6533b7d3fe1ef96bd126160a

RESEARCH PRODUCT

Chemical and isotopic characterization of the gases of Mount Etna (Italy)

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Abstract In the period 1990–1995, 43 samples of dissolved gases in groundwaters (wells, springs and drainage galleries) and 64 samples of free gases (fumaroles, bubbling and soil gases) from the Mount Etna area were collected and analysed. Isotopic analyses were also carried out of both the carbon of the CO 2 in free gases and dissolved inorganic carbon (DIC) in the waters. The chemical composition of the gases depends on the relative abundances of three interacting components. These are gases of (1) atmospheric origin enriched in O 2 and N 2 , present almost exclusively in dissolved gases, (2) deep origin enriched in CO 2 , prevalent in the majority of cases, and (3) more superficial origin enriched in CH 4 , prevailing in peripheral areas. The isotopic composition of CO 2 carbon confirms its mantle origin with either thermometamorphic CO 2 contributions or modifications due to interaction with hot waters.