Search results for " gases"
showing 10 items of 941 documents
The resonant state at filling factor {\nu} = 1/2 in chiral fermionic ladders
2017
Helical liquids have been experimentally detected in both nanowires and ultracold atomic chains as the result of strong spin-orbit interactions. In both cases the inner degrees of freedom can be considered as an additional space dimension, providing an interpretation of these systems as synthetic ladders, with artificial magnetic fluxes determined by the spin-orbit terms. In this work, we characterize the helical state which appears at filling $\nu=1/2$: this state is generated by a gap arising in the spin sector of the corresponding Luttinger liquid and it can be interpreted as the one-dimensional (1D) limit of a fractional quantum Hall state of bosonic pairs of fermions. We study its main…
The Hydrothermal System of the Campi Flegrei Caldera, Italy
2022
In this chapter, we review the state-of-the-art of the Campi Flegrei caldera (Naples) hydrothermal system, and its behaviour during the last decades. The Campi Flegrei caldera has been undergoing unrest since 1950, as evidenced by recurrent bradyseismic episodes accompanied by manifest changes in the degassing budget, degassing patterns and in the composition of the fumarolic fluids. In-depth analysis of geochemical and geophysical datasets acquired over decades has allowed identification of the mechanisms driving volcanic unrest at the Campi Flegrei caldera. We propose a conceptual model of the hydrothermal system feeding Solfatara fumaroles, where geochemical information is integrated wit…
Plume composition changes during the birth of a new lava lake - Nyamulagira volcano, DR Congo
2016
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) with a distance of only 15 km to Nyiragongo, which is well known for its decades-old active lava lake. Nyamulagira is a shield volcano with a 3058 m high and 2000 m wide summit caldera. The volcano is characterized by frequent eruptions, which occur both from the summit crater and from the flanks (31 flank eruptions over the last 110 years). Due to the low viscosity lava, although significantly higher than the one of Nyiragongo, wide lava f…
A model of degassing for Stromboli volcano
2010
International audience; A better understanding of degassing processes at open-vent basaltic volcanoes requires collection of new datasets of H2O–CO2–SO2 volcanic gas plume compositions, which acquisition has long been hampered by technical limitations. Here, we use the MultiGAS technique to provide the best-documented record of gas plume discharges from Stromboli volcano to date. We show that Stromboli's gases are dominated by H2O (48–98 mol%; mean, 80%), and by CO2 (2–50 mol%; mean, 17%) and SO2 (0.2–14 mol%; mean, 3%). The significant temporal variability in our dataset reflects the dynamic nature of degassing process during Strombolian activity; which we explore by interpreting our gas m…
A CO2-gas precursor to the March 2015 Villarrica volcano eruption
2017
We present here the first volcanic gas compositional time-series taken prior to a paroxysmal eruption of Villarrica volcano (Chile). Our gas plume observations were obtained using a fully autonomous Multi-component Gas Analyser System (Multi-GAS) in the 3 month-long phase of escalating volcanic activity that culminated into the 3 March 2015 paroxysm, the largest since 1985. Our results demonstrate a temporal evolution of volcanic plume composition, from low CO$_2$/SO$_2$ ratios (0.65-2.7) during November 2014-January 2015 to CO$_2$/SO$_2$ ratios up to ≈ 9 then after. The H$_2$O/CO$_2$ ratio simultaneously declined to <38 in the same temporal interval. We use results of volatile saturatio…
Spatially resolved SO2 flux emissions from Mt Etna
