Piutonium
in the
marine
environment
of the
Marshall Islands
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Between 1946 and 1958, the United States conducted 66 nuclear
tests in the Pacific atolls of Enewetak and Bikini in the Marshall
Islands. Since 1972, LLNL has conducteda variety of studies related
to the cycling and transport of longer lived residual radionuclides
in the marine environments of these atolls. Our primary concern
is to collect sufficient data to develop recommendationsto minimize
the transfer of man-made radionuclides to people returning to the
atolls. However, we have also attempted to relate our analytical
findings to much wider fields of scientific endeavor and to develop
models thatare useful, first locally, and secondly in other aquatic en- |
vironments receiving inputs from different source terms. One such
program deals with the behavior of plutonium radionuclides in the
marine environment of Enewetak and Bikini.
V. E. Noshkin (422-6621).
Significant quantities of plutonium isotopes and other transuranics will be among the longer
Lagoon sediment and water
with radiological waste materials,
some of which are already being
disposed of in the ocean. It is,
radionuclides deposited in the
lagoon water either settled to the
bottom or remained as dissolved or
particulate species that were eventually discharged to the North
Equatorial Pacific by the prevailing
exchange of water between ocean
and lagoon. Fallout during and
after these tests left a very
heterogeneous distribution of
radionuclides in lagoon sediments.
Figure 1 shows the main features of
plutonium-239 and plutonium-240
(239+240b.,) activity associated with
sediment components in the top
2.9cm of Enewetak lagoon (as
measured in 1972}. Isolines distinguish regions with similar con-
lived toxic radionuclides associated
therefore, essential to understand
by what processes and at whatrates
plutonium, under the influence of
various chemical, physical, and
biological phenomena on the sea
floor, migrates back to the water
coiumn and is accumulated by
marine food chains.
concentrations
After the last nuclear test at
Enewetak in 1958, the residual
centrations, and mean values are
listed within regions. The number
of measurements made is given in
parentheses.
The highest surface concentrations are associated with sediment