Search results for "soil ga"
showing 9 items of 19 documents
Diffuse and focused carbon dioxide and methane emissions from the Sousaki geothermal system, Greece
2006
[1] We report first data on chemical composition of the gas emitted by the geothermal system of Sousaki, Greece. Gas manifestations display typical geothermal gas composition with CO2 as the main component and CH4 and H2S as minor species. Soil gas composition derives from the mixing of two end-members (atmospheric air and geothermal gas). Soil CO2 fluxes range from<2 to 33,400 g m−2 d−1. The estimated diffuse output of hydrothermal CO2, estimated for an area of 0.015 km2, is about 630 g s−1, while a tentative estimation of CH4 diffuse output gave a value of about 1.15 g s−1. Point sources accounted for lower flux values of ∼26 g s−1 of CO2, ∼0.1 g s−1 of CH4 and ∼0.02 g s−1 of H2S.
Organometal(loid) species in geochemical exploration : preliminary qualitative results
1998
Abstract Organic and other volatile metal(loid) species (e.g. hydrides) in environmental gases can be determined with high sensitivity and selectivity by low-temperature gas chromatography coupled on-line to plasma mass spectrometry (LTGC/ICP–MS). A standard reference solution is analysed simultaneously for calibration of the results as well as for monitoring the excitation conditions in the plasma. This highly sensitive analytical method was applied in field screening tests at Cu and Hg deposits in Germany. In some of the soil gas and soil samples investigated, organic compounds of several elements (e.g. As, Hg) could clearly be identified. The implications of these results with respect to…
Helium and CO2 soil gas emission from Santorini (Greece)
1994
Soil gas investigation is a useful tool to detect active faults. The sudden appearance of soil gas anomalies in zones of deep-reaching faults represents a promising potential precursor of earthquakes and volcanic eruptions. In volcanic areas the development of soil gas monitoring techniques is particularly important, as they can represent, together with remote sensing techniques, the only geochemical methods that can be safely applied during volcanic unrest, when it becomes impossible or too dangerous to sample crater fumaroles. A soil gas survey was carried out in June 1993 at the main island of Thera, in the Santorini volcanic complex. CO2 flux and CO2 and helium concentrations were measu…
The summit hydrothermal system of Stromboli: New insights from self-potential, temperature, CO2 and fumarolic fluids measurements, with structural an…
2003
International audience; Accurate and precisely located self-potential (SP), temperature (T) and COi measurements were carried out in the summit area of Stromboli along 72 straight profiles. SP data were acquired every metre and T data every 2.5 m. CO2 concentrations were acquired with the same density as T, but only along seven profiles. The high density of data and the diversity of the measured parameters allows us to study structures and phenomena at a scale rarely investigated. The shallow summit hydrothermal activity (Pizzo-Fossa area) is indicated by large positive SP, T and COi anomalies. These anomalies are focused on crater faults, suggesting that the fracture zones are more permeab…
Relationships between diffuse CO 2 emissions and volcanic activity on the island of Vulcano (Aeolian Islands, Italy) during the period 1984-1994
2002
Measurements of CO2 flux from the ground were periodically carried out on the island of Vulcano (Aeolian Islands, Italy) between 1984 and 1994. Three high-flux areas were identified at the foot of the volcanic cone (La Fossa), either inside or very close to the main village. Effect of the choice of the sampling grid was evaluated. A different sampling grid resulted in similar distribution patterns, but with different CO2 fluxes. Therefore, the absolute estimate of the total flux from the investigated area includes a large degree of uncertainty, but repeated measurements with permanent sampling sites are accurate and can detect small changes. No correlation of the flux with atmospheric param…
Fault-controlled Soil CO2 Degassing and Shallow Magma Bodies: Summit and Lower East Rift of Kilauea Volcano (Hawaii), 1997
2006
Soil CO2 flux measurements were carried out along traverses across mapped faults and eruptive fissures on the summit and the lower East Rift Zone of Kilauea volcano. Anomalous levels of soil degassing were found for 44 of the tectonic structures and 47 of the eruptive fissures intercepted by the surveyed profiles. This result contrasts with what was recently observed on Mt. Etna, where most of the surveyed faults were associated with anomalous soil degassing. The difference is probably related to the differences in the state of activity at the time when soil gas measurements were made: Kilauea was erupting, whereas Mt. Etna was quiescent although in a pre-eruptive stage. Unlike Mt. Etna, fl…
New evidence for the form and extent of the Pernicana Fault System (Mt. Etna) from structural and soil–gas surveying
1998
A multidisciplinary study based on structural and soil–gas surveys was carried out in order to investigate the relationship between soil CO2 degassing and the tectonic setting of the lower northeastern flank of Mt. Etna volcano. The results show that anomalous soil CO2 emissions occur mainly along faults trending WNW–ESE and also where these faults intersect the other main fault set (trending NE–SW) that displaces the study area. In particular, anomalies in CO2 degassing were revealed both along the Pernicana Fault and along another fault (Fiumefreddo Fault) which may represent the prolongation of the former towards the Ionian Sea coast. In the areas where these structures show evident surf…
Interaction between the deep fluids and the shallow groundwaters on Vulcano island (Italy)
2001
The aim of this work is to study the interactions processes between the fluids of deep origin and the shallow groundwaters of the Vulcano Porto area. During 1995, 13 well waters were sampled three times (May, July and November) and analysed for major and some minor elements (B, Br and NH4) and for dissolved gases. The close relationship of these waters with the deep magmatic source is highlighted by the composition of the dissolved gases. Furthermore, the areal distribution of dissolved species is controlled mainly by the gas fluxes from depth and by the presence of a deeper thermal aquifer. The distribution of major anomalies in the parameters measured in the groundwaters, in fact, overlap…
INCIDENZA SULL’ANALISI DI RISCHIO DELLE MODALITÁ DI MISURA DEI SOIL GAS: IL CASO DI UN S.I.N. SICILIANO
2020
Il monitoraggio delle matrici aeriformi sta assumendo importanza crescente nell’ambito dei procedimenti di bonifica di siti contaminati, con riferimento sia all’esecuzione delle analisi di rischio, sia alla conseguente progettazione degli interventi di risanamento. L’utilizzo di misure dirette di campo si rivela di notevole interesse per la verifica di quelle indirette, ottenute con gli algoritmi implementati nei modelli matematici utilizzati per l’analisi di rischio. Obiettivo del lavoro presentato nella nota è stato quello di valutare l’influenza di misure dirette di soil gas e di flussi emissivi sull’analisi di rischio sanitaria. Come caso studio, si è considerato un S.I.N. nel territori…