A CASE STUDY OF THE DNIEPER/PRIPYAT RIVER BASIN: CONSEQUENCES AND LESSONS OF THE MOST SEVERE HUMAN MADE NUCLEAR ACCIDENT

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1 A CASE STUDY OF THE DNIEPER/PRIPYAT RIVER BASIN: CONSEQUENCES AND LESSONS OF THE MOST SEVERE HUMAN MADE NUCLEAR ACCIDENT Dmitri Gudkov Department of Freshwater Radioecology Institute of Hydrobiology National Academy of Sciences of Ukraine

2 Dnieper River: Total length - 2,285 km Drainage area - 504,000 km 2 Average water discharge -1,700 м 3 /s Pripyat River: Total length km Drainage area - 114,300 km 2 Average water discharge м 3 /s The Dnieper River Basin

3 Borysthenes (5 th century BC) Slavutich - "the Slavic river" Dānu apara - "the river on the far side" Danapris, Danaper

4 Slavic Map of the major Varangian trade routes of the 8th-11th centuries

5 The portage, by Nicholas Roerich (1915) Runestone G 280

6 Kiev reservoir (922 km²) Kanev reservoir (675 km²) Kremenchug reservoir (2,250 km²) Dneprodzerzhynsk reservoir (567 km²) Zaporozhye reservoir (420 km²) Kakhovka reservoir (2,155 km²) Dnieper River till the end of 1920-s

7 Smolensk NPP Rovno NPP Khmelnitsk NPP Chernobyl NPP Kursk NPP Zaporozhye NPP

8 95Zr 103Ru 106Ru 131I 140Ba 141Ce 144Ce Radioactive contamination of Ukraine by 137Cs in 1986

9 kbq/l 131 I Water bodies within the Chernobyl accident exclusion zone

10 Total radioactivity of water in Kiev Reservoir pre-accident levels: Bq/l in 1986: 4,000 Bq/l in 2007: Bq/l 137 Cs in bottom sediments of Kiev Reservoir in 1995

11 Concentration of 137 Cs in the water of some water bodies within the Chernobyl exclusion zone in , Bq/l Water body Year Yanovsky Creek Dalekoye-1 Lake Cooling pond of the Chernobyl NPP Azbuchin Lake Glubokoye Lake Pripyat River Uzh River

12 Concentration of 90 Sr in the water of some water bodies within the Chernobyl exclusion zone in , Bq/l Water body Year Yanovsky Creek Dalekoye-1 Lake Cooling pond of the Chernobyl NPP Azbuchin Lake Glubokoye Lake Pripyat River Uzh River

13 Map of the major dams and water bodies within the inner Chernobyl exclusion zone

14 Dynamics of radionuclide content in higher aquatic plants of the Chernobyl Exclusion Zone: a - reed-mace (Typha angustifolia L.) from the Pripyat River; b - water-soldier (Stratiotes aloides L.) from Glubokoe Lake Bq/kg w.w Sr-90 Cs-137 R 2 = 0,8653 R 2 = 0,8565 a Bq/kg w.w Sr-90 Cs-137 R 2 = 0,778 R 2 = 0,0044 b Year Year

15 Dynamics of radionuclide content in predatory (a) and prey fish (b) from Glubokoe Lake Bq/kg Cs-137 Sr-90 R 2 = 0,0114 R 2 = 0,8733 a Bq/kg Cs-137 Sr-90 R 2 = 0,1418 R 2 = 0,9582 b Year Year

16 Dynamics of internal dose rate for the higher aquatic plant (Stratiotes aloides L.) (a) and prey fish (b) in Glubokoe Lake μgy/h Cs-137 Sr-90 a μgy/h Cs-137 Sr-90 b Year Year

17 Spectrum of the main chromosome aberration in cells of the common reed from water bodies within the Chernobyl accident Exclusion Zone 20 Bridges Fragments Plural aberrations Glubokoe Lake Dalekoe-1 Lake Azbuchin Lake Yanovsky Crawl Cooling Pond Pripyat River Uzh River Goloseevo Lake Chromosome aberration rate, % Water bodies

18 Damage of common reed by corkscrew gall mites (Steneotarsonemus phragmitidis) in Dalekoye-1 Lake

19 The dependence of chromosome aberration rate from absorbed dose rate in cells of common reed from water bodies within the Chernobyl accident Exclusion Zone y = 36,256x 0,4318 R 2 = 0,8909 Aberrant cells, % ,05 0,1 Dose rate, Gy/year

