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  • 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring  (11)
  • 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling  (3)
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  • 1
    Publication Date: 2017-04-04
    Description: This work presents the results of hydrogeochemical studies carried out at Vesuvius during the period May 1998 - December 2001, mostly focusing on compositional time variations observed during this time. Based on their chemistry, groundwater samples are distinguished into two groups, 1 and 2, representative of water circulation in the southern and northern sectors of the volcano, respectively. Waters from group 1 are typically more acidic, warmer,and more saline than those of group 2. They also have higher CO2 and CH4 contents, attributed to enhanced input of deep-rising volatiles and prolonged water-rock interactions. Time-series highlight the fairly constant chemical composition of the entire aquifer. Groundwater temperature, pH, bicarbonate content and dissolved CO2 display quite stable values in the study period, particularly in deep wells (piezometric level more than 100 m deep). Shallower water bodies present more evident temporal variations, related to seasonal and anthropogenic effects. This paper also describes some important variations in water chemistry which had occurred by the time of the seismic event in early October 1999, particularly in the Olivella spring located on the northern flank of the volcano. At this site, a great decrease in water pH and redox potential, and increased dissolved CO2 contents and 3He/4He ratios were observed. These changes in chemical and isotope composition support the hypothesis of an input of magma-derived helium and carbon dioxide into the aquifer feeding the Olivella spring by the time of the earthquake.
    Description: Published
    Description: 81-104
    Description: partially_open
    Keywords: Vesuvius ; volcanic surveillance ; groundwater ; hydro-geochemistry ; oxygen-18 ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2017-04-04
    Description: A simple method for determining the d13C of TDIC (Total Dissolved Inorganic Carbon) in natural waters was developed and tested. The proposed method is based on chemical and physical stripping of CO2 from water samples. The sampling apparatus consists of a glass bottle (ca 100 ml) totally filled with water sample in the field and sealed by gas-tight rubber/teflon plug. In the laboratory, we introduce 10 ml of pure Ar as host gas into the bottles and draw out an equal volume of water. About 0.5 ml of 37% extra-pure HCl is then injected into the bottle. Water pH decreases to values close to 1 and, therefore, the only carbon species present is CO2 both as dissolved and gaseous phase. Then the bottle is connected to a vacuum line to extract CO2 gas and to purify it by means of standard techniques for CO2 purification. In order to test this method, several sea water samples were prepared and analysed, as well as a series of standard solutions of Na2CO3 at known isotopic composition of carbon. The accuracy of these measurements was ± 0.2 %° vs V-PDB and their reproducibility was better than 0.2 %° vs V-PDB.
    Description: -National Group for Volcanology, Italy.
    Description: Published
    Description: 313-320
    Description: reserved
    Keywords: Carbon isotopes ; TDIC,CO2 ; HCO3 ; CO2- water interaction ; 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling ; 03. Hydrosphere::03.04. Chemical and biological::03.04.02. Carbon cycling ; 03. Hydrosphere::03.04. Chemical and biological::03.04.04. Ecosystems ; 03. Hydrosphere::03.04. Chemical and biological::03.04.05. Gases ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.08. Instruments and techniques
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Institute of Geophysics of the National Autonomous University of Mexico
    Publication Date: 2017-04-04
    Description: The Jalisco block is a geologically and tectonically complex part of western Mexico. It is considered a distinct crustal unit bounded toward the mainland by rifting and toward the Pacific ocean by the SW section of the Mid-America trench, a contact between the subducting Rivera plate and the continent. On the basis of chemical, helium, and carbon isotopic analyses of 37 groups of thermal springs widely distributed over the Jalisco block, several major tectonic environments can be distinguished. The highest R= 3He/4He ratios with R/Ra (Ra being the atmospheric 3He/4He ratio) approaching MORB values were observed along the Trans-Mexican Volcanic Belt (TMVB) and within the Colima volcanic complex. For springs in the inner part of the block and close to the Pacific coast, including submarine springs at Punta de Mita, typical values were much lower, with R/Ra down to 0.4. A negative correlation between 3He/4He and δ13C of CO2 is suggested to be the result of coupling between radiogenic He and CO2 formed by oxidation of organic-rich sediments. C/3He ratios vary from ~109 for TMVB, typical for volatiles released from the mantle, to 〉 1011 thus suggesting a substantial addition of carbon from the crust.
