PERSISTENCE OF RADIOACTIVE CONTAMINATION IN
lagoon fish was only very roughly proportional
to the external radiation dose over the adjoining
island.
Crabs and clams were found to havea residual
concentration of beta-cmilting radionuclides of
about the same level as fish from the corre-
sponding locality. This is in contrast to the
largerdifferences noted between crabs and clama
as compered to fish at 1 year post delonation.
Snails from Gejen had considerably higher
concentrations of activity than fish from the
same locality, as was noted in the 1-year
resurvey. The higher level of activity of the
snails may berelated to their habit of feeding
on the bottom of the lagoon where higher con-
centrations of radionuclides were found,
The internal distribution of radioactivity im
the tissues of fish (primarily carnivores) col-
lected in the various lagoons indicated that an
average of 20 percent of the total beta and
gamma activity was found in the skeleton
(Table 2). Tho head contained an average of
30 percent of the total beta and 21 percent of
the gammaactivity. Muscle contained approximately 14 percent of the total beta and gamma
activity, The activity of the viscera and contents varied considerably, but contained on the
average about 33 percent of the total beta activity and 16 percent of the totel gammeactivity.
The remainder ofthe activity was found on the
ode
skin and gills.
3
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Viscera
ee
2.8
The internal distribution of
activity, particularly the musele activity concentration, was very similar to that found in
the fish collected and analyzed at one year
post detonation.
Theresults of the radiochemical analyses for
specific radionuclides are presented in Table 3.
The most important finding is the very high
percentage of the total activity in fish which is
contributed by Zn®. The manner in which
this induced activity is concentrated has not
been determined. The Zn* in fish is distributed
fairly evenly among the various tissues. The
Zn® was not found in clams, crabs, or snails,
with the exception of one helmet snail from
Kabelle Island.
The rare earth group of fission products
constituted a small percentage of the total
beta activity in clams and fish. The rare
earth elements as a group do not appear to be
selectively localized. The rare earth activity
of the crabs was high, an average of 20 percent
of the total beta activity. Snails concentrated
the largest amounts of rare earth elements.
The Sr® concentralion was very low, con-
tributing generally a fraction of 1 percent of
the total beta activity. The Sr® content is of
particular importance, since it is the radionuclide of greatest potential hazard. The
Sr® hazard derives principally from its long
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Activity (ym,
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RONGERIE ATOUL!
Eniwetak_.....--.------------- Squirrel...
Percent of total activity. .--.UTIRIg ATOLL:
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Radioactivity (d/m/tissue x 10-1)
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ANIMALS
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TEBRATES
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THE SHORTER-TERM BIOLOGICAL HAZARDS OF A FALLOUT FIBLD
Tani2—DISTRIBUTION OF GROSS BETA AND GAMMA ACTIVITY IN TISSUES OF FISH
212
Tasie 1—SUMMARY OF BETA AND GAMMA ACTIVITY IN
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