Radioactive contamination of aquatic ecosystemsfollowing the chernobyl accident


Published on

1 Like
  • Be the first to comment

No Downloads
Total Views
On Slideshare
From Embeds
Number of Embeds
Embeds 0
No embeds

No notes for slide

Radioactive contamination of aquatic ecosystemsfollowing the chernobyl accident

  1. 1. J. Environ. Radioactivity. Vol. 27 No. 3, pp. 207-219, 1995 Copyright 0 1995Elsevier Science Limited Printed in Ireland. All rights reserved 0265-93 I X/95 $9.50 + 0.00ELSEVIER 0265-931 X(94)00042-5 Radioactive Contamination of Aquatic Ecosystems Following the Chernobyl Accident I. I. Kryshev Institute of Experimental Meteorology, SPA ‘Typhoon’, 82 Lenin Avenue, Obninsk, Kaluga Region, 249020 Russia (Received 9 February 1993; accepted 25 July 1994) ABSTRACT The dynamics of radioactive contamination of aquatic ecosystems (1986 1990) is considered on the basis of observational data in the near and distant zones of the Chernobylfallout (the Chernobyl Nuclear Power Plant (CNPP) cooling pond, the Pripyat River, the Dnieper reservoirs, and the Kopor inlet of the Gulf of Finland). Radionuclide accumulation in aquatic biota is analyzed. The results obtained indicate that the radioecological conditions in the water bodies under investigation were in a state of non-equilibrium over a long period of time following the Chernobyl accident. Reduction in the ‘37Cs concentration proceeded slowly in most of the aquatic ecosystems. The effect of trophic levels which consisted of increased accumulation of radiocaesium by predatory fish was observed in various parts of the contaminated area. INTRODUCTIONThe aquatic environment plays a special role in evaluation of the possibleconsequences of the nuclear accident for people as well as for ecosystems.The radioactive substances enter water bodies not only as a result ofatmospheric fallout and direct discharge but also due to radionuclidewashoff from the water-catchment areas. In contaminated water bodies,radionuclides are quickly redistributed and accumulated in such compo- 207
  2. 2. 208 I. I. Kryshevnents as bottom sediments, benthos, aquatic plants, and fish. This is ofparticular concern from the viewpoint of radiation exposure of aquaticorganisms and humans connected by food-chains within the hydrosphere.Monitoring data on radioactive contamination of surface water and sedi-ments following the Chernobyl NPP accident have been reported (Izrael etal., 1990; Vakulovsky et al., 1990). This paper emphasizes the accumulation of radionuclides in aquaticbiota based on radioactive contamination of aquatic ecosystems in variousareas of the emergency zone that differed significantly in contaminationlevels (Fig. 1): in the CNPP cooling pond, rivers of the Dnieper catchmentarea, the Dnieper reservoirs, etc. (Kryshev, 1991, 1992; Kryshev et al.,1993; Kuzmenko et al., 1991). EXPERIMENTALSamples of water, bottom sediments and aquatic biota were taken fromthe Chernobyl cooling pond, the Pripyat River, the Dnieper cascadereservoirs and others. Radionuclide contents were determined by using the Dniepropetrovsk Fig. 1. The Dnieper reservoir system.
