Gas Phase Processes Relevant to the Mediterranean Some New and Important Topics

2007 ◽  
pp. 235-251
Author(s):  
I. Barnes ◽  
I. Bejan
Keyword(s):  
Gas Phase ◽  
The Mediterranean

scholarly journals Atmospheric occurrence, transport and deposition of polychlorinated biphenyls and hexachlorobenzene in the Mediterranean and Black Seas

2014 ◽  
Vol 14 (7) ◽  
pp. 9747-9781 ◽  
Author(s):  
N. Berrojalbiz ◽  
J. Castro-Jiménez ◽  
G. Mariani ◽  
J. Wollgast ◽  
G. Hanke ◽  
...  
Keyword(s):  
Polychlorinated Biphenyls ◽  
Mediterranean Sea ◽  
Gas Phase ◽  
Oh Radicals ◽  
Anthropogenic Pressures ◽  
Air Mass ◽  
The Mediterranean ◽  
Water Equilibrium ◽  
Mediterranean And Black Seas ◽  
Atmospheric Concentrations

Abstract. The Mediterranean and Black Seas are unique marine environments subject to important anthropogenic pressures due to direct and indirect loads of atmospheric inputs of organochlorine compounds (OCl) from primary and secondary sources. Here we report the results obtained during two east-west sampling cruises in June 2006 and May 2007 from Barcelona to Istanbul and Alexandria, respectively, where gas phase and aerosol samples were collected. Both matrices were analyzed for 41 polychlorinated biphenyls (PCBs), including dioxin-like congeners, and hexachlorobencene (HCB). The values reported in this study for gas phase HCB and ∑41PCB (LOD to 418.3 pg m−3 and from 81.99 to 931.6 pg m−3 respectively) are in the same range of those reported in former studies, possibly suggesting a limited decline in their atmospheric concentrations during the last decade for the Mediterranean region due to land base OCl sources. There is a clear influence of the direction of the air-mass on the atmospheric concentrations of PCBs, with higher concentrations when the air mass was from southern Europe, and the lowest concentrations for air masses coming from the SW Mediterranean and Atlantic Ocean. PCBs and HCB are close to air–water equilibrium for most sampling periods, thus resulting in low atmospheric deposition fluxes at open sea. This is consistent with the oligotrophic character of the Mediterranean Sea with a small influence of the biological pump capturing atmospheric PCBs. Therefore, degradation of gas-phase PCBs by OH radicals is estimated to be the main loss process of atmospheric PCBs during their transport over the Mediterranean Sea. Conversely, atmospheric residence times of HCB are predicted to be very long due to a lack of atmospheric degradation and low depositional fluxes due to concentrations at air–water equilibrium.

scholarly journals Influence of vessel characteristics and atmospheric processes on the gas and particle phase of ship emission plumes: In-situ measurements in the Mediterranean Sea and around the Arabian Peninsula

2019 ◽  
Author(s):  
Siddika Celik ◽  
Frank Drewnick ◽  
Friederike Fachinger ◽  
James Brooks ◽  
Eoghan Darbyshire ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Gas Phase ◽  
Arabian Peninsula ◽  
Combustion Process ◽  
Emission Factors ◽  
Identification System ◽  
Particle Phase ◽  
Atmospheric Processes ◽  
The Mediterranean ◽  
Ship Emission

