yt TABLE IV LEVELS OF Sr°°—yYAND Cs!” IN TERRESTRIAL SAMPLES IN AND NEAR THE ENIWETOK TEST SITE ee Eniwetok Atoll* Soil Spi yea | dimije % | a dry weight Messerschmidia Fimbristylis Sandburrs | 375 wet weight wet weight wet weight OG | 76 | 9.4 ; 5.9 (C3137 d/m/g °% 242 11.9 2.0 7.9 | | 667 3,303 100 | | 3.8 83 86 86.8 Average 7.3 | 85 I Rongelap Atoll Seaevola leaves (March, 1958)** | (Average of 11 samples) Pandanus fruit (August, 1958) ** Pandanus leaves | l Pandanus trunk borings aot Kabelle Island (Rongelap Atoll) ** Pandanus fruit (August, 1958) Pandanus leaves (August, 1958) Pandanus stems (August, 1958) Pandanus bark (August, 1958) | | | ! | | 26.7 4.6 3.1 33.7 95.4 3.5 71.4 28.6 6.5 0.37 | 5.4 | 32.4 92.6 1,2 | 49,2 | 4.6 ! | Einiaetok Island (Rongelap Atoll) ** Pandanus fruit (August, 1958) Pandanus leaves (August, 1958) Average | | 7.0 1.6 ! i 77.0 1.4 15.9 : 38.7 * D.J. South, 1957 (unpublished) ** DJ. South manuscript highest percentages of Sr®°—Y®° (71%), and Cs!37--Ba!3’m accounted for the remaining 29%. Thus on land the radioisotopes of strontium and caesium and their daughter products accounted for a significant fraction of the total radioactivity in the plants. This is not the case in the sea, although these isotopes have been considered to be also of primary importance in the contamination of marine organisms. In a series of plankton samples collected at the Eniwetok Test Site in 1958 3 to 36 hours after contamination, the ratios of observed Sr® to expected Sr®° based on the observed levels of Mo%®—Tc#9m, Tel32—[132, Zr95_Nb%, Cel41__Pr!41, and Ba!4°—La}!4° were calculated. The results are shown in Table V. In the plankton collected three hours after contamination, no Sr® was detected in the large plankton. The level of Sr® in the nannoplankton was, on the average, 0.43 of that expected on the basis of the levels of the abovenamed isotopes. In plankton collected later, no detectable difference in ratios of radioisotopes existed between the large and the small plankton. At 21 hours, Sr® existed at a level 0.06 of that expected, and at 36 hours 0.03 of 130 reyt hy