20 Chromosome aberration rate in snail embryos in water bodies within the Chernobyl exclusion zone and control lakes within the Kiev City area Azbuchin Lake Dalekoe-1 Lake Glubokoe Lake Yanovsky Crawl Pripyat River Uzh River Goloseevo Lake Opechen' Lake Vyrlitsa Lake Chromosome aberration rate, % Water bodies

21 Probabilistic prediction of the chromosome aberration rate for gastropod snails up to spontaneous mutagenesis level ( %) in lakes of the Chernobyl exclusion zone y = -0,6923x + 21,423 R 2 = 0, C hro m oso m e abe rra tion rate, % y = -1,0205x + 27,885 R 2 = 0,5566 Year Yanovsky Crawl Chromosome aberration rate, % Year Azbuchin Lake y = -0,4574x + 22,768 R 2 = 0, Chromosome aberration rate, % Year Glubokoe Lake y = -0,3706x + 23,427 R 2 = 0, Chromosome aberration rate, % Year, Dalekoe-1 Lake

22 Ratio of different types of amoebocytes in the mantle liquid of snails in water bodies within the Chernobyl exclusion zone and control lakes within the Kiev City area and Kiev Region Dead cells Phagocytic cells Young cells 100% 80% 60% 40% 20% 0% Yanovsky Crawl Glubokoe Lake Dalekoe-1 Lake Azbuchin Lake Vyrlitsa Lake Pidbirna Lake Al'ta River Water bodies

23 Deformation of snail s shells from the Yanovsky Crawl Normal Anomalous

24 Conclusions: Radioactive contamination of the Dnieper/Pripyat river basin, induced by the Chernobyl accident, has a complex structure of distribution in different landscapes. It is characterised by the dynamic nature of the state of radioactive substance forms, which affect their migration and redistribution by components of aquatic ecosystems. The basic problems of radioactive safety of the Chernobyl accident exclusion zone concern radionuclides wash-off with surface drainage water to the river systems, their export outside the exclusion zone and their influence of water quality in the Dnieper River. Undoubtedly one of the most important problems is the long-term radiation impact on the aquatic biota within the Chernobyl exclusion zone.

25 Conclusions: Self-purification of closed water bodies within the Chernobyl exclusion zone is an extremely slow process. Therefore, ecosystems of the majority of lakes, dead channels and creeks possess high levels of radionuclide contamination of all components. The main quantity of radionuclides in aquatic landscapes of the exclusion zone are deposited in the bottom sediment of closed water bodies. Hence, the distribution of radioactive substances in biotic and abiotic components of hydrobiocoenoses is defined by biogeochemical regularities and transformations of radioactive substances in bottom sediments of water bodies and in soils of contaminated territories.

26 Conclusions: Construction of a flood-protection dam complex and degradation of the existing soil-reclamation system within the left-bank flood-lands of the Pripyat River has changed a hydrological mode, as well as intensifying over-moistening and swamping processes within embankment territories. As a result increasing 90 Sr in soils of the catchment area and bottom sediments of reservoirs within the exclusion zone, there is an increase in radionuclide specific activity in the water of lakes located on the dammed territory. There is also an increase in intensity of radionuclide accumulation by higher aquatic plants and fish. This is the reason that the dose rate has increased for aquatic organisms due to incorporated radionuclides as well as worsening of the ecological situation within the exclusion zone.

27 Conclusions: Swamping of the contaminated territory results in acceleration of mobilisation processes of deposited forms of 90 Sr, and also their migration and redistribution in closed aquatic landscapes. Thus there is a formation of the peculiar "depot" of the mobile forms of radioactive substances, which can be a source of increase of 90 Sr carryover into the Pripyat River and then beyond the bounds of the exclusion zone during the high water-level periods.

28 Conclusions: The long-term impact of low dose irradiation in closed water bodies within the Chernobyl exclusion zone is shown by the increased level of chromosome aberrations and some other different radiation effects in hydrobionts. It is extremely important to continue studies connected to reconstruction of dose rate on natural populations as well as radiobiological monitoring on contaminated territories, necessary for forecasting and prevention of the negative remote consequences of radiation impact.

29 Acknowledgements This study was supported by the Ministry of Ukraine on the Emergency and Affairs of Population Protection Against the Consequences of the Chernobyl Catastrophe and by the National Academy of Sciences of Ukraine as part of the state budgetary projects 0101U004987, 0102U and the project of young scientists 0102U The authors wish to thank the personnel of the Radioanalytical Laboratory of the "Chernobyl Radioecological Centre" for the radionuclides measuring procedure. Special thanks to the organisers of the Riversymposium for the opportunity to attend the meeting.

30 Thank you!