CESIUM-137 IN SOIL TEXTURE FRACTIONS AND ITS IMPACT ON CESIUM-137 SOIL-TO-PLANT TRANSFER

Field studies at two sites contaminated by the Chernobyl fallout showed Cesium-137 (Cs) soil-to-plant transfer factors in wheat, rye and potato. Transfer values ranged from 0.0017 (potato tuber) to 0.07 (wheat straw). Generally transfer coefficients in cereal grains and potato tubers were significantly below the values of the shoots. A comparison of the two sites led to the conclusion that for all plants investigated Cs-137-transfer factors were higher in Lower Austria (Calcic Chernozem) than in Upper Austria (Eutric Cambisol). The specific activities of the texture fractions of the two soil types increased from sand to silt and clay. In the Calcic Chernozem the ratio of the Cs-137-activity in the silt fraction to the total activity in the soil was considerably higher than in the Eutric Cambisol. At the same time extractability of Cs-137 from the silt fraction of the latter soil was clearly lower. Both results mainly were attributed to the differences between the soils according to the organic matter content of the silt fractions, the Calcic Chernozem being seven times higher. Therefore, the differences in the Cs-137-soil-to-plant transfer can be attributed partly to these soil characteristics.