Fesults
The non-fission products Co57, C058, C062, zn®5 ana mn54
contributed almost all of the activity in gamma spectrum
curves made from filtered plankton samples eleven months after
collection, masking the weaker peaks from the fission products
Zr95-Nb95, Rhl06, Bal37m(cs137) and Cel44 (Fig. 2).
The gamma
peaks of the latter isotopes were detected only in the frac-
tions eluted from the ion-exchange columns (Fig. 3).
Although the non-fission products,
in each instance,
contributed the major part of the gamma activity in the plankton,
they were not always present at a constant ratio to each
other in the different samples.
Thus in some samples the
amount of zn65, based on the gamma spectra, was high in comoarison to radioactive cobalt,
51, 52, 53,
(Fig.
2, plankton stations 50,
Coo’ = 0.19
6
) and in others the reverse relation
zn°>
1,0
existed (Fig. 2, plankton station 42,
Coll =
zn65
5-5)
1.0).
variation was related to the site of collection.
This
A similar
variation was observed in the levels of some other non-fission
radioisotopes and will be discussed later.
DOE ARCHIVES
Detailed descriptions of the elution patterns from ion-
exchange resin columns and the identification of the separated
fission and non-fission radioisotopes appear in
an earlier
paper (16) and are not repeated here.
the gamma
However,
spectrum curves for plankton samples 50,51,52,53 and the separated fractions are shown in Figure 3 to illustrate the small
iw