30
layers of the funnel show
only es t37 and sp° in the deepest
layer.
Buried Organic Layers
The organic matter in buried horizons may become important
in the vertical distribution of radionuclides in the soils.
No
detectable gamma-emitters were found in buried horizons during
the period 1958-1961.
In September 1963 a core was taken through
a buried horizon at 14 inches in old soil.
Radioautographs of
sections of the core show that a small amount of radioactivity
has accumulated in the buried horizon.
The diffuse distribution
of the radioactivity in this case indicates that there is adsorption of the radionuclides from solution as water percolates
through the soils, although the possibility of translocation by
plants cannot be ruled out.
cst?? and naturally occurring «1°
were the only radionuclides present in the buried horizon.
The accumulation of cst?” in the buried horizons is of particular significance in terms of plant-soil relationships,
because a proliferation of roots is often found in the buried
horizons and Cs
137
is the principal fallout radionuclide taken
up by atoll plants.
Roots
1
Roots, which contain Cs 37 and sr?°, in most instances have
higher levels of radioactivity than the surrounding soil except
near the soil surface
(Fig. 12).
The influence of poplar roots
on redistribution in a continental soil has been well demonstrated
37