Search results for " degassing"

Gas geochemistry and CO2 output estimation of Milos Island (Greece)

2018

Several gas samples have been collected from natural gas manifestations in the island of Milos. Most of them are located underwater along its coasts, whereas three anomalous degassing fumarolic areas (Kalamos, Paleochori and Adamas) were identified on land. Almost all the gases have CO2 as the prevailing gas species, with concentrations ranging from 88 to 99% for the samples taken underwater, while the on-land manifestations present a wider range (15-98%), being sometimes heavily contaminated by air. Methane reaches up to 1.0%, H2 up to 3.2% and H2S up to 3.5% indicating a hydrothermal origin of the gases. The isotope composition of He shows values ranging from 2.55 to 3.39 R/RA, highlighti…

UV camera-based monitoring SO2 flux on Mt. Etna

Validation of a novel Multi-Gas sensor for volcanic HCl alongside H

2016

Volcanic gas emission measurements inform predictions of hazard and atmospheric impacts. For these measurements, Multi-Gas sensors provide low-cost in situ monitoring of gas composition but to date have lacked the ability to detect halogens. Here, two Multi-Gas instruments characterized passive outgassing emissions from Mt. Etna’s (Italy) three summit craters, Voragine (VOR), North-east Crater (NEC) and Bocca Nuova (BN) on 2 October 2013. Signal processing (Sensor Response Model, SRM) approaches are used to analyse H2S/SO2 and HCl/SO2 ratios. A new ability to monitor volcanic HCl using miniature electrochemical sensors is here demonstrated. A “direct-exposure” Multi-Gas instrument contained…

Composition and distribution of volcanic gases inside the Lakki Caldera (Nisyros, Greece): preliminary results

2013

PDMS membranes for feasible recovery of dissolved methane from AnMBR effluents

2020

[EN] This study aimed to evaluate the feasibility of degassing membrane (DM) technology for recovering dissolved methane from AnMBR effluents. For that purpose, a PDMS membrane module was operated for treating the effluent from an AnMBR prototype-plant, which treated urban wastewater (UWW) at ambient temperature. Different transmembrane pressures and liquid flow rates were applied for evaluating methane recovery efficiency. Maximum methane recoveries were achieved when increasing the vacuum pressure and reducing the liquid flow rate, reaching a maximum methane recovery efficiency of around 80% at a transmembrane pressure (TMP) of 0.8 bars and a treatment flow rate (Q(L)) of 50 L h(-1). The …

Diffuse degassing of carbon dioxide at Somma-Vesuvius volcanic complex (Southern Italy) and its relation with regional tectonics

2004

Abstract A systematic survey of soil CO 2 concentrations was carried out on the flanks of Somma–Vesuvius volcano in order to constrain possible pathways responsible of carbon dioxide diffuse degassing taking place during the present state of quiescence. Measurements were performed at 1162 sites in late winter–spring 2000, highlighting that soil CO 2 concentrations range from 50 to 10500 ppmV. A statistical analysis was developed in order to define the threshold value of anomaly and separate the biogenic CO 2 component, produced by soil respiration, from the inorganic component of deep provenance. A computer routine was also elaborated to interpret the grid of CO 2 anomalous concentration va…

Monitoring SO2 degassing on Stromboli using a permanent UV Camera network

2020

Chemical characterisation of the gases released at Gyali Island, Dodecanese, Greece and preliminary estimation of the CO2 output

2021

Greece belongs to the most geodynamically active regions of the world and as such, it has to be considered an area of intense geogenic degassing. In terms of carbon, the territory is characterized by the high hydrothermal and volcanic activity of the South Aegean Active Volcanic Arc (SAAVA), and by widespread geological seeps of buried carbon dioxide and methane. In the present work, we investigate the island of Gyali located in the volcanic system Kos-Gyali-Nisyros. Nine gas samples have been collected on the island of Gyali in areas found both on land, in a small lake (∼2000 m2) along its beach, and in the sea close to the shore at shallow depths (<20 m). Results show that CO2 is the p…

Steam and gas emission rate from La Soufriere volcano, Guadeloupe (Lesser Antilles): implications for the magmatic and hydrothermal fluid supply duri…

2014

Since its last magmatic eruption in 1530 AD, La Soufrière andesitic volcano in Guadeloupe has displayed intense hydrothermal activity and six phreatic eruptive crises. Here we report on the first direct quantification of gas plume emissions from its summit vents,which gradually intensified during the past 20 years. Gas fluxes were determined in March 2006 and March 2012 by measuring the horizontal and vertical distributions of volcanic gas concentrations in the air-diluted plume and scaling to the speed of plume transport. Fluxes in 2006 combine realtime measurements of volcanic H2S concentrations and plume parameters with the composition of the hot (108.5 °C) fumarolic fluid at exit. Fluxe…

Spatio-temporal changes in degassing behavior at Stromboli volcano derived from two co-exposed SO2 camera stations

2022

Improving volcanic gas monitoring techniques is central to better understanding open-vent, persistently degassing volcanoes. SO2 cameras are increasingly used in volcanic gas studies, but observations are commonly limited to one single camera alone viewing the volcanic plume from a specific viewing direction. Here, we report on high frequency (0.5 Hz) systematic measurements of the SO2 flux at Stromboli, covering a 1-year long observation period (June 2017-June 2018), obtained from two permanent SO2 cameras using the same automated algorithm, but imaging the plume from two different viewing directions. Our aim is to experimentally validate the robustness of automatic SO2 camera for volcano …