ARCllC
vol.44, NO.4 (OECEMBER1991)P.346-350
EnvironmentalRadiocesiumin Subarcticand Arctic A1askaFollowing Chernobyl
M. BASKARAN,'J.J.TELLTY,, A.S.NAIDUzandD.F. HOLLEMAN3
(Received3 I May 1990;acceptedin revisedform 6 March I99l )
t"Cs)
con""ntrations were measured in soil, plant and wildlife samples from subarctic to arctic Alaska.
ABSTRACT. Radiocesium (t3ocs and
l37cs
ranged from below detectable or low levels in whale and fish samples to as high as242Bqkg in lichen. For all potential
Concentrations of
human food items, the radiocesium concentrations measured in this study were below accepted permissible levels for human consumption.
Chemobyl-derived radiocesium concentrations ranged from below detectable or low levels in all arctic samples (soil, sediment, lichen, whale, fish
and caribou) to 32 Bq/kg in subarctic moss. Thercfore the distribution and subsequentdeposition of Chemobyl-derived radiocesium appears to be
variable but decreasing significantly from the Subarctic (Fairbanks) to the Arctic. The present data support the suggestion that Chemobyl-derived
quantity
debris arrived from westem Canada into central Alaska and subsequently moved to the north (arctic) and to the west, decreasing in the
deposited as the debris transversed the state.
Key words: Chernobyl, radiocesium, lichen, mushroom, caribou, reindeer, soil, fallout, deposition
nESUuE. On a mesur€ les concenrrations de cdsium radioactif (rvCs "t '"Cs
l'-tCsl dans des Cchantillons de sol, de plantes et d'animaux, dans la rdgion
allaient de niveaux peu €lev6s ou infdrieurs au point de d6tection dans
allant de I'Alaska subarctique h I'Alaska arctique. ks concentrationsde
des 6chantillons de baleine et de poisson, A des niveaux qui atteignaient 242Bqlkg dans le lichen. Pour toutes les formes potentielles d'alimentation
humaine, les concentrations de cCiium radioactif mesurdei uu coun de l'6tude dtaient infdrieures au niveau reconnu acceptable pour la consommation
humaine. lrs concentrations de c6sium radioactif provenant de Chernobyl allaient de niveaux p€u 6lev6s ou infCricurs au point de ddtection dans tous
les 6chantillons provenant de I'Arctique (sol, s€diments,lichen, baleine, poisson et caribou), n 32 Bq/kg dans la mousse subarctique. La r€partition et
le d6p6t subscquent du c€sium radioactif provenant de Chernobyl semblent donc varier, selon un mode nettement ddcroissant du Subarctique
(Fairbanks) i l;Arctique. Les donn6es actuelles viennent appuyer I'hypothdse que les d6bris provenant de Chernobyl sont arriv6s de I'ouest du
Canada dans le ccntre,de I'Alaska ct se sont ensuite ddplacdsvers le nord (Arctique) et vers I'ouest, se dcposant en quantitC ddcroissanteau fur et h
mesure qu'ils traversaient I'Etat.
Mots cl6s: chemobyl, c€sium radioactii lichen, champignon, caribou, renne, sol, retombdes' d€p6t
Traduit pour le joumal par Ndsida Loyer.
INTRODUCTION
It has been estimated that for all fallout radionuclides from
atmospheric weapons testing, radiocesium alone (primarily
'"Cs)
contributes about 50Vo of the total radiation dose to
humans in the Northern Hemisphere (Goldman, 1987)'
Recognizing the importance of radiocesium in radiation
dosimetry, investigators have focused considerable attention
on fallout radiocesium and its movement in the subarctic and
arctic food chain, esPecially the fallout to lichen to
caribou/reindeer to human/wolf food chain (Baatli et al.,
1961; Palmer et al., 1963; Liden and Gustafson,1967;
Miettinen and Hasanen, 1967; Hanson, 1967, 1982; Holleman
et al., l97li Holleman and Stephenson,1981; White et al.,
1986;Skogland,1987).
