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Instituto de Investigação
em Vulcanologia e Avaliação de Riscos
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Artigos em livros de actas ► Internacionais


Referência Bibliográfica

CRUZ, J.V., ANTUNES, P., AMARAL, C. (2003) – Caracterização hidrogeoquímica de lagos vulcânicos do arquipélago dos Açores (Portugal). In: Neiva, A.M.R., Neves, L.J.P.F., Silva, M.M.V.G., Gomes, E.M.C. (Eds.), Actas do IV Congresso Ibérico de Geoquímica - XIII Semana de Geoquímica, Coimbra, 375-377.


A field and laboratory investigation was made in volcanic lakes from Azores archipelago (Portugal) in order to characterize the main geochemical processes that explain water composition. Samples are all from cold waters (average temperature equal to 18.3ºC), presenting acid to alkaline pH (4.91-9.42; median=6.83) and low mineralizations (electrical conductivity ranges between 26-623 µS/cm; median=77.4 µS/cm). In the majority of the lakes water composition is controlled by sea salts addition, due to atmospheric input. Although, in a few cases, water composition is also influenced by water-rock interaction and by a volcanic contribution due to seepage of hydrothermal fluids. The latter process is shown by the total CO2 content at Furna do Enxofre lake (365.12 mg/L), as well as by the in-depth enrichments detected in a few hydrogeochemical profiles.