Development of ecological policy, assessment and prediction of the fate of Chernobyl radionuclides in sediments of the Black Sea

Environmental problems in the Black Sea continue to be serious, even though governments have initiated a regional approach to the management and protection of the marine environment. Following the Chernobyl accident in 1986, the Black Sea riparian countries (viz., Bulgaria, Georgia, Romania, Russia, Turkey, and Ukraine) identified radioactive pollution as a serious problem. This paper presents some results of the project which is part of the fundamental research carried out by the P.P.Shirshov Institute of Oceanology of the Russian Academy of Sciences. The aim of the project is to develop the policy and methods for assessing the fate of the Chernobyl radionuclides in the Black Sea. The author sought to incorporate the study of different oceanographic hydrodynamic models to develop an international approach to the problems of measurement and prediction of sea pollution, combining methods of geoecological monitoring and comparative analysis of techniques used in oceanography for assessing marine environmental contamination. Using these results an ecological policy was formulated and recommendations were made for minimizing the negative effect of contamination on the marine environment. Different models were developed to perform further investigations of the hydro-dynamically dominated processes of the fate of radionuclides and other contaminants in the Black Sea. For example, a 3-D hybrid flow/transport model was developed to predict the dynamics of the Black Sea related to the dispersal of pollution. The transport module of this model takes predetermined current data and uses Lagrangian tracking to predict the motion of individual particles, the sum of which constitute a hypothetical plume. Currents used in the model were generated by the high resolution, low-dissipative numerical circulation model, DieCast, which was implemented for the Black Sea. The hybrid model may be implemented for velocity, temperature and salinity fields and it can simulate continuous releases of different tracers (radionuclides, oil) in the coastal waters of the Black Sea. A hydrophysical model based on quasi geostrophical approach and data of the observation of radioactive products after the Chernobyl accident was created and used for study of dynamic and mixing processes in the Black Sea. The models show an increased level of radionuclides in the stable zones of the cyclonic and anticyclonic circulation. Such zones, with 10-15% more /sup 137/Cs, were noted south of the Crimea and in the south/western part of the Black Sea. Horizontal scales of these zones were 80-120 km.