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  • 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes  (8)
  • 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions  (6)
  • Elsevier  (14)
  • American Society of Hematology
  • Essen : Verl. Glückauf
  • International Union of Crystallography
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • 2005-2009  (14)
  • 2005  (14)
Collection
Keywords
Publisher
Years
  • 2005-2009  (14)
Year
  • 1
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    Dynamics of magma ascent and fragmentation in trachytic versus rhyolitic eruptions (2005)
    Elsevier
    Details
    Publication Date: 2020-10-29
    Description: We have performed a parametric study on the dynamics of trachytic (alkaline) versus rhyolitic (calc-alkaline) eruptions by employing a steady, isothermal, multiphase non-equilibrium model of conduit flow and fragmentation. The employed compositions correspond to a typical rhyolite and to trachytic liquids from Phlegrean Fields eruptions, for which detailed viscosity measurements have been performed. The investigated conditions include conduit diameters in the range 30–90 m and total water contents from 2 to 6 wt%, corresponding to mass flow rates in the range 106–108 kg/s. The numerical results show that rhyolites fragment deep in the conduit and at a gas volume fraction ranging from 0.64 to 0.76, while for trachytes fragmentation is found to occur at much shallower levels and higher vesicularities (0.81–0.85). An unexpected result is that low-viscosity trachytes can be associated with lower mass flow rates with respect to more viscous rhyolites. This is due to the non-linear combined effects of viscosity and water solubility affecting the whole eruption dynamics. The lower viscosity of trachytes, together with higher water solubility, results in delayed fragmentation, or in a longer bubbly flow region within the conduit where viscous forces are dominant. Therefore, the total dissipation due to viscous forces can be higher for the less viscous trachytic magma, depending on the specific conditions and trachytic composition employed. The fragmentation conditions determined through the simulations agree with measured vesicularities in natural pumice clasts of both magma compositions. In fact, vesicularities average 0.80 in pumice from alkaline eruptions at Phlegrean Fields, while they tend to be lower in most calc-alkaline pumices. The results of numerical simulations suggest that higher vesicularities in alkaline products are related to delayed fragmentation of magmas with this composition. Despite large differences in the distribution of flow variables which occur in the deep conduit region and at fragmentation, the flow dynamics of rhyolites and trachytes in the upper conduit and at the vent can be very similar, at equal conduit size and total water content. This is consistent with similar phenomenologies of eruptions associated with the two magma types.
    Description: Published
    Description: 93-108
    Description: partially_open
    Keywords: trachytic magma ; conduit flow ; eruption dynamics and numerical simulations ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.07. Instruments and techniques ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
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    The age of the Neapolitan Yellow Tu caldera-forming eruption (Campi Flegrei caldera-Italy) assessed by 40Ar/39Ar dating method (2005)
    Elsevier
    Details
    Publication Date: 2020-12-17
    Description: The Neapolitan Yellow Tuff (NYT) is the product of the largest known trachytic phreatoplinian eruption. It covered an area larger than 1000 km2 with an estimated volume of about 40 km3 of erupted magma. During the course of the eruption a caldera collapsed within the previously formed Campanian Ignimbrite caldera. The resulting nested structure strongly influenced the following volcanic activity in the Campi Flegrei caldera. As previous dating of the NYT does not converge toward a unique result, a new set of 40Ar/39Ar age determinations has been carried out to better constrain the age of the eruption. Two variants of the 40Ar/39Ar dating method were applied to determine the age of the NYT eruption: (1) single-crystal total fusion (SCTF), on an individual phenocryst of feldspar, and (2) laser incremental heating (LIH), on bulk aliquots of feldspar phenocrysts. The results of the SCTF analyses show that the overall sample weighted mean age, derived from the conventional age calculation, is 15.6 ;0.8 ka. A weighted mean of the isochron age is 15.3 ;1.2 ka (2c), and has been assumed as the best indicator of age to be derived from the SCTF analyses. The LIH analyses results show that plateau ages vary from 15.4; 0.5 to 14.5; 0.5 ka. The overall weighted mean age of the isochron results is 14.9;0.4 ka (2c). This result has been assumed as the reference age for the NYT eruption, and agrees with the SCTF age. The new age obtained for the NYT deposits is of great relevance for the understanding of the evolution and the present state of the Campi Flegrei caldera and collocates the NYT in a crucial stratigraphical position to date the climatic oscillations that occurred between the Late Glacial and the Holocene.
