Mineral waters characterization in the Azores archipelago (Portugal)

作者：Cruz J Virgilio^*; Freire Pedro; Costa Andrea

来源：Journal of Volcanology and Geothermal Research, 2010, 190(3-4): 353-364.

DOI：10.1016/j.jvolgeores.2009.12.001

• fluids geochemistry
• mineral waters
• groundwaters
• volcanic aquifers
• Azores
• Portugal

A study of the hydrogeochemistry of more than 100 mineral waters in the Azores archipelago (Portugal) was conducted on Sao Miguel, Terceira, Sao Jorge, Faial, Pico Graciosa and Flores islands. About 75% of the discharges are located at Sao Miguel, whereas the rest are more equally distributed over the other islands. Springs are dominant (74%), but drilled wells and boiling pools comprise about 10% of the studied discharges. Only 2% of discharges represent hand-dug wells. Results show a large range of chemical characteristics and diverse water types: discharge temperature range between 15 degrees C and 99.5 degrees C (median=35 degrees C), conductivity between 139 and 43,100 mu S/cm (median=906 mu S/cm), and pH between 2.2 and 7.82 (median = 5.78). The dominant water types are Na-HCO(3) and Na-Cl, representing two main trends ("hydrothermal" and "marine"), despite a few samples of the Na-SO(4) type. Relative minor and trace element contents reinforce conclusions drawn from major-ion compositions that major hydrogeochemical processes are: evolution of deep hydrothermal fluids, adsorption of magmatic volatiles, steam-heating of perched-aquifers, and mixing of deep fluids with marine or near-surface hydrothermal fluids.

• 出版日期2010-2-20