  3. 3. Radiouctive contamination of aquatic ecos~stt~m.s,follo,c~ing Chernoh~~l 209radiochemical, radiometric or gamma-spectrometric method. 90Sr wasdetermined through its daughter, 9oY. Gamma-spectrometric measure-ments were carried out using the AI-1024 or AI-4096 gamma analyzerwith a semiconductor detector. RADIOACTIVE CONTAMINATION OF THE CHERNOBYL COOLING POND ECOSYSTEMThe CNPP cooling pond is the most contaminated water body in theChernobyl emergency zone (Fig. 2). Therefore it can serve as a model tobe used for estimation and forecasting of potential consequences ofradioactive contamination of aquatic systems. The CNPP cooling pond located to the southeast of the NPP site wasformed by cutting off part of the Pripyat River plain with a dike. The areaof the cooling pond is 22 km2, its average depth is 6.6 m, and volume is 0.15km”. The cooling pond is characterized by moderate values of mineraliza-tion (260-430 mg/l). Transparency of water in autumn and spring is 1.2-1.3 mand in summer it is 0.6 m. The content of suspended matter ranges from 10to 30 mg/l. The distribution of nutrients across the water body is relativelyuniform. The ranges of time dependent parameters of hydrochemicalregime are: ammonia nitrogen, 0.15-3.46 mg N/l; nitrites, 0.0 1-O.17 mg N/l;nitrates, 0.1-2.3 mg N/l; organic nitrogen, 0.01-3.28 mg N/l; phosphates,0.01-0.51 mg P/l; organic phosphorus, O@lO.55 mg P/l; iron, 0.01-0.82mg/l; silicon, 0.1-5.4 mg/l; oxygen, -2612.2 mg/l; pH, 7.487 (Kaftan-nikova et al., 1987). According to monitoring data from May 1986, theradioactivity in the cooling pond water was mainly characterized by ‘j’1and other short-lived radionuclides (Table 1). In the following monthswater activity decreased considerably as a result of radioactive decay andradionuclide deposition to bottom sediments. Since then the radioisotopesof caesium made a principal contribution to water radioactivity. Theconcentration of 90Sr in the cooling pond in August 1986 did not exceed 2-3% of the ‘37Cs concentration. The radionuclide distribution in bottom sediments of the cooling pondwas characterized by a pronounced nonuniformity. Very high radio-nuclide concentrations were registered in silts that comprised 27% of thereservoir bottom area. The maximum total activity concentration levels insilts were 8-10 MBq/kg, fresh weight. Other radionuclides made thefollowing contributions to the total activity of bottom sediments: 95Zr and95Nb, 54-70%; ‘44Ce, 7-20%; ‘06Ru, 4%; ‘37Cs, 2-5%; 134Cs l-2%. Theconcentration of 90Sr in bottom sediments in 1986 was 60 kBq/kg, orabout 35% of ‘37Cs. In 1987-1988 the total activity in bottom sediments
  4. 4. 210 I. I. Kryshev *, 0 1 L-l---l 2 km 1Fig. 2. Scheme of the Chernobyl NPP cooling pond (with isolines of contamination with 13’Cs, MBq/m*).decreased as a result of radioactive decay. The contribution of long-lived*37Cs to the total activity amounted to 20-60% in 1988, and its concen-tration in silts was 0.4 MBq/kg on average. Radioactive contamination of aquatic plants (algae, mainly Cladophoraglomerata Kuetz) in the cooling pond was characterized by differentradionuclides. According to the average data, 95Zr and 95Nb (35%) lUCe(32%) ‘06Ru (4%), ‘37Cs (2-5%) and ‘34Cs (l-2%) contributed primarilyto the total activity of aquatic plants in summer and autumn of 1986. The
