Search results for "gass"

Generation of CO2-rich melts during basalt magma ascent and degassing

2013

International audience; To test mechanisms of basaltic ma gma degassing, continuous decompressions of volatile-bearing (2.7-3.8 wt% H2O, 600-1300 ppm CO2) Stromboli melts were performed from 250-200 to 50-25 MPa at 1180-1140°C. Ascent rates were varied from 0.25 to ~ 1.5 m/s. Glasses after decompression show a wide range of textures, from totally bubble-free to bubble-rich, the latter with bubble number densities from 104 to 106/cm3, similar to Stromboli pumices. Vesicularities range from 0 to ~ 20 vol%. Final melt H2O concentrations are homogeneous and always close to solubilities. In contrast, the rate of vesiculation controls the final melt CO2 concentration. High vesicularity charges ha…

Terminal Strombolian activity at Etna's central craters during summer 2012: The most CO2-rich volcanic gas ever recorded at Mount Etna

2016

By using a permanent network of multi-component gas analyzer systems (Multi-GAS), we report for the first time the H2O-CO2-SO2 composition of the volcanic gases emitted prior to, during, and after terminal Strombolian activity at Mount Etna's central craters (CCs). We show that the summer 2012 Strombolian episodes of the Bocca Nuova crater (BNC), the largest of Etna's CCs, are associated with the emission of the most CO2-rich gas measured at the volcano thus far. The BNC plume was particularly CO2-rich with CO2/SO2 up to 100, H2O/CO2 1 prevailed at the BNC and at other degassing vents such as Voragine and Northeast craters during Strombolian eruptions. Based on the results of numerical simu…

Magmatic gas percolation through the old lava dome of El Misti volcano

2017

International audience; The proximity of the major city of Arequipa to El Misti has focused attention on the hazards posed by the active volcano. Since its last major eruption in the fifteenth century, El Misti has experienced a series of modest phreatic eruptions and fluctuating fumarolic activity. Here, we present the first measurements of the compositions of gas emitted from the lava dome in the summit crater. The gas composition is found to be fairly dry with a H2O/SO2 molar ratio of 32 ± 3, a CO2/SO2 molar ratio of 2.7 ± 0.2, a H2S/SO2 molar ratio of 0.23 ± 0.02 and a H2/SO2 molar ratio of 0.012 ± 0.002. This magmatic gas signature with minimal evidence of hydrothermal or wall rock int…

Gas in volcanic lakes: from dissolved gases to lake gas plumes

Diffuse soil CO2 degassing from Linosa island

2014

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Plume composition and volatile flux from Nyamulagira volcano

2015

Nyamulagira, in the Virunga volcanic province (VVP), Democratic Republic of Congo, is one of the most active volcanoes in Africa. The volcano is located about 25 km north-northwest of Lake Kivu in the Western Branch of the East African Rift System (EARS). The activity is characterized by frequent eruptions (on average, one eruption every 2–4 years) which occur both from the summit crater and from the flanks (31 flank eruptions over the last 110 years). Due to the peculiar low viscosity of its lava and its location in the floor of the rift, Nyamulagira morphology is characterized by a wide lava field that covers over 1100 km2 and contains more than 100 flank cones. Indeed, Nyamulagira is a S…

Continuous SO2 flux measurements for Vulcano Island, Italy

2012

<p>The La Fossa cone of Vulcano Island (Aeolian Archipelago, Italy) is a closed conduit volcano. Today, Vulcano Island is characterized by sulfataric activity, with a large fumarolic field that is mainly located in the summit area. A scanning differential optical absorption spectroscopy instrument designed by the Optical Sensing Group of Chalmers University of Technology in Göteborg, Sweden, was installed in the framework of the European project "Network for Observation of Volcanic and Atmospheric Change", in March 2008. This study presents the first dataset of SO<sub>2</sub> plume fluxes recorded for a closed volcanic system. Between 2008 and 2010, the SO<sub>2</…

Processi innovativi e sostenibili per il trattamento di rifiuti e acque reflue mediante l’utilizzo di acqua supercritica

2022

Il lavoro presentato in questa tesi è basato principalmente sullo sfruttamento dei processi termochimici in presenza di acqua supercritica per lo smaltimento dei rifiuti. Dipendentemente dalla tipologia di questi ultimi è possibile utilizzare processi diversi per scopi diversi. Nell’ottica di una completa distruzione delle componenti inquinanti presenti nel refluo è stato preso in considerazione un trattamento di ossidazione in acqua supercritica (SCWO); se invece l’obiettivo è quello di valorizzare uno scarto è possibile sfruttare il processo di gassificazione in acqua supercritica (SCWG). Dopo una breve introduzione per inquadrare il problema dei rifiuti con gli attuali metodi di trattame…

Realismo noérgico y tragedia intelectual de Zubiri

2018

Se presenta una lectura crítica de Zubiri, imprescindible para comprender la actualidad de su pensamiento, porque pone a prueba sus potenciales aportaciones y propone correcciones y prolongaciones creativas en el horizonte contemporáneo de la filosofía, en relación con la fenomenología, la hermenéutica, las neurociencias y el emergentismo. El libro se centra principalmente en la evolución de la filosofía de Zubiri, su metafísica, noología, antropología y la relación entre ciencia y filosofía, pero también en sus graves crisis. Y cabe contextualizarlo relacionándolo con las propuestas actuales de un nuevo realismo, que están ligadas a nuevas formas tanto de ontología como de hermenéutica.

The role of melt composition on aqueous fluid vs. silicate melt partitioning of bromine in magmas

2018

International audience; Volcanogenic halogens, in particular bromine, potentially play an important role in the ozone depletion of the atmosphere. Understanding bromine behaviour in magmas is therefore crucial to properly evaluate the contribution of volcanic eruptions to atmospheric chemistry and their environmental impact. To date, bromine partitioning between silicate melts and the gas phase is very poorly constrained, with the only relevant experimental studies limited to investigation of synthetic melt with silicic compositions. In this study, fluid/melt partitioning experiments were performed using natural silicate glasses with mafic, intermediate and silicic compositions. For each co…