FEATURES
Environmental pollution of the Black Sea: A search for answers
As part of larger efforts, the IAEA is supporting research to help countries assess pollution problems in the Black Sea region
by V. Fabry, MI any countries around the world increasingly Additionally, the reduction in the flow of the K. Frohlich, and are concerned with the protection of their coastal Don and Kuban rivers has caused a net increase I. Osvath regions and estuaries against pollution and other in salinity in the nearby Azov Sea. This conse- harmful effects of human activities. A case in quently has led to a dwindling of the fisheries' point is the Black Sea region, where govern- production in that region. ments have initiated a regional approach to the Following the Chernobyl accident in 1986, management and protection of the marine en- riparian countries further identified radioactive vironment that is supported by research at na- pollution as having a high priority. Public con- tional and international levels. cern recently has been increased by reports of Environmental problems in the Black Sea are safety deficiencies at some nuclear facilities lo- serious. The Sea's shallow, mixed surface waters cated in the Black Sea basin and possible receive river discharges which are heavily problems related to waste storage. To date, none loaded with nutrients containing nitrogen and of the admittedly limited radionuclide measure- phosphorus and contaminated with industrial ments from the Black Sea suggests that there is a and mining wastes. In addition, coastal in- significant radiological exposure either collec- dustries appear to discharge wastes directly into tively or to critical groups. Nevertheless, a more the sea with little or no treatment. Thus the water detailed dose assessment is still required. quality of the life-supporting surface layer has This article looks at major aspects of the state seriously deteriorated. Eutrophication (an en- of the Black Sea's environment, and outlines the richment in nutrients) presently prevails in many potential of, and first results derived from, the parts of the Black Sea. It has dramatically use of isotope tracers in Black Sea studies. It changed the marine food chain, thus contributing further discusses IAEA initiatives to join con- to the demise of the Black Sea fishery and, espe- certed international actions directed towards cially in the northwestern region, to its rehabilitation of the Black Sea environment. diminished amenity value. Other factors also are at work, including changes in the hydrological balance, overfish- Isotopes in studies of the Black Sea ing, and chemical pollution. (See tables, next page.) Taken together, they have contributed to In recent years, isotope techniques have sig- catastrophic changes in the Black Sea environ- nificantly contributed to the advancement of ment. For example, the run-off to the Black Sea oceanographic and marine environmental has substantially decreased due to the construc- studies. Research in these fields is directed tion of dams on major rivers for irrigation. As a towards a better understanding of fundamental result, there may be an alteration in the water oceanographic processes and phenomena, the exchange through the Bosphorus and a decrease protection and management of the marine en- in the water exchange through the Kerch straits. vironment including the adequate use of marine resources, and the reconstruction of past, and prediction of future, global changes. • In the Black Sea region, further studies of the Mr Frohlich is a senior staff member of the Isotope Hydrology transport and redistribution of radioisotopes Section in the Department of Research and Isotopes. Ms recently introduced into the Sea's surface waters Osvath is a staff member, and Ms Fabry is a former staff member, of the IAEA Marine Environment Laboratory are needed; particularly in response to health (IAEA-MEL) in Monaco. concerns. Studies additionally are needed for a
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Map: The Black Sea — with an area of 461 000 Reduction in annual discharge of some rivers into the Black Sea square kilometers and volume of 540 000 cubic kilometers — is a unique, virtually enclosed and fairly deep (maximum depth of 2212 meters ) water River Natural flow Percent reduction during body shared between Bulgaria, Georgia, Romania, (cubic km/yr) Russia, Turkey, and Ukraine. Its shallow, mixed surface layer has a relatively low salinity, main- 1971-75 1981-85 1991-2000 tained by a large influx of fresh water from two of (projected) Europe's largest rivers, the Danube and the Dnieper, as well as from the Dniester, Don, Kuban Don 27.9 19 27 43 and a number of smaller rivers. The total drainage Kuban 13.4 39 49 65 area extends more than 2 200 000 square Dnieper 53.5 24 52 71 kilometers. The total influx of fresh water is es- Dniester 9.3 20 40 62 timated to be 350 cubic kilometers per year. A slight- ly smaller amount (230 cubic kilometers per year) is Source: Adapted from L.D. Mee, Ambio21 (4)278-286(1992). derived from precipitation falling over the Black Sea area. The Mediterranean waters entering into the Black Sea through the Bosphorus Strait in Turkey rapidly mix with cold waters on the continental shelf Nutrients and pollutants discharged by the and sink to intermediate depth (500 meters), form- Danube river into the Black Sea ing a series of cold intrusions spreading horizontal- ly into the interior of the basin. Unlike any other sea, the Black Sea is permanently anoxic (deficient in Substance Amount (tonnes/year) oxygen) below a depth of 150-200 meters. Its deep water chemistry is thus controlled by entirely dif- Phosphorus 60000 ferent chemical and biological processes than the Nitrogen 340 000 rest Of the world's Oceans. Source Map adapted from L D Zinc 6000 Mee. Ambio. 21. 4 (1992). Lead 4500 Chromium 1 000 Copper 900 Mercury 80 Oil 50000
Source: Adapted from L.D. Mee. Ambio 21 (4)278-286(19921.
