Gas Geochemistry and Fractionation Processes in Florina Basin, Greece

Florina Basin is located in northern Greece, close to Mount Voras where the volcanic activity of Late Messinian age began. In the area, many CO2-rich gas emissions are present as a bubbling free-phase in groundwater (both springs and wells) and soil gases. Volcanism along with the geological and geodynamic regime of the basin, created the ideal conditions for CO2 accumulation in vertically stacked reservoirs. One of these, industrially exploited by the company Air Liquide Greece, produces 30,000 t/a of CO2. Results show that CO2 concentrations in the gases of Florina can arrive up to 99.8% and are mostly above 90%. Moreover, C-isotope composition (-2.1 to + 0.3 h vs. VPDB) indicates a mixed mantle-limestone origin for CO2, while He isotope composition (R/RA from 0.21 to 1.20) shows a prevailing crustal origin with an up to 15% mantle contribution. Helium and methane, with concentrations spanning over three orders of magnitude, show a positive correlation and a consequent high variability of He/CO2 and CH4/CO2 ratios. This variability can be attributed to the interaction of the uprising gases with groundwater that chemically fractionates them due to their different solubility. Based on the CO2, CH4 and He concentrations, gas samples collected in the basin can be divided in 3 groups: a) deep reservoir gases, b) enriched in less soluble gases and c) depleted in less soluble gases. The first group consists of gas samples collected at the Air Liquide extraction wells, which tap a 300m deep reservoir. This group can be considered as the least affected by fractionation processes due to interaction with groundwater. The gases of the second group due to their interaction with shallower unsaturated aquifers, become progressively enriched in less soluble gases (He and CH4). Finally, the third group represents residual gas phases after extensive degassing of the groundwater during its hydrological pathway

Weight filtration on the cohomology of complex analytic spaces

We extend Deligne's weight filtration to the integer cohomology of complex analytic spaces (endowed with an equivalence class of compactifications). In general, the weight filtration that we obtain is not part of a mixed Hodge structure. Our purely geometric proof is based on cubical descent for resolution of singularities and Poincar\'e-Verdier duality. Using similar techniques, we introduce the singularity filtration on the cohomology of compactificable analytic spaces. This is a new and natural analytic invariant which does not depend on the equivalence class of compactifications and is related to the weight filtration.Comment: examples added + minor correction

Long Time Series Of Fumarolic Compositions At Volcanoes: The Key To Understand The Activity Of Quiescent Volcanoes

Long time series of fumarolic chemical and isotopic compositions at Campi Flegrei, Vulcano, Panarea, Nisyros and Mammoth volcanoes highlight the occurrence of mixing processes among magmatic and hydrothermal fluids. At Campi Flegrei temperatures of about 360°C of the hydrothermal system are inferred by chemical and isotopic geoindicators. These high temperatures are representative of a deep zone where magmatic gases mix with hydrothermal liquids forming the gas plume feeding the fumaroles. Similar mixing processes between magmatic fluids and a hydrothermal component of marine origin have been recognized at Vulcano high temperature fumaroles. In both the system a typical ‘andesitic’ water type composition and high CO2 contents characterizes the magmatic component. Our hypothesis is that pulsing injections of these CO2- rich magmatic fluids at the bottom of the hydrothermal systems trigger the bradyseismic crises, periodically affecting Campi Flegrei, and the periodical volcanic unrest periods of Vulcano. At Campi Flegrei a strong increase of the fraction of the magmatic component marked the bradyseismic crisis (seismicity and ground uplift) of 1982-84 and four minor episodes occurred in 1989, 1994 and 2000 and 2006. Increases of the magmatic component in the fumaroles of Vulcano were recorded in 1979-1981, 1985, 1988, 1996, 2004 and 2005 concurrently with anomalous seismic activity. Physicalnumerical simulations of the injection of hot, CO2 rich fluids at the base of a hydrothermal system, asses the physical feasibility the process. Ground deformations, gravitational anomalies and seismic crisis can be well explained by the complex fluid dynamic processes caused by magma degassing episodes. Sporadic data on the fumaroles of other volcanoes, for example Panarea, Nisyros (Greece), Mammoth (California), suggest that magma degassing episodes frequently occur in dormant volcanoes causing volcanic unrest processes not necessarily linked to magma movement but rather to pulsating degassing processes from deep pressurized, possibly stationary, magma bodies

