MIGRATION STUDY OF RADIONUCLIDES IN A MEDITERRANEAN FOREST SOIL USINGSYNTHETIC AEROSOLS

Radionuclide migration in a Mediterranean forest was studied in field conditions. Fresh Holm oak leaves were exposed to a synthetic aerosol including Cs-134, Sr-85 and Ag-110m, and were incubated in the origina l Holm oak forest in two types of cylinder: (1) cylinders in which the contaminated litter lies directly on the original F layer; (2) cylind ers with an exchange resin bag inserted between the contaminated litte r and the underlying F layer. The results for 232 days of incubation s howed that Cs-134 presented an initial rapid leaching period, which co rresponded to the fraction extracted with water from the initially con taminated leaves. Further Cs-134 release was related to litter decompo stiion. Sr-85 migration was studied for only 76 days, and its behaviou r appeared to be similar to Cs-134. Both radionuclides migrated within the litter leachates. After 3 months of incubation, around 70% of the initial Cs-134 was transferred to the underlying layers, mainly to th e F layer. Cs-134 absorbed into the leaves was released at the same ra tes as K. The Ag-110m activity lost from the contaminated litter amoun ted to around 45% in the open cylinders, from which 15-20% was attribu ted to the effect of soil faunal activity. The field method proposed p roved to be useful in describing radionuclide migration in situ and th e mechanisms involved.