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better understanding of processes which will be Physical and Chemical Sciences and the IAEA critical to improved regional environmental Marine Environment Laboratory (IAEA-MEL) management. in Monaco. Tracer studies based on different In view of the present environmental crisis in radioisotopes essentially give different types of the Black Sea, a consultants' meeting, jointly information on oceanographic and biogeochemi- organized by IAEA-MEL and the Isotope Hydro- cal processes. Since any information that can be logy Section, was held in the summer of 1992 in provided is of great importance for developing a Monaco. The meeting, attended by experts from better understanding of the Black Sea, continued eight countries, provided guidelines for further measurements of various tracer substances have research and defined the scope and objectives of been encouraged. (See table, page 24.) For ex- a co-ordinated research programme (CRP) on ample, the anthropogenic radionuclides the application of tracer techniques in the study caesium-137 and strontium-90 can yield valu- of processes and pollution in the Black Sea. able information on decadal time scales. In this The experts recommended the use of natural context, radionuclides released by the Chernobyl and anthropogenic radionuclides and environ- accident in 1986 to Black Sea surface waters are mental isotopes in assessing the inventory of of particular interest. This pulse-like input of radionuclides in the Black Sea; evaluating future tracers can be used to follow physical mixing of trends of radioactive pollution; and studying the surface oxic waters, labelled with the Cher- physical circulation and eutrophication proces- nobyl tracers, and the deeper anoxic waters, ses in the Black Sea. The programme is meant to which were initially free of the Chernobyl com- be implemented by institutes of riparian ponents. (See graphs, next page.) countries. However, other laboratories having Other particle-reactive elements, such as long-term experience in the use of these techni- thorium and plutonium, can be used to define the ques in marine environment research also will be time scale for the removal of particles from the involved. surface layer and shelf regions. The use of radio- The recommendations of the meeting include nuclides such as carbon-14, lead-21, thorium the establishment of a detailed database which isotopes, caesium-137, and plutonium isotopes can then serve to define the baseline activities for for bottom sediments can provide chronologies radionuclide studies in general and for pollution up to tens of thousands of years. Additionally, in and dose assessment questions in particular. It parallel with other relevant parameters, they can was noted that the IAEA-MEL, as part of an be used to record rates of climatic change and existing project, will provide a detailed database eutrophication processes. Information on the for the region. ages of certain biomarkers in the sediments also Experts further noted that, except for the can be obtained. For example, it has been found gamma-spectrometric systems which are up-to- recently that sedimentation rates determined by date, other equipment in countries bordering the carbon-14 are lower than those determined by Black Sea is inadequate for meeting their re- lead-210, suggesting some long-term decrease in quirements of the low-level analyses needed in overall sedimentation rates. Using this newly the application of tracer techniques to marine established deposition information, accurate research. Equipment for stable isotope analyses records over the past 3000 years can be estab- is generally not available at the laboratories lished for any variety of ancillary elements and directly involved in marine research. Therefore, biomarkers in the Black Sea. it was considered necessary that low-level radio- Stable isotope ratios can yield information on metric equipment and some radiochemical the role of river inflows and effects from the processing facilities should be made available to Bosphorus Strait. They further can give informa- selected regional laboratories participating in the tion on the sources of organics and nutrients, and programme. the chronological fluctuations of the plankton Moreover, the meeting strongly recom- population of the surface waters. mended the regular participation of the con- cerned laboratories in the IAEA intercomparison exercises organized through its Analytical IAEA co-ordinated research programme Quality Control Services (AQCS) programme. The exercise should include both high-level and For more than three decades, the IAEA low-level activity samples. In addition, it was Department of Research and Isotopes has in- recommended that intercomparison runs be or- itiated and supported the use of isotope tracer ganized using Black Sea sediment and water techniques in hydrological and marine environ- samples. mental studies through activities conducted by Discussions on existing expertise in the the Isotope Hydrology Section of the Division of riparian countries led to the conclusion that train-
