-~ 24 barium 140, with a half-life of 12.8 days, while
smaller plankton contained higher percentages of
molybdenum 99-technetium 99,
but otherwise the
radioisotopic compositions were
The Collett,
similar.
(Hines,
1962)
following a tract over somewhat the same
general area west of the test site as covered by the Walton
two years earlier,
collected samples of water and plankton
that indicated the distribution of the fallout from a number
of tests conducted at various points in time.
The highest
concentrations of radioactivity came from above the thermocline.
The variations were such,
however,
that it was
obvious the radioactivity was not evenly distributed throughout the mixed
layer.
An unexpected radioelement,
was found in some of the Collett samples.
tungsten-185,
Both plankton and
water samples contained this radioisotope which apparently had
_ been incorporated into some of the devices being tested as a
means of tracing and indentifying the fallout.
The Silverstein,
leaving Eniwetok on September 3,
followed a zigzag track similar to that of the Marsh
two years before.
In the interval between the August
and September surveys the center of ocean radioactivity that had been noted 170 miles northwest of
Eniwetok had moved west-southwest some 250 miles.
Because the Silverstein cruise pattern permitted
observations over a much wider area of ocean,
four