Compilation of Summaries 
34 
System Nordsee 
Radioactive Substances (p. 263 sqs.) 
In 2006 and 2007, monitoring of radioactive substances focused on the radionuclides 
137 Cs, 90 Sr, 3 H (tritium), 238 Pu, ( 239+24 °)p Ui and 241 Am in the German Bight. Compared 
to earlier years, distributions of the activity concentrations of radionuclides generally 
showed only minor spatial differences. Concentrations hardly exceeded those in sur 
face water of the North Atlantic Ocean, which were caused by global fallout from at 
mospheric nuclear weapons tests. Slightly elevated levels of 137 Cs in the northwestern 
sea area, as compared to the coastal area, were attributable to resuspended material 
from highly contaminated sediment in the Irish Sea. The distribution of 90 Sr concentra 
tions reflected the characteristic freshwater discharge from the river Elbe. 
Based on activity ratios, elevated activity concentrations of Transuranium elements 
found in the area of the Elbe river and estuary definitely are not fallout-related, al 
though they cannot be attributed to any local source either. If the latter were the case, 
clearly elevated levels of other artificial radionuclides would also have to be present, 
which is not the case. According to present knowledge, the only remaining hypothesis 
is enrichment in the tidal Elbe via natural transport processes and adsorption to sus 
pended particulate matter. 
The total effective dose in Germany averages 4 mSv per year and person, about half 
of which is attributable to medical measures, primarily x-ray diagnostics. Consump 
tion of fish and seafood is the only exposure path through which contamination of 
the North Sea with artificial radionuclides contributes to radiation exposure of the 
population. Average consumption of 14 kg per year results in an effective dose of max. 
0.3 mSv/a, which is clearly below the »trivial dose< of 10 mSv/a specified in the Ger 
man >Strahlenschutzverordnung< (Radiation Protection Ordinance). As enrichment of 
radionuclides in the food chain has not led to a significant increase in the effective 
dose for humans, the same applies probably to North Sea flora and fauna.