  5. 5. Radioactive contamination of aquatic ecosystems following Chernobyl 211 TABLE 1The Estimated Activity of Water and Sediments in the Chernobyl Cooling Pond (30 May 1986) Radionuclide Water Sediments Activity Total amount Activity Total amount (Bqll) ( TBq) (MBqim’1 ( TBq) 40 * 21 6+4 2.3 f 1.0 50 f 20 330 * 200 50 f 30 54 f 20 1200 zt 450 410 f 210 70+40 50f 18 1100zt400 270 f 100 40f 15 32f 16 700 f 360 13oi70 20f 10 lOf5 220 f 100 1700 f 400 250 f 60 1.4 f 0.4 30f 10 200 k 100 30f 15 2.7 f 1.8 60 f 40 400 f 200 60 zt 30 5.0 f 2.3 llOf50 800 f 500 120 It 70 18f6 400 f 140 530 f 270 80 f 40 13f6 280 f 120 330 f. 200 50 f 30 30f 14 640 f 280 200 * 130 30 f 20 40 zk 20 860 f 400average contribution of 90Sr amounted to about 2%. The maximumobserved levels of activity concentration in aquatic plants in 1986 were2.4 MBq/kg, fresh weight. In 19861987 the radioactive contamination of molluscs in the coolingpond was mainly governed by 90Sr, ‘44Ce, ‘06Ru, 137Csand ‘34Cs. In 1986the maximum total activity concentration in molluscs was O-4 MBq/kg,with the concentration of 90Sr being 5.0 x lo4 Bq/kg, and lUCe being1.8 x 10’ Bq/kg. The mean concentration of ‘37Cs in molluscs was about2.6 x lo4 Bq/kg in 1986 and 1.9 x lo4 Bq/kg in 1987. The estimated average concentrations of long-lived ‘37Cs and 90Sr inecosystem components of the cooling pond are presented in Tables 2 and 3. For most fish species, radioisotopes of caesium occurred in muscletissue (Table 4). In 19861987 the concentration of caesium radioisotopesin gills, scale, skin and fins decreased as compared to muscles. For exam-ple, for a pike-perch of 60&700 g, the ratio of the ‘37Cs content inmuscles, gills and skin was: 1-O: 0.8 : 1.0 in 1987; 1.0 : 0.5 : O-3 in 1988and 1-O: 0.4 : 0.2 in 1990. Fatty tissues were contaminated by caesiumradioisotopes to a lesser extent. Radionuclides such as lWCe, lo6Ru, 95Zrand 95Nb were mainly contained in the GI tract, gills and skin and wererarely detected in fish muscles. Analysis of the dynamics of the 137Cscontent in muscles of various species of fish shows the difference in theprocesses of radiocaesium accumulation for ‘predatory’ and ‘non-preda-tory’ species (Table 4). For ‘non-predatory’ species (carp, silver carp,
  6. 6. 212 I. I. Kryshev TABLE 2The Estimated “‘Cs Content in the Ecosystem Components of the Chernobyl NPP Cool- ing Pond (1986-1990) Year Water (Bqll) Bottom sediments Algae MONUSCS IkBq/kgj:w) CkBq1kg.f.w.) (kBqlkgf1w.j 1986 210f80 170 i 100 90 i 40 26i 7 (I 700) (440) (160) (36) 1987 60 f- 40 60 i 30 16f 10 (700) (170) (30) 1988 19f7 160f90 25f 10 (240) (460) (40) 1990 14&6 140 f 100 19f8 (23) (380) (40)Presented are the average annual concentrations (June-December 1986). Figures inbrackets are the maximum observed “‘Cs concentrations in the ecosystem components. TABLE 3The Estimated 90Sr Content in the Ecosystem Components of the Chernobyl NPP Cooling Pond (July-December 1986), kBq/kg Fresh Weight Ecosystem components ‘(‘Sr concentration Water 0.02 l 0.013 (0.04) Bottom sediments 6Oi25 (140) Algae 15f9 (40) Molluscs 40f 10 (60) Fish 2.0 f 1.2 (4)Presented are the average concentrations. Figures in brackets are the maximum observedconcentrations of 90Sr in the ecosystem components.silver bream) the highest contamination by radiocaesium was reported in1986. For ‘predatory’ species (pike, pike-perch, perch) the maximum levelsof radiocaesium were observed in 1987-1988. It should be noted that themaximum ‘s7Cs contamination level for predatory species exceeded thatof nonpredatory ones by 3-10 times, i.e. the effect of trophic levels inradiocaesium accumulation was clearly reflected. According to monitoring data of 1986, the 90Sr content in fish was about 2kBq/kg fresh weight on average, or about 1% of the ‘37Cs content (Table 3). RADIOACTIVE CONTAMINATION OF RIVER ECOSYSTEMSRadioactive contamination of river ecosystems was noted early afterthe accident: late April-early May 1986. The total activity of water in
  7. 7. Rudioactive contamination of aquatic ecosystems following Chernobyl 213 TABLE 4The Average Values of the 13’Cs Content in Muscles of Various Fish Species in the Cher- nobyl NPP Cooling Pond (19861990), kBq/kg Fresh Weight Year Carp Silver bream Silver carp Perch Pike-perch 1986 loo+40 110*40 140*30 180+40 30f I3 (260) (240) (180) (220) (50) 1987 50 It 30 100 i 50 100 f 50 200 f 100 170*90 (320) (280) (240) (410) (420) 1988 40f 14 401t 18 40f 18 160 f 100 1501t80 (60) (100) (100) (360) (360) 1989 25 & 6 403 13 82% 10 (40) (90) (100) 1990 15&5 8f3 12f8 60 + 20 80 i 40 (25) (15) (70) (90) (170)Presented are the average annual concentrations. Figures in brackets are the maximumobserved ‘37Cs concentrations in fish muscles.this period amounted to 10 kBq/l in the Pripyat River (the Chernobylregion), 5 kBq/l in the Uzh River and 4 kBq/l in the Dnieper River.In this period the short-lived nuclides, primarily 1311, were of princi-pal radio-ecological importance. The dynamics of the ‘st1 content inwater and fish of the Kiev reservoir in May-June 1986 is presented inFig. 3. In the same period, such radionuclides as 13*Te, 14’Ba, 14’La, 99Mo,lo3Ru, ‘44Ce, 14’Ce, 95Zr, 95Nb, 239Np, 137Cs, 134Cs, etc., were also detec-ted. The activity of short-lived radionuclides exceeded that of long-livedcaesium radioisotopes by an order of magnitude (Table 5). The activity of90Sr in the Pripyat River on 1 May 1986 was 30 f 20 Bq/l. The ratio of89Sr/90Sr ranged from 7 to 14. From the end of May to June, the 90Srcontent in the Pripyat River was l-2 Bq/l. The maximum concentration of239,240Pu observed in the Pripyat River water in the first few days of May(0.4 Bq/l) fell to 7.4 mBq/l by August 1986 (Izrael et al., 1990). Theactivity of suspended matter contaminated by the 13*Te, 14’Ba, 99M~, 95Zr,95Nb, 144ce, 141c,, 239 Np exceeded that of the water fraction. The activityof water decreased significantly as the short-lived nuclides decayed anddeposited with particles into bottom sediments. Even in June 1986 it haddecreased by 100 times as compared to the early period of emergencycontamination and was mainly characterized by 134Cs, ‘37Cs and 90Sr.95Zr, 95Nb, ‘44Ce, 14’Ce, lo3Ru and ‘06Ru settled on the bottom withparticles and made a principal contribution to the contamination ofbottom sediments in May 1986 (Table 6). The contribution of caesiumradioisotopes to the total activity in bottom sediments of the Pripyat