    Description: Published
    Description: 157-170
    Description: partially_open
    Keywords: Neapolitan Yellow Tuff ; Campi Flegrei caldera ; 40Ar/39Ar dating method ; Geochronology ; Late Glacial ; Holocene ; 04. Solid Earth::04.04. Geology::04.04.02. Geochronology ; 04. Solid Earth::04.04. Geology::04.04.10. Stratigraphy ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 3
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    Magma-derived gas influx and water-rock interactions in the volcanic aquifer of Mt. Vesuvius, Italy (2005)
    Elsevier
    Details
    Publication Date: 2021-06-25
    Description: We report in this paper a systematic investigation of the chemical and isotopic composition of groundwaters flowing in the volcanic aquifer of Mt. Vesuvius during its current phase of dormancy, including the first data on dissolved helium isotope composition and tritium content. The relevant results on dissolved He and C presented in this paper reveal that an extensive interaction between rising magmatic volatiles and groundwaters currently takes place at Vesuvius. Vesuvius groundwaters are dilute (mean TDS 2800 mg/L) hypothermal fluids (mean T 17.7°C) with a prevalent alkaline-bicarbonate composition. Calcium-bicarbonate groundwaters normally occur on the surrounding Campanian Plain, likely recharged from the Apennines. D and 18O data evidence an essentially meteoric origin of Vesuvius groundwaters, the contribution from either Tyrrhenian seawater or 18O-enriched thermal water appearing to be small or negligible. However, the dissolution of CO2-rich gases at depth promotes acid alteration and isochemical leaching of the permeable volcanic rocks, which explains the generally low pH and high total carbon content of waters. Attainment of chemical equilibrium between the rock and the weathering solutions is prevented by commonly low temperature (10 to 28°C) and acid-reducing conditions. The chemical and isotope (C and He) composition of dissolved gases highlights the magmatic origin of the gas phase feeding the aquifer. We show that although the pristine magmatic composition may vary upon gas ascent because of either dilution by a soil-atmospheric component or fractionation processes during interaction with the aquifer, both 13C/12C and 3He/4He measurements indicate the contribution of a magmatic component with a 13C 0‰ and R/Ra of 2.7, which is consistent with data from Vesuvius fumaroles and phenocryst melt inclusions in olivine phenocrysts. A main control of tectonics on gas ascent is revealed by data presented in this paper. For example, two areas of high CO2 release and enhanced rock leaching are recognized on the western (Torre del Greco) and southwestern (Torre Annunziata–Pompeii) flanks of Vesuvius, where important NE-SW and NW-SE tectonic structures are recognized. In contrast, waters flowing through the northern sector of the volcano are generally colder, less saline, and CO2 depleted, despite in some cases containing significant concentrations of magmaderived helium. The remarkable differences among the various sectors of the volcano are reconciled in a geochemical interpretative model, which is consistent with recent structural and geophysical evidences on the structure of Somma-Vesuvius volcanic complex.
    Description: -European Union, -Ministero dell’Universita’ e della Ricerca Scientifica e Tecnologica; -CNR–Gruppo Nazionale per la Vulcanologia.
    Description: Published
    Description: 963–981
    Description: partially_open
    Keywords: isotopes ; water chemistry ; dissolved gases ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 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 ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring
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  • 4
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    Rapid morphological changes at the summit of an active volcano: reappraisal of the poorly documented 1964 eruption of Mount Etna (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: While the eruptive record of Mount Etna is reasonably complete for the past 400 years, the activity of the early and late 1960s, which took place at the summit, is poorly documented in the scientific literature. From 1955 to 1971, the Central and Northeast Craters were the sites of long-lived mild Strombolian and effusive activity, and numerous brief episodes of vigorous eruptive activity, which led to repeated overflows of lava onto the external flanks of the volcano. A reconstruction of the sequence of the more important of these events based on research in largely obscure and nearly inaccessible sources permits a better understanding of the eruption dynamics and rough estimates of erupted volumes and of the changes to the morphology of the summit area. During the first half of 1964, the activity culminated in a series of highly dynamic events at the Central Crater including the opening of a fissure on the E flank of the central summit cone, lava fountains, voluminous tephra emission, prolonged strong activity with continuous lava overflows, and growth of large pyroclastic intracrater cones. Among the most notable processes during this eruption was the breaching of a section of the crater wall, which was caused by lateral pressure of lava ponding within the crater. Comparison with the apparently similar summit activity of 1999 allows us to state that (a) lava overflows from large pit craters at the summit are often accompanied by breaching of the crater walls, which represents a significant hazard to nearby observers, and that (b) eruptive activity in 1999 was much more complex and voluminous than in 1964. For 1960s standards however, the 1964 activity was the most important summit eruption in terms of intensity and output rates for about 100 years, causing profound changes to the summit morphology and obliterating definitively the former Central Crater.
