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Radioecological Monitoring of the Tobol and Irtysh Rivers

#2558


Radioecological Monitoring of the Tobol and Irtysh Rivers. Study of Biogenic Transfer of Radionuclides and Radiation Risk Assessment for the Population and Environment

Tech Area / Field

  • ENV-MIN/Monitoring and Instrumentation/Environment
  • ENV-MRA/Modelling and Risk Assessment/Environment
  • ENV-WPC/Water Pollution and Control/Environment

Status
8 Project completed

Registration date
15.07.2002

Completion date
02.05.2007

Senior Project Manager
Kulikov G G

Leading Institute
Russian Academy of Sciences / Severtsov Institute of Ecology and Evolution, Russia, Moscow

Supporting institutes

  • Scientific & Production Association “Typhoon”, Russia, Kaluga reg., Obninsk

Collaborators

  • University of Georgia / Savannah River Ecology Laboratory, USA, SC, Aiken\nSENES Oak Ridge Inc. / Center for Risk Analysis, USA, TN, Oak Ridge\nPacific Northwest National Laboratory / Environmental Technology Division, USA, WA, Richland\nNational Nuclear Corporation, UK, Warrington\nVanderbilt University, USA, TN, Nashville

Project summary

The main objective of the project is the assessment and prognosis of radiation risk for public and aquatic organisms on the basis of the comprehensive radioecological monitoring of the Tobol and Irtysh Rivers to support decision making on radiation protection of public and natural environment by the regional and federal authorities. Besides, the objective of the project is elaboration of the developed models of radionuclides migration in rivers ecosystems to use them in future radioecological studies.

The necessity of radioecological monitoring. A great amount of radioactive substances was discharged to the Techa River, which is a part of the hydrological system Techa – Iset – Tobol – Irtysh – Ob’ related to the catchment basin of the Kara Sea. In 1949 – 1956 years about 1017 Bq of radionuclides (89Sr, 90Sr, 137Cs, 95Zr, 95Nb, 103Ru, 144Ce etc.) was discharged from PA “Mayak” into the Techa River. Plutonium isotopes presented in the liquid discharges along with uranium fission products. The average daily discharge rate in 1950 – 1951 was 1.61014 Bq/day.
In September 29, 1957 a thermal explosion took place in the storage of radioactive wastes at PA “Mayak”. As result of this accident 7.41016 Bq of radionuclides dispersed in the environment, part of them deposited into the catchment areas of rivers in Tyumen Region. In the long-term consideration the main danger was caused by the presence of long-lived radioisotope 90Sr in the depositions.
At present the radionuclides discharge into the Techa River is continued mainly by run-off from the contaminated flood-land. One of the most important problem still is a possibility of global radioactive contamination of hydrological system ‘Techa – Iset – Tobol – Irtysh – Ob’ and the Kara Sea as a result of accidental break of the protective engineering barriers of the Techa cascade of water reservoirs, which contain 1.21016 Bq of long-lived radionuclides.
Decrease of evaporation from the surface of the cooling pond of PA “Mayak” after stop of reactors leads to the imbalance between evaporation and intake of water with all discharges, and to the raising of water level in the contaminated water reservoirs in the upper Techa River.
According to the data of SPA “Typhoon” and Chelyabinsk Division of Hydrometeorological Service in 1991 – 2000 years the annual average 90Sr activity concentrations in water of the Techa River varied in the range 6 – 26 Bq/L, which were more than 100 times higher than the regional background. At the same time the measured dynamics of the 90Sr activity concentration in water did not show the tendency to decrease with time.
The increased values of 90Sr activity concentration were observed in the Iset River, which can not serve as a biogeochemical barrier on the way of radionuclides transfer from the Techa River to the Tobol and Irtysh Rivers. Preliminary survey has been performed by the radioecological expedition of the Institute of Problems of Ecology and Evolution (Russian Academy of Science). This survey showed that the 137Cs activity concentrations in fish caught near Tobolsk (Tyumen Region) highly vary in different fish species.
50 years passed since the beginning of the radiation impact due to PA “Mayak” work. However many important problems remain undecided. In particular the experimental information is not sufficient in the remote zone of the impact of the radioactive effluents from PA “Mayak” – on the water collection territories of Tobol and Irtysh rivers. Processes of the biogenic migration and accumulation of radionuclides in the trophic chains have been studied insufficiently. The regional radiation monitoring system needs to be improved.
The methodology and tool of radiation and environmental risk assessment and analysis for the specific region conditions should be developed and approved.

Main project tasks.
· Organisation of the complex radioecological monitoring and development the data base with the data on the radioactive contamination of Tobol and Irtysh rivers;
· Studying processes of biogenic migration of radionuclides in the river ecosystem;
· Development of the dynamic radioecological model of the radionuclides transfer in the river ecosystem, taking into account the fundamental ecological-physiological features of biota species metabolism and the abiogenic limiting factors;
· Development of the methodology of risk assessment for population and environment concerning the radioactive contamination of rivers and carrying out the risk assessment.

