Search results for "Dissolved gas"

showing 7 items of 7 documents

Hydrochemical mercury distribution and air-sea exchange over the submarine hydrothermal vents off-shore Panarea Island (Aeolian arc, Tyrrhenian Sea)

2017

Abstract There is a growing concern about the mercury (Hg) vented from submarine hydrothermal fluids to the marine surrounding and exchange of dissolved gaseous mercury (DGM) between the sea surface and the atmosphere. A geochemical survey of thermal waters collected from submarine vents at Panarea Island (Aeolian Islands, southern Italy) was carried out in 2015 (15–17th June and 17–18th November), in order to investigate the concentration of Hg species in hydrothermal fluids and the vertical distribution in the overlying water column close to the submarine exhalative area. Specific sampling methods were employed by Scuba divers at five submarine vents located along the main regional tecton…

010504 meteorology & atmospheric sciencesMineralogychemistry.chemical_element010501 environmental sciencesOceanographyAir-sea exchange01 natural sciencesHydrothermal circulationWater columnEnvironmental ChemistryHydrothermal fluidMercury evasion0105 earth and related environmental sciencesWater Science and TechnologySubmarineGeneral ChemistryDissolved gaseous mercuryDilutionMercury (element)Hydrothermal fluidschemistryEnvironmental chemistryAeolian processesSeawaterDissolved gaseous mercury; Mercury evasion; Air-sea exchange; Hydrothermal fluids; Panarea IslandPanarea IslandGeologyHydrothermal ventMarine Chemistry
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Thermomineral waters of Greece: geochemical characterization

2020

75 °C). In terms of pH most results vary from 5.5 to 823 °C) ii) warm (23 40 °C) iii) thermal (40 75 °C) and iv) hyperthermal (&gtfew springs show either very low pH (&lt10) proposing serpentinization processes. Regarding TDS concentrations collected waters can be subdivided into low salinity (up to 1.5 g/L) brackish (up to 20 g/L) and saline (up to 43 g/L). The medium high salinities can be justified by mixing with sea water and/or strong waterrock interaction processes. Isotope composition of O and H ranges from 12.7 to +2.7 ‰ SMOW and from 91 to +12 ‰ SMOW respectively and is generally comprised between the Global Meteoric Water Line and the East Mediterranean Meteoric Water Line. Only few water samples show a positive shift for δ18O possibly related to high temperature waterrock interaction processes. Carbon dioxide (18 997000 μmol/mol) or N2 (1100 989000 μmol/mol) or CH4 (&ltMany geothermal areas of Greece are located in regions affected by Miocene or Quaternary volcanism and in continental basins characterised by elevated heat flow. Moreover the majority of them is found along the coast as well as in islands of the Aegean Sea and thus thermal water is often brackish to saline due to marine intrusion into costal aquifer. In the present study almost 300 thermal and cold mineral water samples were collected along the Hellenic territory with their physicochemical parameters (temperature pH electrical conductivity and Eh) and the amount of bicarbonates (titration with 0.1N HCl) being determined in situ. Additionally gases found either in free or dissolved phase were sampled. Both water and gas samples were analysed at the INGVPa laboratories for major ions (Ion Chromatography) silica (Inductively Coupled Plasma Optical Emission Spectrometry) chemical composition of free and dissolved gases (Gas Chromatography) water isotopes (O and H) and carbon and helium isotopes of free and dissolved gases (Mass Spectrometry). The temperature of the investigated waters ranges from 6.5 to 98°C pH from 1.96 to 11.98 whilst Total Dissolved Solids (TDS) from 0.06 to 43 g/L. Based on the temperature parameter waters can be divided into four groups: i) cold (&lt0.5 913000 μmol/mol) are the prevailing gas species found in the studied sites. The δ13CCO2 values ranged from 20.1 to +8.5 ‰ whilst the isotope ratio of He from 0.21 to 6.71 R/RA.4) suggesting interaction with H2Srich gases or very high pH values (&gtSettore GEO/08 - Geochimica E Vulcanologia
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Geochemical characterisation of gases along the dead sea rift: Evidences of mantle-co2 degassing

2016

International audience; The Dead Sea Transform (DST) fault system, where a lateral displacement between the African and Arabian plates occurs, is characterised by anomalous heat flux in the Israeli area close to the border with Syria and Jordan. The concentration of He and CO2, and isotopic composition of He and total dissolved inorganic carbon were studied in cold and thermal waters collected along the DST, in order to investigate the source of volatiles and their relationship with the tectonic framework of the DST. The waters with higher temperature (up to 57.2 °C) are characterised by higher amounts of CO2 and helium (up to 55.72 and 1.91 * 10-2 cc l-1, respectively). Helium isotopic dat…