Long term variations at Campi Flegrei (Italy) volcanic system highlighted by the monitoring of hydrothermal activity

Long time-series of chemical composition of fumaroles and of soil CO2 flux reveal that important variations in the activity of Solfatara fumarolic field, the most important hydrothermal site of Campi Flegrei, occurred in the 2000- 2008 period. A continuous increase of the CO2 concentration and a general decrease of the CH4 concentration are interpreted as the consequence of the increment of the relative amount of magmatic fluids, rich in CO2 and poor in CH4, hosted by the hydrothermal system. Contemporaneously the H2O-CO2-He-N2 gas system shows remarkable compositional variations in the samples collected after July 2000 with respect to the previous ones, indicating the progressive arrival at the surface of a magmatic component different from that involved in the 1983-84 bradyseism. The change starts in 2000 concurrently with the occurrence of relatively deep long periods seismic events which, in our interpretation, were the indicator of the opening of an easy pathway for the transfer of magmatic fluids towards the shallower, brittle domain hosting the hydrothermal system. Since 2000 this magmatic gas source is active and causes ground deformations, seismicity as well as the expansion of the area interested by diffuse soil degassing of deeply derived CO2

Carbon Dioxide degassing at Latera caldera (Italy): evidence of geothermal reservoir and evaluation of its potential energy

In order to test the potentiality of soil CO2 diffuse degassing measurements for the study of underground mass and heat transfer in geothermal systems detailed surveys were performed at Latera Caldera which is an excellent test site, due to the abundant available subsurface data. Over 2500 measurements of soil CO2 flux revealed that endogenous CO2 at Latera Caldera concentrates on a NE-SW band coinciding with a structural high of fractured Mesozoic limestones hosting a water-dominated high-enthalpy geothermal reservoir. The total hydrothermal CO2 degassing from the structural high has been evaluated at 350 t d-1 from an area of 3.1 km2. It has been estimated that such a CO2 release would imply a geothermal liquid flux of 263 kg s-1, with a heat release of 239 MW. The chemical and isotopic composition of the gas indicates a provenance from the geothermal reservoir and that CO2 is partly originated by thermal metamorphic decarbonation in the hottest deepest parts of the system and partly has a likely mantle origin. The ratios of CO2, H2, CH2 and CO to Ar, were used to estimate the T-P conditions of the reservoir. Results cluster at T ~ 200-300°C and PCO2 ~ 100-200 bars, close to the actual well measurements. Finally the approach proved to be an excellent tool to investigate the presence of an active geothermal reservoir at depth and that the H2-CO2-CH4-CO-Ar gas composition is a useful T-P geochemical indicator for such CO2 rich geothermal systems

A shallow layer model for heavy gas dispersion from natural sources: application and hazard assessment at Caldara di Manziana, Italy.

