| Abstract: | Processes such as condensation of rising steam in colder horizons, mixing of deep steam with shallower waters and non-geothermal gas inflow are known to exist in the vapour-dominated geothermal system of Larderello. Deep steam drawn up by geothermal wells modifies its original chemico-physical characteristics in relation to the presence of one or more ‘secondary’ phenomena occurring in each point of the field. 13C/12C ratios in CO2 and CH4, chloride-ammonia-boric acid contents, H2/H2S and gas/steam ratios are used as useful parameters in delimiting the different zones in which this kind of phenomena predominate. Six main areas seem to be characterized geochemically, showing marked variations that are essentially due to differences in the geohydrological situations and thermal conditions. |
