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SUMMARY
The rate of decline of radioactivity in the algae at Eniwetok Atoll
was studied for a period of two years after the detonation of May 14,
1954 (Nectar).
The average pre-Nectar level at Belle Island (Bogorbogo)
was 1.9 uc/kg of wet tissue; this level was attributed to radioactive
tamination from the tests at Bikini Atoll in March 1954.
con-
After the Nectar
test the average level in the algae buiit up to 2500 uc/kg on May 15, 1956,
then declined to 0.10 uc/kg on April 26, 1956.
A logarithmic plot of the
levels at each date of collection gave a negative slope of approximately
1.5; this slope probably could be used to estimate the average level of
radioactivity of the algae at any future date up to about four years after
the Nectar detonation.
The rate of decline of radioactivity in water
samples collected in the same areas as the algae samples paralleled
that of the algae, but the levels were much lower.
Comparison of radioactive decay rates of individual algae collected
at Belle Island showed that Udotea, a semicalcareous alga, had selected
radionuclide mixtures different from the ones taken up by other algae.
Decay rates of algae and water samples collected at Belle Island
showed that for the first two months after detonation the algae had selected some of the longer- lived isotopes from the water.
There were no differences in the amounts of radioactivity in the
algae collected at different parts
ferences
inthe
of Belle Island,
but there were uif-
amounts in the algae collected at different islands of