    Description: Published
    Description: 459-466
    Description: open
    Keywords: Jalisco Block ; helium isotopes ; carbon isotopes ; water and gas geochemistry ; tectonics ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 4
    Publication Date: 2017-04-04
    Description: In the Rocca Busambra area (mid-west Sicily, Italy), from November 1999 to July 2002, 23 water points including wells and springs were sampled and studied for their chemical and isotopic compositions. Two rain gauges were also installed at different altitudes, and rainwater was collected monthly to determine the isotopic composition. The obtained results revealed the Rocca Busambra carbonate complex as being the main recharge area on account of its high permeability value. From a chemical view point, two main groups of water can be distinguished: calcium– magnesium–bicarbonate-type and calcium–magnesium– chloride–sulphate-type waters. The first group reflects the dissolution of the carbonate rocks; the second group probably originates from circulation within flyschoid sediments. Three water wells differ from the other samples due to their relatively high Na and K content, which probably is to be referred to a marked interaction with the ‘‘Calcareniti di Corleone’’ formation, which is rich in glauconite [(K, Na)(Fe3+, Al, Mg)2(Si, Al)4O10(OH)2]. In accordance with WHO guidelines for drinking water (2004), almost all the samples collected can be considered drinkable, with the exception of four of them, whose NO3 -, F- and Na+ contents exceed the limits. On the contrary, the sampled groundwater studied is basically suitable for irrigation.
    Description: Published
    Description: 885-898
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: reserved
    Keywords: Water quality ; Environmental isotopes ; Geochemistry ; Sicily ; 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 5
    Publication Date: 2017-04-04
    Description: Large variations of the CO2 flux through the soil were observed between November 2002 and January 2006 at Mt. Etna volcano. In many cases, the CO2 flux was strongly influenced by changes in air temperature and atmospheric pressure. A new filtering method was then developed to remove the atmospheric influences on soil CO2 flux and, at the same time, to highlight the variations strictly related to volcanic activity. Successively, the CO2 corrected data were quantitatively compared with the spectral amplitude of the volcanic tremor by cross correlation function, cross-wavelet spectrum and wavelet coherence. These analyses suggested that the soil CO2 flux variations preceded those of volcanic tremor by about 50 days. Given that volcanic tremor is linked to the shallow (a few kilometer) magma dynamics and soil CO2 flux related to the deeper (*12 km b.s.l.) magma dynamics, the “delayed similarity” between the CO2 flux and the volcanic tremor amplitude was used to assess the average speed in the magma uprising into the crust, as about 170–260 m per day. Finally, the large amount of CO2 released before the onset of the 2004–2005 eruption indicated a deep ingression of new magma, which might have triggered such an eruption.
    Description: In press
    Description: N/A or not JCR
    Description: reserved
    Keywords: Mt. Etna ; Soil CO2 flux ; Volcanic tremor ; Cross-wavelet spectrum ; Wavelet coherence ; Cross correlation function ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.02. Seismological data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 6
    Publication Date: 2017-04-04
    Description: Five years of gas monitoring from selected sites suggest that Mt Etna’s plumbing system is much more extensive than previously reported. It extends at least 40 km SW from the volcano’s boundary along the NE-SW regional fault, where it discharges about 200 tons/day of gas, containing helium with mantle-type isotopic composition. Synchronous variations of 3He/4He isotopic ratios in gas sampled at sites located 60 kilometers apart have allowed us to detect pulses of ascending magma in the plumbing system, thus providing a powerful tool for eruption forecasting. Following summer 2001 eruption, the still increasing trend of the 3He/4He ratios indicates that magma storage is even now occurring at a shallow depth. Hence, the volcano maintains a high capacity to re-erupt within the next few months.
