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LITAY
C ABSTRACT
TS”
The redistribution of radionuclides in atoll soils following
fallout from a nuclear device is described.
careous,
containing no inorganic colloids,
The soils are caland their exchange
capacity is directly related to organic content.
Comparison
of
gamma-ray spectra of depth increments from young and old soils
shows that Cs
137
and Sb
125
'
move most readily in old soil, while
the principal gamma-emitting radionuclide moving in young soil
is Sb
125 -
%Sr”
90
moves in both old and new soils, and quantitative
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differences in vertical movement between soil types is obscured
by the highly variable surface distribution of the radionuclides.
There is a vertical gradient in the distribution of radionuclides
at the soil surface and bird droppings have added zn°? and co°?
In young soils the highest levels of radioactivity are associated
with soil algae found as a surface crust in undisturbed areas
and in coral fragments in eroded areas.
ry
Litter redeposits est3? and sr?°
ee
even within the surface inch.
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Horizontal movement is
localized and probably is of little overall importance.
Buried
erganic horizons contain more es) 3? than adjacent soil layers,
and roots are generally more radioactive than the surrounding
soil except at the soil surface.
Pumice particles in the soil
adsorb radionuclides but pumice is found infrequently.
Mechani-
cal mixing by animals in old soils and by erosion in young soils
(¢ ONIIA WE 2)
‘