Radionuclides in Drinking Water of Bishkek
Studying the Dynamics of Drinking Groundwater Contamination with Radionuclides in the Kyrgyz Republic’s Capital City, Bishkek
Tech Area / Field
- ENV-MIN/Monitoring and Instrumentation/Environment
3 Approved without Funding
Institute of Water Problem & Hydropower Engineering, Kyrgyzstan, Bishkek
- VNIIEF, Russia, N. Novgorod reg., Sarov
- International Bureau for Environmental Studies, Belgium, Brussels\nMaryland Geological Survey, USA, MD, Baltimore
By virtue of its regional geology, the northern part of the Kyrgyz Republic is a uranium-thorium geochemical province. Of special scientific interest and practical significance are densely populated regions with elevated radiation background. These include the city of Bishkek, the capital of the Kyrgyz Republic having a population of over 1 million located north of the Ala-Archinsk groundwater field, from which drinking water is supplied to the community.
Task 1 is to identify the source of uranium propagation in the groundwater used for water supply of Bishkek.
Up to 1990, the Groundwater Protection Team of the Kyrgyz Hydrogeological Expedition had been sampling water from production wells for uranium and trace element determination. In order to analyze the production-related hydrochemical trend in the vicinity of Bishkek, we have processed analytical data on uranium levels in groundwater of the Ala-Archinsk field and in the territory of Bishkek over three time periods:
- 1965-1976 – low-water season (92 wells);
- 1977-1983 – middle-water season (45 wells);
- 1984-1990 – high-water period (70 wells).
These time periods saw the trend of uranium halo growth and spread in the territory of Bishkek from the south to the north. For example, over 1965-76, Bishkek was surrounded with a uranium anomaly above 0.5 MCL (maximum contaminant level) in the south and southwest, with the uranium anomaly in excess of 1 MCL only in the southwest. During 1977-83, the uranium anomaly grew in size by a factor of three and enveloped the south-eastern, the southern and the south-western portion of the city. Uranium levels above > 1 MCL were observed in the west and south-west of the city. During 1984-90, uranium anomalies at > 0.5 MCL and > 1 MCL covered Bishkek almost completely. The causes of the long-term steady growth of uranium levels and the area of its propagation have not been established yet.
The second and probably the most pressing task is to evaluate current levels and behavior of radon-222 in groundwater used for water supply. Radiomedical research efforts in many countries have shown that on average up to 70-90 percent of population exposure is produced in particular by internal exposure to radon. According to U.S. radiologists, a significant fraction of lung cancer cases is attributed to the inhalation of radon in everyday life. Thus, the problem of radon is essential to the radiation safety of the public.
The problem of radon is closely related to the problem of uranium. The analysis of the world-wide databank on radon has shown that its concentration closely correlates with that of uranium. In nature, a number of daughter fission products of uranium, with radium-226 and radon-222 being the most hazardous of them, have time to accumulate over the life period of aquifers. The measurements have shown that e.g. at uranium levels of no more than 0.1-0.15 MCL, as specified in the NRB-99/03 radiation safety standards, radon levels in groundwater may be as high as n*100 Bq, with admissible α-activity of 0.1 Bq/l and interference level by radon-222 of 60 Bq/l.
For this particular reason, it is the core task of the project to reveal the current status and dynamics of the uranium water spread, and to assess the hazard related to radon-contaminated drinking water, which has never been assessed, except occasional measurements. Let us also recall that there has been no water sampling for radioisotope determination since 1990; therefore it is one of the project’s top priorities to evaluate the current status of the sources of radionuclide accumulation in groundwater.
The second priority is to develop recommendations with regard to public protection from groundwater contamination with radionuclides and a plan of actions to reduce the levels of natural radionuclides in water.
Goals and objectives of the project.
The objective of the project is to identify the location and intensity of natural uranium and radon-222 sources in groundwater of Bishkek, and to assess the risk of environmental intake of these radionuclides.
The following tasks need to be accomplished to achieve the project goals.
- Measure the levels of uranium (and a number of other trace elements) and radon-222 in groundwater samples, identify the location and intensity of the sources of natural groundwater contamination with the radionuclides on the basis of the measured data, and make maps (diagrams) of present-day uranium and radon-222 spread in groundwater of Bishkek;
- Measure the levels of noble gases in groundwater samples to estimate the age of groundwater by the uranium/helium and tritium/helium-3 techniques;
- Create an on-line hydrodynamic (filtration) model for the Ala-Archinsk artesian basin to form the basis for a conceptual groundwater radionuclide migration model and simulate possible contingency scenarios for different operational conditions of water intake facilities;
- Develop a methodological foundation for making a groundwater monitoring network of Bishkek and a mathematical and software framework for assessing the risks of environmental intake of these radionuclides based on the analysis of data acquired by the monitoring system and operation of the on-line model;
- Create a website on the Internet to deliver current geoecological and radiological information on the status of drinking water in the Kyrgyz capital city, Bishkek.
Project participants are highly qualified specialists in the area of radiation hygiene, hydrogeoecology, spectroscopy and spectrometry; they have adequate experience in the development of materials and equipment used to measure and characterize ionizing radiation by various techniques, in the area of radioecological monitoring of the environment and nuclear wastes. These specialists possess techniques and devices for project investigations and methods for experimental data interpretation. In addition, some of them have participated in the radioecological survey of radioactive wastes of ore mining facilities in Kyrgyzstan. Project participants have twenty years of work experience in the area of geographic information systems (GIS), geofiltration and geomigration simulation in ore mining regions.
Expected results and their application.
The following final results will be achieved under the project:
- Methodological recommendations to water use and geoecology supervising organizations and public health institutions will be developed with regard to the ways to monitor the levels of natural radionuclides in drinking water and to reduce these by excluding the sources of groundwater with increased natural radionuclide contamination risk from the general water intake system.
- Methodological recommendations for contingency simulation on the basis of the on-line Ala-Archinsk groundwater model as applied to possible scenarios of drinking water contamination with radionuclides will be developed.
- The use of the models developed will enable prediction of risks at changing the structure of water supply facilities.
- Should the actions developed be taken, the final result of the project will be enhanced protection of the public in the form of a lower sickness rate.
- A public geoecological information service involving electronic mass media, the press and the Internet, which will comply with the spirit of open community and make inpidual life support systems of the Kyrgyz Republic more sustainable, will be created.
The project belongs to the category of Applied Research.
Meeting ISTC goals and objectives.
The project proposed is in full compliance with the ISTC goals and objectives as:
- It contributes to the solution of a topical ecological problem – acquisition of current data on the levels of radionuclides in drinking water of Bishkek for adequate administrative decision making;
- It meets the principal ISTC goal – redirection of CIS weapon scientists and engineers to peaceful activities;
- The project promotes closer integration of Kyrgyz and Russian scientists into the international scientific community through joint activities with Foreign Collaborators, participation in international conferences and research projects.
The role of Foreign Collaborators under the project is related both to consulting and to audit. All the Collaborators of this project are outstanding experts in the area of radiogeoecological audit and monitoring. The project provides for information exchange with the Foreign Collaborators, provision of recommendations with regard to the accomplishment of project tasks, joint interpretation of results and verification of equipment and techniques developed under the project, conduction of joint seminars and workshops.