Rift010504 meteorology & atmospheric sciencesGeochemistry[SDU.STU]Sciences of the Universe [physics]/Earth SciencesMineralogychemistry.chemical_elementCrust010502 geochemistry & geophysics01 natural sciencesMantle (geology)TectonicsGeophysicsHeat fluxchemistry13. Climate actionGeochemistry and PetrologyIsotopes of carbonDissolved organic carbonHeliumGeologyDead Sea Fault Fluid geochemistry Dissolved gases Helium isotopes Carbon isotopes0105 earth and related environmental sciencesJournal of Volcanology and Geothermal Research
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USE OF SUPERCRITICAL CO2 AS DISSOLVED GAS FOR THE ATOMIZATION OF ETHANOL

2011

Supercritical dissolved gas atomization (SDGA) is an atomization process in which carbon dioxide at temperatures and pressures above its critical point is used as atomizing gas. In this work SDGA has been experimentally studied when ethanol is used as the liquid to be atomized. The spray characteristics in terms of droplets size and distribution have been investigated using a droplet size analyzer based on a laser diffraction method. Very narrow droplet size distributions were produced down to 2.5 μm. The main parameter that influences the droplets size is the gas to liquid mass ratio. From the point of view of the atomization mechanism, mean droplet diameter is mainly influenced by the two…

Settore ING-IND/25 - Impianti Chimicisupercritical fluids atomization dissolved gas
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Use of supercritical CO2 and N2 as dissolved gases for the atomization of ethanol and water

2012

Supercritical dissolved gas atomization (SDGA) is an atomization process in which a gas at temperatures and pressures above the critical point is used as the atomizing medium. The concept of SDGA has been applied mainly using CO 2 as atomizing gas in various processes developed for the production of fine particles of pharmaceuticals, polymers, and chemical products and for the atomization of fuels. In this work, SDGA, using ethanol and water as the liquids to be atomized, has been experimentally studied. The spray characteristics, in terms of droplet size and distribution, have been investigated using a laser diffraction analyzer. Ethanol has been chosen due to the large miscibility with CO…

Spray characteristicsGeneral Chemical EngineeringAnalytical chemistryMiscibilityLaser diffractionIndustrial and Manufacturing EngineeringPhysics::Fluid DynamicsGas to liquidschemistry.chemical_compoundAtomizing gas Dissolved gas Droplet sizes Fine particles Gas to liquids Laser diffraction Supercritical fluids Supercritical CO2Fine particlesCritical point (thermodynamics)Gas to liquidsPhysics::Atomic and Molecular ClustersChemical Engineering (all)Physics::Atomic PhysicsDissolved gasCondensed Matter::Quantum Gaseschemistry.chemical_classificationAtomizing gasSupercritical fluidsChemistry (all)Droplet sizesGeneral ChemistryPolymerSupercritical CO2Supercritical fluidCondensed Matter::Soft Condensed MatterSolventchemistryCarbon dioxide
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Multiple origins of methane in fluids circulating in the Othrys ophiolite, central Greece

2018

The complex geology of Greece includes two important parallel running ophiolitic belts. The Othrys Massif in central Greece belongs to westernmost of them. In and around this wide ophiolite outcrop, some cold hyperalkaline and some hypothermal (T < 40°C) alkaline springs are present. Thirty water samples were collected at 17 different sites and both bubbling and dissolved gases were analysed for their chemical (He, Ne, H2, O2, N2, CH4, C2H6, CO2 and H2S) and isotope (He, δ13C-CO2, δ 13C-CH4, δ 2H-CH4) composition. All samples except one have H2S contents below detection limit (10 μmol/mol), whilst H2 (from <2 to 2500 μmol/mol), CO2 (up to 26,000 but generally below 1000 μmol/mol) and …

continental serpentinization hyperalkaline springs bubbling and dissolved gasesSettore GEO/08 - Geochimica E Vulcanologia
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A PTFE membrane for the in situ extraction of dissolved gases in natural waters: Theory and applications

2005

A new method for extracting dissolved gases in natural waters has been developed and tested, both in the laboratory and in the field. The sampling device consists of a polytetrafluroethylene (PTFE) tube (waterproof and gas permeable) sealed at one end and connected to a glass sample holder at the other end. The device is pre-evacuated and subsequently dipped in water, where the dissolved gases permeate through the PTFE tube until the pressure inside the system reaches equilibrium. A theoretical model describing the time variation in partial gas pressure inside a sampling device has been elaborated, combining the mass balance and "Solution-Diffusion Model" (which describes the gas permeation…

helium isotopeVulcano Islandinstruments and techniquesstable isotope geochemistrydissolved gasePTFE membrane
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