ‘ . Land Plants, comparison of amounts of Cs in copra and pandanus Soil, Bikini Island, pit 1, gamma-emitters.* / Soil, Bikini Island, pit 5, TLD location 147, gamma-emitters Soil, Bikini Island, pit 6, TLD location 148, gamma-emitters Soil, Eninman Island, pit 2, gamma-emitters Department of Energy

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Gamma-Emitting Radionuclides in Bird Tissues Collected at Bikini Atoll/ no. Island Species Tissue 60 Co per gram dry weight 25006 Namu Noddy tern Liver 1.0±0.5 NNNN 25011 Romurikku II II II NNNNN 25005 Namu Noddy tern Bone 0,6±0.3 N N 0.510.4 0.210.2 25010 Romurikku II II

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Gamma-Emitting Radionuclides in Bird Tissues Collected at Bikini Atoll, per gram wet weight

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Collected at Bikini in Spiny Lobster Picocuries per gram wet weight Tissue 60 Co 65 Zn 137Cs 207 Bi Department of Energy

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Collected at Rukoji Island, Bikini Atoll, to two significant figures) - Ref, letter; 5 December 67 Hardy to Held^ “ Note:. Error given is 95% counting error..’,? Department of Energy

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Department of Energy Comparison of Analyses of 1967 Bikini Coconut Crab Si

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Spectroscopy of Whole Dried Tissue and of the' f Muscle of Coconut Crabs Collected at Rukoji Island, Bikini Atoll, 1967-. Values in picocuries per gram dry tissue Sample Aliquot Filtrate Muscle . ficient subtraction of counts due Values obtained from the filtrates - t *' may be low due to possible loss ofrC

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Gamma-Emitting Radionuclides in Land Plants Collected at Bikini Atoll,. Picocuries per gram dry weigl

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Gamma-Emitting Radionuclides In Land Plants Collected at Bikini Atoll, Picocuries per gram Vet. weight ^

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Comparison of Amounts of Cesium-137 in Copra and Pandanus from Bikini, Rongelap, Uterik, and Majuro Atolls ■s Rongelap Atoll Copra . (1958-1964) Rongelap Atoll Pandanus Leaves, (1958-1963) No. of samples Average ^ ' Range No. of samples Average 1 Department of Energy