Several non-volcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under stable atmospheric conditions and/or in presence of topographic depressions, the concentration of CO2, which has a molecular mass greater than that of air, can reach high values that are lethal to humans or animals. Several episodes of this phenomenon were recorded in central Italy and elsewhere. In order to validate a model for the dispersion of a heavy gas and to assess the consequent hazard, we applied and tested the code TWODEE-2, an improved version of the established TWODEE model, which is based on a shallow layer approach that uses depth-averaged variables to describe the flow behavior of dense gas over complex topography. We present results for a vented CO2 release at Caldara di Manziana in central Italy. We find that the model gives reliable results when the input quantity can be properly defined. Moreover, we show that the model can be a useful tool for gas hazard assessment, by evaluating where and when lethal concentrations for humans and animal are reached.Several non-volcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under stable atmospheric conditions and/or in presence of topographic depressions, the concentration of CO2, which has a molecular mass greater than that of air, can reach high values that are lethal to humans or animals. Several episodes of this phenomenon were recorded in central Italy and elsewhere. In order to validate a model for the dispersion of a heavy gas and to assess the consequent hazard, we applied and tested the code TWODEE-2, an improved version of the established TWODEE model, which is based on a shallow layer approach that uses depth-averaged variables to describe the flow behavior of dense gas over complex topography. We present results for a vented CO2 release at Caldara di Manziana in central Italy. We find that the model gives reliable results when the input quantity can be properly defined. Moreover, we show that the model can be a useful tool for gas hazard assessment, by evaluating where and when lethal concentrations for humans and animal are reached.Several non-volcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under stable atmospheric conditions and/or in presence of topographic depressions, the concentration of CO2, which has a molecular mass greater than that of air, can reach high values that are lethal to humans or animals. Several episodes of this phenomenon were recorded in central Italy and elsewhere. In order to validate a model for the dispersion of a heavy gas and to assess the consequent hazard, we applied and tested the code TWODEE-2, an improved version of the established TWODEE model, which is based on a shallow layer approach that uses depth-averaged variables to describe the flow behavior of dense gas over complex topography. We present results for a vented CO2 release at Caldara di Manziana in central Italy. We find that the model gives reliable results when the input quantity can be properly defined. Moreover, we show that the model can be a useful tool for gas hazard assessment, by evaluating where and when lethal concentrations for humans and animal are reached.Several non-volcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under stable atmospheric conditions and/or in presence of topographic depressions, the concentration of CO2, which has a molecular mass greater than that of air, can reach high values that are lethal to humans or animals. Several episodes of this phenomenon were recorded in central Italy and elsewhere. In order to validate a model for the dispersion of a heavy gas and to assess the consequent hazard, we applied and tested the code TWODEE-2, an improved version of the established TWODEE model, which is based on a shallow layer approach that uses depth-averaged variables to describe the flow behavior of dense gas over complex topography. We present results for a vented CO2 release at Caldara di Manziana in central Italy. We find that the model gives reliable results when the input quantity can be properly defined. Moreover, we show that the model can be a useful tool for gas hazard assessment, by evaluating where and when lethal concentrations for humans and animal are reached.Several non-volcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under stable atmospheric conditions and/or in presence of topographic depressions, the concentration of CO2, which has a molecular mass greater than that of air, can reach high values that are lethal to humans or animals. Several episodes of this phenomenon were recorded in central Italy and elsewhere. In order to validate a model for the dispersion of a heavy gas and to assess the consequent hazard, we applied and tested the code TWODEE-2, an improved version of the established TWODEE model, which is based on a shallow layer approach that uses depth-averaged variables to describe the flow behavior of dense gas over complex topography. We present results for a vented CO2 release at Caldara di Manziana in central Italy. We find that the model gives reliable results when the input quantity can be properly defined. Moreover, we show that the model can be a useful tool for gas hazard assessment, by evaluating where and when lethal concentrations for humans and animal are reached

A shallow-layer model for heavy gas dispersion from natural sources: Application and hazard assessment at Caldara di Manziana, Italy

Several nonvolcanic sources in central Italy emit a large amount of carbon dioxide (CO2). Under stable atmospheric conditions and/or in the presence of topographic depressions, the concentration of CO2, which has a molecular mass greater than that of air, can reach high values that are lethal to humans or animals. Several episodes of this phenomenon were recorded in central Italy and elsewhere. In order to validate a model for the dispersion of a heavy gas and to assess the consequent hazard, we applied and tested the code TWODEE-2, an improved version of the established TWODEE model, which is based on a shallow-layer approach that uses depth-averaged variables to describe the flow behavior of dense gas over complex topography. We present results for a vented CO2 release at Caldara di Manziana in central Italy. We find that the model gives reliable results when the input quantity can be properly defined. Moreover, we show that the model can be a useful tool for gas hazard assessment by evaluating where and when lethal concentrations for humans and animals are reached

Acute kidney injury and acute kidney disease in high-dose cisplatin-treated head and neck cancer

