title: Total (fumarolic + diffuse soil) CO2output from Furnas volcano.
abstract: Furnas volcano, in São Miguel island (Azores), being the surface expression of rising hydrothermal steam, is the site of intense carbon dioxide (CO2) release by diffuse degassing and fumaroles. While the diffusive CO2output has long (since the early 1990s) been characterized by soil CO2surveys, no information is presently available on the fumarolic CO2output. Here, we performed (in August 2014) a study in which soil CO2degassing survey was combined for the first time with the measurement of the fumarolic CO2flux. The results were achieved by using a GasFinder 2.0 tunable diode laser. Our measurements were performed in two degassing sites at Furnas volcano (Furnas Lake and Furnas Village), with the aim of quantifying the total (fumarolic + soil diffuse) CO2output. We show that, within the main degassing (fumarolic) areas, the soil CO2flux contribution (9.2 t day-1) represents a minor (~15 %) fraction of the total CO2output (59 t day-1), which is dominated by the fumaroles (~50 t day-1). The same fumaroles contribute to ~0.25 t day-1of H2S, based on a fumarole CO2/H2S ratio of 150 to 353 (measured with a portable Multi-GAS). However, we also find that the soil CO2contribution from a more distal wider degassing structure dominates the total Furnas volcano CO2budget, which we evaluate (summing up the CO2flux contributions for degassing soils, fumarolic emissions and springs) at ~1030 t day-1.
authors.affiliation: DiSTeM, Università di Palermo, via Archirafi, 36, Palermo, 90123 Italy ; Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, via Ugo La Malfa, 153, Palermo, 90146 Italy.
authors.forename: M
authors.initials: M
authors.lastname: Pedone
authors.affiliation: Centro de Vulcanologia e Avaliação de Riscos Geológicos, University of the Azores, Rua Mãe de Deus, Ponta Delgada, 9501-801 Portugal.
authors.forename: F
authors.initials: F
authors.lastname: Viveiros
authors.affiliation: DiSTeM, Università di Palermo, via Archirafi, 36, Palermo, 90123 Italy ; Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, via Ugo La Malfa, 153, Palermo, 90146 Italy.
authors.forename: A
authors.initials: A
authors.lastname: Aiuppa
authors.affiliation: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, via Ugo La Malfa, 153, Palermo, 90146 Italy.
authors.forename: G
authors.initials: G
authors.lastname: Giudice
authors.affiliation: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, via Ugo La Malfa, 153, Palermo, 90146 Italy.
authors.forename: F
authors.initials: F
authors.lastname: Grassa
authors.affiliation: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, via Ugo La Malfa, 153, Palermo, 90146 Italy.
authors.forename: A L
authors.initials: AL
authors.lastname: Gagliano
authors.affiliation: Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, via Ugo La Malfa, 153, Palermo, 90146 Italy.
authors.forename: V
authors.initials: V
authors.lastname: Francofonte
authors.affiliation: Centro de Vulcanologia e Avaliação de Riscos Geológicos, University of the Azores, Rua Mãe de Deus, Ponta Delgada, 9501-801 Portugal.
authors.forename: T
authors.initials: T
authors.lastname: Ferreira
keywords: Carbon dioxide flux; Fumaroles; Furnas volcano; Soil diffuse degassing