~ 32 mended and adopted.
Distribution of Radiotsotopes in the Sea
The radioisotopes present in the sea are those
that (1) occur naturally, (2) have been created by the
detonation of atomic devices, or (3) have been disposed
of as waste from the operation of atomic reactors or from
research and clinical laboratories.
The naturally occurring radioisotopes in sea
water are listed in Table II.
These isotopes have been
and will continue to be present in the ocean at the level
of abundance given in the table,
and H’.
with the exception of cl4
Carbon-14 is formed naturally in the atmosphere
by a two-stage process which involves the shattering of
a nitrogen atom by a high-energy proton from space.
Most
ci4 exists in the form of carbon dioxide for which the
residence times are an average of five years in the atmosphere,
five years in the surface layer of the ocean and
1,200 years in the deep waters.
explosions also produce cht,
However,
thermonuclear
Since the detonation ot the
first thermonuclear device in 1952,a ton
of C14 has been
produced which equals about one per cent of the total