18
zn°> peak.
peak,
The presence of zn°? is corroborated by the 0.5-mev
Fig. 8 also shows the gamma-ray spectrum of noddy tern
guano collected in this area.
over the 1.17 peak of Co
60
The 1.12-mev peak predominates
and the 0.51 peak of Zn
65 ,
.
is evident.
.
.
.
'
.
1
The foliar contribution to the litter contains only Cs 37 from
among the gamma-emitters.
‘
137
90
.
.
In undisturbed areas Cs
and Sr
are being deposited
with the litter and are thus replacing at the surface some of
the Cs
137
and Sr
90
:
lost by leaching.
‘
+s
There is not sufficient
data from the field work to determine whether there eventually
will be a loss of these radionuclides from the soil-plant system,
or a steady state (excluding physical decay of the radionuclides).
Long-term experiments, under simulated field conditions, with
monolith lysimeters
and controlled and uniform addition of the
radionuclides would define this point.
Young
Fig. 9 gives the spectra of the 0 to l-inch,
and 9 to 10-inch increments of a young soil.
pr iat
1 to 2~inch,
co°®, zn°>, cel44 _
and Eur?> were detected only in the surface layers,
and
with increasing depth the 0.60 to 0.66-mev photopeak region of
25
eee vel
the spectra shifts toward the 0.60-mev peak of spt?>,
The spec-
trum of the 9 to 10-inch increment is compared with that of an
spt25 spike in Fig. 10, showing that the photopeaks of the soil
and spike gamma spectra are identical.