    Description: Published
    Description: 203-218
    Description: partially_open
    Keywords: Mount Etna ; Summit eruption ; Crater morphology and Lava overflows ; 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::05.02.03. Volcanic eruptions
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  • 5
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    The aquatic geochemistry of arsenic in volcanic groundwaters from southern Italy (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This paper discusses the abundance, speciation and mobility of As in groundwater systems from active volcanic areas in Italy. Using literature data and new additional determinations, the main geochemical processes controlling the fate of As during gas–water–rock interaction in these systems are examined. Arsenic concentrations in the fluids range from 0.1 to 6940 mg/l, with wide differences observed among the different volcanoes and within each area. The dependence of As content on water temperature, pH, redox potential and major ions is investigated. Results demonstrate that As concentrations are highest where active hydrothermal circulation takes place at shallow levels, i.e. at Vulcano Island and the Phlegrean Fields. In both areas the dissolution of As-bearing sulphides is likely to be the main source of As. Mature Cl-rich groundwaters, representative of the discharge from the deep thermal reservoirs, are typically enriched in As with respect to SO4-rich ‘‘steam heated groundwaters’’. In the HCO3 groundwaters recovered at Vesuvius and Etna, aqueous As cycling is limited by the absence of high-temperature interactions and by high-Fe content of the host rocks, resulting in oxidative As adsorption. Thermodynamic modelling suggests that reducing H2S-rich groundwaters are in equilibrium with realgar, whereas in oxidising environments over-saturation with respect to Fe oxyhydroxides is indicated. Under these oxidising conditions, As solubility decreases controlled by As co-precipitation with, or adsorption on, Fe oxy-hydroxides. Consistent with thermodynamic considerations, As mobility in the studied areas is enhanced in intermediate redox environments, where both sulphides and Fe hydroxides are unstable.
    Description: Published
    Description: 1283–1296
    Description: partially_open
    Keywords: Hydrogeochemistry ; Arsenic ; volcanic groundwaters ; speciation ; 03. Hydrosphere::03.01. General::03.01.01. Analytical and numerical modeling ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems
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  • 6
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    The influence of conduit processes on changes in style of basaltic Plinian eruptions: Tarawera 1886 and Etna 122 BC (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Basaltic volcanism is most typically thought to produce effusion of lava, with the most explosive manifestations ranging from mild Strombolian activity to more energetic fire fountain eruptions. However, some basaltic eruptions are now recognized as extremely violent, i.e., generating widespread phreatomagmatic, subplinian and Plinian fall deposits. We focus here on the influence of conduit processes, especially partial open-system degassing, in triggering abrupt changes in style and intensity that occurred during two examples of basaltic Plinian volcanism. We use the 1886 eruption of Tarawera, New Zealand, the youngest known basaltic Plinian eruption and the only one for which there are detailed written eyewitness accounts, and the well-documented 122 BC eruption of Mount Etna, Italy, and present new grain size and vesicularity data from the proximal deposits. These data show that even during extremely powerful basaltic eruptions, conduit processes play a critical role in modifying the form of the eruptions. Even with very high discharge, and presumably ascent, rates, partial open-system behaviour of basaltic melts becomes a critical factor that leads to development of domains of largely stagnant and outgassed melt that restricts the effective radius of the conduit. The exact path taken in the waning stages of the eruptions varied, in response to factors which included conduit geometry, efficiency and extent of outgassing and availability of ground water, but a relatively abrupt cessation to sustained high-intensity discharge was an inevitable consequence of the degassing processes.