    Description: Published
    Description: 1057
    Description: partially_open
    Keywords: helium isotopes ; geochemical monitoring ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2017-04-04
    Description: We have developed a quantitative model of CO2 and H2O isotopic mixing between magmatic and hydrothermal gases for the fumarolic emissions of the La Fossa crater (Vulcano Island, Italy). On the basis of isotope balance equations, the model takes into account the isotope equilibrium between H2O and CO2 and extends the recent model of chemical and energy two-end-member mixing by Nuccio et al. (1999). As a result,the H2O and CO2 content and the dD, d18O, and d13C isotope compositions for both magmatic and hydrothermal end-members have been assessed. Low contributions of meteoric steam, added at a shallow depth, have been also recognized and quantified in the fumaroles throughout the period from 1988 to 1998. Nonequilibrium oxygen isotope exchange also seems to be occurring between ascending gases and wall rocks along some fumarolic conduits. The d13CCO2 of the magmatic gases varies around -3 to 1‰ vs. Peedee belemnite (PDB), following a perfect synchronism with the variations of the CO2 concentration in the magmatic gases. This suggests a process of isotope fractionation because of vapor exsolution caused by magma depressurization. The hydrogen isotopes in the magmatic gases (-1 to -35‰ vs. standard mean ocean water [SMOW]), as well as the above d13CCO2 value, are coherent with a convergent tectonic setting of magma generation, where the local mantle is widely contaminated by fluids released from the subducted slab. Magma contamination in the crust probably amplifies this effect. The computed isotope composition of carbon and hydrogen in the hydrothermal vapors has been used to calculate the dD and d13C of the entire hydrothermal system, including mixed H2O-CO2 vapor, liquid water, and dissolved carbon. We have computed values of about 10‰ vs. SMOW for water and -2 to -6.5‰ vs. PDB for CO2. On these grounds, we think that Mediterranean marine water (dDH2O 10‰) feeds the hydrothermal system. It infiltrates at depth throughout the local rocks, reaching oxygen isotope equilibrium at high temperatures. Interaction processes between magmatic gases and the evolving seawater also seem to occur, causing the dissolution of isotopically fractionated aqueous CO2 and providing the source for hydrothermal carbon. These results have important implications concerning fluid circulation beneath Vulcano and address the more convenient routine of geochemical surveillance.
    Description: Published
    Description: 759–772
    Description: partially_open
    Keywords: isotope geochemistry ; volcanic gases ; mixing modeling ; 04. Solid Earth::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 8
    Publication Date: 2017-04-04
    Description: Two distinct eruptive events characterize the volcanic activity at Mount Etna during the 2002 to 2005 period.We identified signals of magma ascent preceding these eruptions by geochemical monitoring of both chemical composition and He-isotope ratio of gas emissions from five locations in the peripheral area of the volcano. The geochemical signals are interpreted using the models proposed by Caracausi et al. (2003a, 2003b) and allow identification of episodes of magma ascent and estimation of the pressures of degassing magma. As observed for the 2001 eruption (Caracausi et al., 2003b), magma ascent probably triggered the onset of the 2002–2003 eruption, and minor events of magma ascent were observed between May and December 2003. In contrast to the previous two eruptions, the 2004–2005 eruption was not preceded by significant geochemical signals of volcanic unrest, suggesting that this eruption was mainly triggered by the failure of the upper portion of the volcanic edifice under the magmatic hydrostatic pressure in the conduits. High 3He/4He ratio revealed new volatile-rich magma accumulation. The 2002–2003 eruption was preceded by a much shorter period of new magma accumulation from deep levels of the feeding system. Few minor signals of magma migration were detected at some of the sites during the months preceding the 2004–2005 eruption, suggesting that the degassed 3He-depleted magma resident in the volcanic conduits was not replaced by new volatile-rich magma. This is in agreement with the lack of explosive activity during the 2004–2005 eruption and with petrologic observations that the parent magma probably erupted in 2000 and 2001. New geochemical signals of magma ascent from the deep reservoir have been identified since June 2005, indicating that the volcanic activity of Mount Etna is evolving toward new pre-eruptive conditions.