Therc has been a gradual decreasein bioavailable radiocesium since the cessationof atrnospheric weapons testing; thus
for Alaska, radiocesium concentrations in lichen, caribou and
reindeer have decreased from peak concentrations of 12001800 Bq/kg in the mid-1960s to less than 300 Bq&g in
January 1986 (White et al., 1986). The total amount of radiocesium discharged into the atmosphere following the
Chernobyl accident on 26 April 1986 was at most 5-l0Vo of
the total amount of radiocesium releasedfrom all afinospheric
nuclear weapons tests (Goldman, 1987). However, the
Chernobyl radiocesium radiation dose to humans in the
Northem Hemisphere has been estimated to be about 6O7oof
the total radiocesium radiation dose from the earlier atmospheric weapons tests (Goldman, 1987). This unusually high
radiation dose from a significantly smaller quantity of atrnospheric releasedradiocesium is primarily due to the relatively
close proximity of large human populations near the
Chernobyl accident site, namely, in the central U.S.S.R. and
eastem Europe.
Chernobyl-derived radiocesium can be identified by the
presence of-lvcs and provides a unique means to assessthe
pattern of environmental distribution, deposition and subsequent movement of fallout radionuclides from a single event
occurring in the Northern Hemisphere. Knowledge of such
patterns for atmospheric released radionuclides from the
Chernobyl accident may be helpful in evaluating the potential
effects of future accidents as well as in understanding the
transport pathways and processesof radionuclides associated
with such accidents in the atmospheric, terrestrial and aquatic
reservoirs (Santschi et al.,1988). Highly variable regional
deposition rates of Chernobyl-derived radionuclides have been
reported from Scandinavia, Germany, the United Kingdom
and the Mediterranean region, as suggestedby the wide-ranging values, for example, from 40 to several thousand Bq/m'
(Davidson et al., 1987; Santschi et al., 198.p).ln the westem
""Cs
was typically
United States, the total deposition rate of
37-74Bqln2, while at several locations in the Midwest and on
the east coast, the values ranged from 3.7 to 37 Bqlmz
(Davidson et al., 1987).In Alaska, the radiocesium deposition
rate was estimated at approximately 0.5 Bq/m'for the period
April 1986 (pre-Chernobyl) to August 1986 (post-Chernobyl)
for the Fairbanks area (White et al.,1986). There is some indirect evidence suggestingwide regional differences in the deposition rate of the Chernobyl-derived radionuclides in Alaska.
For example, some airborne measurements show that the integrated radioiodine 1'"! concentrationsare significantly different in Fairbanks and Barrow (unpubl. data, Kipphut, 1986),
which could lead to differencesin the deposition rates.
tDeparr-entof MarineScience,TexasA&M University,Galveston,
U.S.A.
Texas77553-1675,
2lnstirute MarineScience,Universityof AlaskaFairbanks,Fairbanks,
U.S.A.
Alaska99775-1080,
of
3lnstitute Arctic Biology,Universityof AlaskaFairbanks,Fairbanks,
Alaska99775-0180'U.S.A.
of
@TheArctic Instituteof North America
FOLLOWING
CHERNOBYLI 347
RADIOCESIUM
ENVIRONMENTAL
The objective of the present investigation was to determine
radiocesium concentrations in selectedenvironmental samples
t"C,
*as used to
in subarctic and arctic Alaska. In addition,
determine the variability and extent of Chernobyl-derived
radiocesium in the environment.
MATERIALS
ANDMETHODS
The locations and brief descriptions of the samplesused in
this study are given in Figure I and Table L Samplesof soil,
mixed lichens (primarily Cladonia spp.), mushrooms (mixed
unidentified spp.), mosses (Sphagnum spp.), ledum (Ledum
spp.), bowhead whale (Balaena mysticetus), two anadromous
fishes (humpback white frsh, Coregonus clupeaforrnus; arctic
least cisco, Coregonus sardinella) and caribou (Rangifer
tarandus) were obtained from arctic Alaska. Additional samples of lichens and mushrooms were collected from Ester
Dome near Fairbanks. A single lichen sample was collected in
extreme western Alaska near Nome. Samplesof about 30-60 g
of dried soil, 2-ll g of dried lichen/mossAedumand 60 g of
wet (frozen until ground) whale/fish/caribou muscle were
ground using a blender. The ground samples were transferred
into aluminum cans, capped and then analyzedusing a
Princeton Gamma (GeLi) detector coupled to a 4096 Channel
Multichannel Analyzer (Canbena Industries, Inc.). The detector was shjelded by_approximately l0 cm of lead and there
'"Cs
""Cs
peaks in the background spectrum.
