on the occurrence of uranium and thorium in the biosphere of

on the occurrence of uranium and thorium in the biosphere of

P iotr SZEFER, Stanislaw OSTROWSKI
Medical A cadem y in G dansk
D epartm ent of A nalytical C hem istry
ON THE OCCURRENCE OF URANIUM AND THORIUM IN
THE BIOSPHERE OF NATURAL WATERS. PART I. URA­
NIUM AND THORIUM IN PLANKTON AND INHERENT
PLANTS
C o n t e n t s : 1. Introduction, 2. U ranium and thorium in plankton of natural w a ­
ters, 3. Uranium and thorium in inherent plants; Streszczenie; R eferences
1. INTRODUCTION
Lim iting uranium and thorium levels in n atu ra l w aters usually vary
betw een several h u ndredths to several m icrogram s per dm 3 and in th e
m arine and oceanic sedim ents from several to a dozen or so ppm. Lower
levels of the two elem ents w ere found in other com ponents of the m arine
environm ent, among others in the algae and plankton.
The objective of the p resen t study is to com plem ent an earlier review
of literatu re on the occurrence of uranium and thorium in n atu ral w aters
[43] and in m arine sedim ents [41].
The uranium levels in the above-ground organs of te rre strial plants,
in freshw ater organism s and in hum an tissue have been found to be re la ­
tively low, varying betw een 10~9 and 10'5 per cent [8, 10, 11, 20, 21, 29,
32, 47, 48, 51].
Some te rre strial p lants adsorb uranium and thorium to com parable
levels, accum ulation coefficients of th e two elem ents being sm allest in
young p arts (sprouts, leaves) and attain m axim um values in old p arts
(branches, bark, wood) [15], The variations in the uranium and thorium
levels m ay depend, how ever, not only on th e age of the organs of a plant
but also on the site of its grow th, n atu re of th e soil and the species [5, 28,
49]. Some species of m icroorganism s and low er plants (fungi, lichens) are
exceptionally active in sorbing uranium [9, 17, 33]. On the other hand,
increased levels of u ranium in other organism s usually occur w hen they
grow in an environm ent (w ater, soil) enriched in the elem ent [30, 44, 52],
Oceanology No 13(1980)
2. URANIUM AND THORIUM IN PLANKTON OF NATURAL
WATERS
2.1. General remarks
There is an enorm ous am ount of suspended living and dead m atter in
n atu ra l w aters. It floats or swims in th e w ater, th e dead com ponents
being referred to as detritus. The m atter can be divided into two compo­
nents, the organic (dead fragm ents of organisms) and inorganic (clays,
erosion slime, slime from m elting glaciers, desert dust, volcanic dust,
calcareous and siliceous skeletons of microscopic algae).
P lankton is a representative of th e living biomass. This te rm defines
all living organism s drifting w ith th e current. They m ay m ake slight
m ovem ents or move vertically, b u t are helpless in respect of horizontal
w ater currents. P lankton consists of phytoplankton, including the d rif­
ting plant m a tter such as Diatomae, D inoflagellatae, Coccolitliinae, and
zooplankton, including animals, th e size of w hich ranges from 0.01 him
to several m etres, w hich have some ability to move by them selves, e.g.
Crustacea, Pteropoda, A urelia and free-sw im m ing larvae of benthic an'.mals. Despite this classification, it is freq u en tly difficult to draw th e
line betw een phytoplankton and zooplankton, as some of the species
bear features of both plants and animals. This group includes G lobigerina, R adiolaria and other species, referred to as th e transitional p lank­
ton [45].
2.2. The uranium level in inland w aters plankton
The 232Th isotope was found [1] to be m ore adsorbed by sm all algae, Chlo­
rella ellipsoides and Scenedesm us accum inatus than th e 238U isotope.
