The impact of Mt. Etna volcanic emissions on the atmospheric deposition: developments and improvements during three decades of studies

Volcanic emissions are an important source of gases and particles to the atmosphere. Mount Etna discharges a permanent volcanic plume consisting of water vapor and gaseous species (CO2, SO2, HCl and HF, mainly), metals, acid droplets, and solid particles. This plume interacts with meteoric water during precipitations events, so the chemical signature of the plume is impressed on the rainwater. Over the past 32 years, the impact of Etna's emissions on atmospheric deposition has been investigated in many research projects by our team. Sampling methodologies and analytical procedures have been improved over the years. The first study of the concentration of water-soluble inorganic ions in weekly wet-only atmospheric deposition was carried out between December 1990 and December 1991 Between 1997 and 2003 the same analyses together with the isotopic composition of the water (δ18O) were made in monthly bulk atmospheric depositions. The first determination of the concentration of trace metals in Etna's atmospheric bulk deposition was first carried out between 2006 and 2007 and subsequently between 2017 and 2018. In the framework of the project HEAVEN, started in March 2021 and still ongoing, we aim to determine for the first time Technology Critical Elements (TCEs) in Etna's atmospheric bulk deposition, as well as concentration of water-soluble and insoluble inorganic ions, and trace metals. Less soluble elements attached to particulate matter, often neglected in similar studies, will also be investigated. In addition to the isotopic composition of oxygen and hydrogen (δ18O and δD), the isotopic signature of B (δ11B) and Sr (87Sr/86Sr) will also be determined for the first time in Mt Etna’s plume. Coupling new data, with the long historical series of studies will allow us to characterize the environmental impact of Etna’s volcanic activity and constitute a precious point of reference for similar studies on other volcanoes of the world.