35
Figure 8 represents the activity at each of the five depths
sampled relative to the highest activity at each station of the
Marsh survey, anc Pigure 9 represents the same thing for the
Walton survey.
In general,
the presence of relatively higher levels of
Botivity at greater depths at the Walton stations corresponds to
the situation at the Marsh stations except in the area south and
west of 12° N and 157° E, where the Marsh etations had a marked
preponderance of aotivity in the surface water.
The Walton sur-
vey was msde during the test series when radioactive mterials in
the water had had only a few days or at most, a few weeks, to be
moved by ocean currents fro: the érea of fallout.
In addition,
the bulk of the activity was found to the north and northwest of
the test
site.
Barnes® reports that the surface layers in this
region move about three times faster than the layers at 300 meters, and Yosnide | shows the westward velocity of the surface
water as about 14 times the velocity at 4O meters at 17° N.
It
seams possible, therefore, that the Marsh stations south of 12° N
and west of the test site represent,
for the most part, a region
which received its radioactivity via the ocean currents.
Stations
4 to 9 are exceptional in this region but they are also stations
with high levels of activity (Figs. 3 and 5, and Table 1), probdably due to fallout from tests made after the completion of the
Walton survey.
DOE ARCHIVES
There are unusually high levels of radioactivity at depths
of 50 m to 100 m at the three stations immediately east of Eniwetok and at station 68 which is about 2° N of Bikini.
The
d+ |