F urther, differences have been detected in the accum ulation of uranium
and thorium in bottom sedim ent, d etritu s and lake plants [12, 13], The
232Th isotope was sorbed to th e greatest ex ten t by th e fresh w ater d etri­
tus, w hereas aquatic p lants displayed the highest affinity to th e 238U iso­
tope. The 226Ra isotope was found to be uniform ly distributed in th e two
com ponents of th e environm ent.
P lankton of th e Issyk-K ul Lake was m arked for its m axim um u ra ­
nium level am ounting to 2.2X10'4 p er cent based on dry m atter. The
w ater of the lake was found to be enriched w ith this elem ent (30 ]xg
U /d m 3). The C hara genus alga is w orth m entioning here, the accum ula­
tion factor for this being as high as 700— 1000 [16, 47],
2.3. Extent of accumulation of uranium in freshwater algae
The biological accum ulation of uranium by th e Scenedesm us quadricanda
alga was studied un d er laboratory conditions [31]. The in terp retatio n of
the results was difficult owing to diversity of physico-chem ical form s
of occurrence of th e u ran y l ion and physiological processes taking place
in the living mass of th e alga. The accum ulation of uranium was found
to occur in two phases. In th e first phase, already one m inute after th e
alga had been in contact w ith the uranium -enriched w ater, about 60 per
cent of the total am ount of th e elem ent was bound. In th e second phase,
equilibrium betw een th e u ranium level in w ater and th a t of th e algal
biomass was noted after 6 hours only. The ex ten t of accum ulation depen­
ded on the u ranium level in solution and in exceptional cases on the
content of the algal biomass.
2.4. The uranium and thorium levels in plankton of seas and oceans
The levels of uranium in the m arine plankton range w ithin (0.01— 1.8)
X10'4 per cent based on d ry m atter [18, 23, 40], The lowest levels of the
elem ent w ere found in organisms of th e transitional plankton (Globigerina) (nXlO~6 p er cent U). On the other hand, in th e phytoplankton or­
ganisms, m ainly diatoms, inhabiting tropical w aters, th e level of uranium
was 1X 10'4 p er cent [17].
According to Risik and associates [36] th e level of uranium in th e
A driatic plankton am ounts to (0.83— 6.03)X10'G p er cent based on moist
w eight and (0.92— 2.44) X 10'5 per cent based on ash. The respective
concentration factors are 3.5 — 23.2. In A driatic w aters, plankton binds
(1.8— 3.3) X 10'9 g U /d m 3, which corresponds to 0.1 per cent of th e
total uranium in sea w ater. In oceanic w ater, only 0.08 — 0.003 p er cent
of the total uranium occurs in suspension [34].
Concentration factors determ ined for plankton taken during th e
night w ere 2—3 tim es higher th an those for plankton taken during th e
day. This difference is due to th e varying content of isopodes and copepodes in m arine plankton. D uring the day copepodes predom inate (up
to 90 per cent), w hereas during th e night — isopodes (up to 70 p er cent).
The la tter enrich them selves in uranium , as for the g reater period of th eir
lifetim e they reside in th e bottom mud which contains a higher uranium
level [35, 36],
M iyake [22, 23] studied the bioaccum ulation of uranium by m arine
plankton. The author found the ex ten t of sorption of uranium to be 7— 15
tim es higher than th a t of th e 230Th and 232Th isotopes and 3000 tim es
higher than th a t of radium . A t a m ean level of uranium in Pacific w ater
of 3.34 x 10'6 g /d m 3, the m ean concentration of the elem ent in plankton
was (1.7 — 7.8) x 10'7 g /g and th e concentration factors ranged from 48 to
260 [24],
K harkar and associates [46] analysed zooplankton (predom inantly
calanoids and cyclopoids) from th e Caribbean for content of 238U, 234U,
232Th, 228Th, 228Ra, 226Ra, 210Pb and 210Po. They found the concentration
factors in the zooplankton relative to sea w ater to be th e highest for 210Po
and slightly lower for 22»Th and 210Pb.
