Strontium-90 in environmental samples from Northern Germany before and after the Chernobyl accident

The analytical procedure for determining 90Sr in environmental samples is presented and alternative methods are discussed. The HNO3-method seems to be the best method because it is well proven, has a satisfactory limit of detection and can be used for different kinds of environmental samples. In soil, grass and milk the 90Sr concentrations are given for samples taken from January 1985 to April 1986 and those taken from May to September 1986. In soil, no increase of 90Sr due to Chernobyl fallout was observed. In grass, an increase by a factor of about 3 was observed in the first month after the Chernobyl accident, probably from a surface contamination. In milk, there was an increase by a factor of about 2 in the first month. Compared to values obtained since 1961, the absolute concentration of 90Sr in milk was by a factor of 10 higher in 1963, and it was higher for over 20 years than the average after the Chernobyl accident. Compared to 90Sr, the 89Sr content was higher by a factor of 5. The ratio of 137Cs to 90Sr was approximately 35:1 compared to a ratio of 5:1 in 1963. (orig.)