5 
Contents 
1 Introduction 7 
2 Sources of Radioactive Substances in the Baltic Sea 9 
2.1 Introduction 9 
2.2 Discharges from facilities in the Baltic Sea drainage area 9 
2.2.1 Nuclear facilities (NPPs, research reactors, waste 
handling, fuel handling, etc.) 9 
2.2.2 Non-nuclear facilities 
(e.g. hospitals, non-nuclear industries, etc.) io 
2.3 Discharges from facilities located outside the Baltic Sea 11 
2.3.1 Nuclear reprocessing plants 11 
2.3.2 Chernobyl accident 11 
2.3.3 Atmospheric nuclear weapons tests 12 
2.3.4 Dumping of radioactive waste 13 
2.4 Conclusions 13 
3A Radionuclides in Seawater is 
3A.1 Introduction 18 
3A.2 Distribution and temporal evolution of 137 Cs 18 
3A.3 Effective half-life and target levels of 137 Cs 22 
3A.4 Inventories of 137 Cs in seawater 23 
3A.5 Other radionuclides 23 
3A.6 Conclusions 24 
3B Radionuclides in Sediments 25 
3B.1 Introduction 25 
3B.2 Material and methods 25 
3B.3 Sources of artificial radioactivity 25 
3B.4 Results and discussion 25 
3B.5 Recommendations and future work 29 
3C Radionuclides in Biota 
3C.1 Introduction 30 
3C.2 Material 30 
3C.3 Use of a box model for comparison with measured data 30 
3C.4 Results and discussion 30 
3C.4.1 Concentration factors 30 
3C.4.2 Activity concentrations 31 
3C.4.3 Activity ratios 32 
3C.4.4 Trends in activity concentrations 33 
3C.4.5 Conclusions 35 
Baltic Sea Environment Proceedings No. 117