MIXING PHENOMENA DUE TO SEA-WATER INTRUSION FOR THE INTERPRETATION OF CHEMICAL AND ISOTOPIC DATA OF DISCHARGE WATER IN THE APULIAN COASTAL CARBONATE AQUIFER (SOUTHERN ITALY)

The chemical and isotopic features of waters drained from coastal springs, through which groundwaters of the Apulian karst, carbonate and coastal aquifer flow into the sea, turn out to be mostly affected by mixing phenomena between fresh- and sea-water intrusion waters. Some chemical parameters allow intruding sea-water to be differentiated in the areas considered, depending, above all, on the different residence time in the aquifer of sea-water origin. Through the isotopic characteristics of mixed water with reference to the iso- topic composition of sea-origin groundwater, one is able to trace the original isotopic composition of feeding waters. From the whole of such information and further data likely to be used as envi- ronmental tracers, one is able to obtain more reliable data on the flow system of groundwaters and intruding sea-water on the basis of coastal discharge.