-28-
for the additions from the 1956 fallout would only tend to steepen the
decline slightly, thus increasing the difference between decay and decline slopes.
The consistent agreement in decay rate between the two plankton
samples resulting from paired tows (last column of Table 3) is a phenomenon of special interest.
As examples, the pair of samples from
Ailinginae on October 23, 1955 had decay slopes of -1.58.and -1. 53
while the pair of samples from the same lagoon on the following day
had slopes of -1.71 and -1.73; the counts in January 1955 also show
nearly equal decay rates for the paired tows.
This uniformity in decay
rate for paired plankton tows suggests uniformity in radiochemical composition at any one time and locality, but different composition in the
plankton at different times or localities.
During the first two years (1954-55) Kabelle Island samples were
2-3 times as radioactive as those from Rongelap Island.
The 1956 Red-
wing series raised the July 1956 values of the Rongelap Island region
above those of Kabelle Island, but by July 1957 Rongelap values declined
to a level far below Kabelle, only to exceed (although not significantly)
Kabelle again in March 1958.
cantly higher than Kabelle.
By August of 1958 Rongelap was signifiThe fallout from the Hardtack series is re-
flected in the higher levels of activity in August, than in March
1958.