BIBLIOS

Document type
Journal articles

Document subtype
Full paper

Title
Environmental Stable and Radioactive Isotopes in the Assessment of Thermomineral Waters in Lisbon Region (Portugal): Contributions for a Conceptual Model

Participants in the publication
Rayco Marrero-Díaz (Author)
Maria Carvalho (Author)
Dep. Geologia
IDL
Paula Carreira (Author)

Summary
The existence of thermomineral waters in the Lisbon region (western Portugal), has been known for centuries. Several authors have investigated the characteristics of these thermomineral waters, but their conceptual model (recharge zone, processes controlling the origin and chemical evolution, depth of circulation, etc.) remains unknown. This work highlights the advantages of assessing the conceptual model in urban coastal areas, where different saline sources coexist, combining chemical analyses with environmental isotopes and geochemical modeling. The final physicochemical composition of thermomineral waters seems to be mainly controlled by water–rock interaction processes and different mixing degrees between HCO3-Ca regional groundwaters, cold dilute shallow groundwaters and highly salinized fluid (brackish or brine or non-recent seawater) probably trapped at depth. Based on these results, neither the contribution of polluted water nor the leaching of evaporite rocks seems to be the main salinization factor of the warmer and saline waters. A positive correlation exists between the lowest radiocarbon activities (average apparent ages ~6 ka BP) and highest water temperature and salinity (up to 39 °C and 6.3 g/L), suggesting progressive salinization and deeper circulation (up to 1200 m depth) into the hosting formations, where mixing with trapped salinized fluids probably took place, as confirmed by geochemical modeling. Finally, very favorable geological conditions in the Estoril region allow for fast rising and the occurrence of these thermomineral waters at relatively shallow depths.


Where published
Water

Publication Identifiers
ISSN - 2073-4441

Publisher
MDPI AG

Collection
Special Issue "The Use of Environmental Isotopes in Hydrogeology"



Document Identifiers
URL - https://doi.org/10.3390/w15040766
URL - http://dx.doi.org/10.3390/w15040766

Rankings
SCIMAGO Q1 (2021) - 716 - Water Science and Technology
Web Of Science Q2 (2021) - 3.530 - WATER RESOURCES - SCIE
SCOPUS Q1 (2021) - 4.8 - Water Science and Technology

Keywords
environmental isotopes; thermomineral waters; groundwater salinization; radiocarbon dating; Lisbon region; Estoril;Portugal