  8. 8. 214 1. I. Kryshev 4;20 5/l 5/10 5/20 5130 WlO 6120Fig. 3. The 13r1content in water and fish muscles of the Kiev reservoir in May-June 1986. TABLE 5The Radionuclide Content in River Waters in the Early Period After the Accident (I May 1986), Bq/l Radionuclide Pripyat River (Chernobyl) Kiev Reservoir (Lyutezh) Water Suspended matter Water Suspended matter 131* 2100f600 100 f 30 14ozt40 80 f 25 132 I 750 f 300 240 f 100 60 k 20 220 k 80 14*Ba 1400*400 18Oi70 240 i 100 99Mo 670 It 200 70 f 25 200 f 70 lo3Ru 550 f 200 230 f 90 l5f6 310 f 120 “Ye 380 f 150 l60f60 200 f 80 14’Ce 400 f 140 260 f 100 250 f 80 95Zr 400 f 150 270 f 100 7*4 250 f 100 “Nb 420 i 160 250 f 100 614 230 f 90 239N~ 360 50 ’34cs 130f50 lOf6 4f2 lOzt6 I37cs 250 f 100 20f 10 lOf5 20f 10 “Sr (water and 30 f 20 5f2 suspended matter)
  9. 9. Radioactive contamination of aquatic ecosystems,fofiowing Chernobyl 215 TABLE 6The Estimated Content of Radionuclides in the Bottom Sediments of the Dnieper Reser- voirs and the Pripyat river (kBq/m2) Radionucfide Pripyat River (mouth) Kiev reservoir Kanev reservoir 95Zr 6000 f 3800 190 f 80 120 It 50 y5Nb 800 + 500 200 zt 80 170 f 70 ‘03RLl 3 600 l 2000 90 f 50 100 f 60 131 1 800 III 500 2oxt 12 30 f 20 ‘34cs 900 f 500 6f3 8f4 137Cs 1500 f 800 12 f 5 16 f 7 14’Ba 2400 zt 1700 30 f 20 60 f 38 14’La 2600 it 1800 70 f 46 85 f 50 14’Ce 4500 + 1600 100 f 40 100 * 30 ‘44Ce 6200 f 2400 120 f 50 120 f 40River, Dnieper River, Kiev and Kanev reservoirs in that period was about2-7%. For other reservoirs (Kremenchug, Dneprodzerzhinsk, Kakhovka)located downstream in the Dnieper River, the contribution of caesiumradioisotopes to the total activity of bottom sediments was somewhathigher, i.e. lO--30%. Distribution of radionuclides in bottom sedimentswas characterized by notable inhomogeneity (‘spottiness’). Very highlevels of radioactive contamination were registered in the upper layer ofsilts (Vakulovsky et al., 1990; Kryshev, 1992). The long-term radioecological consequences of the Chernobyl acci-dent are largely estimated from contamination of the affected territoryby long-lived radionuclides ( ‘37Cs, ‘34Cs, 90Sr). As noted above, in thefirst period following the accident the contribution of long-lived radio-nuclides in the rivers of the Dnieper catchment area and its reservoirsamounted to 10% of the total activity. But as short-lived radionuclidesdecayed, the contribution of caesium and strontium radioisotopes tothe exposure dose of organisms increased and then prevailed. Tables 7and 8 show estimates of the annual mean content of ‘37Cs and 90Sr inwater, molluscs and fish based on observational data for 1986-1989(Pankov, 1990; Volkova, 1990; Kryshev, 1992; Kryshev et al., 1993).Highest levels of contamination by ‘37Cs occurred for all ecosystemcomponents of the Kiev reservoir. The Kanev reservoir, which isdownstream in the Dnieper River showed concentrations of ‘37Cs infish and molluscs 3-4 times lower than those in the Kiev reservoir.Downstream along the cascade of reservoirs (the Kremenchug reservoirand others), the ‘37Cs levels were increasingly lower. Mean levels of 90Srconcentration in water for the Kiev reservoir in 1987-1989 practicallydid not differ from the annual mean concentration in 1986. For
