- 31 - ; plant in which the Rongelap Island value was almost three times greater : than for the other collecting areas. The corms had been washed and peeled - . to avoid contamination from the adhering soil. Since there is no evidence | : to indicate that the rate of uptake of radioactive materials should be higher at one island than another, andsince the levels of activity in the soils at Rongelap Island varied considerably in two neighboring locations (from 1,7 pe/kg to 20 uc/Kg), it is probable that the arrowroot at Rongelap Island was collected in relatively "hot" spots. In the early surveys it was found that the meter readings were highest in soil depressions and in pits such as those used by the natives for growing crops, and this may account for the values, During October 1955 the radioactivity in the soil was much higher than . | that in the plants, indicating a low rate of uptake. This seems to be corre- : - lated with the loss from the soil of those isotopes which are readily taken as by the plants. The ratio of soil/plant activity has increased from 8 to 190inthe period from March 1954 to October 1955. This would be trueif “ : there was a selective uptake of short half-life fission products by the plants. tewas also borne out by the radiochemical determinations, which showed that in gddition to the rare earth isotopes, zr95 was the principa} source ‘ ‘oftradioactivityin the soil in March 1954 5*, whereas it was Ru!in July of 1955 6 Although Ru!06 comprised a relatively large fraction (23.3%) of “the activity in the soil, in most plants it was minor (7.8%). Much of the abe. _ activity in the plants - up to 96 percent - was due to C537 which com- ; Prised a very small part of the total activity in the soil (1. 1%)8 — TNT ye pee UNS eye: UNIV,