Background: In locally advanced head and neck squamous cell carcinoma (LA-SCCHN) at least 200mg/m2 (standard dose 300 mg/m2) of cisplatin concomitant with radiotherapy represents the standard of care, both in postoperative and conservative settings. Nevertheless, high dose administration every 3 weeks is often replaced with low dose weekly cisplatin to avoid toxicities like kidney injury, though often failing to reach the therapeutic dose. Our aim was to investigate the incidence of renal impairment in the real-life setting, integrating high dose cisplatin with adequate supportive therapy, and to explore both Acute Kidney Injury (AKI) and Acute Kidney Disease (AKD), a recently described clinical renal syndrome that encompasses functional alterations of the kidney lasting fewer than 3 months. Methods: One hundred and nine consecutive patients affected by LA-SCCHN and treated with at least a cumulative dosage of 200 mg/m2 of cisplatin concomitant with radiotherapy were enrolled in this prospective observational study. Results: AKI was reported in 12.8% of patients, 50% of whom were stage 1 (KDIGO criteria), while 25.7% of the cohort developed AKD. Patients with baseline estimated Glomerular Filtration Rate (eGFR) < 90 ml/min showed a higher incidence of AKD (36.2% vs 17.7%). Hypertension, baseline eGFR, and therapy with Renin-angiotensin-aldosterone system inhibitors proved to be significant factors associated with both AKI and AKD. Conclusion: AKI and AKD are not rare complications of high-dose cisplatin, but an appropriate prevention strategy and accurate monitoring of patients during treatment could lead to a reduction of the burden of these conditions

Surface gas measurements and related studies for the characterization and monitoring of geological CO2 storage sites; experiences at Weyburn and in Salah.

Preliminary baseline soil gas data collected in the summer and autumn of 2001 above the Phase 1A injection area of the EnCana Enhanced Oil Recovery project at the Weyburn oilfield in south Saskatchewan was presented at GHGT-6 in Kyoto. Data can now be presented for all three years of the study with conclusions, the predominant one being that the major controls on soil gas levels are seasonal and meteorological with no indications of leakage from depth. In the autumns of 2002 and 2003 further in situ monitoring of CO2, CO2 flux, O2, CH4, radon (222Rn) and thoron (220Rn) was carried out. Soil gas samples were also collected for laboratory analysis of helium, permanent gases, sulphur species and light hydrocarbons. All sampling was repeated over the same 360 point sampling grid and more detailed profiles for both follow-up years. Marked changes in CO2 levels (especially flux) for each of the three-year datasets indicate changes in surface conditions, rather than CO2 from a deeper source. The radon and thoron data was found to be similar for the three years but appears to vary in response to drift composition, and seasonal effects, rather than migration from a deep source. In 2003 further work was agreed in addition to the main grid and profile data. A control area was sampled for the same suite of gases, 10km to the northwest of the oil field. It included similar topography, land use and drift composition to the main sampling grid. There were 35 sample locations on a 7 x 5 point grid with 100m spacing and two additional sites. Early conclusions indicate that the soil gas results in the control area are very similar to those from the main grid, vindicating control site selection and further supporting a lack of deeply sourced CO2 over the injection area. Along with the control site, five zones of possible CO2 leakage were also surveyed and sampled. Two cross a river lineament that may be associated with deep faulting, two were abandoned oil well sites and one site overlays a deep salt dissolution feature. (Unfortunately CO2 flux and gamma measurements were not carried out at these sites.) A northeast/southwest trending lineament, just north of the main grid, was sampled along two profiles perpendicular to the feature, with an increased density of sampling over the feature. The feature generally followed an incised river valley and anomalous CO2 was only detected on the valley floor, where it would be expected as there was lush vegetation in this zone. There were no coincident anomalies for other gases. Soils around two abandoned wells were also sampled. A 16-site grid was surveyed around each well. One well had been completely abandoned and the other was suspended due to failed casing. Such boreholes represent possible points of weakness that may be routes for CO2 migration. The well with failed casing had weakly anomalous CO2 locally to the south, again unmatched for other gases. The fully abandoned well had background CO2 values. Two perpendicular profiles of 10 sites at 25m spacing were sampled for soil gas over the mapped centre of the dissolution feature. Background values were obtained. In 2003 two vertical profiles were performed both indicating an increase in CO2 to a depth maximum of 1.80m; this increase is matched by a corresponding decrease only in O2, indicating biological respiration. Radon concentration indicated no anomalies. Portable gamma spectrometric data was collected in 2003 over the west-centre area of the grid, the profiles and over the control grid. The composition of soils from both areas was found to be very similar.PublishedBerkeley, California4.5. Degassamento naturaleope