14
spt?5 change with increasing depth.
In the 0.60 to 0.66-mev
photopeak region of the 0 to l-inch increment, the relatively
1
broad peak is a combination of the 0.60-mev photopeak of Sb 25
137
and the 0.66-mev peak of Cs”
-B a
137m
.
In the l to 2-inch
increment the peak becomes sharper and is oriented toward the
0.66-mev photopeak of Cs
137
-B a
137m
-
At the 9 to 10-inch incre-
.
.
ment there is almost complete orientation toward the Cs
pale’m peak, with little shi? remaining.
137
-
In Fig. 6 a comparison
is given of the spectrum of the 9 to 10-inch increment
(Fig. 5)
and the gamma spectra of cst3? and spi? spikes.
Fig.
7 shows the gamma spectra of increments taken from an
undisturbed area in 1958.
The first spectrum is from the 0 to
1/4-inch depth and the subsequent spectra are from 1/8~-inch
depth increments to a depth of 1 inch.
spt2>, the rare earths,
The highest levels of
and cof which move more slowly than
cst? or sr??, are in the 1/2 to 5/S-inch increments, whereas
1
.
‘
.
,
3
the Cs 37 which moves most rapidly in this soil type, is in
the 3/4 to 7/8-inch increment.
Litter and Guano
The gamma-ray spectrum of litter,
consisting of leaves,
twigs and floral parts splattered with tern droppings,
from old soil in 1961 (Fig.
collected
8) shows the cst?? photopeak to be
.
125
much higher than the Sb
peak.
The 1.17 peak of Co
60
is
skewed to the left, indicating the presence of the 1.12-mev
DOE ARCIIIV1:3