    Description: Published
    Description: Q06008
    Description: JCR Journal
    Description: reserved
    Keywords: chemical composition ; geochemical monitoring ; He isotope ; magma migration. ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
    Publication Date: 2017-04-04
    Description: Reaction path modelling, coupled with preparatory inverse modelling, was applied to test this model’s ability to reproduce the wide compositional range of ground waters circulating in a restricted area in Piedmont, Italy. This approach is based on the assumption that the chemistry of groundwater evolves through a series of partial equilibria with secondary minerals until it reaches its final composition. PHREEQC (Purkhurst and Appelo, 1999) and EQ3/6 (Wolery and Daveler, 1992) software packages were used to effect simulations. Reaction-path modelling was performed in time mode, taking into account the different rates of dissolution of each dissolving mineral. Data from literature regarding the kinetic parameters of dissolving minerals and the mineralogical composition of the host-rock were used. The results of the reaction-path modelling show that the composition of the analysed water samples was adequately reproduced, notwithstanding the hydrogeological complexity of the studied area. Modelling results provided very different water compositions as an effect of the chemical maturity, the physico-chemical parameters (fCO2, fO2, and temperature) and the variable amounts of gypsum among dissolving rock-forming minerals, which occur in Miocene levels of the sedimentary sequence. Further variability is related to the occasional contribution of brackish waters trapped in euxinic marly sediments, locally sealed by overlying clays, that have assumed an artesian character. The composition of some of the water samples can only be predicted by simulation runs performed at a temperature higher than that of the outlet (40°C). These warm waters probably circulate in a restricted area near the town of Nizza Monferrato. The same area has recently been affected by moderate seismicity, which has been accompanied by changes in either the temperature or chemistry, or both, of the ground waters. The changes recorded, interpreted as having been triggered by variations in the local/regional stress load and/or seismic activity, have to be ascribed to the vertical heterogeneity of the aquifers, where waters of different temperature, salinity and chemical composition circulate and occasionally mix.
    Description: In press
    Description: 2.4. TTC - Laboratori di geochimica dei fluidi
    Description: JCR Journal
    Description: open
    Keywords: reaction-path modelling ; EQ3/6 ; Inverse modelling ; Tertiary Piedmont Basin ; Monferrato ; Seismicity ; 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 10
    Publication Date: 2017-04-04
    Description: We report on a comprehensive study of major-ion chemistry, dissolved gases, and stable isotopes measured in water wells at Vulcano Island since 1988. The work focuses on a quantitative model describing steam condensation and boiling phenomena in shallow water bodies. The model is based on the differences in partition coefficients between liquid water and vapor characterizing oxygen and hydrogen isotopes, as well as volcanic gases (CO2, S species, and HCl). Based on both physical conditions of aquifers identified during drilling campaigns and the composition of the volcanic vapor, mass and enthalpy balances are applied in a multistep process of steam separation and condensation in shallower aquifers. By comparing the model results with measured data, we infer that (i) strong isotope enrichment observed in some shallow thermal waters can result from an increasing mass rate of condensing deep vapor, even in water meteoric in origin; (ii) the high CO2 content measured in the fumarolic vapor during 1988–1993 affected the δ18O value of the steam-heated water due to CO2–H2O isotope exchange; (iii) the high pCO2 measured in the coldest and peripheral waters are explained by the progressive enrichment of this gas in the vapor phase during multistep boiling; and (iv) the high Cl− and SO4 2−contents in the hottest waters can be attributed to the direct condensation (single-step) of volcanic vapor. The model also takes into account both the mass fluxes and the compositions of the involved endmembers (steam and shallow groundwater), which provides important inferences on the modifications observed or expected during periods of increasing mass and heat input from depth.
    Description: Published
    Description: 178-190
    Description: 1.2. TTC - Sorveglianza geochimica delle aree vulcaniche attive
    Description: JCR Journal
    Description: reserved
    Keywords: stable isotopes ; stea-heated waters ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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