on
ATOLL SOIL TYPES IN RELATION TO THE
DISTRIBUTION OF FALLOUT RADIONUCLIDES
INTRODUCTION
The redistribution of radionuclides in atoll soils following
contamination with radioactive fallout is the subject
paper.
Rongelap Atoll, northern Marshall Islands,
of this
in the central
Pacific Ocean, presents a unique opportunity for such studies
since it was substantially contaminated with radioactive fallout
only once.
The fallout resulted from a thermonuclear device
detonated at Bikini Atoll eighty miles to the west on March l,
1954.
Although there was some additional contamination from
nuclear tests in 1956 and 1958 the total contribution of radionuclides from the fallout of these subsequent test series
amounted to a fraction of one per cent of the amount from the
1954 fallout.
Gamma radiation dose rates at Rongelap at
detonation plus one day ranged from 3.5 r/hr at the southern
islets of the atoll to 35 r/hr at the northern islets (Dunning
1957).
These rates declined at approximately the rate pre-
dicted for mixed fission products by Miller and Loeb (1958).
Rongelap Atoll has a lagoon area of 388 square miles and
an average depth of 168 feet (Nugent 1946, p. 748).
The emer-
gent land area is about three square miles, consisting of