Long-term dynamics of Cs in dairy products in Austrian Alpine regions

Among the Western European Countries Austria was one of the most heavily effected by the radioactive fallout from the Chernobyl accident. Initial ground deposition levels of 137Cs between < 10 and 150 kBq/m2 resulted in considerably contaminated agricultural products. On average these contamination levels dropped fast after the first winter following the accident, when contaminated feeding produced in the summer after the radionuclide deposition accident had to be used for feeding the livestock. However, in seminatural environments in the alpine regions, which are only inhabited and used for agricultural production during the summer time, higher soil-to-plant transfer resulted in a long-term contamination of the local produced foodstuff. For 137Cs the effective half-life in these regions ranges between 3 and 8 years. These effects are most pronounced in areas with silicate bedrock material and they seem to be closely associated with slow migration of the radiocaesium into deeper soil layers. A considerable fraction of the nuclide inventory is cycling within the organic layer on top of the soil.