- 36 In October 1955, the highest values in the marine algae were at Kabelle and Labaredj Islands and the lowest in the shallow water of the lagoon at Enibuk Island, Ailinginae Atoll. The highest of all were the fresh-water and brackish water algae from Rongelap Island which were collected in locations where fission product material would tend to accumulate. These algae were collected from the bottom of a concrete cistern which was used to collect rainwater and from the sides of a well which contained water originating from the fresh water lens. In both of these locations the water contained much more activity than the water in the lagoon (see Table 13). Considering alk the samples collected on this date, the ratio of the activity in the soil to that in the algae varied from 1 to 15, an indication that the level in the soil is not the primary factor in determining the level of activity in the algae. A comparision of the radioactivity in the algae collected in the shallow water near the lagoon shore with that of those collected at the bottom of the lagoon in deeper water shows that the latter were slightly more radioactive at Enibuk Island and less radioactive at Rongelap Island. The radioactivity in the algae at Rongelap Atoli is declining at a rapid rate. This is illustrated in Figure 11, a log-log plot of radioactivity in the algae at Kabelle Island from March 26, 1954 to October 21, 1955. The slope of this line is -2.5, which is steeper than that for beach sand (-1.5). It is also Steeper than that for the land plants (-1.25), which indicatesthat different fission products were being absorbed by the two types of plants. This differ- ence in compasitim of the radioactive material is algo borne out bythe faster UNIVERSITY ecm; UNIV. CP Wt OTR