Geochemistry of thermomineral waters in the overexploited Alto Guadalentinaquifer (South-East Spain)

The hydrochemical study of Alto Guadalentin aquifer shows an unusually high bicarbonate content between 15 to 35 mmol l(-1) and P-CO2 between 0.044 to 1.289 bars and, in accordance with electric geophysical data, he is in rel ation with horst areas. The waters have temperatures between 19 to 32 degre es C and conductivity between 1087 and 6810 mu S cm(-1) (which increased in zones with high exploitation) and are fundamentally sulphate and chloride types. Chemical equilibrium modelling shows that the waters are oversaturat ed in quartz, calcite and dolomite and undersaturated in anhydrite and gyps um. O-18, H-2 and C-13 isotopes revealed that there is an enrichment in O-1 8 and mixing processes between meteoric waters and deep circulating waters. (C) 1998 Elsevier Science Ltd. All rights reserved.