  10. 10. 216 I. I. Kryshev TABLE 7 The Estimated 13’Cs Content in the Ecosystem Components of the Dnieper Reservoirs Yeur Water (Bqllj Mollusc Dreissena Fish (Bq1kgf.w.j bugensis (Bq1kg.f.w.) Bream Pike-perchKiev reservoir 1986 2.0 * 1.0 670 f 160 960 f 400 220 f 100 1987 o-5 i 0.2 110*30 480 f 160 590 + 170 1988 0.4 + 0.1 70 x?T 20 440 zt 100 1 040 f 360 1989 0.4hO.l 70% 16 370 i 80 440 i 150Kanev reservoir 1986 0.1 f 0.04 100&40 190 f 100 60 i 20 1987 0.1 f 0.03 100 % 30 90 f 20 280 i! 60 1988 0.2 i 0.05 5oi IO 30f 14 170*50 1989 0.2 f 0.04 30 f 4 26xt IO 80f 16Kremenchug reservoir 1986 0.05 + 0.02 lOf4 -. 1987 0.03 zt 0.01 30 f 8 180&50 260 f 80 1988 0.04 i 0.01 40 It 5 23 f 4 3Ozt 16 i989 0.05 i 0.0 1 3066 IO&6 30 * 7The data presented in Tables 7 and 8 are taken from the following publications: water(Kryshev, 1992); biota, 1986 (Ibid.); molluscs, 1987-1989 (Pankov, 1990); fish, 1987-1989(Volkova, 1990).molluscs accumulating 90Sr in their shells, the contamination by 90Srsignificantly exceeded that of ‘37Cs. RADIOACTIVE CONTAMINATION OF SEA ECOSYSTEMSThe Chernobyl accident resulted in radioactive contamination of someregions distant from the Chernobyl site. Some coastal regions of the BalticSea, in particular, were affected by the CNPP radioactive release. TABLE 8The Estimated “Sr Content in the Ecosystem Components of the Kiev Reservoir (1986 1989) Year Water (Bqll) Mollusc Dreissena Fish (Bq/kgf.w.) bugensis (Bq1kgf.w.) Bream Pike-perch 1986 0.85 f 0.30 1000 f 400 60 f 30 1987 0.56 xt 0.18 700 f 200 16f3 10+4 1988 0.78 f 0.23 1 100 f 300 30 * 5 70 f 20 1989 0.37 f 0.10 1 200 f 300 20 f 6 40* 15
  11. 11. Radioactive contamination qf‘aquatic ecos~stems,fi)lloM,ing Chernobyl 217According to the monitoring data from Sosnovy Bor (Leningrad region),located on the coast of the Gulf of Finland, atmospheric fallout andradionuclide washoff from the catchment areas were responsible forradioactive contamination of sea and river ecosystems (Kryshev, 1991,1992). By 1 May 1986 the concentration of ‘j’1 in the river water inSosnovy Bor amounted to 130-150 Bq/l. The concentration of “‘I in fishmuscles in the coastal waters of the Gulf of Finland from 2 May to 22May 1986 was 40-50 Bq/kg. After the decay of iodine and other short-lived radionuclides, radioisotopes of caesium were of particular radio-ecological concern for aquatic biota. Table 9 shows the dynamics of “‘Cscontent in aquatic ecosystem components of the Kopor inlet of the Gulf ofFinland. From the monitoring data obtained in 1989-1990 the concen-tration of ‘37Cs in components of aquatic ecosystems exceed the back-ground levels of contamination for 1985. A distinct effect of trophic levelson radiocaesium accumulation was observed for predatory species of fish.For example, the concentration of ‘37Cs in perch was growing after theChernobyl accident and since 1987, it is 2-5 times higher than that ofsprat. CONCLUSIONThe studies of radioactive contamination of aquatic ecosystems carriedout in the areas affected by the Chernobyl contamination in 1986-1990show: (i) One of the most contaminated water bodies in the zone of the Chernobyl accident is the cooling pond of the Chernobyl NPP. TABLE 9The “‘Cs Content in the Ecosystem Components of the Kopor Inlet, the Gulf of Finland (1985-1990) Year Sea water Bottom sedi- Algae Perch Sprat fmBqll) ments (Bqjkg) (Bqlkg) (Bq1kg.f.w.i (Bqlkg.1:rv.j 1985 10&3 I .2 f 0.6 3.9 l 1.4 3.5 f 1.0 1.4 It 0.5 1986 1 050 i 500 40 f 20 175 + 120 22 + 8 54 * 30 (185)* (2 770)* 1987 230 f 110 19f4 30f 12 120f40 60 f 20 1988 120f40 lOzt.5 30% 10 130f40 25 f 8 1989 56f II IO-f5 24 zt 8 120 f 30 26i IO 1990 50+ 10 5It-3 141t6 116f30 36i IO*The maximum observed concentration.