    Description: Published
    Description: 1-14
    Description: partially_open
    Keywords: basaltic Plinian eruption ; Etna ; Tarawera and explosive volcanism ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 7
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    The buried caldera of Misti volcano, Peru, revealed by combining a self-potential survey with elliptic Fourier function analysis of topography (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: This survey proposes a new approach to identify buried caldera boundaries of a volcanic cone, combining (1) a systematic elliptic Fourier functions (EFF) analysis on the contour lines based on the external shape of the edifice with (2) self-potential (SP) measurements on volcano flanks. The methodology of this approach is to investigate the relationships between (1) vertical morphological changes inferred from EFF analysis and (2) lateral lithological transition inside the edifice inferred from SP/elevation gradients. The application of these methods on Misti volcano in southern Peru displays a very good correlation. The three main boundaries evidenced by hierarchical cluster analysis on the contour lines coincide with the two main boundaries characterised by SP signal and with a secondary SP signature related with a summit caldera. In order to explain these results showing a very good correlation between morphologic and lithologic changes as function of elevation, caldera boundaries have been suggested. The latter would be located at an average elevation of (1) 4350–4400 m, (2) 4950–5000 m, and (3) 5500– 5550 m. For the lowest boundary in elevation, the coincidence with the lateral extension of the hydrothermal system inferred from SP measurements suggests that caldera walls act as a barrier for lateral extension of hydrothermal systems. In the summit area, the highest boundary has been related with the summit caldera, inferred by a secondary SP minimum and geological evidence.
    Description: - Institut de Recherche pour le Développement (IRD) - Instituto Geofisico del Peru´ (IGP).
    Description: Published
    Description: 283– 297
    Description: partially_open
    Keywords: caldera ; elliptic Fourier functions ; geomorphology ; self-potential ; Misti volcano ; Peru ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 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::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.02. Exploration geophysics::04.02.04. Magnetic and electrical methods ; 04. Solid Earth::04.04. Geology::04.04.03. Geomorphology ; 04. Solid Earth::04.04. Geology::04.04.09. Structural geology ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.04. Hydrogeological data ; 05. General::05.05. Mathematical geophysics::05.05.99. General or miscellaneous ; 05. General::05.08. Risk::05.08.99. General or miscellaneous ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 8
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    Groundwater radon measurements in the Mt. Etna area (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Radon levels were measured in 119 groundwater samples collected throughout the active volcanic area of Mt. Etna by means of a portable Lucas-type scintillation chamber. The measured activity values range from 1.8 to 52.7 Bq l 1. About 40% of the samples exceed the maximum contaminant level of 11 Bq l 1 proposed by the USEPA in 1991. The highest radon levels are measured in the eastern sector of the volcano, which is the seismically most active zone of the volcano. On the contrary the south-western sector, which is both seismically active and a site of intense magmatic degassing, display lower radon levels. This is probably due to the formation of a free gas phase (oversaturation of CO2) that strips the radon from the water. Comparison of the data gathered at Mt. Etna with those of other areas indicates that 222Rn activity in groundwater is positively correlated with both the content of parent elements in the aquifer rocks and the temperature of the geothermal systems that interacts with the sampled aquifers.
