Physicochemical characterization, elemental speciation and hydrogeochemical modeling of Santa Lucía peloid used for therapeutic uses

Abstract

"Santa Lucia peloid is a sediment, extracted from salt mines, used in pelotherapy in Cuban primary health care services. Therefore, in addition to classical quality control analyses of total metal concentrations in sediments, speciation and complementary analyses are required to understand potential geochemical element availability for their use in human health. The present study was conducted to characterize the Santa Lucia peloid, based on the total metal content and geochemical speciation of major elements and transition metals (Cr, Cu, Fe, Ni, Mn, Pb and Zn), using a sequential extraction procedure and inductively couple plasma emission techniques. In order to predict the distribution of majoritarian and trace elements in different geochemical fractions, the physicochemical parameters, the particle size (electronic microscopy), mineralogy (X-ray diffraction), and the hydrogeochemical models (Pourbaix phase diagrams) were used. The results showed that the predominant cation was Na with high mobility and exchange capacity; meanwhile most of the trace elements studied (Cr, Pb, Ni) in this investigation appeared in the less mobile fractions, which suggested low availability in the sediment, under the studied conditions. The findings were useful to predict the behavior of the metals regarding solubility, potential motility and availability in the sediment, and it was concluded that most of the metals are strongly retained in the peloid and that sediment was considered as non-polluted, according to USEPA normative."