“20+
involve either adsorption of the particle onto the organism
or ingestion of particulate material.
The latter would
include both food perticles and non-living particulate
detritus.
Several other factors, however, also control the uptake
of specific radioelements.
In the case of strontium and
cesium chemical competition plays a major role.
occurring potassium, the competitor to cesium,
sea water at a high level of about 380 ppm.
Naturally
is present in
In comparison
to this level of occurrence, Cs137 would be present in very
sm&ll amounts, even in an area of heavy fallout.
Because of
the limited ability of animals to differentiate between potassium and cesium, uptake of the latter would be low.
Natural calcium occurs at a level of about 400 ppm in
sea water and exhibits chemical competition to strontium with
regard to uptake by marine organisms.
elements,
however,
the uptake
In the case of these
is not directly proportional to
occurrence in the water; rather strontium is discriminated
against with reference to and in the presence of naturally oc-
curring calcium by factors of approximately 3 in calcareous
a&lgae and foraminiferans,
2 in arthropods,
2 to 7 in molluscs,
2.5 in bryozoans (25) and 3 to 10 in marine fishes (19). DOE ARCHIVES
In laboratory experiments utilizing radioactive strontium
Chipman (2) observed that Artemia larvae reached a steady
state in the level of radiostrontium about 0.7 that of sea
water and Burroughs, Townsley, and Hiatt (1) reported a value
25