WILL THE APPLICATION OF AMMONIUM-FERRIC-HEXACYANO-FERRATE ENHANCE THEVERTICAL MIGRATION OF RADIOCESIUM

The consideration of a possible enhanced vertical migration of radioca esium with the application of ammonium-ferric-hexacyano-ferrate (AFCF) as counter measure, due to the colloidal nature of AFCF, made us set up a series of migration experiments. For the study two soil types wer e considered, which were either left unplanted or cultivated with ryeg rass. Two AFCF concentrations, 1 and 10 gm(-2), and an untreated contr ol were applied. A simple diffusion-convection model was fitted to the data. The application of AFCF did not enhance the downward migration of radiocaesium in the profile. Moreover, for an unplanted sandy soil the application of AFCF significantly retarded the migration: 10 g AFC F m(-2) decreased the convection term, V,from 0.78 to 0.42 cm a(-1) an d the diffusion component, D, from 0.21 to 0.09 cm(2) a(-1). For all o ther experimental conditions (unplanted loamy soil, ryegrass cultivate d sandy and loamy soil), the application of AFCF did not have any effe ct on radiocaesium migration. Since AFCF does not promote the vertical migration of radiocaesium, enhanced groundwater contamination is impr obable. (C) 1998 Elsevier Science Ltd. All rights reserved.