plants, the algae contribute to the food supply of animal populations.
Minerals as well as organic materials, concentrated and incorporated
into the algae, are passed on in the food chain to the animals that feed
upon them.
Thus the radioactive materials pass through the algae to
the animals in the normal course of food gathering.
The affinity of algae for some of the radioisotopes is well known.
For example, Asparagopsis, a marine alga found
on the
reefs
at
Bikini and Eniwetok, has a great affinity for iodine (Palumbo, 1955 ).
In the presence of yi31 Asparagopsis becomes radioactive.
This alga
is a succulent morsel sought by fishes; thus the 1131 passes to the
fish and along the food chain.
The land plants of the tropical islands of
the Pacific atolls become
contaminated with radioactive materials in two ways: (1) by fallout of
material from the air or from
the rain water with direct absorption
through the leaves, and (2) by absorption from the soil.
The soils of the atolls are generally deficient in potassium.
deficiency speeds the uptake of Cs137 by the plants.
This
Although Cel 44 is
present in the soils it is so firmly bound there that little is available to
the plants.
The radioisotopes remain concentrated in the top two inches or less
of soil.
The rooting habits of the plants, therefore, are associated with
uptake of the radioisotopes.
The plants with feeder roots close
to
the
surface thus take up more of the radionuclides than do those with deeper
root systems.
While all of the tissues
ofthe plants may contain radioisotopes, the