410365
QUALITATIVE DISTRIBUTION OF
RADIONUCLIDES AT RONGELAP ATOLL
tirely dependent on cisterns as a source of water.
Rainfall in this area is comparativeiy iow and the
islets small, so that there is not a wei!-deve! oped
fresh water lens. There is, however. some potab':
water in wells at Rongelap and Eniwetok Islets.
E. BE. HELD
cat ry of Rad tion 2 odass
te tte
The native style wattle and palm frond build-
ot aad tata
Seattle. Washinueton
In March. 1958. a radioeculogical study of
1. Ate 4 wes instituted iw here nest of the
bi..s.on of Bivlowy and Medicine. U. 3. Atomic
kiuer.; Commassi:a (AEC).
This report wili be con-
cerned with generalizations regaraing the distribution of radionuclides at the atoll in the fall of
ivoy. some five vears after contamination with
radioactive failout.
norgedap Ato!l was accidentally
on «.ren Ll.
contaminated
i954, with radioa.tive fallout trom a
the: onuclear device detonated at Bikini: Atoll some
SC a..es to the west.
Gamma radiation dose rates
at Rongelap or D* |
‘detonation * «ae day) ranyed
trom 3.5 roentgens per hour ut the southern islets
wi ow atoll tu 55 roentyens per hour at the nor‘hern .slets (Dunning, 1957).
Eighty-two natives resid'sg on Rongela) Island, in the south. were evac~
uated and did not return until June, 1957.
At that
time the returning populatiun
approached 300 in
Rhumoer but since appears to have stabilized at 230.
Several radiologicai ane viological surveys,
primarily of a monitoring nature. were conducted
rrom the time of the first contamination until
1958 (Dunning, 1957).
Ouring this time the gamma
radiation dose rates over iand areas declined at
approximately the rate predicted for mixed fission
prowucts by Miller and . eb (.958). Slight rises
in. nma dose rate were -nserved in 1956 and 1958.
resu ‘ing from tests conducted during these years.
However, the total contribution of radionuclides
from these subseqcent fallouts amounted to a frac-
tton of one per cent of the amount from the 1954
faliout.
songelap Atoll is ierated in the Marshall Isiands, in the Central Paci‘... Ocean. at about 119
North.
It is a typical atull with a lagoon area of
2h square miles and iboct 1&O-tcot average depth
The emergent lan. grea is about three square miles
ana is made up wf #: small islets rang..¢ in size
from a fract um of an acre tu the largest :sland,
Rereelap, which is about tour miles long and onehalf rile acruss at 1:8 widest point.
There is one sma!i isl-t on the western reef
ang ihe remaincer are strung along the northern,
eastern
and southern reefs,
fhe 1siets on the
“.cthernm reef are not ag well cevelopeu as those to
‘be engt and south.
The waters of the lagoon are
ess. ntial!y isothermal (Robinson. 1954).
The circ.’.t1on, generated by the northeast trade winds,
1S ++ 4 east to west at the surface with a returning bottom currest (Von Arx. 1954).
The estimated
mae
ug renewal of water in the lagoon is about
Tavs
The parent material of both 4 14s and the la~
weco Det om is primarily calcium zrbonat: origiwees
ma:niy from coralli-:s algae. corals and
‘watt viera
There .* also some accumulaticr of
Mitr oo Tf .m
ve So. s
“e naltve: of Lhe ares e Mierone ions
K.oeature eS aamtted 2
oeuristy
of prowuets
foo
Ue vbay SiePibacapt
sport ws cops:
About
wif
o¢* the toud conSumed af the or. sens
ome 15
vmporte :
Fisch and other “arine crcsanisms are
eater Set imese sources ura aot exploited a= nulh
es tie, cou a te
The fongelapese are almost en1
feed
ints ave been rtepiaced ‘y flywood 24°
. .ni num
structures built to Rongelapese specifications by
the AEC.
Sanitation habits have been altered by
the advent of pit toilets.
The terrestrial fauna
is itimited in variety
The only mammal present is the small fieid rat,
Rattus exulans. The most common birds are the
fairy
tern, cygis alba,
stolidus
an ck
numbers on some
and the noddy terns, Anous
tenuirostris. which nest in large
of the uninhabited islets.
The
reptiles are represented by skinks. geckos. and a
blind snake.
Land crabs are common. the most spec-
tacular being Rirgus latro, tne coconut or robber
crab.
InsectsareFew, both in aumper 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 .5 a tremendous proliferation of both numbers and variety
of organisms on the reefs and in the lagoon.
example, there are over 700 species of fish.
For
Plankton, however, is extremely sparse and as a
consequence the water ig 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
wel] 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 studv betore the
addition of radiation as an ecological factor, it
is difficult to do more than speculate concerning
the cause of the sr2cific anomalies observed.
Fosberg (1959) has accurately described the poor
condition of the plants at the northern islets of
Rongelap 4toll and has suggested that the primary
vause 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,
Eniweiok. Rongelap, and uncontaminated atolls that
while there is evidence of genetic changes caused
Ly radiation other factors mask the radiation
effects
In short. it is not likely that such
questions will be resolve i 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, cohalt-60 and manganese-54
ur.
‘ound primarily in the marine organisms.
Stil!
detectable in the soil are manganese-54,
iiov-55. copalt-5/. cobailt-60, zinc-65, strontium-
90.
2irconium-95,
ruthenium-106
antimony-125,
‘2S1um-137, cerium-144, and europium-155. which
remain .oncentrated
in the upper one to two inches.
wherc hischer levels of radionuclides have been
present itese nuclides have been reported in a wide
variety, or organisms.
It is likely that most of
trese cadionuclides are actually sresent ia most if
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Manian ene Dedinacnlnoy edited hv Schulez and Klement, Reinhold Publishing