-~7T-
Results
The non-fission products Co57, Cod8, C060, zn©5 and mn%
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
Zr?5-Nb95, RnlO6, Bal37m(csl37) ana 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.
amount of zn©5,
in some samples the
based on the gamma spectra,
parison to radioactive cobalt,
51, 52, 53,
Thus
(Fig.
2,
was high in com-
plankton stations 50,
= - a) and in others the reverse relation
existed (Fig. 2, plankton station 42,
Go = 234
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.
Detailed descriptions of the elution patterns from ton-
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 sepa-
rated fractions are shown in Figure 3 to illustrate the small
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