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fhe soil and sand samples included those from the islan
oper,
from the beach,
and from the lagoon bottom.
The radio-
tivity of a somple taken from the top inch of soil on
pared J Island March 26, 1954, was 6.8 microcuries per gram,
hioh is equivalent to one curie per 325 pounds of top soil.
activity of this sample ten months later, January 29, 1955,
‘s one thirtieth its original value, 1i.e.,
; ough nearly five half-lives.
it had passed
The decay rate for this period
é expressed by the formula, r = p2-32, with March 1, 1954,
s the date of origin (Figure 12).
This rate approximates the
\ixed fission product decay rate and in general approximates
ihe decay rate for many of the biological samples.
For these
jeasons the decay factor for correcting counts back to the day
collection was based on the decay curve of a similar soil
¥
ample.
The decline in radioactivity of the soil samples can be
|
ibserved from the figures in Appendix Table X.
Considerable
ariation in the activity of soil samples from the same area on
he same day can be expected because of the nature of the fallfat pattern and should be kept in mind when interpreting results.
:
consideration is given to the Kabelle Samples only, the rate
. decline is greater than the decay rate from March to July
95%, but less from July 1954 to January 1955.
When the sample
founts from all islands are averaged, the relative decline in
betivity of the March 1954 samples and the January 1955
samples
Be the same as the decline in activity of the decay sample.