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Map: The Chernobyl accident in April 1986 dis- persed caesium-137 over surface waters of the A. Black Sea. During an observation period from 12 Caesium-134 June to 6 July 1986, measurements showed that the Caesium-137 (Bq/m3) Caesium-137 Salinity (parts per thousand) eastern part of the sea was more contaminated 0 20 40 60 80 100 0.1 0.30.6 16 17 18 19 20 21 22 23 because of higher fallout levels in this area. Before i i I j 1 1 f 1 A l | i i lil the accident, the caesium content of the surface i t / \ ,j4 -%- waters (about 0.5 picocuries per liter, or 18 bec- \ fA L ^S) querels per cubic meter) was uniform over the sea. «• 50 ^,,-cr' - +- - The maximum concentration level recorded in June- o** £** m t \s\\\ July 1986 (14 picocuries per liter, or 520 becquerels S 100 - 4 - per cubic meter) was almost 30 times this pre-acci- 1 I \ \ *s dent value, but still about three orders of magnitude 1 \ \ below the maximum permissible concentration. 0 150 - \ / - *V-t - f \ Source: Adapted from A.I. Nikitin. Atomnaya Energiya 65. 2 (1988). / / O T \ S Graphs: The graphs show caesium isotope and 2 -'' i i i i rl' I I I I 1 i i L i ancillary data versus depth at the mouth of the 0 4 8 12 16 20 24 28 Bosphorus Strait (a) and at the interior of the south- western Black Sea (b) in May 1987 and June 1988, respectively. The profiles manifest a rapid penetra- a tion of caesium from the Chernobyl accident below Temp. (°C) or the oxic/anoxic interface that cannot be explained Oxygen x 2 (milligrams/liter) by vertical mixing processes alone. The data sug- 0 20 40 60 80 100 0.1 0.30.6 16 17 18 19 20 21 22 23 gest that the outflowing surface waters are 0 i i i -
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ing is required as soon as possible in the CRP's The European River Ocean System (EROS), implementation. In particular, the need was cited funded by the Commission of the European for a regional training course on sampling, Communities (CEC) since 1988, is a long-term sample preparation, analytical methods, and data research project on biogeochemical processes in processing covering marine environmental the European coastal environment. Thus far, radioactivity and stable isotope analyses, as well EROS has focused on the Mediterranean Sea. as artificial tracer techniques. The course is Recently a proposal to extend EROS to the Black being organized by IAEA-MEL in co-operation Sea has been submitted to CEC for funding. It with the IAEA Isotope Hydrology Laboratory. has been envisaged to investigate the sig- nificance of the Black Sea as a source for green- house gases; the consequences of river input; eutrophication processes; and source levels and International co-operative projects fate of key pollutants in the Black Sea. The Bathy-Black project of the United The Black Sea crisis calls for a concerted Kingdom focuses on a regional survey of the international approach. Assistance to set up a Black Sea to assess resources and environmental 3-year programme on "Environmental Manage- hazards. The objectives of the 2-year project ment and Protection of the Black Sea" has been include, among other things, a survey of the requested by the riparian governments. This seabed gamma radioactivity in areas at risk from project —under auspices of the Global Environ- artificial radionuclide contamination. The In- ment Facility initiated in 1992 by the World stitute of the Biology of the Southern Seas Bank, United Nations Environment Programme (Sevastopol) would serve as host and provide (UNEP), and United Nations Development survey vessels. The United Kingdom would pro- Programme (UNDP)— should provide the vide side-scan sonar, high resolution sonar, and framework for urgently needed support of en- a towed seabed gamma-ray spectrometer. Scien- vironmental assessment, among other activities, tists from Russia, Ukraine, Bulgaria, Romania, Potential use of and for improving the capabilitites of institu- and Turkey will participate. stable and tions. It also will provide basic data for the very The Co-operative Marine Science radioactive large investments required for controlling pollu- Programme for the Black Sea (CoMSBlack) was isotopes in tracing tion and for supporting initiatives to rehabilitate formed in 1991 as a non-governmental organiza- the Black Sea's the Black Sea that are presently planned or under tion to help co-ordinate the marine science and environment way in the region. monitoring efforts in the Black Sea. CoMSBlack will serve as an advisory body to the national, multinational, and international governments Process Medium Isotopes and agencies who have an interest in the Black Sea environmental status. The programme in- Circulation, ventilation Water strontium-90, caesium-137, cludes all the Black Sea riparian countries, and hydrogen-3, will operate through a Steering Committee in carbon- 14 which two institutes of the United States also are River inflow, Bosphorus effect Fresh water oxygen-1 8, represented. The role of this programme will be hydrogen 2 to provide the highest quality of integrated and Vertical mixing of deep water, Water radon-222 co-ordinated scientific studies and results, as air-sea interactions well as appropriate monitoring programmes, to Scavenging Suspended matter thorium isotopes assure that the management and policy decisions Particle removal, biological Trap sediment plutonium, are based on the best possible science. processes americium, and radium isotopes In summary, it is critical for the future of the Sedimentation Sediment cores lead-210, Black Sea that various programmes addressing plutonium and the Black Sea's environmental problems be co- caesium isotopes, ordinated to work together. In this context, the carbon-14 IAEA's co-ordinated research programme can Pollution Water, sediment, biota All be considered as a timely and important con- Biogeochemical cycling Water, sediment, biota carbon-14, tribution to support national and international hydrogen-3, efforts towards improved environmental sulphur-35, nitrogen-15, management in the Black Sea region. O phosphorus-32, stable isotopes of carbon, nitrogen, sulphur
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