~36- On the basis of the increase in background levels of radioactivity at Eniwetok Atoll after the March 1954 tests at Bikini Atoll, and the steep slopes of decay plots of in- dividual plant samples, it is believed that the relatively high amounts of radioactivity in the Eniwetok pre-Nectar gamples were due to contamination from the Bikini fallout material. After the Nectar test the levels of beta radioactivity of land plants at the various islands were directly related to geographical distance from ground zero and to time after detonation. Uptake of Radioisotopes by the Plants A comparison of the rates of decline of radioactivity of the soils and plant tissues shows that the radioactivity of some of the land plant tissues declined at the same rate as that of the goil samples. The rate of decline for the first 100 days was similar to the decay of mixed fission products. This similarity indicates that the radioactive ma-~ terial had adhered to the external surfaces of the leaves of the tall plants such as Scaevola and Messerschmidia during fallout. Splattering of contaminated soil particles on the low plants such as Triumfetta, Boerhaavia and Portulaca may