Granite redox conditions

Radionuclide transport in natural waters is strongly dependent on sorption, desorption, dissolution, and precipitation processes. The first two sections discuss laboratory investigations of these processes. Descriptions of sorption and desorption behavior of important radionuclides under a wide range of environmental conditions are presented in the first section. Among the sorbents studied are basalt interbed solids, granites, clays, sediments, hydrous oxides, and pure minerals. Effects of redox conditions, groundwater composition and pH on sorption reactions are described. 

The distributions of these various iron minerals can yield information concerning the variability of the redox conditions in the fractures and fractured zones. The heterogeneous distribution of ferric oxyhydroxides, and pyrite in the granite at Tono, suggest the possibility that each fracture and fractured zone has distinctive A-pH conditions. In the Tono area, iron hydroxides have been observed in the micro-fractures of... 

Neretnieks (1985) came to similar conclusions from a different conceptual standpoint with regard to the redox buffer capacity of granites in the deep Scandinavian Shield and regarded it unlikely that oxidizing conditions in recharge waters could penetrate more than a few metres or tens of metres into granitic rock over a million year time period. 

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