    Description: Published
    Description: 187–201
    Description: partially_open
    Keywords: Groundwater ; Radon ; Mount Etna ; Active volcanic areas ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.06. Water resources ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters ; 03. Hydrosphere::03.04. Chemical and biological::03.04.07. Radioactivity and isotopes ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.08. Risk::05.08.01. Environmental risk
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 9
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    Contrasting triggering mechanisms of the 2001 and 2002–2003 eruptions of Mount Etna (Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Mount Etna produced two significant eruptions in 2001 and 2002–2003, which we have analysed using geological, seismic and deformation data. These eruptions showed some similarities, such as the activating of two magmatic plumbing systems (central–lateral and eccentric), but they differed in their triggering mechanisms. While the 2001 eruption was largely the result of the emplacement of a N–S eccentric dike (independent from the central conduits) consistent with E–W regional extension, the 2002–2003 eruption occurred in response to a major flank slip on the eastern and southeastern sides of the volcano. This is demonstrated by the spatial and temporal distribution of seismicity and deformation preceding and accompanying the two eruptions. During the months prior to the 2001 eruption, most epicenters were concentrated on the southern flank, at depths of 5–15 km below sea level. During the 4 days before the eruption, earthquake hypocenters migrated to shallower levels (from 5 km bsl. upward) indicating the emplacement of the eccentric dike. This is confirmed by the patterns of ground fracturing observed in the field and deformation documented by electronic distance measurements (EDM). In contrast, the months before the 2002–2003 eruption were characterised by shallower seismicity, mainly concentrated along the active faults bordering the slipping flank sector. Flank slip accelerated in September 2002 and a second, more vigorous acceleration of flank slip occurred on 26–27 October 2002, accompanying the opening of eruptive vents. The very short (2 h) seismic crisis preceding the onset of eruptive activity stands in neat contrast with the 4 days of intense seismicity before the 2001 eruption. Subsequently, flank slip-deformation extended all over the eastern and southeastern flanks of the volcano, causing serious damage in this sector. The events of 2001–2003 can be seen as a continuous chain of intimately interacting processes including regional tectonics, magma accumulation and eruption, and flank instability. In this scenario the 2001 eruption led to increased flank instability that subsequently accelerated and culminated with the massive flank slip, which in turn facilitated the 2002–2003 eruption. This sequence of events points to a long-term feedback mechanism between magmatism and flank instability at Etna.
    Description: Published
    Description: 235-255
    Description: partially_open
    Keywords: eruption triggering ; central–lateral vs. eccentric eruptions ; flank instability and slip ; volcano-tectonics ; Mt. Etna ; instrumental monitoring ; 04. Solid Earth::04.07. Tectonophysics::04.07.07. Tectonics ; 04. Solid Earth::04.08. Volcanology::04.08.06. Volcano monitoring ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions ; 04. Solid Earth::04.08. Volcanology::04.08.08. Volcanic risk
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  • 10
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    A new collector for sampling volcanic aerosols (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: A new apparatus, Venturi Effect System (VES), designed for sampling volcanic plumes is described and tested at Vulcano (Italy). This device, together with purified basic NH4OH solutions, supplies optimal conditions to obtain reliable Stotal/Cl/F ratios and enrichment factors for metallic trace elements (MTE). Good concordance for acid gas ratios and metal enrichment factors in both the gas phase and the related plume allows the procedure to be validated. The VES appears in Vulcano conditions as a simple, robust and easily portable apparatus that allows reliable collection of both acid gases and MTE within a single sample and the analysis with current chemical methods (High Pressure Liquid Chromatography, Inductively Coupled Plasma-Mass Spectrometry. This apparatus may be suitable for more difficult volcanoes where only the plume can be sampled.
    Description: Published
    Description: 95-103
    Description: partially_open
    Keywords: volcanic plume ; acid gases ; metallic trace elements ; sampling ; monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.02. Hydrological processes: interaction, transport, dynamics ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes
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  • 11
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    Scaling characteristics of local geomagnetic field and seismicity at Etna volcano and their dynamics in relation to the eruptive activity (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: The evolution of scaling characteristics of the local geomagnetic field and of the seismicity at Etna volcano is studied in relation to the strong eruptive activity occurred here from 2000 to 2002. Scaling laws are found in the hourly time variability of magnetic data and in the seismicity pattern. The scaling exponents suggest the presence of persistent temporal fluctuations. Clear links between the dynamics of the measured data and the eruptive volcanic episodes are revealed. Fractal dimensions of seismicity seem to be always correlated to the beginning of main eruptive events, while strong alterations of the dynamics of the local magnetic field take place only when the eruptive fractures opened very close to the magnetic sites.
