islands have lesser concentrations of 137Cs in the soil.
The average !37cs
concentration varies over a considerable range among the islands.
The 137¢5
concentration in soil and vegetation on Eneu Island, the other major residence
island,
is about 10 to 13% that of Bikini Island.
islands
large
enough
to be potential
residence
Nam, one of two other
islands,
has
a
137¢5
concentration in soil about 70% that of Bikini Island; the !37Cs concentration
in soil at Enidrik, the other large island, is about 15% that of Bikini Island.
The transuranic radionuclide concentrations, and their ratios to !37Cs
and 90sr, vary around the atoll reflecting the difference in the design of the
devices employed for shots near the various islands.
islands large enough to support residence,
For the other two
the transuranic
radionuclide
concentrations in the soil on Nam exceed those on Bikini Island, while those
on Enidrik are somewhat less than those on Bikini Island.
The radionuclide concentration decreases exponentially with depth in the
soil column, with concentrations significantly higher in the surface than at
depth.
There are, of course, exceptions in various regions of some of the
islands.
The rate of change with depth does vary depending on past events.
For example, on Eneu Island the distribution of 20Sr, 239+240py, and 24lAm is
constant to a depth of 40 cm reflecting some past history where the top
portion of the soil column apparently was mixed.
fhe island was used as the
major residence island for a few thousand personnel during the. test program
and also for personnel during the 1968 to 1971 cleanup project.
Furthermore,
only a few soil profiles were collected on most islands and, for the most
part, the profiles are insufficient in number and not adequately distributed
to determine
islands
where
contamination,
the actual
surface
radionuclide distribution with depth.
soils
the general
have
been
relatively
undisturbed
distribution pattern for al]
exponential with depth in the soil
However, on
after
radionuclides is
column, with concentrations being much
higher in the surface horizons (Robison et al., 1982a).
MEGETATION
There is a direct correlation at the Atoll between the concentration of a
radionuclide in the soil
plants.
r
.
wi be
2 4
3
to
radionuclide
in
Thus, although radionuclide data are not available from other islands
because edible food crops
Rm
feo.
and the concentration of that
were
unavailable
65
on most
islands
and
scrub