mare yah
er
7 50 = \
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cline, at a rate of about 8 feet per hour.
The distribution
of radioactivity within the mixed layer was not homogeneous
at the time of sampling.
In three other surveys during 1956
and 1958 in which samples were collected up to six weeks
after detonation,
the radioactivity also was not distributed
homogeneously in the mixed layer.
However, one year after
the 1954 test series, the radioactivity in the water above
the thermocline was well mixed,
from which it is concluded
that the time required for fallout materials in the surface
waters of the ocean to mix thoroughly is greater than six
weeks and less than a year.
Below the thermocline,
hours after fallout,
in the period from 28 to 48
the radioactivity in the particulate
form descended at more than 10 meters per hour,
four times
the rate of movement through the mixed water layer (Lowman
1960).
The increased rate of movement is assumed to be the
gravitational effect upon the heaviest fraction of the par-
ticulate matter.
The chemical and physical form of fallout materials
as they enter the sea may change upon interaction with the
Salts and other materials in the sea.
Fallout that enters
the sea as particulate matter may go into solution,
and
material in the lonic form may change to the particulate