Search

Hydrothermic features in Galicia (northwest Spain) have been used since ancient times for therapeutic purposes. A characterization of these thermal waters was carried out in order to understand their behaviour based on inorganic pattern and water-rock interaction mechanisms. In this way 15 thermal water samples were collected in the same hydrographical system. The selected thermal water samples were classified using principal component analysis (PCA) and partial least squares (PLS) regression analysis in two groups according to their chemical composition: group I with the young water samples and group II with the samples with longest water-rock contact time. This classification agreed with the results obtained by the use of geothermometers and hydrogeochemical modelling, where the samples were classified into two categories according their residence time in the reservoir and their water-rock interaction.

Summary Thermal waters are certainly a substantial asset of the Galicia region of Spain. They can be regarded as worth developing because of their human health implications and, if thermal tourism is promoted, their importance to the local economy. In this paper the chemistry of major and trace inorganic elements in about 45 thermal springs and wells discharging in the same hydrographical system are presented and discussed. For handling the results of all measurements, graphical representations of B/Li vs. SO 4 2 - /Cl− ratios, Hill–Piper diagram, discriminant analysis (DA) and principal component analysis (PCA) were employed. All this with the intention to classify, based on their inorganic pattern, both thermal springs and wells waters, but also waters circulating through adamellite and granodiorite rocks. The results of the hydrogeochemistry analysis showed three main water families: sulphated, chlorinated and bicarbonated waters. The results show also the presence of saline materials with chloride influence in the deeper aquifer, allowing its classification in deeper and younger/shallow waters.

Hydrothermal features in Galicia have been used since ancient times for therapeutic purposes. A characterization of these thermal waters was carried out in order to understand their behaviour based on inorganic pattern and water-rock interaction mechanisms. In this way 15 thermal water samples were collected in the same hydrographical system. The results of the hydrogeochemistry analysis showed one main water family of bicarbonate type sodium waters, typical in the post-orogenic basins of Galicia. Principal component analysis (PCA) and partial lest squared (PLS) clustered the selected thermal waters in two groups, regarding to their chemical composition. This classification agreed with the results obtained by the use of geothermometers and the hydrogeochemical modelling. The first included thermal samples that could be in contact with surface waters and therefore, their residence time in the reservoir and their water-rock interaction would be less important than for the thermal waters of the second group.

Thermal waters can be regarded as worth developing because of their human health implications and, if thermal tourism is promoted, their importance to the local economy. Galicia, in the North-West of Spain, has numerous sources of thermal waters spread all over the region. They have been used for therapeutic purposes since Roman times. Ourense, with 82 sources (9 spas), is becoming one of the richest Spanish provinces in hydromineral and thermal resources. In this work, the most representative springs of thermal waters from the city of Ourense – Outariz, Chavasqueira, Tinteiro and As Burgas – were analysed in order to identify the presence of several chemical classes of soluble organic compounds responsible for their biological activity. The waters studied are hyperthermal, with temperatures ranged between 45 and 66 °C. Different extraction techniques, liquid–liquid extraction (LLE), solid phase extraction (SPE) and solid phase micro-extraction (SPME), combined with gas chromatography–electron impact ion trap mass spectrometry (GC–(EI)ITMS) were used to cover a wide variety of compounds. The most characteristic chemical families of extractable organic compounds detected are thoroughly discussed. Most of the substances belonging to phenol, aldehyde, esther, ketone, and elemental sulphur groups occur in all samples. Large amounts of elemental sulphur were found in Tinteiro spring, providing to this water of numerous beneficial clinical effects.