were no
or
TABLE l. Collectionsite,dateanddescriptionof samples
Sample
code
Material
Collection
date
Arctic samples
Al
soil,lichen
A2
soil, lichen
,4'3
lichen
A4
soil,lichen
Collection
site
Unknownsiteon arcticcoast
I 56.3'w)
Atkasuk(?0.0"Nr,
Unknownsiteon arcticcoast
AnaktuvukPass
(68.1\,151.7'W)
AnaktuvukPass
t987
,A'5
lichen
1987
Unknownsiteon arcticcoast
A6
soil,lichen
1987
Research
site
A7
soil,lichen
(68.5"N,149.3\v)
BarrowLake
A8
lakesediment t987
(71.2'N,156.7w)
1987
ColvilleRiver
A.9
white fish
(70.0\,1s1.05v)
r987
ColvilleRiver
Al0
leastCisco
Arctic Ocean
Al I bowheadwhale 1987
(71.0\,157.0'w)
Arctic Ocean
A12 bowheadwhale 1987
Oct. 1985 Barrow(71.2"N,156.7W)
Al3
caribou
Nov. 1986 Banow
Al4
caribou
Al5
caribou
Sept.1987 ColvilleRiver
Subarcticsamples
S1-S2
lichen
moss
53
54
ledum
S5-S9 mushrooms
lichen
S10
1987
1987
1987
1987
Counting times rangedfrom 12 to 48 h. The minimum detecI37Cs
'3tcs
and
tion limits were 0.21 and 0.28 Bqlkg for
respectively, based on a 48 h count and the 95Eo confidence
level. The details on the counting procedureand data analysis
are given in Baskaranet a/. (198^8).
''obs
*us detected,the quantity
For thosesamplesin which
'"Cs
that was derived from the Chernobyl accident was
of
calculated. The procedure and its assumptions are as follgws.
r3aCs
Due to its relatively short physical half-life (2.05 yr)r.all
'3tcs/l3oCs
ratio
was assumedto be Chernouyt-aerivea.Th"
for Chernobyl releasedradiocesium at the time of the accident,
26 April 1986, was taken to be equal to 2.5 (Watson, 1986;
Davidson et al., 1987). A decay colrected ratio was calculated
by correcting for physical decay of both isotopes from the
time of accident to the time of sample assay. The Chernobyl'"Cs
con"entration of theiample was calculated as
derived
l3acs
concentration and the decay
the product of the measured
corrected ratio. All radiocesium concentrations are reported in
Bq/kg as of the time of counting,winter 1988.
RESULTS
ANDDISCUSSION
l37Cs
'3'Cs
and
in the samples
The total concentrations of
l37Cs
concentrationsderived from the Chernobyl
as well as the
accident are given in Table 2. The radiocesium concentrations
are presented as radioactivity per unit dry-weight for the soil
and plant samples and as radioactivity per unit wet-weight for
the fish, whale and caribou samples.The errors in the activity
are propagated I sigma error arising from counting statistics,
background and efficiency of the detector.
't'C,
Conrrntration in Soilsand Lichens
l3tcs
levels in the arctic soil samples analyzed are gener""Cs
levels are
ally lower than in the arctic lichens and the
below detection limit in all the soil samples (Table 2). The
t"C,
"on"entrations ranged from 2. I to 44.0 Bq/kB, with a
geometric mean of 7.3 BqRg, in the soil samples and from
16.3 to 24.2BqRg, with a geo.metricmean of 59.9 Bq/kg, in
'"Cs
concentration is comparalichen samples.This range of
ble to the range of 59-l8l Bq/kg reported earlier for lichens in
the study area just before the Chemobyl accident (Hanson,
1982; White et al., 1986). However, the mean concentration
(59.9 Bq/kg) of our arctic lichen samples is much lower than
the values (approximately 600 Bq/kg) expected from the phys'"Cs
for the values reported between 1962 arr,d
ical decay of
'"Cs
concentration in
1968 (925-1100 Bq/kg). The ratio of
lichens to soils varies from 0.51 to 28.2 (ratio of geometric
mean = 59.9fi.3 = 8.2).Earlier studies have shown that the
t"Cs
concentrations in lichens were about five times those in
soil (Hanson,1982).The ratios of lessthan 1.0 could be due to
new llchen growth that has been exposed to low levels of falll3?Cs.
out
't'C,
July 1988 Fairbanks
(64.8\, 147.7\M)
July 1988 Fairbanks
July 1988 Fairbanks
Aug. 1988 Fairbanks
Nome
1987
(64.5\,165.2"W)
Con "rtrations in FishandWhale Tissues
Of the two fis! analyzed,the freshwater species(humpback
I37Cs
whitefish) had
concentration below the detection limit,
while that of the estuarine fish (least cisco whitefish) had a
l37cs
concentration
low concentration (0.52+0.09 Bq&g). The
was below the detection limit in bowhead whale blubber and
liver, while the muscle sample had a low concentration of
'"Cs (0.57
Bq/kg). This may be expected since fallout radio-
3,18/ M. BASKARAN et a/
a cic, l|,t t,1(;l.,too,
i,t
A9,10,15
A U
n O u
c o' '
a'st to ss\
a l o\' ft
e€etilo
lrrn
' '
'i:.
