Biomineraization in Sarcocornia pruinosa growing in the tidal area of Río Tinto, an extreme acidic environment.

We present the localization of Na, Ca, Mg and Fe biominerals in Sarcocornia pruinosa (Chenopodiacaeae), a halophyte species that grow in the estuarine area of the Río Tinto basin. The estuarine soils of the Tinto basin are characterized by an extreme low pH, a slightly high salinity and high concentration of S and Fe, together with Na, Mg, P, Cu and Zn salts. It is exposed to the daily tides, with the correspondent increase in the pH and the concentrations of Na and Mg.

The aim of this work was to characterize the elemental composition and identify the biominerals and their distribution in different organs and tissues of S. pruinosa.

Analytical techniques (ICP-MS), X-Ray diffraction and microscopy such as OM (optical microscopy) with histochemical staining (Prussian blue stain), SEM and TEM (scanning and transmission electronic microscopy) coupled with EDX (energy dispersive X-ray) have been used to analyze the plant tissues, for mineral characterization.

A high accumulation of salts has been observed in all the analyzed parts, highlighting the high content of Na and K between the major elements, followed by Ca, Mg, together with a high concentration of Fe, Cu, Zn and Mn.

We documented the occurrence of halite, silvite, whewellite, weddellite, glushinkite and Fe oxides as biominerals in S. pruinosa. We highlight the scarcity of data related to the presence of these biominerals in plants. Our data suggest the importance of plants in the biogeochemical cycles in the estuarine areas.