Radioactive contamination of soils in lower Saxony, Germany, after the Chernobyl accident.

The horizontal and spatial distribution of artificial and natural radionuclides in soils, and the vertical migration velocity of 0.8-2.0 cm per annum for caesium were examined in order to determine whether caesium is still in the root zone of major plants and, therefore, part of the food-chain. The vertical distribution patterns of caesium are dependent on the different physico-chemical soil properties. The soil samples were analysed with a pure Ge detector. In south-eastern Lower Saxony, the maximum gamma-activity for 137Cs of 33.3 kBq m-2 was found in a depth range of 0-20 cm (January 1, 1989). This was correlated with areas that had received heavy rainfall on May 4, 1986. On January 1, 1989 approximately 60% of the Chernobyl caesium was still in the top 0-2 cm of the topsoil.