Caracterización hidroquímica de aguas termominerales contaminadas con CO2, mediante iones minoritarios y trazas en el acuífero del Alto Guadalentín (Murcia, España)

Abstract

The waters of the Alto Guadalentín aquifer show a temperature between 23 and 31 °C, pH between 6.07 and 7.07, conductivity between 1200 and 4900 μmhos/cm and total dissolved solids between 1100 and 5950 mg/land PC02 between 0.041 and 1.497 bars. These waters are calcium-magnesium sulphate-carbonate-chloride type. The origin of ions has a direct relationship with the disolution of evaporitic materials, sulphate-chloride salts, carbonate and dolomite rocks, and possibly ore-deposits and agricultural contamination processes. The base temperatures are between 74 to 96 °C (silica-quartz thermometry), 91 to 130 °C (Na-K thermometry) and 84 to 162 °C (Na-Li thermometry). Temperature and chemical composition of the waters shows a thermal anomaly directly relatable with the tectonic activity in the area. Ion exchange processes and CO2-loss occur. Mixing processes with cold waters possibly also occur. The presence of CO2 in the detrital aquifer should be the result of migration from underlying materials. The migration can be related with the wells that surpass the aquifer substratum and with the important faults affecting the area. The presence of gas in points of the aquifer in which not existed, is related with the overexploitation.