The levels of the 228Th isotope in the pByto- and zooplankton found
in the w aters around South Africa am ounted respectively to (9 — 65)
x 10‘18 and (2 — 27) x 10"18g per g of moist mass suspended in oceanic
w ater, the level of the dissolved form of this isotope being 2.7 x 10-15
g /d m 3 [3]. Shannon [37] supplem ented these data and the correspon­
ding values obtained by him (in g per g of d ry m atter) w ere 4.7 x 10'6 g
of 228Th, 1.7 x 10'12 g of 230Th and 2.7 x 10‘7 g of 232Th. The ratio of the
m ean activity of 228Th/232Th in the plankton is com parable w ith th at
of sea w ater and am ounts to about 15.
For the Black Sea phytoplankton, th e accum ulation factor of 234Th
am ounts to about 20,000, being low er for zooplankton [50].
2.5. EXTENT OF ACCUMULATION OF URANIUM IN MARINE
ALGAE
Heide and associates [2, 19] attem pted to isolate uranium from sea w ater
by using single-cell Chlorella algae grown, selected and exam ined in th e
laboratory. A p articular m utant, subjected to the action of uran iu m -en ­
riched sea w ater (0.006 ppm U), is characterized by a high selectivity of
sorption, optimal dispersion degree enabling rapid isolation, facile and
cheap production of living biomass and a relatively high concentration
factor exceeding 1000. This algal biomass accum ulates as m uch as 95 per
cent of the total uranium p resent in sea w ater [7].
\
Degens [6] found small U m bilisosphera organism s — coccolites, to
concentrate uranium from sea w ater as a resu lt of th eir vital functions.
Owing to this featu re the biggest uranium deposits of sedim entary origin
are to be found in the Black Sea basin. They w ere form ed by the depo­
siting of coccolite plankton rich in uranium over m ore than 5000 years.
2.6. MECHANISM OF CONCENTRATION OF URANIUM
IN MARINE PLANKTON
There are no reports in the literatu re on the mechanism of concentra­
tion of uranium in m arine plankton. According to Degens, uranium in
the coccolite plankton is bound w ith proteins and sugars p resen t in the
cells of the plankton, hence its concentration is 10.000 tim es higher than
th a t in sea w ater [6].
3. URANIUM AND THORIUM IN AQUATIC PLANTS
3.1. General remarks
Among aquatic plants, the m ost num erous group constitute m arine algae
w hich include more th an 20,000 species.
In this section, the contents of th e two elem ents in sm all m arine
algae have not been taken into account, as these organisms belong to
the previously described (section 2.4) m arine plankton. O nly th e levels
of uranium and thorium in large species of m arine macroalgae and some
freshw ater plants have been discussed here. The levels of uran iu m and
thorium in m arine and fresh w ater plants v ary and depend on a v ariety
of factors such as th e specific features of a plant, its age, region of
vegetal, jn, level of the elem ents in the surrounding environm ent (w ater,
bottom sediments) and n atu re of p articu lar organs of th e p lan t (roots,
shoots, stem, leaves, etc.).
3.2. THE LEVELS OF URANIUM AND THORIUM
IN FRESHWATER PLANTS
The 238U isotope was found to be more readS y accum ulated by feshw ater
plants than th e 232Th isotope [12, 13]. This phenom enon was also obser­
ved, on the basis of analysis for the two elem ents, in Elodea, M yriophyllum [14] and 13 other plan t species, including pilew ort (Ranunculus)
and Potam ogeton [1]. Both plants and fish taken from th e Shinkaw a
R iver w ere found to contain 0.002—0.3 ppm U based on w et m atter [25].
3.3. ACCUMULATION FACTOR OF URANIUM IN PLANTS
SUBJECTED TO THE ACTION OF FRESH WATER
CONTAINING THE ELEMENT
In laboratory experim ents, concentration factors w ere determ ined for
rice and bean plants exposed for 5—7 days to th e action of w ater artifi­
cially enriched in uran iu m up to a level of 25 ppm. The accum ulation
factors w ere 2— 5 and 0.1—0.2 for th e roots and leaves, respectively [25].
