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27
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Variability in the radioactivity present in the algae was found to be
high, even in samples from the same clump of algae.
Thus, in comparing
the relative amounts of radioactivity in samples from different locations or
of different species, it is important to consider the amount of variation
that is usually encountered and not
variations in radioactivity.
place undue importance on slight
It was found that the different genera of algae
at Belle Island contained essentially the samelevels of radioactivity regardless of where they were collected.
The radioactivity of the algae at
different islands of Eniwetok Atoll, however, varied from island to island, those islands closest to and in the downwind path of the fallout having
the highest levels of radioactivity during the period of the survey.
Study of radioactive decay rates of the algae and water at Belle Island
showed that the radioactivity in the algae was decaying ata relatively slow
rate and that this rate became
survey.
slower with samples collected later in the
These observations indicate that the longer-lived radioisotopes
were being taken up by the algae.
This is in agreement with the results
of studies in which ion-exchange techniques and gamma spectrum analyses
were used
(to be published later).
These results show that the radioiso-
topes Ce 144_p,144 zr?5 -Nb??, and Rul06_ pp, 106 are the most common
ones present in algae collected shortly after a nuclear detonation.
(11)
such as y? 1 >
,
>
,
, and isl
Others,
have been
found, but only in isolated instances, and sometimes in very low amounts