    Description: Published
    Description: 96-106
    Description: partially_open
    Keywords: scaling characteristics ; volcanic eruptions ; geomagnetic field ; seismic activity ; Mt. Etna ; 04. Solid Earth::04.05. Geomagnetism::04.05.02. Geomagnetic field variations and reversals ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
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    Dissolved helium isotope ratios in ground-waters: a new technique based on gas–water re-equilibration and its application to Stromboli volcanic system (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Here, a new technique for the determination of dissolved He isotope ratios in ground-waters is presented. This method is based on the extraction and subsequent equilibrium of dissolved gases in an added ‘‘host’’ gas phase. Ultra pure N2 is placed in glass flasks (250 cc), containing water samples, that were hermetically sealed after their collection. After shaking in an ultrasonic bath for 10 min, an aliquot of the separated gas phase was removed from the flask for MS analysis. 3He/4He ratios are measured by using a modified double collector mass spectrometer (VG 5400-TFT). Helium and Ne concentrations are calculated by comparing the partial pressures of masses 4 and 20 of the samples with those of the air-standard measured by a quadrupole mass spectrometer (QMS;VG Quartz). Using He and Ne equilibrium partitioning coefficients, it is possible to calculate the amount of gas originally dissolved in the water. The technique was tested on both air-saturated waters (ASW) and thermal waters from Stromboli (Aeolian Islands, South Italy), the results of which confirmed good reproducibility (ffi5%) and accuracy (ffi3%) of the data. The method was then applied to three thermal water samples collected from the same volcanic area and the results compared with those of a fumarolic and a soil gas. The isotope ratios for dissolved He gave values of 4.06–4.23 Ra, which are significantly higher than those previously reported in the literature (3.0, 3.5 and 2.9 Ra) and that measured at the fumarole (3.09 Ra), suggesting a newer and higher isotopic signature for the volcanic system. The proposed method appears to be a useful tool in the determination of 3He/4He ratios in ground-water systems, especially when free gases are not available or are dangerous to collect.
    Description: Published
    Description: 665–673
    Description: partially_open
    Keywords: dissolved helium isotopes ; gas water interaction ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.04. Chemical and biological::03.04.06. Hydrothermal systems ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 539 bytes
    Format: 439948 bytes
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  • 13
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    Natural and anthropogenic factors affecting groundwater quality of an active volcano (Mt. Etna, Italy) (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: New geochemical data on dissolved major and minor constituents in 276 groundwater samples from Etna aquifers reveal the main processes responsible for their geochemical evolution and mineralisation. This topic is of particular interest in the light of the progressive depletion of water resources and groundwater quality in the area. Multivariate statistical analysis reveal 3 sources of solutes: (a) the leaching of the host basalt, driven by the dissolution of magmaderived CO2; (b) mixing processes with saline brines rising from the sedimentary basement below Etna; (c) contamination from agricultural and urban wastewaters. The last process, highlighted by increased concentrations of SO4,NO3, Ca, F and PO4, is more pronounced on the lower slopes of the volcanic edifice, associated with areas of high population and intensive agriculture. However, this study demonstrates that natural processes (a) and (b) are also very effective in producing highly mineralised waters, which in turn results in many constituents (B, V, Mg) exceeding maximum admissible concentrations for drinking water.
    Description: Published
    Description: 863–882
    Description: partially_open
    Keywords: Hydrogeochemistry ; water quality ; Mt. Etna ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 03. Hydrosphere::03.02. Hydrology::03.02.04. Measurements and monitoring ; 03. Hydrosphere::03.02. Hydrology::03.02.06. Water resources ; 03. Hydrosphere::03.04. Chemical and biological::03.04.03. Chemistry of waters
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 539 bytes
    Format: 787985 bytes
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  • 14
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    Isotopic, chemical and dissolved gas constraints on spring water from Popocatepetl volcano (Mexico): evidence of gas–water interaction between magmatic component and shallow fluids (2005)
    Elsevier
    Details
    Publication Date: 2017-04-04
    Description: Geochemical research was carried out on cold and hot springs at Popocatepetl (Popo) volcano (Mexico) in 1999 to identify a possible relationship with magmatic activity. The chemical and isotopic composition of the fluids is compatible with strong gas–water interaction between deep and shallow fluids. In fact, the isotopic composition of He and dissolved carbon species is consistent with a magmatic origin. The presence of a geothermal system having a temperature of 80–1008 C was estimated on the basis of liquid geothermometers. A large amount of dissolved CO2 in the springs was also detected and associated with high CO2 degassing.
    Description: Published
    Description: 91– 108
    Description: partially_open
    Keywords: Popocatepetl volcano ; helium isotope composition ; carbon isotope composition ; dissolved gases ; gas–water interaction ; 03. Hydrosphere::03.02. Hydrology::03.02.03. Groundwater processes ; 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::04.04. Geology::04.04.12. Fluid Geochemistry ; 04. Solid Earth::04.08. Volcanology::04.08.01. Gases
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 539 bytes
    Format: 899823 bytes
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