Competence of the project participants. Scientists and specialists from the Institute of Problems of Ecology and Evolution (IPEE) of Russian Academy of Sciences, SPA “Typhoon” of Roshydromet will take part in the research activity enlisting the experts from Russian Research Centre “Kurchatov institute”.
The leading research organisation in the project will be IPEE. This institute is one of the key research centres in Russia in the field of radioecology. The scientists of this institute actively participated in the investigations of impact of nuclear weapon tests on the living organisms; in studies of radiobiological and radioecological consequences of the Kyshtym radiation accident (Southern Ural) and the Chernobyl accident. In Tobolsk IPEE has the radiochemical laboratory, the floating fish-factory with river transport means and the expeditional permanent establishment.
SPA “Typhoon” is the leading institute in Russia in the area of the radiation environmental monitoring. The specialists of SPA “Typhoon” actively participated in the investigations of impact of nuclear weapon tests on the environment; in the studies of radioecological consequences of radiation accidents at PA “Mayak” and the Chernobyl NPP; radioactive discharges to the Techa and Yenisei Rivers; radioactive waste dumping in the area of Novaya Zemlya.
The researchers from the RRC «Kurchatov institute» will take part in the project. They have a considerable experience in the development of tools for health risk assessment and analysis for different applications, including the risk assessment from technogenic and natural sources of ionising radiation.

The foreign collaborators (NNC, UK; RIS, Denmark; ENEA, Italy; STUK, Finland) can participate in the analysis of the results of radioecological monitoring and risk assessment; carrying out the joint symposia and working seminars. The project participants believe that the assistance and support of the foreign collaborators will be very helpful. This assistence and support will be accepted with gratitude.

Expected results. The following results are expected to be obtained in the framework of the project:
1. Creation of the experimental database of the parameters of radioactive contamination of the Tobol and Irtysh Rivers;
2. Determination of the mechanisms of biological migration of radionuclides in the ecosystems of the Tobol and Irtysh Rivers;
3. Development and validation of a dynamic radioecological model of radionuclides bioaccumulation and migration in the river ecosystem;
4. Development of methodology for the health and ecological risk analysis in application to the estimation of consequences of regular and accidental radioactive contamination of rivers for the population and river biota, including development of the regional health-demographic data base required for the risk assessment;
5. The materials of radioecological monitoring of the Tobol and Irtysh Rivers and the risk assessment results will be obtained, processed and presented to the International Scientific and Technical Centre;
6. An international seminar will be held to discuss the course and results of the project.

Technical Approach and Methodology. Fulfilment of the project is based on the functionally concerted use of the methodology of the complex radioecological monitoring of the Tobol and Irtysh rivers and the risk analysis for population and environment. It gives possibility to obtain experimental data on the radioactive contamination of the river biota, to make the estimation of the current and prognostic levels of the radioactive contamination of the river ecosystem, radiation risk for population and nature biota, taking into account the different pathways of the radiation impact, and by this to achieve the goals of the project. The important part of the project is the development of methodology for ecological risk analysis and its application to estimate the potential radioecological consequences for population and the radiation impact on the reference biota organisms.
Methods of hydrobiological, ichtiological, radiochemical and spectrometric analyses are applied for determination of the ecological parameters and radionuclides content of the samples prepared. The modern means of development of the data base and statistical analysis are used. The expedition trips along rivers Tobol, Irtysh and Ob’ will be carried out. The length of the routes can reach a few hundred kilometres.
Complex of the ecological and radioecological models ECOMOD is used for preparation of the functional block-scheme and equations of the dynamic model, describing the biomass dynamics of hydrobionts, the radionuclides migration in the river ecosystem, including the equations for determination of ecolo-physiological parameters of the model. Verification of the model is carried out with the radioecological monitoring data which are not used for development of the model. Doses of the internal and external exposure of the hydrobionts are estimated using the IAEA methods and taking into account the geometric characteristics of the sources and targets of the exposure, parameters of the ecological metabolism and phases of the ontogenesis of living species.
Development of the risk assessment tool for ionising radiation and other sources of risk is made on the basis of the previous achievements of the specialists of RRC “Kurchatov institute” (in the national and international (EU, IAEA) projects including ISTC one’s # 150 and 1224). The data base of the health-demographic data is prepared for the territory under the study. The complex of models of radiation and non-radiation risk assessment (BEIR VI, UNSCEAR 2000, EPA, etc.) and elements of the interface are modified and renovated. Test and verification calculations of risk for population are made. Indices of radiation risk are calculated for the reference biota species in the different ontogenesis periods.
To conduct the project the office and laboratory rooms, transport, technical and other means of the floating fish-factory in Tobolsk (including the radiochemical lab.) and the expeditional permanent establishment “Mission” on the river Irtysh.


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