EVALUATION OF THE RADIONUCLIDE CONCENTRATIONS IN
SOIL AND PLANTS FROMTHE 1975 TERRESTRIAL SURVEY
OF BIKINI AND ENEU ISLANDS
Abstract
.
In June 1975, personnel
from LLL
Lea
.
:
60 Co, /6. for 90 Sr,
Island
(0.86 for
a ¢
137
239,240
and from other laboratories and
43 for
agencies conducted a radiological
2.4 For oada).
survey of the terrestrial environment
activity is unevenly distributed over
of Bikini and Eneu Islands
the surface of these islands and that
Atoll)
(Bikini
to evaluate the potential
radiation dose to
population.
Cs,
3.0 for
,
Pu,
We found that radio-
the distribution of activity with
the returning Bikini
In this report, we pre-
soil depth varies greatly in different
parts of
the islands.
Concentrations
sent measurements of the radionuclide
in the soil of 905, and RSTn gs are
concentration in soil profiles and in
greater
dominant species of edible and noned-
and
ible,
indicator piants.
cribe the use of
and
We aiso des-
these data to derive
relationships to predict the plant
uptake of radionuclides from soil.
Approximately 620 soil and vegeta-
.
than concentrations of
239, 240 Pu
which,
in turn,
241
Am
are
;
6
greater than concentrations of
Co.
To quantitatively evaluate the
plant uptake of
239,240
90
SY ,
137
C s,
and
Pu, we develop soil-plant
concentration factors as well as
tion samples from Bikini and Eneu
leaf-leaf and fruit-leaf concentra-
Islands were analyzed by Ge(Li)
tion ratios
gamma
for indicator and edible
spectrometry and by wet chemistry.
plant species from the same location.
The predominant. radionuclides in
In general,
137
these samples are 6006, 20
2
2
239,240), 24d and
fh,
ral,
Cs,
,
In gene-
the radionuclide concentrations
the concentration factors
137.
.
.
for
Cs in terrestrial vegetation
90
are preater
than those
for
sr.
concentration factors Lor both of
four areas of Bikini Island appear
these nuclides exceed those for
239,240
,
Pu by one to two orders of
to approximate log-normal distribu-
magnitude (10 to 100 times).
tions.
90.6, and 239,240), ,
in soil from Eneu Tsland and from the
The median surface-soil
concentrations (pCi/g) of Eneu Island
by fruit
(0.067 for 6006, 4.1 for 706)
leaves;
2.9 for t3/es.
and 0.22 for
lower
than
é
3
0.25 for 739>74 py
241
Am)
are
>
.
ten times
those measured
on
Bikini
The
is less
however,
true for IST og,
tribution of
species
to
For
nuclide uptake
than
that by mature
the opposite is
The relative con-
the individual plant
the internal dose,to man