~ 25 major concentrations of waterborne radioactivity were
found--one 270 miles due north of Eniwetok, another
330 miles to the northwest,
and two to the west-—north-
west at distances of 390 and 570 miles.
The leading
edge of the contaminated area extended in September
almost to Guam.
In one plankton sample taken 110
miles northeast of Guam on September 7 the gross beta
radioactivity was 39,000 disintegrations per minute
per gram (dry weight),
and in a sample taken 80 miles
southeast of the island on September 9 the level was
at
28,000 disintegrations per minute.
Water taken at
the same stations produced readings of 6,200 and
3,000 disintegrations per minute for 5-liter amounts.
Plankton taken north of Guam,
Rota,
toward the island of
contained activity producing only 3,200 dis-
integrations per minute,
in the water there.
and no activity was detectable
(Hines,
1962)
During the summer of 1962 a series of high altitude tests
were held at Christmas and Johnston Islands.
The fallout from
the tests was measured in the sea from samples of sea water,
plankton,
and fish.
The Japanese used the oceanographic
vessel Shoyo Maru and the United States used the_Charles H.
Gilbert,
Interior,
a research vessel of the United States Department of
Bureau of Commercial Fisheries.
The fallout was
evaluated over a large portion of the central Pacific, and
samples of sea water,
plankton,
and fish were collected before,