Ion beam investigation of issues relevant to the migration of heavy elements in the geosphere

Two issues of geological and environmental significance have been addressed by ion beam analysis: (i) the role of organic compounds (humic acids), present in natural solutions, on the release of heavy elements from natural and high-level radioactive waste glasses, (ii) the retention on mineral surfaces of heavy elements transported by underground water. The present work deals with laboratory simulations in which polished sections of glasses and minerals are put into contact with aqueous solutions in static conditions and subsequently analyzed with RBS and in some cases with the 15N(1H, αγ)12C nuclear reaction for H depth profiling. These techniques have proved particularly useful for deciphering the underlying mechanisms. Some implications for the safety of radioactive waste disposal in a geological repository are discussed. (orig.)