Risultati preliminari delle indagini isotopiche svolte sulle acque delle falde profonde della Bassa Pianura Friulana.

The following paper reports the preliminary results of isotopic analyses that have been carried out on the basis of 55 water-wells of the alluvial Friuli Plain. Most wells are located in the Low Plain between the spring and the coast lines, where a multistrata aquifer system characterizes the underground environment. One well is located in the High Plain, bounded by the Tagliamento moraines to the N and the spring line to the S; it reaches the unconfined aquifer system continuously developing in the highly pervious alluvial sediments of the sector. Hydrogen and oxygen isotopic composition of the waters (sampled in April 2003 – April 2006 – July 2006 – October 2006 – March 2007) are shown and compared to the ones coming from 17 sampling points of surfacing spring waters and to the weighted mean composition of the precipitations registered in some stations of the area (Trieste, Basovizza, Udine and Rivo). The outcoming distribution of the above-mentioned isotopes related with the Northern Italy Meteoric Water Line (MWL_S) and the Global Meteoric Water Line (GMWL) supports the meteoric origin of the studied groundwaters. The involvement of precipitations occurring at higher altitude and/or at lower temperature in past ages is pointed out. Radiocarbon data, related to three water samples of the deepest Aquifer H (more than -300 m b.s.l.), are also reported and discussed.