GNGTS 2013 - Atti del 32° Convegno Nazionale

since typical seawater values range around 655±4 (Alcalà and Custodio, 2008). This finding coupled with elevated dissolved CO 2 concentra- tions is consistent with the results of Custodio and Herrera (2000), suggesting a volcanic origin. The 18 O/ 16 O and 2 H/ 1 H isotopic composition of the studied water were determined, by laser absorp- tion spectrometry using the CRDS LOS GATOS LWIA 24d isotopic analyzer. Results were reported as δ 18 O and δD (relative to SMOW) in Tab. 2 and Fig. 2. Tab. 2 – Oxygen and hydrogen isotopic analyses of the San Calogero thermal water, expressed as δ units respect to SMOW (Standard Mean Oceanic Water). The label Sg refers to the samples taken in the proximal point of emission of the spring, while the label Th refers to samples taken in the old thermal building named tholos. δD‰ δ 18 O‰ sampling date Sg 08/08/2012 -24.4 -6.54 31/08/2012 -23.4 -6.57 29/03/2013 -28.0 -5.53 09/04/2013 -28.7 -5.58 Th 08/08/2012 -27.3 -5.03 31/08/2012 -26.2 -5.13 28/12/2012 -29.1 -4.45 30/12/2012 -28.6 -4.90 Fig. 2 – The isotopic ratios of oxy- gen and hydrogen show deviation from the global meteoric water line (GMWL; Craig, 1961), the South- ern Italy Local Meteoric Line (SILMWL; Longinelli and Selmo 2003) and from the precipitations on Stromboli and Vulcano. Sg and Th waters from San Calogero are represented with grey squares and black triangles, respectively. As- terisks and black circles represent the rainfall in Stromboli and Vul- cano, respectively (Cortecci et al. , 2001; Liotta M. et al. 2006; Feder- ico et al. , 2010). Fig. 1 – Pie chart showing the major elements relative abundance of San Calogero thermal waters (starting compositions expressed as milliequivalents per liter). The label Sg refers to the samples taken in the proximal point of emission of the spring, while the label Th refers to samples taken in the old thermal building named tholos. 275 GNGTS 2013 S essione 1.3