23 amounts of 59co and 137cg and lower amounts of 55Fe than did mullet from Nam. However conyict surgeon and mullet (Appendix Table 22) from Nam had higher amounts of ©¥¢o and 13/cs than did convict surgeon fron Eneu Island the least contaminated area of Bikini Atoll. It is likely that the mullet range more widely within the lagoon than do the smaller convict surgeon, hence mullet captured in one area may have accumulated the radionuclides while in another area. Comparison of Radioactivity between Islands in Rongelap Atoll At Rongelap Atoll radionuc!ide concentrations tin the soil increase as one moves northward along the east side of the atoll (Figure 5, Table 4). Of the islands sampled at Rongelap Atoli, soil from Rongelap Island has the least amount of radioactivity, while soil from the northern islands of Lukuen, Gejen, and Lomuilal has the most. Islands (Mellu, Kabelle) on the east Side of the atoll have intermediate amounts of radionuclides in the surface soil. This soil distribution pattern corresponds with the fallout pattern determined shortly after the Bravo test at Bikini Atoll on 1 March 1954. On the second of March 1954 gamma dose rates were estimated to be 3.5 roentgens per hour (r/hr) at Rongelap Island, 19 r/hr on Kabelle Island, and . r/hr on Lomuilal Island in the northern part of the atoll (Held, 1965). Ratios of 137¢s/90Sr and 2414m/2392240py in soil from Rongelap Atoll are similar (1 to 2) to the ratios found in soil from Nam and Bikini Islands at Bikini Atoll again indicating the major source of these radionuclides was the Bravo test. Radioactivity in the biota also varied with island. Coconut crabs (Appendix Table 6), fish (Appendix Table 9) and plants (Appendix Table 13) from the southern islands of Rongelap Atoll had less radioactivity than did similar samples from the northern island. However, the amounts of radioactivity in the biota did not differ as much as was noted for the surface soil. Cesium-137 and 90sr amounts in soil from the northern islands were 4 or more times the amgunts found in soil from Rongelap Island, while the usual differences in Cs and 20Sr amounts in plants and coconut crabs from these two areas were factors of 2 to 4. Differences in Radioactivity due to Sample Type As noted for surveys since 1964 (Welander, et al.,1967; Held, 1971; Lynch et al. 1975), 99sr and 137cs are the primary radionuclides in biological ang soil samples from the terrestrial environment. In addition are important in soil, especially from Bikini and of the quantity of these radionuclides present in alpha-emitting radionuclides, which have a higher most of the gamma~emitting radionuclides. Of the Am and ¢29:240py Rongelap atolls, both because soil and because they are potential health hazard than plants sampled, Pandanus leaves are the best indicator species for 137Cs because they concentrate T3/cs, are abundant and are easily sampled throughout the year. The fruit of the Pandanus contains greater amounts of 137cs than do the leaves, however, the fruit 1S available for only part of the year. Pandanus leaves may also be used as an indicator for 30sr, if coconut crabs are not available. The exo- skeleton of this crab contains the most 90Sr of any sample type analyzed, however, coconut crabs are not present in all areas. When available coconut crabs are also good indicator organisms since they integrate 13/c gs well 90sr, from a wide area on an island, whereas the Pandanus integrate 13 Cs and 88¢, from a relatively small area of an island.