varies with deration. the nuclide Thus, under concentration ratios to predict consi- nuclide concentrations in fruit from we also describe the use of concentration Factors and those observed in soil or leaves. Introduction Since the The longer-lived fission and termination of nuclear testing on Bikini Atoll in 1958, activation products are the nuclides periodic environmental surveys have of primary concern at Bikini Atoll. been conducted Previous studies have shown that to evaluate the radio- early surveys of Bikini Atoll as well because of their long half-lives and 4 137 90 Cs, an Sr, large inventories, as 239,240, | contribute nearly all the logical status of the atoll. The the recent survey and assessment at nearby Enewetak Atoll indicate population dose from the terrestrial that + In this study, our major concentrations of radionuclides in pathway. certain terrestrial foods are rela- emphasis is on 0c tively high, suggesting that 239,240, the Pu. terrestrial However, los and « the results ob- for 065 and 2 vam are also foodchain could be a major 1-4 exposure pathway. in June 1975, included because Bikint Atoll was e tributed and is present in the marin resurveyed to deter- tained ere is widely dis- the pathway and because the concentration terrestrial environments of Bikini and of 241 Ay is still increasing slightly 241 mine Eneu the residual Islands, the the atoll (Pig. radioactivity in two main lL). islands of Pu. due to the decay of In this report, we describe the The 1975 survey the soil and vegetation included measurement of environmental results of gamma-ray exposure rates and studies of the 1975 survey. the col- discuss the use of the data to derive lection and analysis of samples of soil, ground water, cistern water, We also and relationships that predict the plant vegetation for use in assessing the uptake of nuclides from soil on internal dose via various ingestion Bikini Atoll. 60 90 Sr, of Co pathways. (The dose from external gamma exposure and the radionuclide i Geometric mean values 137A, 239,240, 24). . surface-soil Am u, “ ? . concentrations concentrations in cistern and ground developed for Eneu Island and for water have been previously each c reported.??°) of Xikini the four areas Island was and are into which divided. ‘We alse