Characterization of trace elements in thermal and mineral waters of Greece

Abstract

Natural thermal and mineral waters are widely distributed along the Hellenic region and are related to the geodynamic regime of the country. The diverse lithological and tectonic settings they are found in reflect the great variability in their chemical and isotopic composition. The current study presents 276 (published and unpublished) trace element water data and discusses the sources and processes affecting the water by taking into consideration the framework of their geographic distribution. The dataset is divided in groups using temperature- and pH-related criteria. Results yield a wide range of concentrations, often related to the solubility properties of the individual elements and the factors impacting them (i.e. temperature, acidity, redox conditions and salinity). Many elements (e.g. alkalis, Ti, Sr, As and Tl) present a good correlation with temperature, which is in cases impacted by water rock interactions, while others (e.g. Be, Al, Cu, Se, Cd) exhibit either no relation or an inverse correlation with T possibly because they become oversaturated at higher temperatures in solid phases. A moderately constant inverse correlation is noticed for the vast majority of trace elements and pH, whereas no relationship between trace element concentrations and Eh was found. Seawater contamination and water-rock interaction seem to be the main natural processes that influence both salinity and elemental content. All in all, Greek thermomineral waters exceed occasionally the accepted limits representing in such cases serious harm to the environment and probably indirectly (through the water cycle) to human health.

Hellenic karst waters: geogenic and anthropogenic processes affecting their geochemistry and quality

“…Many regions of Greece, especially in the northern part, are affected by elevated concentrations in groundwater 67 . The highest As concentration was found in the groundwater of the geothermal area of Chalkidiki in northern Greece, with values up to 1000 µg L −1 68 .…”

“…The highest As concentration was found in the groundwater of the geothermal area of Chalkidiki in northern Greece, with values up to 1000 µg L −1 68 . The main sources of As in Greece are geothermal fluids arising from active tectonic and volcanic areas 67 .…”

“…Indeed, the involved karstic systems were formed within carbonate formations at the contact with metamorphic and metavolcanic formations of the Ampelakia Unit (Blueschist unit) and Pelagonian Unit 15 . Many occurrences of As-rich mineralisations have been found in the area mainly related to the metamorphic rocks 67 , 69 . In some cases, the As contamination can be related to the presence within the aquifer of As-rich Karst-Type Bauxites 70 .…”