  12. 12. 218 I. I. Kryshev This water body could be used as a model for assessing extreme consequences of an accident for aquatic ecosystems., (ii) As a result of the processes of radioactive decay and settling of radionuclides on the bottom of water bodies, the radioactive contamination was notably reduced for most components of aquatic ecosystems beyond the nearest zone affected by the Cher- nobyl accident. However, in future the reduction of radioactive contamination levels will, most likely, go more slowly since the radiation situation in water bodies at the present time is largely determined by long-lived radionuclides of 13’Cs and 90Sr. For most of the surveyed water bodies the effect of trophic levels was clearly seen in radiocaesium uptake by predatory fish. The results of this investigation indicate that the processes involved inthe formation of the current radioecological situation in water bodiescaused non-equilibrium for a long period after the Chernobyl accident.Further studies on radioecological processes in the Chernobyl contami-nated areas should, probably, focus on the role of aquatic biota inbiogenic migration and possible transformation of migration character-istics of long-lived radionuclides. Serious attention should also be given tothe problems of radionuclide migration and accumulation in trophicchains of aquatic ecosystems, assessment and prediction of long-termirradiation dose for man through the aquatic food chain. ACKNOWLEDGMENTThe author would like to express his gratitude to Dr William L. Temple-ton for his suggestions, discussions and valuable comments. REFERENCESIzrael, Yu. A., Vakulovsky, S. M., Vetrov, V. A., Petrov, V. N., Rovinsky, F. Ja. & Stukin, E. D. (1990). Chernobyl: Radioactive Contamination of the Envir- onment. Gidrometeoizdat, Leningrad, pp. l-296 (in Russian).Kaftannikova, 0. G., Protasov, A. A., Sergeeva, 0. A., Kahnichenko, R. A., Vinogradskaya, T. A., Lenchina, L. G., Kosheleva, S. I., Novikov, B. I., Afanasiev, S. A., Sinitsina, 0. O., Movchan, N. B. & Pankov, N. G. (1987). The Ecology of NPP’s Cooling Pond. Ukraine Academy of Sciences, Kiev, pp. 1-97 (in Russian).Kryshev, I. I. (1991). Radioactive contamination and radioecological conse- quences of the Chernobyl accident. In Nuclear Accidents and the Future of Energy, Proc. Int. Conf., Paris, 15-17 April 1991. FNS, Paris, France pp. 167-78.
  13. 13. Radioactive contamination of aquatic ecosystems fotIowing Chernobyl 219Kryshev, I. I. (ed.) (1992). Radioecological Consequences of the Chernobyl Acci- dent, Nuclear Society, Moscow, Russia, pp. l-142.Kryshev, I. I., Ryabov, I. N. & Sazykina, T. G. (1993). Using a Bank of Preda- tory Fish Samples for Bioindication of Radioactive Contamination of Aquatic Food Chains in the Area Affected by the Chernobyl Accident. Sci. Total Environ,, 1391140, 279-85.Kuzmenko, M. I., Pankov, I. V., Volkova, E. N. & Shirokaya, Z. 0. (1991). Artificial radionuclides in aquatic biota of major European rivers. In Seminar on Comparative Assessment of the Environmental Impact of Radionuclides Released during Three Major Nuclear Accidents: Kyshtym, Windscale, Cher- nobyl. Proc. Seminar, Luxembourg, I-5 October 1990, Vol 2. CEC, EUR 13574, Brussels, Belgium, pp. 665-77.Pankov, I. V. (1990). Fission Fragments of Uranium in Molluscs in the Dnieper Reservoirs after the Chernobyl Accident. Ukraine Academy of Sciences, Kiev, pp. 1-28 (in Russian).Vakulovsky, S. M., Voitsekhovich, 0. V., Katrich, I. Yu., Medinets, V. I., Niki- tin, A. I. & Chumichev, V. B. (1990). Radioactive contamination of river systems in the area affected by releases from the Chernobyl nuclear power plant accident. In Environmental Contamination Following a Major Nuclear Accident, Proc. Int. Symp., Vienna, 16-20 October 1989, Vol 1. IAEA-SM- 306/l 15, IAEA, Vienna, Austria, pp. 23146.Volkova, E. N. (1990). Radioactive Contamination of Fish Fauna in the Dnieper Reservoirs after the Chernobyl Accident. Ukraine Academy of Sciences, Kiev, pp, l-25 (in Russian).