33
growth of the organisms and
population.
There is a loss
materials in the transfer
(3)
the rate of increase of the
in the total amount of radio-
from one trophic level to another,
although not necessarily a decrease in concentration in indi~
vidual organisms.
In a discussion of the effects of the ecological system
on the transport of elements in the sea,
Ketchum
(1957)
sum-
marized the characteristics of the distribution of elements
in the sea which can be attributed to gravitational effects
on the ecological cycle:
{1)
the accumulation of elements at
intermediate depths as a result of sinking and decomposition;
(2) the concentration of elements in areas of opposed flow
where deep water is brought to the surface by upwelling or
vertical mixing; and
(3) the impoverishment of areas where the
supply of water is from the surface and the loss from greater
depths.
Seymour
(1959)
and Lowman
(1960) have reviewed the
marine biological investigations conducted in connection with
the nuclear testing programs at the Pacific Proving Ground in
the Marshall Islands where the occurrence of the induced
radioisotopes of the transition elements in marine plankton
and fish
increased with time after contamination.
The initial
uptake of radioelements by plankton consisted primarily of