3.4. THE LEVELS OF URANIUM AND THORIUM IN SEAWEEDS
M iyake and associates [24] found 0.04 — 2.35 ppm U bassed on dry m atter
in algae. Sim ilar levels w ere found in inh eren t seaweeds harvested in
1961 — 1968 in several sites off th e coast of P u erto Rico. The uranium
levels in them ranged from 0.07 to 1.64 ppm. Among Chlorophyta living
in this area, the highest levels of uranium w ere found in Halimeda
opuntia (1 .4 6 X 1 0 '4 p er cent) and Penicillus capitatus (1.64X10"4
per cent), w hereas th e lowest levels w ere found in Ulva lactuca (0.16X 10*4 per cent) and Codium isthm ocladium (0.1 3 X 1 0 '4
per cent). Among Rhodophyta, th e highest accum ulation factors w ere
found in G alaxaura cylindrica (0 .8 5 X 1 0 '4 per cent) and Acanthophora
specifera (0 .6 1 X 1 0 '4 per cent) and the lowest in Bryotham nion triq u etrium (0 .0 7 X 1 0 “4 per cent). The Dictyota divaricata phaephyte contains
1.27X10"4 per cent U and Sargassum polyceratium 0.44X 10"4 per cent
only.
The thorium levels in these seaweeds ranged from 0.02 to 0.62
ppm [4],
The m ean level of uranium in seaweeds of th e Lam inaria species
is 0.101 ppm and in the P o rp h y ra ten era rhodophyte 0.164 ppm [39].
In the Black Sea and A driatic Chlorophyta levels of uranium ra n ­
ged from 0.004 to 0.135 ppm, w hereas in Phaeophyta. and R hodophyta
from 0.154 to 0.71 ppm [35], These values are by 1— 2 orders of m agnitu­
de lower than those reported for tropical species. This difference is
probably due to th e low degree of calcification of the seaweeds taken from
the Black Sea and A driatic. As shown by S trohal and P in te r [38], A d­
riatic Chlorophyta and Phaeophyta cotain 0.01— 0.66 ppin of 232Th, and
the Rhodophyta taken from this basin show increased levels of 232Th
(1—2.3 ppm). Considerable variations in the accum ulation factors of
234Th w ere observed in the Black Sea C hlorophyta Uva rigida and Cystoseira barbata [26, 50] and in E nterm orpha linza [50], The accum ulation
factors for these plants w ere 1200, 60 and 700 respectively. The kinetics
of bioaccum ulation of the 232Th and 234Th isotopes in various kinds of
algae was investigated and th e concentration factors of these isotopes
were determ ined for four species [27],
C haracteristic m ean value of the U /C a ratio for seaweeds from
P u erto Rico is only slightly low er than th a t calculated for sea w ater.
The Baltic Fucus vesiculosus phaeophyte contains 0.26—0.41 ppm
of U and 0.25—0.33 ppm of Th based on dry m atter. A sim ilar level
of uranium (approx. 0.25 ppm) was found in Cladophora chlorophyte
and in Zostera m arina, the levels of thorium in these plants being 0.30
and 0.3—0.6 ppm respectively. The mean concentration and selectivity
factors of the two elem ents w ere determ ined for these plants. W ith
Zostera m arina, some variations of th e level of uranium and thorium
w ere noted, depending on the location. The age of the plant was also
found to affect th e levels of both elem ents, as was dem onstrated by ana­
lysing young and old p arts of Fucus vesiculosus [42].
3.5. Mechanism of concentration of uranium and thorium in seaweeds
Based on statistical evidence [4] one can assume th a t w ith strongly cal­
cified seaweeds uranium is eith er co-precipitated w ith C aC 03 in the
form of carbonate com plexes or it is concentrated owing to th e ionexchange process. On th e other hand, in w eakly calcified algae, the
accum ulation of uranium is by the form ation of organic complexes. In
the case of thorium also both concentration m eans are possible depen­
ding on the kind of plant. W ith Rhodophyt.a and m ore calcified Chlorophyta seaweeds, thorium is probably concentrated by ion exchange and
co-precipitation. The accum ulation of the elem ent in the tissue of P h aeophyta, how ever, occurs owing to the form ation of thorium — protein
complexes.
