Mineral-Rich Brines from Portuguese Coastal Lagoons: Insights into Their Use in Thalassotherapy and Skin Care

This study characterized saline waters from traditional and semi-industrial saltpans located in the Ria Formosa and Ria de Aveiro Portuguese coastal lagoons, aiming to evaluate their potential for thalassotherapy and dermatological applications. Five saline water samples were collected and analyzed for physicochemical parameters (pH, electrical conductivity, dissolved oxygen, and total dissolved and suspended solids) and chemical composition (major, minor, and trace elements), complemented by SEM-EDS analyses of the suspended solids. All samples exhibited salinities above 70 g/kg, classifying them as mineral-rich brines. Sodium was the dominant element, followed by Mg, K, and Ca, with concentrations significantly higher than those of seawater. Apparent geochemical differences were observed between the two lagoons, with Ria de Aveiro water enriched in Ca, while Ria Formosa showed higher Mg and K contents. Suspended solids were composed mainly of halite, gypsum, K-Mg salts, and biogenic aggregates, reflecting the interaction between evaporitic and microbial processes. These findings highlighted the high therapeutic potential of Portuguese saline waters for skin-related applications, supporting the safe use of natural saline resources in evidence-based wellness and dermatological practices.