137
soils and approximately 1.7 times the
Cs concentration.
A ratio of 9 was
90... and 2394240),
found between the
u concentrations in the roof wash,
indicating
that
components
contains
resuspended
collected
15 m
on
of
soil
the
water.
surface.
A full
239+ 240,
the
u-_and
into the cistern,
would increase only by 0.12 and 1.1
contaminates
is
a
could
roof
If
roof was eventually washed
particulates
continuous
£Ci/l,
process
also
be
cistern
90,
at
respectively.
the
year
the
building
deposited
the concentrations
over
among.
on
10
the
in the water
If resuspension of
and
the
amounts
of
radionuclides deposited on the roof of building 10 over the 2-wk interval are
representative of the amounts accumulated during any 2-wk interval,
90...
annual
amount
concentration
of
in
accumulated
a
full
insignificant
compared
deposition.
Unlike
concentrations
137
of
cistern
to
only
present
the
Cs
by
ratio.
and
28
global
of
drained
would
fCi/l.
This
fallout
905,
in cistern water exceeds
increase’
137605
the
the
concentration
levels
to
then the
in
in
annual
soils,
is
wet
the
levels of 905,
Some
contamination results from resuspension, but the amounts are not sufficiently
large to account for the changes in concentration detected in the water since
1975.
Radionuclide
concentrations
in
the
cistern
water
during
each
sampling
period at Bikini are averaged and summarized in Table 7.
By November of 1977
90.
13706 and 2394240,|
the
average
concentrations
of
had
to approximately 19% of the concentrations measured in 1975.
occurred
in
the
13766
and
chloride
were
deposition.
nearly
After
concentration.
equivalent
1977,
the
Also,
to
mean
the
fallout
decreased
A similar change
concentrations
levels
concentrations
of
of
905,
expected
in wet
1376,
90,..
and
increased while the concentrations of Pu slightly declined.
The
changes
moved
the
change
that
in
concentrations
o.curred
back to Bikini
amount
satisfied
stored
normal
in
at
Island.
of
average
the
13706
Atoll.
By
requirements.
previously
concentration of
closely
1975,
paralleled
fewer
There was no large demand
the cistern attached
between 1975 and 1978.
many
Bikini
of
A
large
to
individual
increase
in
than
60
the
social
people
had
for fresh water and
residences probably
population
occurred
The need for fresh water increased and inventories in
unused
cisterns
radionuclides
were used.
in
the
water
During this period,
decreased
the
significantly.
In September 19/78 all the Bikini residents were removed from the island by the
Trust
Territory
Government.
The
average
12
concentrations
of
1376,
and
90.Sr