\
ortor
pActFtc
t@
o
tQ
200
t&
100
5@
nc. t. Locations of the samplesanalyzed. Refer to Table I for further details.
cesium is greatly diluted in seawaterand, as a re,srrlt,the bow'''Cs,
head whale's prey is unlikely to concentrate
despite
high fallout.
t3ocs
and
"'C,
Con rrtration in Caribou
The seasonalvariation in radiocesium concentrationsin
caribou muscle samples has been recognized for a long time
(Hanson, 1982) and appearsto follow the changein the pattern
'"Cs
of grazing habits; for example, low values of
zue generally found in caribou muscle tissues following the summer
feeding season,when the caribou's diet is mostly vascular
plants and sedges.These summer forages contain much lower
"'Cs
concentrationsthan do lichens, a forage consumed
extensively during^winter.Another possible factor of signifi'"Cs
cance for the low
levels in caribou durins summer is the
t37cs
relatively higher excretion of
during s,i-me. as comparedto winter (Holleman et al., 197l).It has been shown that
the model-derived value of three- to sevenfold increase in
radiocesium levels neededto explain the seasonalvariation in
radiocesium concentration (Holleman et al., I97l) agreesreasonably well with empirical data obtained by Hanson (1982),
reporting a five- to tenfold seasonal difference. The muscle
sample of caribou harvested in September 1987 has perhaps
'"Cs
the lowest
concentrationsreported after the last seriesof
nuclear tests (Table 2).
Permissible Concentrationsfor H uman C onsumption
r37cs
The maximum permissible intake for
is approximately 100 000 Bq/yr for a human adult. This value is calculated from the radiation dose limit for the whole population of
1.7 mSv/yr (NCRP, 1971)qqd the radiationdoseequivalentof
'"Cs
intake (NCRP, 1977).Such
0.000017mSv per Bq of
limits suggestpermissible concentrationsin human food items
ranging from 300 Bq/kg for milk and meat to 1500 Bq/kg for
berries and mushrooms. Similar values for permissiblecont37cs
centrationsof
in human foods were adopted by the
Scandinavianand European countries following the Chemobyl
'"Cs
accident(Jones,1989).The
concenFationsreportedhere
are substantially less than the acceptablelimits, thus suggesting little health risk for persons consuming foods at these
'"Cs
concentrations.A similar conclusion was reported by
Taylor et al. (1988), who assessedthe post-Chernobyl radiocesium levels at some localities in northem Canada.
CHERNOBYL
FOLLOWING
RADIOCESIUM
I 349
ENVIRONMENTAL
when the snow melted. In this case, we would expect to find
high concentrations of radiocesium in lakes in the area. The
residencetime of radiocesium in lake water was reported to be
relatively short. For example, Santschi.eta/. (1.!!8) showed
rvCs
and'3tcs in Lake
that about 757o of the totai fallout of
Zurich was eliminated from the water column in about six
months. Thus. the washed-outradiocesium should reach the
rsCs
level was high
bottom of the lake. In order to see if the
grab
sample was
sediment
one
sample,
in a bottom sediment
collecredf{gr-na small pond (71.3oN,156.2W) in 1988and no
''"Cs
was found in the sample. Also a single sample
detectable
environmental
in
selected
TABLE 2. Radiocesiumconcentrations
of lichen (Sl0) from the extreme west coast of Alaska had no
samples
significant'*Ct. Th"t*Cs concentrationsin samplesfrom the
subarctic Fairbanks area ranged from below detection to 6.0
Chernobyl-derived
Total activity
Bq/kg. Since lichens were the only environmental samples
r3?cs
r34cs 'rtcr/ttc,
,rtc,
collected in both the Subarctic and Arctic, these samples were
Sample
used to assesspossible differences in deposiqipnof Chernobyl(vo)
(Bq/ke)
(Bq/kg) ratio
(Bq/ke)
code
''"Cs
ranged from
derived radiocesium. Concentrations of
Arctic soil sediment
below detection (0.21 nqAS) in all arctic lichen samplesto 6.0
BD
4.tx4.2
AI
Bq/kg in a subarctic lichen sample. Assuming that the physical
M.0tr.3
BD
A2
and physiological aspectsof lichens are similar at the various
BD
2.8+3.5
A4
collection sites, e.g., lichen density, radiocesium collection
BD
A6
8.111.7
efficiency, etc., then the data in this study suggestthe deposiBD
2.rt2.2
A7
tion rates were highly variable and were greater than a factor
BD
2.4123
A8
of 28.