2016
Abstract We report on a systematic record of SO2 flux emissions from individual vents of Etna volcano (Sicily), which we obtained using a permanent UV camera network. Observations were carried out in summer 2014, a period encompassing two eruptive episodes of the New South East Crater (NSEC) and a fissure‐fed eruption in the upper Valle del Bove. We demonstrate that our vent‐resolved SO2 flux time series allow capturing shifts in activity from one vent to another and contribute to our understanding of Etna's shallow plumbing system structure. We find that the fissure eruption contributed ~50,000 t of SO2 or ~30% of the SO2 emitted by the volcano during the 5 July to 10 August eruptive inter…
Lidar detection of carbon dioxide in volcanic plumes
2015
Volcanic gases give information on magmatic processes. In particular, anomalous releases of carbon dioxide precede volcanic eruptions. Up to now, this gas has been measured in volcanic plumes with conventional measurements that imply the severe risks of local sampling and can last many hours. For these reasons and for the great advantages of laser sensing, the thorough development of volcanic lidar has been undertaken at the Diagnostics and Metrology Laboratory (UTAPRAD-DIM) of the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA). In fact, lidar profiling allows one to scan remotely volcanic plumes in a fast and continuous way, and with high s…
Towards a new protocol for field measurements of greenhouse gases from wastewater treatment plant
2016
Emissions into the atmosphere of greenhouse gases (GHGs), i.e., carbon dioxide, methane and nitrous oxide from wastewater treatment plants are of increasing concern in the water industry. In order to produce useful and comparable information for monitoring, assessing and reporting GHG emissions from wastewater treatment plants, there is a crescent need for a general accepted methodology. This paper aims at proposing the first protocol for monitoring and accounting GHG emissions from wastewater treatment plants taking into account both direct and internal indirect emissions focusing on sections known to be major responsible of GHG emissions i.e. oxidation tanks and sludge digestion. The main…
Geochemistry of Gas Manifestations in Greece
2018
Κατά την περίοδο 2004 με 2017, συλλέχθηκαν περισσότερα από 350 δείγματα ελεύθερων και διαλελυμένων αερίων στην Ελλάδα. Μαζί με αυτά συνυπολογίστηκαν και βιβλιογραφικά δεδομένα. Για καλύτερη κατανόηση της μελέτης, η χώρα διαιρέθηκε σε τέσσερις γεωλογικές ενότητες (Εξωτερικές [EH] και Εσωτερικές [IH] Ελληνίδες, Ελληνική Ενδοχώρα [HH] και ενεργό ηφαιστειακό τόξο [VA]) και με βάση τον συγκεκριμένο διαχωρισμό ερευνήθηκε η πιθανή σχέση της κύριας γεωχημικής σύστασης των αερίων με τα διάφορα γεωλογικά και γεωδυναμικά καθεστώτα των περιοχών δειγματοληψίας. Τα δείγματα αναλύθηκαν για την χημική (O2, N2, CH4, CO2, He, Ne, Ar, H2, H2S και C2-C6 υδρογονάνθρακες) και ισοτοπική τους (R/RA, δ13C-CO2, δ13C…
MOBILITY OF MERCURY IN THE VOLCANIC/GEOTHERMAL AREA OF NISYROS (GREECE)
2017
Το καλοκαίρι του 2013, προσδιορίστηκαν οι συγκεντρώσεις υδραργύρου στο έδαφος και τον αέρα του ενεργού ηφαιστείου της Νισύρου (Ελλάδα), το οποίο ανήκει στο ενεργό ηφαιστειακό τόξο του νοτίου Αιγαίου. 102 δείγματα εδάφους συλλέχθηκαν και 2119 αναλύθηκαν για υδράργυρο με τη χρήση ψυχρού ατμού ατομικής απορρόφησης αναλυτή, σύμφωνα με τη μέθοδο ΕΡΑ 7473. Ταυτόχρονα, στα ίδια σημεία πραγματοποιήθηκαν συγκεντρώσεις υδραργύρου στον αέρα, με φορητό φασματοφωτόμετρο (Lumex RA- 915M). Οι τιμές των εδαφικών συγκεντρώσεων υδραργύρου κυμαίνονται από 0.023 έως 13.7 mg/g. Οι συγκεντρώσεις υδραργύρου στον αέρα έδειξαν υψηλότερες τιμές υποβάθρου στην περιοχή Λακκί της καλδέρας, μεταξύ 21 και 36 ng/m3 και μέ…