necessary properties which suit it to marine environmental
studies involving the use of biological concentrators of zinc.
zine is a constituent of sea water,
the dissolved state in the sea
therefore,
and exists primarily in
(Krauskopf,
available to marine organisms.
1956).
It is,
The 245 day
radioactive half-life of zinc-65 is an appreciable fraction
of the life span of a great variety of marine organisms,
and
consequently of its biological half-life in these organisms.
The average residence time of zinc in the sea can be estimated
from the geochemical balance of the elements in sea water as
reported by Rankama and Sahama
(1950), and an assumption of a
constant volume for the oceans over most of geologic time as
proposed by Conway (1943) and Kuenen
(1950).
On this basis,
the average residence time in the sea for zinc is on the order
of 3.5 x 109 years.
Thus the biological half-life of zine in
any organism is an insignificant fraction of the residence
time of the element in the sea.
The desirability of studying the fate of zinc-65 introduced into a marine environment was emphasized by reports of
its occurrence and persistence in waters and aquatic organisms
contaminated by fallout or the discharge of reactor wastes.
Marine biological investigations at the Eniwetok Test Site
showed that zinc-65 was one of the principal radionuclides
CS