Trace elements in the thermal groundwaters of Vulcano Island (Sicily)

The chemical concentrations of many trace elements that have never before b een examined in Vulcano Island groundwaters are reported. Chemical data ind icate that rock composition is not the only factor determining the metal co ntent in the aqueous system. The observed concentrations depend mainly on: (1) the chemical composition of the host rocks; (2) the chemical-physical c onditions of the weathering solution (temperature, acidity, redox condition s); (3) input of magmatic gases; (4) adsorption of metal ions on oxide part icles, formation of soluble complexes and/or precipitation of solid phases. Chloride complexes in solution are of minimal significance for all element s with the exception of Cd, whereas carbonate complexes are important for P b, UO2, Zn and Ni. Temperature and trace element distribution maps are also presented. (C) 2000 Elsevier Science B.V. All rights reserved.