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|Authors: ||Sciarra, A.*|
|Title: ||Soil gas survey in Valentano area (volcanic district of Vulsini Mounts, Central Italy): study of high natural emissions.|
|Issue Date: ||17-Aug-2008|
|Keywords: ||soil gas surveys, anomalies, radon hazard,|
|Abstract: ||The Valentano area is located in the volcanic district of Vulsini Mounts, in the northern part of the Latium region (Central Italy).
Geometry and shallow distribution of gas anomalies together with geophysical data on deep structural elements and anomalous geothermal gradient, confirm the presence of gas fluxes from a geothermal reservoir. The Valentano area is characterized by widespread natural emission phenomena, hazardous to human and animal health (many animals deaths have been recorded).
A soil gas survey has been carried out in this area with the aim to understand the spatial distribution of the gaseous species and so the location of the main pathways (faults and fractures) causing the gas uprising.
A detailed survey has been carried out at NW of Valentano town, where gas vent phenomena are characterised by high CO2 and CH4 concentrations. In this area, 75 soil gas samples (60 samples/km) have been collected. Data have been treated statistically (by normal probability plots), and by contour maps.
CO2 and CH4 concentrations show maximum values up to 100% and 1000ppm respectively, detected over the highest emission points. CO2 and CH4 contour maps show high anomalous concentrations in the central and in the southern sector of the studied area and distributions have a spot geometry. Highest Rn concentrations (> 100Bq/L) show a good spatial continuity in N-S direction overlapping the CO2 and CH4 highest values only in the central part of the anomaly.
He concentrations show anomalous values only in the southern sector. The good correlation of the gas concentrations allow us to infer that the geochemical anomalous areas and the deep geothermic reservoir are strictly related. Besides, the good association between Rn and CO2 distributions confirms the CO2 carrier gas role for trace elements.
Since this study has been partially funded by local authorities for the gas risk assessment, radon hazard map has been elaborated in order to highlight the risk areas for the human and animal health.|
|Appears in Collections:||Conference materials|
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|Poster Valentano.ppt||Valentano poster||16.57 MB||Microsoft Powerpoint||View/Open
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