410349
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QUALITATIVE DISTRIBUTION OF
RADIONUCLIDES AT RONGELAP ATOLL
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tirely dependent on cisterns as a source of water.
Rainfall in this area is comparativeiy low and the
islets small,
E. E. HELD
The native style wattle and palm frond buildings have been repluced by plywood and aluminum
Laboratery of Radiation Biology. University of Washington,
structures built to Rongelapese specifications by
the AEC.
Sanitation habits have been altered by
the advent of pit toilets.
Seattle. Washington
In March, 1958, a radioecological study of
Rongelap Atoil was instituted at the request of the
Division of Binlogy and Medicine, U. 8. Atomic
This report will be conEnergy Commission (AEC).
cerned with generalizations regarding the distribution of radionuclides at the atoll in the fall of
1959, some five years after contamination with
radioactive
fallout.
Rongelap Atoll was accidentally
contaminated
om March L, 1954, with radioactive fallout from a
therronuclear device detonated at Bikini Atoll some
80 miles to the west.
Gamma radiation dose rates
at Rongelap or D+ 1 ‘detonation + one day) ranged
from 3.5 roentgens per hour at the southern islets
of the atoll to 35 roentgens per hour at the north-
ern islets (Dunning, 1957).
Eighty-two natives residing on Rongela> Island, in the south. were evac~-
uated and did not return until June, 1957.
At that
time the returning population
approached 300 in
number but since appears to have stabilized at 230.
Several radiological anu biological surveys,
primarily of a monitoring nature, were conducted
trom tie time of the first contamination until
1958 (Dunning, 1957).
OUuring this time the gamma
radiation dose rates over land areas declined at
approximately the rate predicted for mixed fission
products by Miller and . eb (1958). Slight rises
in gamma dose rate were observed in 1956 and 1958,
resulting from tests conducted during these years.
However, the tot21 contribution of radionuclides
from these subsequent fallouts amounted to a fracLion of one per cent of the amount from the 1954
fallout.
Rongelap Atoll is located in the Marshall
Is-
lands, in the Central Pacific Ocean, at about 11°
North.
It is a typical atoll with a lagoon area of
J88 square miles and bout 180-fcot average depth
The emergent land area is about three square miles
and is made up of 61 small islets rangisx in size
from a fract on of an acre to the largest :sland,
Renge ap, which is about four miles long and one-~
half :1le across at its widest puvint.
There is one small islet on the western reef
and the remainder are strung along the northern,
eastern. and southern reefs.
The islets on the
neurthern reef are not as well developed as those to
the east and south.
The waters of the lagoon are
essentially isothermal (Robinson, 1954).
The circulation, generated by the northeast trade winds,
iS irc 4 east to west at the surface with a return-
ing bottom current (Von Arx.
1954).
The estimated
time ‘ur renewal of water in the lagoon is about
30 days
The parent material of both soils and the la<oot Butiom is primarily calcium « srbonate origi-~
catir- mainly from coralline algae. corals and
furami>ifera.
There is also some accumulation of
sumaice Jr oft in rhe soils
ees
so that there is not a weli-deve! ped
fresh water lens. There is, however. Some potab’*
water 1n wells at Rongelap and Eniwetok Islets.
mec “re natives uf the area are Microne ians.
sedi agricutture iS limited i. varisty of prouucts
aid tne oniy Signifscant export 18 copra
About
nalf of the food consumed af the oresen. t:me 15
imported.
Fish and other marine curganisms are
eaten but these sources are not exploited as much
es they Couia be
The Fongelapese are almost en-
The terrestrial fauna is limited in variety.
The only mammal present is the small field rat,
Rattus exulans.
The most common birds are the
fairy tern,
is alba, and the noddy terns, Anous
stolidus and A. tenuirostris, which nest in large
numbers on some Of the uninhabited islets.
The
reptiles are represented by skinks, geckos, and a
blind snake.
Land crabs are common, the most spectacular being Birgus latro, the coconut or robber
crab.
Insects are
few, both in aumber of species
and individuals.
The most severe pest appears to
be the beetle, Brontispa sp., which attacks the
coconut palm.
in contrast to the land areas there is a tre-
mendous proliferation of both numbers and variety
of organisms on the reefs and in the lagoon.
For
example, there are over 700 species of fish.
Plankton, however, is extremely sparse and as a
consequence the water is so clear that green algae
are found growing at depths of 180 feet.
Since the question of the effects of radiation
on the organisms inevitably arises, it might be
well to consider it briefly before going on to the
main subject.
There is no doubt that the levels
of radiation were of sufficient intensity to affect
living organisms,
However, under actual field conditions and without benefit of study before the
addition of radiation as an ecological factor, it
is difficult to do more than speculate concerning
the cause of the specific anomalies observed.
Fosberg (1959) has accurately described the poor
condition of the plants at the northern islets of
Rongelap Atoll and has suggested that the primary
cause of this condition is radiation.
In our opinion. however, other factors, particularly edaphic
factors, have probably been more important than
radiation.
The fact that the nitrogen content of
the soils of the northern islets is lower than that
of the rest of the atoll is at least circumstantial
evidence that for some time there have been
differences between these areas with respect to
plant growth.
Stone et al. (1957) have concluded
from studies of Drosophila populations at Bikini,
Eniwetok. Rongelap, and
uncontaminated atolls that
while there is evidence of genetic changes caused
by radiation other factors mask the radiation
effects.
In short, it is not likely that such
questions will be resolve: without controlled ex-
perimentation with the species involved, under
varying conditions, and with an eye toward the
possibility of synergistic effects.
Approximately five years after fallout the
long-lived fission products cesium~137 and strontium-90 are the principal radionuclides found in
the land organisms. while the neutron-induced
radionuclides z:nc-65, cobalt-60 and manganese~54
are
found primarily in the marine organisms.
Still detectable in the soil are manganese-54,
irov-55. cobalt-57. cobalt-60, zinc~65, strontium90. zirconium-95, ruthenium-106. antimony-125,
“esium-137, cerium-144, and europium-155. which
remain .oncentrated in the upper one to two inches.
Wherc hi<zner levels of radionuclides have been
present these nuclides have been reported in a wide
variety or organisms.
It is likely that most of
these radionuclides are actually present in most if
BEST COPY AVAILABLE
Reprinted from Rediovecology, edited by Schultz and Klement, Reinhold Publishing
Crenneatian and tha Amarican Pnctiniuwe af Rinlasical Sciences New York. 1963.
161