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Instituto de Investigação
em Vulcanologia e Avaliação de Riscos

Artigos em revistas ► nacionais com arbitragem


Referência Bibliográfica

CRUZ, J.V. (2002) - Águas termais e minerais do arquipélago dos Açores: uma história geoambiental. Geonovas 16: 41-56.


​The present paper establish a so-called environmental history of the numerous mineral and thermal springs that are spread in the Azores archipelago, which are characterised by a marked variability of chemical types and dissolved solids content, reconstructing all the influences along the flow path by means of a conceptual model. The first, reference to those waters, and to their therapeutic use, are dated immediately after the islands settlement that took place in the 15th century. From the numerous thermal hospitals that were constructed in the archipelago several are today in ruins or with restricted access. Thermal waters are from the sodium bicarbonate and sodium chloride bicarbonate type and present collection temperatures between 27.9°C e 75.2°C, with a median value of pH equal to 6.30 and a TDS in the range 209-776 mg/L, which suggests a large range of mineralization. Discharges associated to fumarolic fields present higher collection temperature and TDS, as well as contrasting water types: sodium sulphate type waters, with a acid pH in the range 2.02-2.27, and sodium bicarbonate type waters, with a pH range between 7.75 and 8.73. Geochemical signatures of the thermal waters suggest a range of mechanisms as steam heating, mixture and water-rock interaction. There are also waters from the sodium chloride type, which are influenced by mixture with seawater and explains the high TDS observed in certain cases. Cold mineral waters are from the sodium bicarbonate and sodium chloride bicarbonate type and present a TDS range between 77 and 192 mg/L. However, in the seawater-influenced discharges, waters are from the sodium chloride type and present an higher TDS. The pH range is 4.70-5.33, but in the springs with sea salts mixture the values are higher (5.14-6.28).