Groundwater quality assessment in a karst coastal region of the West Aurunci Mountains (Central Italy)

This paper presents the results of a groundwater quality assessment carried out in the karst coastal region of the West Aurunci Mountains (Central Italy). 55 spring and 18 well water samples, collected from 2016 to 2018, were analysed to study the main processes controlling the hydrogeochemical evolution and groundwater quality properties. In the study area, groundwater samples are mostly characterized by a Ca-HCO3 facies, indicating that the groundwater hydrogeochemical evolution is mainly controlled by the carbonate mineral dissolution/precipitation. The cationic and anionic concentrations confirm that groundwater samples belong to the order of Ca2+ > Mg2+ > Na+ > K+ and HCO3− > Cl− > SO42−, respectively. Well water samples show, over time, an increasing mineralization with respect to the spring water samples. In more detail, the enrichment of Ca2+, Na+, and Cl- in well water samples is mainly due to the dissolution of calcite, dolomite, and halite minerals and secondly to a probable ion exchange related to seawater intrusion. Seawater intrusion, probably affecting the chemical composition of well water samples, was studied using ionic ratios, graphical approaches, and specific indices, such as the BEX index. Results suggest that carbonate weathering, ion exchange, and seawater intrusion in this karst coastal region are the major factors controlling groundwater geochemistry. This study shows that groundwater quality assessment, based on hydrogeochemical investigation techniques, has been a useful tool to characterize and model carbonate aquifers in Central Italy, with the aim of achieving proper management and protection of these important water resources.