P iotr SZEFER, Stanisław OSTROWSKI
A kadem ia Medyczna w Gdańsku
Zakład Chemii Analitycznej
O WYSTĘPOWANIU URANU I TORU W BIOSFERZE WÓD
NATURALNYCH
CZĘSC I. URAN I TOR W PLANKTONIE I WODOROSTACH
Streszczenie
Dokonano przeglądu literatury dotyczącej w ystępow ania uranu i toru w planktonie
i roślinach osiadłych wód naturalnych. Wykazano, że tor w porównaniu z uranem
jest w w iększym stopniu adsorbowany przez niektóre drobne glony słodkowodne.
Zawartości uranu i toru w planktonie morskim w ynoszą kolejno 0.01—1,8 ppmU
oraz 0,27 ppm 232xh (w przeliczeniu na suchą masę). Zawartości dwóch pozostałych izo­
topów toru w yrażone w 1 g suchej m asy planktonow ej w ynosiły 4,7.10-16 g 2S8Th
oraz 1,7.10-12 g 230Th, przy czym fitoplanktoti charakteryzuje się silniejszą aku­
m ulacją w ym ienionych izotopów w porównaniu z zooplanktonem .
W yznaczony dla planktonu stosunek średnich aktyw ności 228Th/232Th jest zbli­
żony do w ody m orskiej, w ynosi ok. 15.
Scharakteryzowano w ystępow anie uranu i toru w słodkow odnych i m orskich
roślinach osiadłych. W w odorostach tropikalnych stężenia obu pierw iastków w y ­
n osiły 0,07— 1,64 ppm U oraz 0,02—0,62 ppm Th. Stężenia uranu w tych roślinach
są o 1—2 rzędy w ielkości w yższe n iż w czarnom orskich i adriatyckich wodorostach,
co można tłum aczyć w yższym stopniem k ałcyfik acji gatunków tropikalnych. Śred­
nia w artość stosunku stężeń U /C a dla roślin osiadłych jest n iew iele niższa od w ar­
tości obliczonej dla w ody m orskiej.
Przedstawiono zaproponowany przez niektórych autorów pogląd na m echanizm
akum ulacji uranu i toru w roślinach osiadłych.
REFERENCES
1. Accumulation of radium-238, thorium-232 and radium-226 b y fresh w a ter plants.
I s k r a A. A., B a k h u f o v V. G., K u l i k o v N. Y., G i l e v a E. A., M etody
Radlioetool. Issled, 1971, s. 87-93 (Ed. VerikhoviSikaya I. N.), Altoim'izdat, Moscow,
U.S.S.R., C.A., 1972, 76, p. 82927.
2. Apparatus and m e th od for extracting uranium from sea water. Kernforschungsanalage Juelich G-im.b.H., Fr. Dem ande 2,243,264. (Cl. C 22 B, A 01 H), 04 Apr.
1975, Ger. Appl. P 23 45 430,0, 08 Sep. 1973, 7 pp.; C.A., 1976, 84, p. 7908v.
3. C h e r r y R. D., G e r i c k e I. H., S h a n n o n L. V., Thorium-228 in marine
plankton and sea w ater, Earth P lanet Sei. Lett., 1969, 6(6), -p. 451.
4. The concentration of radium, thorium and uranium b y tropical marine algae.
E d g i n g t o n D. N., G o r d o n S. A., T h o m m e s M. M., Alm odovar, Limnol. Oceanogr., 1970, 15(6), p. 945.
5. D e a n M. H., A s u rv e y of the uranium content of vegetation in Great Britain,
J. Eco-1., 1966, 54(3), p. 589.
6. D e g e n s E. T., Plankton m orski źródłem uranu, Przem . Cheto., 1978, 57(5),
p. 274.
