~19-—
"unsorted"
(Appendix Table 2).
“Unsorted” and “remainder"
samples contained essentially the same types of organisms.
The radioactivity found in the unsorted and remainder
plankton samples is plotted in Figure 2.
zinc-65,
zirconium-niobium-95,
The radionuclides
and cerium-141,144, because
they occurred most frequently in the samples and are representative of the results as a whole,
diagram.
are plotted in the scatter
Detectable amounts of zirconium-niobium-95 and
cerium-141,144 were found in more than 70 of 120 samples.
Zinc-65 was found in 19 of 120 samples.
The graph shows that there was considerable variation in
levels of radioactivity in the samples and indicates an increase
in samples collected late in the surveys north and west of
Christmas Island.
The samples which showed the highest levels
of radioactivity were collected in July and August at stations
51 through 55,
68,
80,
84,
face samples.
Some of the
85,
and as far west as 161°40'w.
and 86.
All of these were sur-
stations are as far north as 19°42'N
The radioactivity in the
samples
ranged from 1 to 687 pc/g dry weight for zirconium-niobium-95
at station 53, 1 to 120 pc/g for cerium-141,144 at station 86
and 1 to 29 pe/g for zinc-65 at station 28.