Isotopic composition of precipitation in Sicily, Italy

The isotopic composition of meteoric water inSicily,Italy was investigated from May 2004 until June
2006. Samples were sampled monthly from anetwork of50rain gauges.During the same period 580
groundwater samples were collected from springs and wells toobtain insight into the isotopic composi-
tion ofthe water circulati nginthe main aquifers ofthe area.The mean weighted precipitation values
were used to definethe weighted local meteoric water line for fivedifferent sectors ofSicily.The use
of Geographical Information System tools,coupled with isotopic vertical gradients,allowed designing
an isotopic contour map ofprecipitation inSicily.The definedmeteoric compositions were highly consis-
tent with most ofthe groundwater samples ineach sector.However,insome areas fractionation pro-
cesses occurring during and after rainfall slightly modify the isotopic composition ofthe groundwater.
The obtained data set definesthe present day isotopic composition ofmeteoric water inthe central Med-
iterranean area and provides baseline values for future climatic and/or isotope-based hydrology studies.