7. Extraction of uranium from sea w ater b y cultured algae, H e i d e E. A., W ag e i n e r K., P a s c h k e M., W a l d M., N aturw issenschaften, 1973, 60(9), p. 431.
8. G eokh im icheskye poiski u ranovykh mestrorozhdenii v Yaponii, M u r a k a m i
Y , F u d z i t a r a S., S a t o M., O h a s h i S. In: Tr. 2-oy Mezhdunarodnoy
konf. po m irnom u ispolzovan iyu atomnoi energii (Geneva, 1958), >t. 8., Atomizdlat,
M oscow 1959, p. 4.
9. G r o d z i ń s k i d D. M., G o l u b k o v a M. G., M ikroelem en ty v S el’sko-Khoz.
Med. Sb. 1963, p. 461-4; C. A., 1965, 62, p. 13479.
10. H a m i l t o n E. I., Concentration of uranium in man and his diet, H ealth Phys.,
1972, 22(2), 149; p. C. A., 1973, 76, p. 83003W.
11. H o f f m a n J., Bioelement Uran in Pflanzen und Tierreich sowie im m enschli­
chen Organismus, Biochem . (Z., 1943, 313(5/6), p. 377.
12. I is k r . a A. A., K u l i k o v N. V., B a k h i u i r o v V. G., Role of fresh w ater v e ­
getation during the migration and distribution of natural radioactive elements
in a reservoir, Ekologiya, 1970, 2, p. 83; C. A., 1970, 73, p. 127803b.
13. I s k r a A. A., K u l i k o v N. V., B a k h u i o v V. G., Behaviour <of natural
radioactive elements in a w a ter reservoir, I. At. Energ., 1969, 27(2), p. 134; C. |A.,
1970, 72, p. 498e.
14. Is kt ri a A. A., K u l i k o v N. V., B a k h i u r o v V. G., Accumulation of ura­
n ium — 238, thorium — 232 and radium — 226 by fresh w ater plants dependent
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
on plant biomass in an aqueous m edium , Radiobiologiya, 1970, 10(3), p. 473;
C. A,. 1970, 73, p. 106005c.
K o v a l e v , s k i i A. L., A dsorption of natural radioactive elements b y plants,
Mikroelem. BioiSfere Ikh Priimen. Sel. Khoiz. Med. Sib. D al’nego Vostoka, Dokl.
Sib. Konf. 2nd 1964, p. 93, Buryat Knizhin. Izd. U lan-U de, U.S.S.R.; C. A., 1968,
69, p. 65343d.
K o v a l’s k i i V. V., V o r o t n i t s k a y a I. E., The biogenic migration of ura­
nium, Ukr. Biokhim . Zh., 1966, 38(4), p. 419; C. A., 1966, 65, p. 20779f.
K r a s i l ’n i k o v N. A., Rol’ m ikroorganizm ov v migratsii estestvenno radioaktiv n y k h elem entov v porodakh i pochvakh, Izd. A.N. S.S.S.R., Ser. biol., 1967,
5, p. 714.
K u T. L., A n evaluation of the U2MIU23s m e th o d as a tool for dating pe­
lagic sediments, J. Geophys. Res., 1905, 70(14), p. 3457.
M atrix of cultivable m u ta n ts of singlecell green algae for uranium re co v ery
from sea w ater, H e i d e E. A., P a s c h k e M., W a g e i n e r K., W a l d M.,
Ger. Offen. 2,345,430 (Cl. c 12 K), 17 Apr. 1975, Appl. P 2345 430 0-41, 08 Sep.
1973, 5 pp; C. A., 1975, 83, p. 46222r.
M a l e n c h e n k o A. £. , S h c h e k i n a G. D., S e r e g i n V. V., Natural ura­
nium in man, Dokl. Aka‘d. Nauk Beloruss. SRR, 1972, 16(1), p. 87; C. A., 1972,
76, p. 150569a.
