17
_
And, at the same time, the difference in
60
Co content between
the goatfish from near the crater and those at Bikini I.
is
by a factor of about ten.
.
:
.
.
207_. .
It appears that the physical redistribution of
Bi is
ss
60
Similar to that of
oo
Co,
but since the
levels of
207_.
Bi are
lower than those of 6006 by a factor of about 20, we are at the
limits of detection, with the method used,
from the crater.
for samples distant
The use of larger samples,
chemical separation
and more sensitive counting methods would make it possible to
.
determine
60
Co:
207_,
.
.
.
Bi ratios in sediments,
lagoon water and
organisms in different parts of the lagoon.
These ratios would
indicate whether transported radionuclides were primarily in
solution or on particles.
If the ratios remained constant, that
would be a strong indication of transport on particles.
results of analyses of selected samples for
The
207_.,
. BL by gamma-ray-
spectrometry and by chemical separation are compared in Table
13.
Bismuth-207 will be a useful tracer in the future because
it has a long half-life,
30 years compared to 5:2 years for
60C0.
Plutonium-239,
with a half-life in excess of 24,000 years,
is another potentially useful tracer.
The samplesanalyzed for
plutonium were selected on the bases of collection location
and content of gamma-emitting radionuclides, which indicate