35
SUMMARY
—
Rongelap Atoll received a single heavy dose of radioactive
fallout in 1954.
The atoll soils are calcareous and contain no inorganic
colloids; the exchange capacity is related to organic centent.
Comparison of gamma-ray spectra of depth increments from old
and new soils shows that es3? and sp225 move most readily
in the old soil; the principal gamma-emitting radionuclide
moving in new soil is sb? ,
.
‘
sx?° moves in both eld and young soils.
The distribution of radionuclides at the surface is very
spotty.
There is a vertical gradient in the distribution of radio-
nuclides within the surface one-inch layer.
Litter redeposits Cs
137
and Sr”
90
over the soil surface and
bird droppings have added zn? and co°?,
The principal reservoir of radionuclides in young soils is
the surface algal crust.
In eroded areas radioactivity is associated with large coral
fragments, which are infiltrated with algae.
There is some localized horizontal movement of radionuclides
in old soils.
be