18
zn?” peak.
The presence of zn°> is corroborated by the 0.5-mev
peak.
8 also shows the gamma-ray spectrum of noddy tern
Fic.
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
The foliar contribution to the
65
,
:
is evident.
1
litter contains only Cs 37 from
among the gamma-emitters,
.
In undisturbed areas Cs
137
and Sr
90
.
.
are being deposited
with the litter and are thus replacing at the surface some of
the Cs
137
and Sr
90
_
,
lost by leaching.
ets
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 Soil
Fig. 9 gives the spectra of the 0 to l-inch,
and 9 to 10-inch increments of a young soil.
pr itd
1 to 2-inch,
co°®,
an°?,
and Eul?> were detected only in the surface layers,
ce 44_
and
with increasing depth the 0.60 to 0.66-mev photopeak region of
the spectra shifts toward the 0.60-mev peak of spit,
The spec-
trum of the 9 to 10-inch increment is compared with that of an
Sb
12
.
‘
i
° spike in Fig. 10, showing that the photopeaks of the soil
and spike gamma spectra are identical.