# Exploring Rare Earth Element behavior in the Mount Etna volcanic aquifers (Sicily)

## TL;DR

This study explores rare earth elements in Mount Etna's aquifers, revealing insights into mineral dissolution and water-rock interactions.

## Contribution

The paper provides the first REY data for Mount Etna's aquifers and links patterns to geochemical processes.

## Key findings

- REY patterns suggest dissolution of ferromagnesian minerals like olivine and clinopyroxene.
- Negative Ce anomalies and positive Y anomalies indicate an oxidizing environment with iron/manganese oxide formation.
- REY concentrations in the aquifer are below safety limits for surface water.

## Abstract

This study presents the first data on REY (Rare Earth Elements plus Yttrium) in the aquifer of Mount Etna (Sicily, Italy). Patterns normalized to chondrites indicate strong water–rock interaction, facilitated by a slightly acidic pH resulting from the dissolution of magma-derived CO2. REY patterns provide insights into the processes of both mineral dissolution and the formation of secondary phases. The relative abundance of light to heavy rare earth elements is compatible with the prevailing dissolution of ferromagnesian minerals (e.g., olivine or clinopyroxenes), reinforced by its strong correlation with other proxies of mineral dissolution (e.g., Mg contents). Pronounced negative Ce anomalies and positive Y anomalies demonstrate an oxidizing environment with continuous formation of secondary iron and/or manganese oxides and hydroxides. The Y/Ho fractionation is strongly influenced by metal complexation with bicarbonate complexes, a common process in C-rich waters. In the studied system, the measured REY contents are always below the limits proposed by Sneller et al. (2000, RIVM report, Issue 601,501, p. 66) for surface water and ensure a very low daily intake from drinking water.