Abstract. 252 emission plumes of ships operating in the Mediterranean Sea and around the Arabian Peninsula were investigated using a comprehensive dataset of gas and submicron particle phase properties measured during the two-month shipborne AQABA field campaign in summer 2017. The post-measurement identification of the corresponding ship emission events in the measured data included the determination of the plume sources (up to 38 km away) as well as of the plume ages (up to 115 min) and was based on commercially available historical records of the Automatic Identification System. The dispersion lifetime of chemically inert CO2 in the ship emission plumes was determined as (70 ± 15) min, resulting in levels indistinguishable from the marine background after (260 ± 60) min. Emission factors (EFs) as quantities that are independent of plume dilution were calculated and used for the investigation of influences on ship emission plumes caused by ship characteristics and the combustion process as well as by atmospheric processes during the early stage of exhaust release and during plume aging. Combustion efficiency and therefore emission factors of black carbon and NOx were identified to depend mostly on the vessel speed and gross tonnage. Moreover, larger ships, associated with higher engine power were found to use fuel with higher sulfur content and have higher gas phase SO2, particulate sulfate, particulate organics and particulate matter EFs. Despite the independence of EFs on dilution, significant influence of the ambient wind speed on the particle number and mass EFs was observed that can be traced back to enhanced particle coagulation in case of slower dilution and suppressed vapor condensation on particles in case of faster dilution of the emission plume. Atmospheric reactions and processes in ship emission plumes were investigated that include NOx and O3 chemistry, gas-to-particle conversion of NOx and SO2 and the neutralization of acids in the particle phase through the uptake of ambient gas phase ammonia, the latter two of which cause the inorganic particulate content to increase and the organic fraction to decrease with increasing plume age. The results enable identification of the most important influences on (or processes in) ship emission plumes and to describe those quantitatively by parameterizations, which could be used for further refinement of atmospheric models.

scholarly journals Influence of vessel characteristics and atmospheric processes on the gas and particle phase of ship emission plumes: in situ measurements in the Mediterranean Sea and around the Arabian Peninsula

2020 ◽  
Vol 20 (8) ◽  
pp. 4713-4734 ◽  
Author(s):  
Siddika Celik ◽  
Frank Drewnick ◽  
Friederike Fachinger ◽  
James Brooks ◽  
Eoghan Darbyshire ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Gas Phase ◽  
Arabian Peninsula ◽  
Combustion Process ◽  
Emission Factors ◽  
Identification System ◽  
Particle Phase ◽  
Atmospheric Processes ◽  
The Mediterranean ◽  
Ship Emission

Abstract. A total of 252 emission plumes of ships operating in the Mediterranean Sea and around the Arabian Peninsula were investigated using a comprehensive dataset of gas- and submicron-particle-phase properties measured during the 2-month shipborne AQABA (Air Quality and Climate Change in the Arabian Basin) field campaign in summer 2017. The post-measurement identification of the corresponding ship emission events in the measured data included the determination of the plume sources (up to 38 km away) as well as the plume ages (up to 115 min) and was based on commercially available historical records of the Automatic Identification System. The dispersion lifetime of chemically inert CO2 in the ship emission plumes was determined as 70±15 min, resulting in levels indistinguishable from the marine background after 260±60 min. Emission factors (EFs) as quantities that are independent of plume dilution were calculated and used for the investigation of influences on ship emission plumes caused by ship characteristics and the combustion process as well as by atmospheric processes during the early stage of exhaust release and during plume ageing. Combustion efficiency and therefore emission factors of black carbon and NOx were identified to depend mostly on the vessel speed and gross tonnage. Moreover, larger ships, associated with higher engine power, were found to use fuel with higher sulfur content and have higher gas-phase SO2, particulate sulfate, particulate organics, and particulate matter EFs. Despite the independence of EFs of dilution, a significant influence of the ambient wind speed on the particle number and mass EFs was observed that can be traced back to enhanced particle coagulation in the case of slower dilution and suppressed vapour condensation on particles in the case of faster dilution of the emission plume. Atmospheric reactions and processes in ship emission plumes were investigated that include NOx and O3 chemistry, gas-to-particle conversion of NOx and SO2, and the neutralisation of acids in the particle phase through the uptake of ambient gas-phase ammonia, the latter two of which cause the inorganic particulate content to increase and the organic fraction to decrease with increasing plume age. The results allow for us to describe the influences on (or processes in) ship emission plumes quantitatively by parameterisations, which could be used for further refinement of atmospheric models, and to identify which of these processes are the most important ones.

scholarly journals Atmospheric occurrence, transport and deposition of polychlorinated biphenyls and hexachlorobenzene in the Mediterranean and Black seas

