Search results for "gass"
showing 10 items of 164 documents
Valorization of waste solvents through supercritical water gasification
2017
The supercritical water gasification of various organic species belonging to the groups of organic acids, aldehydes, ketones, alcohols and phenols, has been studied as a possible waste disposal method for polluted water stream produced in industries and laboratories. Gasification has been investigated using a 200 cm3 down flow reactor working continuously at 24 MPa and 660 °C. Supercritical water gasification (SCWG) is effective for the syngas production at very high conversion rate for all the species investigates, but phenol. Phenol, when mixed with other species, has an inhibitory effect of the radical chain gasification mechanism that dramatically reduced the gasification performance. …
Elevated CO2 emissions during magmatic-hydrothermal degassing at Awu Volcano, Sangihe Arc, Indonesia
2020
Awu is a remote and little known active volcano of Indonesia located in the northern part of Molucca Sea. It is the northernmost active volcano of the Sangihe arc with 18 eruptions in less than 4 centuries, causing a cumulative death toll of 11,048. Two of these eruptions were classified with a Volcanic Explosivity Index (VEI) of 4. Since 2004, a lava dome has occupied the centre of Awu crater, channelling the fumarolic gas output along the crater wall. A combined Differential Optical Absorption Spectroscopy (DOAS) and Multi-component Gas Analyzer System (Multi-GAS) study highlight a relatively small SO2 flux (13 t/d) sustained by mixed magmatic&ndash
Halogens and trace metal emissions from the ongoing 2008 summit eruption of Kīlauea volcano, Hawai`i
2012
Volcanic plume samples taken in 2008 and 2009 from the Halemàumàu eruption at Kīlauea provide new insights into Kīlauea's degassing behaviour. The Cl, F and S gas systematics are consistent with syn-eruptive East Rift Zone measurements suggesting that the new Halemàumàu activity is fed by a convecting magma reservoir shallower than the main summit storage area. Comparison with degassing models suggests that plume halogen and S composition is controlled by very shallow (<3m depth) decompression degassing and progressive loss of volatiles at the surface. Compared to most other global volcanoes, Kīlauea's gases are depleted in Cl with respect to S. Similarly, our Br/S and I/S ratio measurem…
Elemental and isotope covariation of noble gases in mineral phases from Etnean volcanics erupted during 2001–2005, and genetic relation with peripher…
2008
Abstract During 2001–2005, Mount Etna was characterized by intense eruptive activity involving the emission of petrologically different products from several vents, which involved at least two types of magma with different degrees of evolution. We investigated the ratios and abundances for noble-gas isotopes in fluid inclusions trapped in olivines and pyroxenes in the erupted products. We confirm that olivine has the most efficient crystalline structure for preserving the pristine composition of entrapped gases, while pyroxene can suffer diffusive He loss. Both the minerals also experience noble gas air contamination after eruption. Helium isotopes of the products genetically linked to the …
First combined flux chamber survey of mercury and CO2 emissions from soil diffuse degassing at Solfatara of Pozzuoli crater, Campi Flegrei (Italy): M…
2014
Abstract There have been limited studies to date targeting gaseous elemental mercury (GEM) flux from soil emission in enriched volcanic substrates and its relation with CO 2 release and tectonic structures. In order to evaluate and understand the processes of soil–air exchanges involved at Solfatara of Pozzuoli volcano, the most active zone of Campi Flegrei caldera (Italy), an intensive field measurement survey has been achieved in September 2013 by using high-time resolution techniques. Soil–air exchange fluxes of GEM and CO 2 have been measured simultaneously at 116 points, widely distributed within the crater. Quantification of gas flux has been assessed by using field accumulation chamb…
Excess volatiles supplied by mingling of mafic magma at an andesite arc volcano
2010
We present the results of a study of volcanic gases at Soufriere Hills Volcano, Montserrat, which includes the first spectroscopic measurements of the major gas species CO2 and H2S at this volcano using a Multisensor Gas Analyzer System (MultiGAS) sensor. The fluxes of CO2 and H2S were 640.2750 t/d and 84.266 t/d, respectively, during July 2008, during a prolonged eruptive pause. The flux of CO2 is similar to estimates for the entire arc from previous geochemical studies, while the measured H2S flux significantly alters our interpretation of the sulphur budget for this volcano. The fluxes of both sulphur and carbon show considerable excesses over that which can be supplied by degassing of e…
Non-stationary nature of SO2 degassing at Etna’s North-east crater (Italy).
2012
Investigating Etna’s long-term SO2 flux behaviour has led to important conclusions on the structure of the volcano’s magma feeding system, magma production (and degassing) rates, and causes for the excess degassing behaviour. Nonetheless, our knowledge of the short-term (timescales of seconds to a few hours) behaviour of magmatic volatiles (e.g., bubble coalescence, separate ascent and surface bursting of gas-rich bubbles) in the volcano’s upper feeding conduit system is still fragmentary, and based on indirect evidences (petrologic-textural data, observation of geophysical signals , physical modelling and laboratory experiments). In the past, direct gas flux measurements at Etna have been ta…