WATER CHEMISTRY, DELTA-C-13 VALUES AND RN-222 ACTIVITY IN GROUNDWATERS OF WESTERN SICILY

The waters of 64 springs from western Sicily have been examined for th e main chemical-physical parameters and major chemical constituents. A ccording to the delta(13)C values of dissolved carbonate species, CO2 arises from decomposition of organic matter and/or dissolution of carb onate minerals. Only for a few thermal springs a contribution of CO2 f rom deep sources cannot be excluded. A radon distribution map delimits an area comprising Partanna, S. Ninfa, Gibellina and Salemi, with rad on content higher than the background. This anomalous area is characte rized by several faults responsible for catastrophic earthquakes in th e past, The anomaly does not seem to be related to lithological differ ences or to a peculiar presence of radioactive elements in the rocks, but it is hypothesized that the radon content is controlled by a trans port mechanism favoured by the presence of a gaseous phase.