BEHAVIOR OF RADIOCESIUM IN FOREST MULTILAYERED SOILS

The migration potentials for Cs-134 in spruce soil columns (undisturbe d profile) following a surface contamination and also the redistributi on of the radionuclide through the profile have been investigated. The radiocaesium bioavailability in the different horizons was estimated by activity measurements in the soil solution and from extractions mad e of the solid phase. The calculation of a Kd ratio indicates that ret ention mechanisms increase very rapidly with depth. Cs-134 speciation reveals the high affinity of the radionuclide for specific sites on mi neral components. In spite of its organic nature, the O Ah horizon has a great efficiency for Cs accumulation; the role of humic clay compon ents and/or microflora is unforeseen.