Garcia-solsona, E. ., Universitat Autonoma de Barcel, Bellaterra, Spain, Esther.Garcia@uab.cat
Masqué, P. ., Universitat Autonoma de Barcelona, Institut de Ciencia i Tecnologia Ambiental, Dep. de Fisica, Bellaterra, Spain, Pere.Masque@uab.cat
Garcia-Orellana, J. ., Universitat Autonoma de Barcelona, Institut de Ciencia i Tecnologia Ambiental, Dep. de Fisica, Bellaterra, Spain, Jordi.Garcia@uab.cat
Radakovitch, O. ., CEREGE-Université Paul Cézanne Aix Marseille III. Europole de l’Arbois, Aix en Provence, France,
Mayer, A. ., IDPA-CNR, Milano, Italy,
Estradé, S. ., Observatori Socioambiental de Menorca, Maó, Spain,

EVALUATION OF GROUNDWATER DISCHARGE INTO A KARSTIC COVE IN THE WESTERN MEDITERRANEAN SEA BY USING RA ISOTOPES

Many karstic Mediterranean islands have limited water reserves that are intensively exploited by the demographic and tourism pressure. In Minorca (Balearic Islands, Spain), the most important aquifer is highly eroded by karstification processes, with springs visibly discharging in some coastal areas, such as the Alcalfar cove. Concentrations of radium isotopes (²²³Ra, ²²⁴Ra, ²²⁶Ra and ²²⁸Ra) and ²²²Rn were determined in water samples from the cove, sea, submarine springs and wells. The relationship between Ra and salinity points out an evident mixing process occurring between springs and seawater endmembers whereas no detectable groundwater flows out through the sea bed. Ra mass balances of the four radium isotopes provided very comparable estimates of the groundwater fraction in cove waters, averaging 17 ± 4 %. Taking the Ra-derived residence time for cove waters of 1.6 days, a submarine groundwater discharge (SGD) flux of 2•105 m³•y^-1 was estimated. When extrapolating this groundwater flow to the entire karstic coastline of the island, a total SGD of aprox. 4•107 m³•y^-1 was estimated, in good agreement with estimations derived from hydrological balances.

Oral presentation

Presentation is given by student: Yes
Session #:089
Date: 03-03-2008
Time: 17:15