Open AccessHydrogen in the gas plume of an open‐vent volcano, Mount Etna, Italy
Author(s) -
Aiuppa A.,
Shinohara H.,
Tamburello G.,
Giudice G.,
Liuzzo M.,
Moretti R.
Publication year - 2011
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2011jb008461
Subject(s) - plume , volcano , flux (metallurgy) , magma , geology , atmosphere (unit) , volcanic gases , hydrogen , lava , panache , geochemistry , atmospheric sciences , meteorology , materials science , chemistry , metallurgy , physics , organic chemistry
We report here on the first hydrogen determinations in the volcanic gas plume of Mount Etna, in Italy, which we obtained during periodic field surveys on the volcano's summit area with an upgraded MultiGAS. Using a specific (EZT3HYT) electrochemical sensor, we resolved H 2 concentrations in the plume of 1–3 ppm above ambient (background) atmosphere and derived H 2 ‐SO 2 and H 2 ‐H 2 O plume molar ratios of 0.002–0.044 (mean 0.013) and 0.0001–0.0042 (mean 0.0018), respectively. Taking the above H 2 ‐SO 2 ratios in combination with a time‐averaged SO 2 flux of 1600 Gg yr −1 , we evaluate that Etna contributes a time‐averaged H 2 flux of ∼0.65 Gg yr −1 , suggesting that the volcanogenic contribution to the global atmospheric H 2 budget (70,000–100,000 Gg yr −1 ) is marginal. We also use our observed H 2 ‐H 2 O ratios to propose that Etna's passive plume composition is (at least partially) representative of a quenched (temperatures between 750°C and 950°C) equilibrium in the gas‐magma system, at redox conditions close to the nickel‐nickel oxide (NNO) mineral buffer. The positive dependence between H 2 ‐SO 2 , H 2 ‐H 2 O, and CO 2 ‐SO 2 ratios suggests that H 2 is likely supplied (at least in part) by deeply rising CO 2 ‐rich gas bubbles, fluxing through a CO 2 ‐depleted shallow conduit magma.