Geochemical insights on minor and trace elements in groundwater of Mount Etna

Abstract

Mt. Etna ground water has a high content of dissolved CO2 influencing the processes of iso-chemical dissolution of the host – rock. This ground water shows, low pH, low temperature reaction and a short residence time in the aquifer. The low variability in the concentration of ions and dissolved complexes is due to high permeability of the host-rocks, mainly Hawaiti as well as short travel time and low water-rock interaction. All ground water is bicarbonate alkaline-earth, with bicarbonate amount ranging from 5 to 25 meq/l. The pH ranges between 5,9 and 7,7, and the temperatures between 9,5 and 20 degrees centigrade. The isotopic composition values (∂18O, ∂D) show an evident meteoric origin. Trace and minor elements can give an important contribute to interpret the geochemical processes. In ground water, there is a huge variety of trace elements from different sources. Many elements are carried in groundwater by water-rock interaction processes, others by anthropogenic pollution and also, like gases, by high-temperature deep fluids. In B-Cl diagram the theoretical values of B and Cl concentrations of Basalt hosted water (BHW) and Sediment hosted water (SHW) have been reported together with the concentration values of rocks (Tholeiti, Basalt, Alkali-basalt). Preliminary results indicate that Boron, in Etnean ground water, derives from water/basaltic-rock and water/sedimentary-rock interaction processes. The amount of Boron in ground water of Mount Etna ranges from 31 ppb to 4217 ppb. The ground water’s trace elements, shared in three main sectors of Etna areas, have been compared to remark existent correlation among waters, the influence of dilution processes and the water-host rock interaction.