Marianna Cangemi

Preliminary geochemical characterization of groundwater drained by the Roman emissary of Lake Albano (Italy)

Many lakes have been the object of hydraulic works in historical times, and the drainage tunnel carved by Romans for regulating the level of Lake Albano (Central Italy) can be considered as one of the most important historical hydraulic tunnels in the world. We sampled and analysed lake water, as well as groundwater samples from the Lake Albano emissary and another hydraulic work in the area (Ninfeo), which were analysed for their geochemical and isotopic composition in order to extract useful information for a possible reuse of the tunnel for anthropogenic purposes. The collected water samples exhibit common chemical features, typical of water–rock interaction processes in volcanic areas. Analyses of minor and trace elements confirmed the abovementioned results, indicating the presence of an atmospheric pollution source for heavy metals, although their concentrations are mostly below the Maximum Admitted Concentrations for drinking water issued by the World Health Organization. The chemical composition of dissolved gases indicated that both lake and groundwater are mainly enriched in CO2. Isotopic analyses suggested a clear volcanic origin for CO2 dissolved in lake water, while carbon dioxide in groundwater from the Roman emissary is produced by soil respiration. As further confirmed by Oxygen and Deuterium isotopic composition, the Roman emissary drains local suspended aquifers neither in contact with the lake water body nor influenced by volcanic activity, suggesting the opportunity to use the tunnel as a “zero-condition” monitoring site for individuating a possible future renewal of volcanic activity.

Geochemical and Isotopic Characterisation of Actual Lacustrine Sediments from the Hydrothermal Lake Specchio di Venere, Pantelleria Island (Italy)

Hydrothermal lakes are a very common feature in volcanic environments, and among these lake Specchio di Venere (Pantelleria island, Italy) has attracted the interest of several researchers due to its peculiar characteristics. With the aim of improving the knowledge of its mineralogy, our work pointed out the characterisation of the bottom lake sediments. We collected and analysed 5 sediments cores around the shoreline, determining the mineralogical phases, concentration of major, minor, and trace elements, and the isotopic composition of carbon and oxygen in the carbonate phases. Our findings remarked a general compositional homogeneity in both the vertical and horizontal distribution of mineral phases, with the exception of peculiar geological niches connoted by biological and hydrothermal activities.

Possible Micrometeorological Anomalies Induced by Volcanic Activity Recorded at Stromboli Island (Aeolian Archipelago, Italy)

Hourly values of atmospheric pressure and air temperature have been acquired at the top of two volcanic islands, Stromboli and Salina in the Aeolian Archipelago (Italy), very similar in height and morphology but completely different with regard to their volcanic activity state: the former is permanently active, whereas the latter is extinguished. During the last four years Stromboli experienced normal activity, volcanic unrests, and an effusive eruption (August–November 2014). The comparative analysis of the recorded data, both in the time and frequency domains, evidenced a peculiar micrometeorological regime at Stromboli, more turbulent during unrests with respect to the quieter periods, but showing an apparent paradox during eruptions, characterized by a lower atmospheric turbulence. These observations suggest that the studied volcanic-micrometeorological system is chaotic, due to contemporary opposite transients generated in the atmosphere by volcanic activity changes, and that micrometeorological conditions in volcanic areas are controlled both by exogenous processes and volcanic activity.