M a l u g a D. P., Biogeokhimicheskii m etod p oiskov ru dn ykh mestorozhdenii,
M oscow, Izd. A. N. S.S.S.R., 1963. ,
M i y a k e A., Biogeokhimicheskii baians estestve n n yk h ra d io a k tivn yk h ele­
m e n to v v okeanakh, Tezisy dokl. II M ezhdunar. okeanogr. kongressa, Nauka,
Mosco'w, 1966, p. 274.
M i y a k e Y., S a r u h a s h i K., S u g i m u r a Y., Biogeochemical balance of
natural radioactive elem ents in the ocean, Rec. Oceanogr. Works Japan, N ew
Series, 1968, 9(2), p. 179.
M i y a k e Y., S u g i m u r a Y., M a y e d a M., Uranium content and the acti­
v i ty ratio uranium-234/ uranium-238 in marine organisms and sea w ater in the
w estern N orth Pacific, Nippon K aiyo G akkai-Shi, 1970, 26, p. 123; C.A., 1971,
75, p. 30875e.
M i z u m i K., S h i n i i c h i O., Uranium concentration in fishes and plants
associated w ith the discharge of low level uranium liquid w aste, Tokai Jigyo-sho, D oryoku-do, Kakunenryo K aihatsu Jigyo-dan (Rep), 1972 PNCT 831-72-0,
1, 180-4; C. A., 1973, 78, p. 68817n.
N a z a r o v A. B„ Z e s e n k o A. Ya., Accumulation of thorium-234 b y sea­
weed, R adiobiologiya, 1971, 11(5), p. 799; C. A., 1972, 70, p. 22584q.
N a z a r o v A. B., Z e s e n k o A. Ya., E xperim ental stu d y of the isotopes ac­
cumulation b y marine organisms, Report 1972, EUR-4800 (Vais. 1 and 2), p.
1321-6; C. A., 1973, 79, p. 28992e.
N i k o l a e v a A. V., Concentration of thoriu m and rare earth b y plants in v a ­
rious periods., Tr. Buryat. Inst. Estestv. Nauk Buryat. F ilial Sib. Otd. Akad.
Nauk S.S.S.R., 1969, 5, p. 141; C. A., 1971, 74, p. 103123j.
29. P e r t s o v L. A., P rirodn aya radioaktivn ost biosfery, A tom izdat, M oskva, 1964.
30. P o l i k a r p o v S. S., Radioekologiya m orskikh organizmov, Atom izdat, M os­
cow 1964.
31. P r i b i l S., M a r v a n P., Accum ulation of uranium b y the chlorococcal al­
ga Scencdesmus quadricanda, Arch. Hydrobiol. Suppl., 1976, 49(2), p. 214; C. A.,
1977, 86, p. 13891s.
32. P r i s t e r B. S., O povedenii urana v n ekotorykh z v e n ’y a k h biologocheskoi
tsepi, Dokl. V sesoy. akad. c.-kh. nauk im. V. I. Lenina, 1967, 1, p. 31.
33. P . s h e n i n L. P., O nakoplenii U — U Xi azot-fiksiruyushchdmi mikroorganismon Chornogo moriya. Doki. A. N. S.S.S.R., 1960, 33(6), p. 1448.
34. R a d ioaktivn o st’
okeanicheskikh
vzvesyey.
2. Uran v okeanicheskikh
vzve sya k h . K u z n e t s o v Yu. V., L e g i n V. K., L i s i t s i i n A. P., S i m o n y a k Z. I., Radiokhim iya, 1967, 4, p. 489.
35. R i s i k N. S., N akopleniye i m ikroraspredeleniye urana v m o rsk ikh organizm a k h v prirodn yk h u sloviyakh. Isk usslven nye i estestvenn ye radionuklidy
v zhizini gidrobiontov, N aukova Dumka, K iev, 1973, p. 58.
