Cs-137 losses from a loamy surface water gleyed soil (Inceptisol); A laboratory simulation experiment

Cs-137 was applied with simulated rainfall to 0.25 m(2) soil boxes at an intensity of 20 mm hr(-1) for 30 minutes. Ten simulations were performed on six soil boxes at 2 degrees and 4 degrees slopes. Soil was compacted in one box to simulate the effects of tractor wheelings. The depth distribution of Cs-137 was analysed in six soil cores. In addition, a 1 m long x 16 cm wide soil trough was placed under the simulator until a constant rate of overland flow was generated. Cs-137 was added at four locations at increasing distance from the trough outflow. Overland flow, drainage water and suspended sediments were collected and analysed separately for Cs-137 in all experiments. At 2 degrees slopes, the highest proportion of the Cs-137 input was lost by drainage. At 4 degrees slopes, and with compaction, the greatest amount of Cs-137 was eroded with sediment. Approximately 10% of the added Cs-137 was lost from the compacted soil over the ten simulations. Cs-137 retention in the upper 10 cm of the profile ranged from more than 95% (compacted soil) to less than 45% (uncompacted soils). Results from the trough experiment suggested that Cs-137 could be preferen tially adsorbed by sediments entrained in overland flow.