Four decades of radioecological research on the Danube river: a reliable basis for protecting the freshwater resources of central Europe of tomorrow

This paper gives a comprehensive review on the radioecological work which has been carried out in the freshwater ecosystem of the Danube by numerous research groups in Central Europe within the last four decades. The review focuses on the essential results and guiding conclusions up to date to support a reliable overview and improved knowledge for solving freshwater radiation protection problems in the future. The atmospheric nuclear weapons testperiod starting in the late fifties brought a large amount of artificial radionuclides in the global water cycle. Since then many radioecological studies and environmental monitoring programs have been performed in the Danube basin. The main objective of all the research and monitoring programs was to assess possible health effects in exposed groups. The second significant contamination of the northern hemisphere, in addition to the relatively insignificant contribution due to the normal operation of nuclear facilities in Central Europe, was the large-scale contamination by the fallout from the Chernobyl accident in 1986. Although the accident brought about a setback for the peaceful use of nuclear energy it increased the knowledge about the radiological impact of radioactive point emissions, meteorological transport phenomena and long-term behaviour of radionuclides in the freshwater environment. In this paper the most important facts for environmental radiation protection problems of large freshwater systems are discussed. Based on this present review an outlook of the most applicable methods and models for environmental monitoring programs, radioanalytical procedures and dose assessments are presented. (author)