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  • 1
    Publication Date: 2021-02-23
    Description: We report on original geochemical data, which combine the rainfall trace metal contents from three different areas of Mt. Etna, variably fumigated by the volcanic plume, and those from soils, collected over the whole volcano. Trace element contents in rainfall appear mostly related to acidic ash leaching, while only for the most volatile elements (Cu, Zn, Cd, Pb, As, Sb, Tl, Se). We analyzed separately the labile fraction of soil samples, considered the fraction bioavailable to plants and soil organisms living in. The complexing medium used to extract the bioavailable fraction simulates the growth environment of plant roots.The contents of trace elements in the bioavailable fraction from soil samples showed peculiar patterns, apparently unrelated to the plume fumigation. The transition metal contents in the bioavailable fraction account for less than 15 % of the pseudo-total fraction and the highest contents were measured in the less acidic soil samples and farthest from the summit craters. In particular, high Fe, Mn, Co, Ni, Pb, Zn, Cd contents were paralleled by high soil organic carbon concentrations, which increased in the samples collected downwind the summit vents. Concerning immobile elements, their abundance in the bioavailable fraction was related to the degree of alteration of soils. Two elements, Se and Tl, were enriched in soil samples collected at closer distance from the summit vents. Their origin is probably related to the plume deposition.The study highlighted that the accessibility of plants to potentially harmful trace elements present in the soil is not simply related to the exposure to pollutants, but also to their fate in the pedogenetic environment.
    Description: Published
    Description: 57-78
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Keywords: trace elements ; Mt. Etna ; soil ; rainwater ; 03.04. Chemical and biological
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 2
    Publication Date: 2021-06-14
    Description: The complex geology of Greece includes two important parallel running ophiolitic belts. The Othrys Massif in central Greece belongs to the westernmost of them. In the current study, 33 water samples from cold hyperalkaline and hypothermal (T 〈 40°C) alkaline springs and 30 gas samples (either dissolved or free) were collected at 17 different sites in and around this wide ophiolite outcrop, aiming to determine the origin of fluids and evidence gas-water-rock interaction processes taking place in the area. Water samples were analysed for their chemical (major ions and trace elements) and isotope (δ18O-H2O, δ2H-H2O) composition. They can be subdivided into alkaline (pH 〈11) of both Mg-Ca-HCO3 and Na-HCO3 composition and hyperalkaline (pH 〉 11 and Ca-OH composition). Trace elements generally showed very low concentrations and mostly inversely correlated with pH. Gases were analysed for their chemical (He, Ne, Ar, H2, O2, N2, CH4, C2H6, CO2 and H2S) and isotope (δ13C-CH4, δ2H-CH4, δ13C-CO2) composition. Samples from alkaline waters were mainly dominated by CH4 (from 128,000 to 915,000 μmol/mol), while hyperalkaline waters showed a N2-rich composition (from 727,000 to 977,000 μmol/mol). Methane had a wide range of isotope compositions (δ13C-CH4 from -74.5 to -14.5 ‰ and δ2H-CH4 from -343 to -62 ‰). Alkaline waters present the most negative isotope values for CH4, evidencing a biogenic (both thermogenic and microbial) origin. Many of the hyperalkaline waters had CH4 isotope values compatible with an abiogenic origin through serpentinization processes but occasionaly very negative values were recorded, indicating sometimes a clear biogenic contribution. Finally, few samples both from alkaline and hyperalkaline waters showed some evidence of secondary oxidation processes.
    Description: Published
    Description: 42-56
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Keywords: hydrogeochemistry ; trace elements ; stable isotopes ; methane ; continental serpentinization ; 05.09. Miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
    Publication Date: 2023-10-26
    Description: 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 prevailing gas species with concentrations above 833,000 μmol/mol, whilst minor enrichments in N2 are noticed in some of the samples. Helium isotope ratio suggests an up to 70% mantle origin (considering a MOR type source) with the contribution of the atmospheric component being negligible, whereas C presents a mixed mantle-limestone origin with organic sediment being unimportant. Such isotope values fall in the range that characterizes the Kos-Gyali-Nisyros Volcanic Field. First estimations on the CO2 release suggest an output in the range from 18 to 28 t/d for Gyali Island, which is much lower than the total output of Kos ~75 t/d and Nisyros ~100 t/d. However, such results highlight that Gyali is an active system and, despite its small size, its degassing is not trivial.
    Description: Published
    Description: 16-28
    Description: 6A. Geochimica per l'ambiente e geologia medica
    Description: JCR Journal
    Keywords: flux measurements ; carbon degassing ; SAAVA ; 05.09. Miscellaneous
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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