VARIABILITY OF THE RELATIONSHIP BETWEEN CESIUM AND SOIL LOSSES BY WATER EROSION

The relationship between Cs-134 loss and soil erosion was investigated on two sites with different soil textures. Three successive applications of 3700 Bq m-2 were incorporated at two different depths. After each one of these applications, soil and cesium losses were measured following two simulated rainfalls. Cs-134 losses increased with soil losses. A logarithmic relationship was developed between these two parameters. However, this relationship fluctuates depending on soil texture and soil tillage. Cs-134 losses and sediment radioactivity were higher under shallow tillage than under deeper incorporation of cesium. The sediments coming from the light textured soil showed a greater enrichment in clay and organic matter, resulting in a higher activity in Cs-134. The addition of cesium with time increased the radioactivity of sediments and the specific losses of Cs-134. The relationship between cesium loss and soil erosion is therefore variable and may be influenced by numerous factors. Consequently, this variability should be considered when estimating soil movements from Cs-137 data under field conditions.