210Po in the Gessoso Solfifera Formation of Perticara Mine

The Perticara sulphur mine is a historically important mine located in the province of Rimini (Italy), known for the large crystals of sulfur that were extracted there, and for the abundance of ore. The mine was developed in the Gessoso-Solfifera Formation, a rock succession mainly formed by gypsum and limestone that is well preserved in the western Romagna Apennines area (Roveri et al., 2003). The Gessoso-Solfifera Formation comprises primary and clastic, resedimented evaporites with interbedded organic-rich shales, which were deposited during the evaporitic and post-evaporitic stages of the Messinian salinity crisis (Roveri et al., 2003). The Perticara mine was active for a few centuries until the mid-twentieth century. In 2016 the mine was re-explored by the Federazione Speleologica Regionale Emilia Romagna and starting from this data various environmental matrices (rocks, minerals, water, air) were sampled over time. Samples of natural epsomite crystals (general formula Mg(SO4)·7H2O), that extensively grow on rock walls and blocks with a fibrous habit, were collected and morphologically and chemically investigated using SEM-EDS, XRPD, ICP-AES and alpha spectrometry measurements. Most of the fibres are of inhalable size and can be potentially adsorbed from all parts of the respiratory tract. Their solubility and the presence of significant amounts of toxic elements (As, Co, Fe, Mn, Ni, Sr, Ti, Zn) and radioactive isotope 210Po (and to a less extent 228Th) make the inhalation of these fibres potentially hazardous to human health. These preliminary results were recently published by Giordani et al. (2022). Moreover, a significant concentration of 222Rn (238U decay series), as well as CO2 and CO in the air of the mine, could play an important role in the accumulation of 210Po in epsomite, while very few amounts of 210Po were detected in the water springs and pools inside the mine or in host rocks, but further investigation is needed. Giordani M., Meli M.A., Roselli C., Betti M., Peruzzi F., Taussi M., Valentini L., Fagiolino I. & Mattioli M. (2022) - Could soluble minerals be hazardous to human health? Evidence from fibrous epsomite. Environ. Res., 206, 112579. Roveri M., Manzi V., Lucchi F.R. & Rogledi S. (2003) - Sedimentary and tectonic evolution of the Vena del Gesso basin (Northern Apennines, Italy): implications for the onset of the Messinian salinity crisis. Geol. Soc. Am. Bull., 115(4), 387-405.