2014 ◽  
Vol 14 (17) ◽  
pp. 8947-8959 ◽  
Author(s):  
N. Berrojalbiz ◽  
J. Castro-Jiménez ◽  
G. Mariani ◽  
J. Wollgast ◽  
G. Hanke ◽  
...  
Keyword(s):  
Polychlorinated Biphenyls ◽  
Mediterranean Sea ◽  
Gas Phase ◽  
Limit Of Detection ◽  
Oh Radicals ◽  
Air Mass ◽  
The Mediterranean ◽  
Water Equilibrium ◽  
Mediterranean And Black Seas ◽  
Atmospheric Concentrations

Abstract. The Mediterranean and Black seas are unique marine environments subject to important anthropogenic pressures due to direct and indirect loads of atmospheric inputs of organochlorine compounds (OCls) from primary and secondary sources. Here we report the results obtained during two east–west sampling cruises in June 2006 and May 2007 from Barcelona to Istanbul and Alexandria, respectively, where gas-phase and aerosol-phase samples were collected. Both matrices were analyzed for 41 polychlorinated biphenyls (PCBs), including dioxin-like congeners, and hexachlorobenzene (HCB). The values reported in this study for gas-phase HCB and ∑41PCB limit of detection (LOD) to 418.3 pg m−3 and from 81.99 to 931.6 pg m−3 respectively) are in the same range of those reported in former studies, possibly suggesting a limited decline in their atmospheric concentrations during the last decade for the Mediterranean region due to land-based OCl sources. There is a clear influence of the direction of the air mass on the atmospheric concentrations of PCBs, with higher concentrations when the air mass was from southern Europe, and the lowest concentrations for air masses coming from the SW Mediterranean and Atlantic Ocean. PCBs and HCB are close to air–water equilibrium for most sampling periods, thus resulting in low atmospheric deposition fluxes at open sea. This is consistent with the oligotrophic character of the Mediterranean Sea with a small influence of the biological pump capturing atmospheric PCBs. Therefore, degradation of gas-phase PCBs by OH radicals is estimated to be the main loss process of atmospheric PCBs during their transport over the Mediterranean Sea. Conversely, atmospheric residence times of HCB are predicted to be very long due to a lack of atmospheric degradation and low depositional fluxes due to concentrations at air–water equilibrium.

Residual Gas Reactions in the Electron Microscope: I. Qualitative Observations on the Water Gas Reaction

1968 ◽  
Vol 26 ◽  
pp. 292-293
Author(s):  
Richard E. Hartman ◽  
Roberta S. Hartman ◽  
Peter L. Ramos
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Gas Phase ◽  
Absolute Temperature ◽  
Residual Gas ◽  
Gas Reactions ◽  
Image Position ◽  
The Right ◽  
Water Gas ◽  
Thinning Rate

The action of water and the electron beam on organic specimens in the electron microscope results in the removal of oxidizable material (primarily hydrogen and carbon) by reactions similar to the water gas reaction .which has the form:The energy required to force the reaction to the right is supplied by the interaction of the electron beam with the specimen.The mass of water striking the specimen is given by:where u = gH2O/cm2 sec, PH2O = partial pressure of water in Torr, & T = absolute temperature of the gas phase. If it is assumed that mass is removed from the specimen by a reaction approximated by (1) and that the specimen is uniformly thinned by the reaction, then the thinning rate in A/ min iswhere x = thickness of the specimen in A, t = time in minutes, & E = efficiency (the fraction of the water striking the specimen which reacts with it).

Integration of Core-Edge Spectroscopy Methods for the Study of Polymers

1996 ◽  
Vol 54 ◽  
pp. 154-155
Author(s):  
E. G. Rightor
Keyword(s):  
Excited State ◽  
Polymer Blends ◽  
Gas Phase ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Electronic States ◽  
Core Electron ◽  
Bulk Solids ◽  
Development Application

Core edge spectroscopy methods are versatile tools for investigating a wide variety of materials. They can be used to probe the electronic states of materials in bulk solids, on surfaces, or in the gas phase. This family of methods involves promoting an inner shell (core) electron to an excited state and recording either the primary excitation or secondary decay of the excited state. The techniques are complimentary and have different strengths and limitations for studying challenging aspects of materials. The need to identify components in polymers or polymer blends at high spatial resolution has driven development, application, and integration of results from several of these methods.

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