HR: 14:55h
AN: V13G-06    [Abstracts]
TI: Volcanic Plume Degassing of CO2: High Resolution Analysis With a Multi-Sensor gas Analyzer, and Applications to Etna, Stromboli and Vulcano Island (Italy)
AU: * Aiuppa, A
EM: aiuppa@unipa.it
AF: Dip. CFTA - Palermo University, Via archirafi 36, Palermo, 90123 Italy
AU: Federico, C
EM: c.federico@pa.ingv.it
AF: INGV - Sezione di Palermo, Via La Malfa 153, Palermo, 90146 Italy
AU: Giudice, G
EM: g.giudice
AF: INGV - Sezione di Palermo, Via La Malfa 153, Palermo, 90146 Italy
AU: Gurrieri, S
EM: s.gurrieri@unipa.it
AF: INGV - Sezione di Palermo, Via La Malfa 153, Palermo, 90146 Italy
AB: The acquisition of high-resolution time series of CO2 emissions from active volcanoes is a challenge of current volcanic gas research. Recently, we have developed a field-portable gas analyzer, allowing the real-time measurement of CO2 and SO2 in volcanic plumes (Aiuppa et al., 2005). The gas analyzer integrates an IR spectrometer (for CO2), an electrochemical sensor specific to SO2, and a data-logger board enabling data capture, analysis and logging with a 3s time step. At open conduit volcanoes (Etna and Stromboli), the gas analyzer was used for the real time monitoring of CO2 and SO2 concentrations in the near-vent volcanic plumes. At Etna, the CO2 to SO2 ratio was relatively constant in the short term (on time scales of hours), while displaying larger fluctuations over longer periods: the CO2 to SO2 ratio ranged 2.2 to 10.8 during passive degassing over September 2004-August 2005. The highest CO2 to SO2 ratio were interpreted as due to degassing of more primitive CO2-rich magmas feeding the shallow volcano plumbing system. At Stromboli, high-frequency variations were observed, with the CO2 to SO2 ratio fluctuating from 8-14 during passive degassing to 25-35 during strombolian explosions. At both volcanoes, combining of these data with high-frequency DOAS determinations of SO2 output rates will provide the real time determination of CO2 output rates. At Vulcano Island, the gas analyzer was exposed to gas effluents released from several tenths of fumaroles (for a minimum of 30 determinations at any given fumarole and for each species over an observation period of 90s). This allowed defining the chemical structure and heterogeneity of the fumarole field in terms of the CO2 to SO2 ratio (H2S was also measured by specific electrochemical sensor). The main degassing fumaroles (T > 150°C) had an average CO2/(SO2+H2S) molar ratios of 35, while S-poor compositions (CO2/(SO2+H2S) > 50) characterized the field margins, probably due to deposition of native sulfur. The over 3000 measurements performed (in the short interval of two hours) guaranteed a more confident computation of CO2 output rates from the volcano; with a SO2 flux of 18 t/d, we estimated a CO2 flux of 420 t/d. Aiuppa, A.; Federico, C.; Giudice, G.; Gurrieri, S., 2005, Chemical mapping of a fumarolic field: La Fossa Crater, Vulcano Island (Aeolian Islands, Italy), Geophys. Res. Lett., Vol. 32, No. 13, L13309, 10.1029/2005GL023207
DE: 8400 VOLCANOLOGY
DE: 8410 Geochemical modeling (1009, 3610)
DE: 8419 Volcano monitoring (7280)
DE: 8430 Volcanic gases
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005