The present data indicate a low Chernobyl-derived radioceArctic lichen.moss,ledum
sium deposition in arctic Alaska and on the extreme west coast
BD
16.6!4.2
AI
of Alaska as compared to the subarctic Fairbanks site. It is
BD
22.3X1.3
A2
pertinent to compare this observation with the radioiodine data
BD
A3
92.2t3s
in the aerosolsat Barrow and Fairbanks. The ratio of the timeBD
39.3tr.7
A4
integrated concentrations of radioiodine at Barrow to that of
BD
242.0!2.2
A5
Fairbanks was 0.628 just after the Chernobyl accident (5-19
BD
39.7!2.3
A6
May 1986, unpub. data, Kipphut, 1986). These data are conBD
A7
58.514.2
sistent with the observations of others who have investigated
distribution of Chernobyl debris in North America. For examArctic fish. whale. caribou
ple, Davidson et al. (1987) determined that Chemobyl-derived
BD
BD
A9
radiocesiummoved from the U.S.S.R. and Scandinaviaover
BD
0.52f0.09
Al0
Greenland and into central Canadathen spread to the east and
All
west. Assuming that the debris entered Alaska from the east
BD
BD
blubber
via Canada, deposition should decreasefrom eastern to westBD
muscle 0.57t0.1I
ern Alaska. Further, if the Chernobyl debris entered Alaska
BD
liver
BD
south of the Brooks Mountain Range, deposition may be
At2
to decreasesignificantly going from central to northexpected
BD
BD
blubber
ern
Alaska.
BD
BD
Iiver
BD
InUKTUK BD
CONCLUSIONS
BD
60.0x4.2
Al3
;
2.1
31.011.0 Q.4fl.2 7'1.0
Al4
The radiocesium concenffations in all the sampleswere low
BD
1.110.2
A15
and, therefore, present no appreciablehealth hazard to humans
who might consume them directly or indirectly via food
Subarcticlichen,moss,ledum,mushrooms
chains. The deposition rate of radiocesium from the
2.7;7
27.0
97.011.0 5.ot0.4 19.0
SI
Chernobyl-derived radiocesium in arctic/subarctic Alaska
ii.q
24.Q
19.0
89.011.0 4.6t{ .4
s2
appearsto be highly variable, possibly by a factor of greater
ii.z
32.0
86.013.0 6.Gr2.0 14.0
S3
than 28. Deposition of radiocesium was greater in subarctic
23.0
1a.i
-:
60.0+1.0 4.3fl.4 14.0
s4
Fairbanks as compared to extreme western and arctic Alaska,
BD
3.511.1
s5
which presumably reflects the dispersal pathway of the
BD
BD
56
Chernobyl debris in the area of study.
BD
3.8+1.0
Deposition of Chernobyl-Derived Radiocesium in Alaska
''ocs
in all samplescollected in the
The Chernobyl-derived
Arctic, namely, above 67oN, were below the detecqionlimit
'3ocs
conwith the exception of a single caribou sample. The
centration for the caribou sample was 0.4 Bq/kg, which was
only slightly above the detection limit. Perhaps this could be
attributed to the fact that snow cover existed on the arctic soil
when the Chernobyl plume arrived at the study area and that
most of the snow-depositedradiocesium was washed away
s7
s8
s9
32.CIil.0 1.410.3 23.0
43.011.0 5.210.3 8.3
stO
513t22
BD
Bq/kg= Becquerelperkilogram.
BD = Below detection.
;
28.0
24.2
65.4
ACKNOWLEDGEMENTS
We thank Dr. George Kipphut for providing some of his unpublished data on the radionuclide measurements on air filter samples
collected by Dr. Glen Shaw just after the Chernobyl accident. We
also express our gratitude to Drs. Peter Santschi and George Kipphut
350 / M.BASKARANeta/.
for their critical review of an earlier draft of this manuscript. We are
grateful to the Department of Wildlife Management, North Slope
Borough, Alaska, for their generouscooperation in obtaining pre- and
post-Chernobyl event samples from the Alaskan arctic regions. We
thank Dr. Gary Laursen, University of Alaska Fairbanks, for his
assistancewith the acquisition of mushrooms in the Tanana Valley,
Alaska. This is Institute of Marine ScienceContribution #837.
