The rate of decline of radioactivity in some biological samples from
an
2d to
Therefore, the decay and decline slopes were plotted logarithmically.
ere
sion
aletAgree
Belle
tam si
5
the
Rongelap Atoll also has been observed to follow a similar pattern
arn
adio-
ee ee
read
RESULTS
ras
Studies at Belle Island
tter
A.
din
Rate of Decline of Radioactivity in the Algae
In order to determine the levels of radioactivity in several genera
ion
of algae during the period from April 1954 to April 1956, samples were
mining
collected on thirty-six different dates,
May 14,
per
of dry
r mil-
1954.
three of these before the test of
The results of these surveys are summarized in Table 1,
and a log-log presentation of the average decline in radioactivity is illustrated in Figure 2.
The values plotted are based on the average of
seventeen samples for each date after May 14, 1954.
The individual rates
of decline for representatives of six genera of algae (Halimeda, Caulerpa,
Spyridia, Dictyota, Lyngbya, and Udotea) were found to be approximately
ee iif1ates
0)
the same.
The radioactivity in the samples collected before May 14, 1954,was
due to the residual radioactivity of the 1952 test series at Eniwetok Atoll
(Operation Castle) plus some airborne contamination from the early tests