http://hdl.handle.net/2122/140 Fri, 24 May 2013 08:30:36 GMT 2013-05-24T08:30:36Z http://hdl.handle.net/2122/4005 Title: Isotopic composition of single rain events in the central Mediterranean Authors: Liotta, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Bellissimo, S.; Dipartimento di Chimica e Fisica della Terra, Universita` degli Studi di Palermo; Favara, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Valenza, M.; Dipartimento di Chimica e Fisica della Terra, Universita` degli Studi di Palermo Abstract: The ratios of stable isotopes of single rain events were investigated during the period October 2005 to September 2006 in the central Mediterranean. Clear seasonal trends were identified in both oxygen isotope ratios and the deuterium-excess parameter, and these were ascribed to the dominant circulation systems during both cold and hot intraannual periods. Rain events were classified on the basis of the origin of rain-bearing systems. Air masses coming from the south usually give rise to rainwater with a low deuterium excess. Air masses coming from the north and the northeast are often dry and cold, and are associated with high evaporation from the Mediterranean Sea that occurs under isotopic nonequilibrium conditions. Kinetic fractionation enhances lighter isotopomers in the vapor phase, increasing the deuterium excess. During cold periods large vapor fluxes from the Mediterranean Sea, as estimated by the ECMWF (European Centre for Medium-Range Weather Forecasts), usually precede rain events with a high deuterium excess. However, the isotope signatures of the Mediterranean moisture contribution may be masked by the original isotope content of the circulating air masses and/or by secondary evaporation effects. Tue, 19 Aug 2008 22:00:00 GMT http://hdl.handle.net/2122/4005 2008-08-19T22:00:00Z http://hdl.handle.net/2122/2527 Title: Isotopic composition of meteoric water in Sicily Authors: Liotta, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia Abstract: The isotopic composition of meteoric water in Sicily (Italy,) was investigated from May 2004 until Jun 2006; a rain gauge network (50 sites) was installed and sampled monthly. During this same period most of the circulating groundwater in the investigated area was sampled from more than 560 springs and wells related to the main aquifers. The mean weighted precipitation values were used to define the weighted local meteoric water line (WLMWL) for several sectors of Sicily. The use of GIS tools, coupled with isotopic vertical gradients, allowed us to design an isotopic contour map of precipitation in Sicily. The defined meteoric compositions fitted well with most of the groundwater samples for each sector. However, in some areas fractionation processes occurring during and after rainfall, slightly modified the isotopic composition of the groundwater Description: Poster Thu, 20 Sep 2007 12:50:08 GMT http://hdl.handle.net/2122/2527 2007-09-20T12:50:08Z