REFERENCES
B A A R L I , J . , M A D S H U S ,K . , L I D E N , K . , a n d M c C A L L , R . 1 9 6 1 .
Radiocesium
andpotassiumin Norwegians.
Nature191:436.
BASKARAN, M., KELLEY, J.J.,NAIDU, A.S., and HOLLEMAN, D.F.
concentrations
in Alaskanarctic
1988.Radiocesiumand radiopotassium
soils,plantsand animals.ReportNo. R88-1.Availableat the lnstituteof
Marine Science,University of Alaska Fairbanks,Fairbanks,Alaska
9977s-1080.
M.J., MONDAVIDSON.C.I.. HARRINGTON,J.R.,STEPHENSON,
A G H A N , M . C . , P U D Y K I E W I C Z ,J . , a n d S C H E L L , W . R . 1 9 8 7 .
Radioactivecesiumfrom the Chernobylaccidentin the Greenlandice
sheet.Science237:633.
GOLDMAN, M. 1987.Chemobylradiationdose.Science237:575.
processes
characterizHANSON, W.C. 1967.Radioecological
concentration
i n g a r c t i c e c o s y s t e m sI .n : A b e r g , B . , a n d H u n g a t e ,F . P . , e d s .
processes.
Prcss.p. 183.
Radioecoloqiqal
concentration
Oxford:Pergamon
'''Cs
concentrations
in northemAlaskanEskimos,1962-79:
--E-""t" 1982.
of ""ological,culturalandpoliticalfactors.HealthPhysics42:433.
HOLLEMAN, D.F., and STEPHENSON,
R.O. 1981.Preyselectionandconsumptionby Alaskanwolvesin winter.Joumalof Wildlife Management
45(3):620.
HOLLEMAN, D.F., LUICK, J.R., and WHICKER, F.W. 1971. Transfer of
radiocesium from lichen to reindeer. Health Physics 2l:657.
JONES, B.E.V. 1989. Effects of the Chemobyl accident on animal husbandry
and production from a Swedish perspective. Journal of American
Veterinary Medical Association I 94:900.
LIDEN, K., 4nd GUSTAFSON, M. 1967. Relationships and seasonal variation ofr3TCsin lichens,reindeerand man in northem Sweden l96l-1965.
In: Aberg, B., and Hungate, F.P., eds. Radioecological concentration processes.Oxford: Pergamon Press.p. 93.
MIETTINEN, J.K., and HASANEN, E. 1967.'"Cs in Finnish Lapps and
other Finns in 1962. In: Aberg, B., and Hungate, F.P., eds.
Radioecologicalconcentrationsprocesses.Oxford: Pergamon hess. p. 261.
NCRP. 1971. Basic radiation protection criteria. National Council on
Radiation Protection Report 39.
1977. Cesium-137 from the environment to man. National Council on
Radiation Protection Report 52.
PALMER, H.E., HANSON, W.C., GRIFFIN, 8.I., and ROESCH, W.C. 1963.
Cesium-I37 in Alaskan Eskimos.Science142:54.
SANTSCHI, P.H., BOLLHALDER, S., FARRENKOTHEN, K., LUECK, A.,
ZINGG, S., and STURM, M. 1988. Chemobyl radionuclides in the environment: Tracen for the tight coupling of atmospheric, terrcstrial and aquatic
geochemical processes.Environmental Science and Technology 22:5 10.
SKOGLAND, T. 1987. Radiocesium concentrations in wild reindeer at
Dovrcfjell, Norway. Rangifer 7(2):42.
TAYLOR. H.W., SVOBODA, J., HENRY, G.H.R., and WEIN, R.W. 1988.
'3?Cs
t3ocs
levels at some localities in northern
and
Post-Chernobyl
Canada.Arctic 4 | (4):293-296.
'rCs/'3?Cs
levels in Scotland after Chemobyl.
WATSON, W.S. 1986. Human
Nature 323:763.
WHITE, R.G., HOLLEMAN, D.F., and ALLAYE-CHAN, A.C. 1986.
Radiocesium concentrationsin the lichen-reindeer/cariboufood chain:
Before and after Chemobvl. Ransifer l:24.