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  • Volcanic activity  (2)
  • Key words Geochemistry  (1)
  • 1
    ISSN: 1432-0819
    Keywords: Etna ; Carbon dioxide ; Soil degassing ; Seasonal influences ; Volcanic activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Wide variations were measured in the diffuse CO2 flux through the soils in three selected areas of Mt Etna between August 1989 and March 1993. Degassing of CO2 from the area of Zafferana Etnea-S. Venerina, on the eastern slope of the volcano, has been determined to be more strongly influenced by meteorological parameters than the other areas. The seasonal component found in the data from this area has been excluded using a filtering algorithm based on the best fitting equation calculated from the correlation between CO2 flux values and those of air temperature. The filtered data appear to have variations temporally coincident with those from the other areas, thus suggesting a common and probably deep source of gas. The highest fluxes measured in the two most peripheral areas may correlate well with other geophysical and volcanological anomalous signals that preceded the strong eruption of 1991–1993 and that were interpreted as deep pressure increases. Anomalous decreases in CO2 fluxes accompanied the onset and the evolution of that eruption and have been interpreted as a sign of upward migration of the gas source. The variations of CO2 flux at the 1989 SE fracture have also given interesting information on the timing of the magmatic intrusion that has then fed the 1991–1993 eruption.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Environmental geology 39 (2000), S. 1205-1215 
    ISSN: 1432-0495
    Keywords: Key words Geochemistry ; Surface and groundwaters water quality
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  A hydrogeochemical study of the Salso River highlighted the chemical and isotopic space-time evolution along its flow path and the main contamination processes. Within the basin, three different hydrogeochemical facies have been individuated: (1) Ca-Mg-HCO3, (2) Ca-Mg-SO4 and (3) Na-Cl. The first facies reflects the chemical composition of the groundwaters hosted in the carbonate reliefs that belong to the Madonie Mountains. The second and the third facies are the result of the interaction processes between surface waters and the gypsum and salty clays, respectively. Two pollution sources have been also located in the basin downstream from the salt mine and downstream from a discharge area of wastewater from the town of Gangi. On the basis of the location of natural and anthropogenic pollution sources, the waters available for drinking and irrigation use are also indicated.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0819
    Keywords: Key words Etna ; Carbon dioxide output ; Magma degassing ; Volcanic activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  An estimated average CO2 output from Etna's summit craters in the range of 13±3 Mt/a has recently been determined from the measured SO2 output and measured CO2/SO2 molar ratios. To this amount the CO2 output emitted diffusely from the soil (≈ 1 Mt/a) and the amount of CO2 dissolved in Etna's aquifers (≈ 0.25 Mt/a) must be added. Data on the solubility of CO2 in Etnean magmas at high temperature and pressure allow the volume of magma involved in the release of such an amount of this gas to be estimated. This volume of magma (≈ 0.7 km3/a) is approximately 20 times greater than the volume of magma erupted annually during the period 1971–1995. On the basis of C-isotopic data of CO2 collected in the Etna area and of new hypotheses on the source of Mediterranean magmas, significant contributions of CO2 from non-magmatic sources to the total output from Etna are unlikely. Such large outputs of CO2 and also of SO2 from Etna could be due to an anomalously shallow asthenosphere beneath the volcano that allows a continuous escape of gases toward the surface, even without migration of magma.
    Type of Medium: Electronic Resource
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