Considerations On Hydrogeochemical Characteristics Of Groundwater From Carbonate Aquifers Of Southern Latium Region

Spring and well water samples, from carbonate aquifers of Latium region, Central Italy, have been characterized to determine the hydrochemical processes governing the evolution of the groundwater. Most of the spring samples, issuing from Lepini, Ausoni and Aurunci Mts., are characterized as alkaline earth HCO3 waters, however, some samples show a composition of Cl-SO4 alkaline earth type. Groundwater samples from Pontina Plain shows three different hydrochemical facies: alkaline-earth HCO3 type, Cl-SO4 alkaline earth and Cl-SO4 alkaline type waters. Geochemical modeling and saturation index computation of the sampled waters shows an interaction with calcareous and calcareous-dolomitic lithologies. Most of the springs and wells were kinetically saturated with respect to calcite and dolomite, and all the samples were below the equilibrium state with gypsum. This indicates that the groundwater has capacity to dissolve gypsum along the flow paths. Thus, the addition of Ca++ from the dissolution of gypsum could lead to the observed saturation with respect to calcite and dolomite.The electrical conductivity (EC) and Cl- concentrations of the sampled waters show a trend of increase with the decrease in the discharge altitudes of springs and wells highlighting seawater intrusion in the coastal area. Hydrochemistry results show that the dissolution of carbonate formations and seawater intrusion as dominant processes in controlling the hydrochemical characteristics of groundwater in this region.