14
spi?> 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
and the 0.66-mev peak of Cs
137
-B
137m
a
°
In the 1 to 2-inch
increment the peak becomes sharper and is oriented toward the
0.66-mev photopeak of Cs 137 B gi 37m
At the 3 to 10~inch incre-
.
13
ment there is almost complete orientation toward the Cs 7
pal?’ peak, with little spt?s remaining.
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 spt? 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.
2
spt 5 the rare earths,
Cs
13
? or sr??,
The highest levels of
and co°?, which move more slowly than
.
:
are in the 1/2 to 5/8-inch increments, whereas
the es 137 which moves most rapidly in this soil type, is in
the 3/4 to 7/8-inch increment.
andGuano
The gamma-ray spectrum of litter, consisting of leaves,
twigs and floral parts splattered with tern droppings, collected
from old soil in 1961 (Fig.
8) shows the cs??? 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
Aw