e
t
ee
eae te
mes
re
wy
a? mm
* pa
f
mh oa
Bote
:
r y BPRSre
s
te ete
rere
(Ga TARPS ic
a adihe
2
:
v
ee a reteNr the Be le
See be a Be
-ll-
Island
BELLE
Figure 4 shows the decline
for island soil as well as the
only two observations for beach
sand at Belle.
The slope for
island soil of -1.06 (Table 1)
corresponded closely with that
of survey meter readings.
From an initial level on
the first day of 13 millicuries
per kilogram, the island soil
declined fairly regularly for a
period of two years.
The dip
at 130-200 days is reflected in
the decline curves for land
hermit crab but is not appsrent
in the data for green leaves of
plants on Belle.
Figure 5 shows the decay of
OAYS
te
AFTER
100
may 14, 1954
Fig. 4
samples of island soil from Belle
(plate 7542) and from Edna (plate 9170),
and of intertidal beach sand from Henry
(plate 9711A).
A slope of -1.2 is in-
Soll decay
cluded for comparison.
the basis for computation of the decay
correction factors for converting values
back to date of collection. The same
s
The Belle island soil decay curve
is for plate number 7542 which served as
Radioactivity
factors were used for all types of
material except rats collected post-
Nectar at Eniwetok Atoll.
The dashed,
early portion of the curve is not a
;
.
.
76
+e
Days offer May 6 AT~e
straight line because it was originally
Fig. 5
For comparison, Figure 6 shows the
decay of the sample of lagoon bottom sand.
TOT
extrapolated on semi-log paper.
TT
Mike soll decay
test residues Superimposed upon the Nectar
test effect.
—1-1-F
curve of Figure 2 is striking.
It was
practically uninfluenced by residues from
previous detonations.
The more pronounced
flexures in the curve for Belle island soil,
&3 well as its generally more gradual slope
are the result of the influence of the Mike
b
Tr
1952(Donaldson 1953:25), and for 20-1000
days its similarity to the theoretical
Radiaactiylty
calculation of decay correction factors for
the collections following the Mike test in
7&
dredged November 7, 1952 off Tilda (northwest of Vera). This decay was used for
~
‘,
Dayt after Movember 1 t45E
Fig. 6
a
_}
mee