32
kinetics of catabolic or anabolic enzymes.
A number of organic
carcinogens are known to metabolize to metal-binding agents
which can aid the entrance of certain metals into cells.
3.3
Ecological Factors in the Distribution of Radioisotopes
in a Marine Environment.
Krumholz, Goldberg and Boroughs
ecological
(1957) reviewed the
factors involved in the uptake,
accumulation and
loss of radionuclides by aquatic organisms.
For this purpose,
they considered the aquatic biosphere to be divided into three
trophic levels based on energy sources:
such as the photosynthetic plants;
herbivores;
and
(3)
(1) primary producers
(2) primary consumers,
secondary consumers,
the carnivores.
the
In
general, they stated that organisms of the first trophic level
take up radiomaterials in the ionized state,
though some in
particulate form will be adsorbed to their surfaces.
Particu-
late radiomaterials tend to be concentrated in the second
trophic level, especially by mucous, ciliary and pseudopodal
feeders among the zooplankton which accumulated more radioac=-
tivity from nuclear tests than did the setal or rapacious
feeders.
The transfer of radiomaterials from one trophic
level to another depends upon
(1)
the concentration of the
radiomaterials by the individual organisms,
(2)
the rate of