36. R ii :s i k N. S., S t r o g o n o v A. A., Z e 1 e z i n is k a y ia L. M., Content of uranium-238 in M editerranean Sea hydrobionts, R adioekologicheskie Issled. Sredizemnogo Morya, N aukova Dumka, K iev, 1970, p. 182; C. A., 1971, 75, p.
137317b.
37. S h a n n o n L. V., Marine alph a -radio activity off Southern Africa 2. Thorium
in marine life, Invest. Rep. Div. Sea Fish., S. Air., 1972, 99, p. 20.
38. S t r o h a l P., P i n t e r T., Thorium in w ater and algae from the Adriatic Sea,
Lrmmol. Oceanogr., 1973, 18(2), p. 250.
39. S >u C hing-Shen, D eterm ination of uranium concentrations in seaweeds b y nu­
clear track detectors, Radiat. Eff., 1972, 14(1-2), p. 109; C. A., 1972, 77, p. 31159c.
40. S w a n s o n V. E., Geology and geochem istry of uranium in marine black sha­
les, US Geol. Surv. Profesis., Paper 1961, v. 356-C, p. 67.
41. S z e f e r P., O w y stę p o w a n iu uranu i toru w m orskich osadach dennych, S tu ­
dia i M ateriały Oceanologiczine, 1977, 17, p. 353.
42. S z e f e r P., Badania nad zawartością uranu i toru w w y b ra n y c h roślinach
osiadłych południowego B ałtyku , Studia i M ateriały O ceanologiczne, 1977, 17,
p. 393.
43. S z e f e r P., O s t r o w s k i S., O w ystępoioaniu uranu i toru w środow isku
w ód naturalnych, Studia i M ateriały Oceanologiczne, 1977, 17, p. 313.
44. T e l i t c h e n k o M. M., O nakoplenii i raspredelenii urana, toriya i strontsiya
v dafniyakh i ry bakh, Biul. Mo'sk. Obshch. iispyt. prirody, otd. biol., 1958, 63(3),
p. 57.
45. T h o r is on G., Zycie w morzu, Wyd. M orskie, Gdańsk 1976.
46. Uranium and th orium decay series nuclides in plankton from the Carribbean.
K h a r ' k a r D. P., T h o m s o n J., T u r e ' k i a i n K. K., F o r s t e r W. O.,
L im nol. Oceanogr., 1976 21 (2), ip. 294.
47. Uranovye biogeokhim icheskiye pishcheve tsepi v u sloviyakh I s s y k - K u l’skoi
kotlo vin y, K o v a l s k i i V. V., V o r o t n i t s k a y a I. E., L e k a r e v I. S.,
N i k i t i n a E. V., Tr. Biogeokhimdche-skoi laboratorii, t. 9, Nauka, M oskva
1968.
48. V o y n a r A. L., Biologicheskaya rol mtikroelementov v organizme zh ivo tn y k h
i cheloveka, V ysshaya Shkola, M oscow 1960.
49. V e r k h o v s k a y a I. N., V a v i l o v P. P., M a s l o v V. I., The migration
of natural radioactive elements under natural conditions and their distribution
■according to biotic and abiotic environm ental components, Raidioecol. Concentr.
Processes, Proc. Int. Syimip., Stockholm 1966, p. 313.
50. Z e s e n k o A. Ya., N a z a ’ o v A. B., Thorium-234 accumulation b y marine
organism s, Radioekol. Vodn. Org., 1973, 2 p. 274; C. A. 1975, 83, p. 24449t.
51. Z h e z h e l N. G. Effect of natural radioactive substances on the crops of ag­
ricultural plants. S essiya Akad. Nauk S.S.S.R. po Mirnomu Isp ol’zovain'iyu A to¡minoy Energii, 1955, iZasedaniya Otdel. Bi'ol. Nauk, 1955, p. 149-60; C. A., 1955,
49, p,16082e.
52. Z l o b i n V. S., Nakopleniye urana i plutoniya m o rsk im i vodoroslyam i, R adiotoiologiya, 1966, 4, p. 613.