Carreira, Paula M.

Carvalho, M. R.

Marrero Diaz, Rayco

Policarpo, A.

Carvalho, M.R.

Repositório do LNEG

Hydrogeochemical study of thermo-mineral waters in Lisbon region (Portugal): contributions for hydrogeological conceptual models   R. MARRERO-DIAZ Geology, Hydrogeology and Coastal Geology Unit - National Laboratory of Energy and Geology (LNEG), Alfragide, 2610-999 – Amadora, Lisbon.  e-mail: rayco.diaz@lneg.pt M.R. CARVALHO & A. POLICARPO Universidade de Lisboa, Faculdade de Ciências, Departamento de Geologia, CeGUL. e-mail: mdrcarvalho@fc.ul.pt P.M.CARREIRA Campus Tecnológico e Nuclear, Instituto Superior Técnico, Universidade de Lisboa. e-mail: carreira@ctn.ist.utl.pt      In the Lisbon region, Portugal, existing thermo-mineral waters have been historically exploited in balneological centers. However, currently, the majority is abandoned or is dilapidated (Acciaiuoli, 1952; Lopo-Mendonça et al., 2004; Ramalho e Lourenço, 2006). Physical-chemical composition of these thermo-mineral waters have been briefly characterized by previous studies (Andrade, 1932; Acciaiuoli, 1952; Almeida, 1952), showing a complex diversity of hydrochemical facies (HCO3-Na, HCO3-Ca, SO4-Ca and Cl-Na) and mineralization contents (between 0.5 and 6 g/L). These characteristics have been firstly correlated to different aquifer lithologies, recharge conditions and local vs regional flowpaths (Almeida et al., 1991; Lopo-Mendonça et al., 2004; Ferreira et al., 2011; Carvalho et al., 2013). Some of these thermo-mineral waters are probably related to deep circulation through sedimentary aquifers of limestone and sandstone formations, which are lacking a hydrogeological conceptual model, except for the Estoril thermal water (Lopo-Mendonça et al., 2004).   The main objective of this study was to identify and quantify the processes related to the hydrochemical and mineralization complexity of these thermo-mineral waters in order to define or update their hydrogeological conceptual models. In this work we present new physical-chemical and isotopic data (stable and radioactive) from 20 thermal and/or mineral waters sampled (15 wells, 3 springs and 1 borehole) in the Lisbon region between March and June and November to December of 2013. The results obtained show that mineralization is mainly controlled by water-rock interaction processes, as well as by mixing process with saline waters from different origins (seawater, ancient groundwater, etc.). A significant positive correlation between sodium and chloride concentrations and salinity parameters has also been identified. Stable isotopes signatures show a meteoric origin and in some cases a minor fractionation signature related to seawater mixing, calcite precipitation and/or gypsum dissolution.  Keywords: thermo-mineral waters, hydrogeological conceptual model, Lisbon, aquifer.  References Acciaiuoli, L. (1952): “Le Portugal Hydromineral”. Direction Génèrale dês Mines e dês Services Geologiques. V.I, 284 pp. Andrade, C.F. (1933). “A tectónica do estuário do Tejo e dos vales submarinos ao largo da costa da Caparica, e a sua relação com as nascentes termo-medicinais de Lisboa (Considerações Preliminares)”. Separata do tomo XIX das Comunicações dos Serviços Geológicos de Portugal, 21 pp. Almeida, A. (1952): “Lisboa, Capital das Águas”. Revista Municipal. Separata dos nºs 49 e 50, 27 pp. Almeida, C., Carvalho, M.R., Almeida, S. (1991): “Modelação de Processos Hidrogeoquímicos Ocorrentes nos Aquíferos Carbonatados da Região de Lisoba-Cascais-Sintra”. Hidrogeologia y Recursos Hidráulicos, t. XVIII, 289-304.  Carvalho, M.R., Ferreira, F., Silva, C., Almeida, C. (2013). “Origin of dissolved carbon in groundwaters from carbonated aquifers in Lisbon-Cascais region (Portugal) using δ13C”. AIG10, Budapest, Hungria, 22-27 Septembro.    Ferreira, F., Carvalho, M.R., Silva, C., Almeida, C. (2011). “Variabilidade hidrogeoquímica nos aquíferos carbonatados entre Lisboa e Cascais”. 8ºSeminário sobre águas subterrâneas, Lisboa, 10-11 de Março.  Lopo-Mendonça, J., Oliveira da Silva, M., Bahir, M. (2004). “Considerations concerning the origin of the Estoril (Portugal) thermal water”. Estudios Geológicos, 60, 153-159. Ramalho, E.C., Lourenço, M.C. (2006). “As águas de Alfama – a riqueza esquecida da cidade de Lisboa”. Edição Especial Boletim de Minas, 40 (1), pp. 5-24.   

Hydrogeochemical study of thermo-mineral waters in Lisbon region (Portugal) : contributions for hydrogeological conceptual models

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Hydrogeochemical study of thermo-mineral waters in Lisbon region (Portugal) : contributions for hydrogeological conceptual models

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