- 53 general level of radioactivity at Rongelap Island, but does illustrate the problem introduced by sample variation when too few samples are taken. The other soil sample from Rongelap Island contained 1.7 uc/kg of top 3 inches of soil and agrees favorably with that expected from a consideration of the values obtained in previous collections when radioactivity decline is taken into consideration. The rate of decline of radioactive contamination in the combined soil ‘samples from Kabelle and Labaredj Islands between the dates, March 26, 1954 and October 23, 1955 is best represented by a straight line on log-log coordinates with a slope of approximately -1.6. The decay curve for a Labaredj Island soil sample extending through the same period of time 5 is expressed by the formula r=t “1,31 In both curves March 1, 1954 is the date of origin. Enibuk Island (Ailinginae Atoll) soil contained 1.2 yc/kg of top inch of soil or an average of 0.61 uc/kg of top 3 inches of soil on October 23, 1955. Thus the soil at Enibuk was about 1/3 as radioactive as was soil from Rongelap Island, a relationship which was reflected in the radioactivity levels of land plants from the same islands. The sand at low tide line at Enibuk also contained about 1/3 as much radioactive contamination as did a like sample from Rongelap. level At both Enibuk and Rongelap the radioactivity in the low tide line sand was about 1/18 that found in the island soil (top 3 inches). The levels of radioactivity in the top 6 inches of sand profiles taken on the lagoon bottom off Kabelle Island varied from 1/3 to 1/1 that for the