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Articoli di riviste sul tema "Particules individuelles atmosphériques"
Paris, Jean-Daniel, Andreas Stohl, Philippe Ciais, Michel Ramonet e Philippe Nedelec. "Relations source-récepteur transcontinentales identifiées avec un modèle Lagrangien de dispersion et une analyse en clusters". Pollution atmosphérique, NS 2 (1 settembre 2010): 143–48. http://dx.doi.org/10.54563/pollution-atmospherique.7131.
Testo completoDONNARS, C., P. CELLIER e J. L. PEYRAUD. "Nouvelles de la recherche : expertise sur les flux d’azote liés aux élevages". INRAE Productions Animales 25, n. 4 (2 ottobre 2012): 389–92. http://dx.doi.org/10.20870/productions-animales.2012.25.4.3226.
Testo completoFrank, Kenneth T., Jae S. Choi e Brian Petrie. "MARINE ECOSYSTEM ASSESSMENT: PAST, PRESENT AND FUTURE ATTEMPTS WITH EMPHASIS ON THE EASTERN SCOTIAN SHELF". Proceedings of the Nova Scotian Institute of Science (NSIS) 43, n. 2 (1 novembre 2006). http://dx.doi.org/10.15273/pnsis.v43i2.3642.
Testo completoTesi sul tema "Particules individuelles atmosphériques"
El, Haber Manuella. "Rôle des surfactants sur la formation des nuages : impact de la composition des aérosols et tension de surface de particules individuelles d'aérosols atmosphériques". Electronic Thesis or Diss., Lyon 1, 2024. http://www.theses.fr/2024LYO10243.
Testo completoIn Earth's atmosphere, aerosols play a crucial role in the diffusion and absorption of solar radiation, and as condensation nuclei in cloud formation. Water vapor gradually condenses on aerosol particles to form cloud droplets. This phenomenon is governed by the Köhler equation, where surface tension is a key parameter. For a long time, this parameter was not taken into account in atmospheric models: the surface tension value of aerosols was considered equal to that of water (~72.5 mN/m). However, significant concentrations of surfactants in atmospheric aerosols have been identified in recent years. Based on those results, there has been an increasing interest for determining the surface tension of atmospheric aerosol particles. In this work, the effects of the presence of typical aerosol components e.g., organic acids (oxalic acid and glutaric acid) and inorganic salts (NaCl and (NH4)2SO4) on the surface tension of amphiphilic surfactant solutions (TritonX100, Brij35, SDS, CTAC) were studied. Strong non-ideal behaviors were observed in most of the studied mixtures with synergies detected in some cases. The main atmospheric components increased the efficiency of the amphiphilic surfactants. In parallel, a technique for determining the surface tension of individual micron and submicron atmospheric particles was developed. The application of the micro Wilhelmy method in an atomic force microscope (AFM) using a cylindrical tip, made it possible to quantify the surface tension of droplets condensed on atmospheric particles under controlled relative humidity. This method was validated by surface tension measurements on reference liquids and subsequently applied to various atmospheric samples. The surface tension values determined in individual atmospheric particles are lower than the surface tension of water. Furthermore, these studies showed that the condensation of water on these aerosol particles is correlated with the surface tension, for a relative humidity of 82 ± 2%. Within this work, the surface tension of individual atmospheric particles was directly measured for the first time. Moreover, the effect of surface tension on cloud formation has been elucidated
Seng, Samantha. "Phototransformation de composés d’intérêt atmosphérique : études spectroscopiques en phase gaz, en matrice cryogénique et à l’échelle des particules individuelles". Electronic Thesis or Diss., Lille 1, 2017. http://www.theses.fr/2017LIL10127.
Testo completoMarine aerosols represent more than half of the global emission of particles into the atmosphere. Furthermore, sulfur organic compounds are generated by biological activities in the oceans and are emitted into the troposphere in the gaseous phase or are transported with sea-salt particles. These particles are subject to physicochemical changes due to atmospheric gases, sunlight and humidity exposure. The study of these transformation processes in the laboratory is essential for a better understanding of the mechanisms which are involved in these processes, and of the aerosols impact on the physical and chemical properties of the atmosphere.In this work, the photochemical evolutions of inorganic and sulfur organic compounds, similar to compounds of marine origin, have been studied by spectroscopy in the gas phase, in cryogenic matrix and at the single particle scale. The acoustic levitation system coupled to micro-Raman spectrometry is a relevant tool for studying the photochemical mechanisms at the particle scale. The impact of the phototransformation of NaNO3 particles on their hygroscopic properties has been demonstrated. The experiments carried out in cryogenic matrix are especially interesting for the study of unimolecular processes involved in the photodegradation of the sulfur organic compounds and are complementary to studies in gas phase. The compounds produced by photolysis in gas phase and condensed phase are of atmospheric interest and have a potential impact on the atmospheric sulfur balance. The presence of oxygen and water modified the mechanisms and the nature of the photoproducts
Seng, Samantha. "Phototransformation de composés d’intérêt atmosphérique : études spectroscopiques en phase gaz, en matrice cryogénique et à l’échelle des particules individuelles". Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10127/document.
Testo completoMarine aerosols represent more than half of the global emission of particles into the atmosphere. Furthermore, sulfur organic compounds are generated by biological activities in the oceans and are emitted into the troposphere in the gaseous phase or are transported with sea-salt particles. These particles are subject to physicochemical changes due to atmospheric gases, sunlight and humidity exposure. The study of these transformation processes in the laboratory is essential for a better understanding of the mechanisms which are involved in these processes, and of the aerosols impact on the physical and chemical properties of the atmosphere.In this work, the photochemical evolutions of inorganic and sulfur organic compounds, similar to compounds of marine origin, have been studied by spectroscopy in the gas phase, in cryogenic matrix and at the single particle scale. The acoustic levitation system coupled to micro-Raman spectrometry is a relevant tool for studying the photochemical mechanisms at the particle scale. The impact of the phototransformation of NaNO3 particles on their hygroscopic properties has been demonstrated. The experiments carried out in cryogenic matrix are especially interesting for the study of unimolecular processes involved in the photodegradation of the sulfur organic compounds and are complementary to studies in gas phase. The compounds produced by photolysis in gas phase and condensed phase are of atmospheric interest and have a potential impact on the atmospheric sulfur balance. The presence of oxygen and water modified the mechanisms and the nature of the photoproducts
Sader, Mikel. "Photoréactivité et comportement de phases des particules d'intérêt atmosphérique : étude à l'échelle de la particule individuelle en lévitation". Electronic Thesis or Diss., Université de Lille (2022-....), 2023. https://pepite-depot.univ-lille.fr/ToutIDP/EDSMRE/2023/2023ULILR086.pdf.
Testo completoAtmospheric particles play a significant role in climate change. They modify the microphysical properties of clouds, and consequently their optical properties, their proportion, and their lifetime. The oceans are the main source of natural aerosols in the atmosphere. The composition of these aerosols is complex, and freshly emitted particles reflect the composition of the seawater from which they originate. In addition, marine biological activity enriches these aerosols to some extent with organic matter. The composition of these particles evolves in the polluted marine atmosphere and during aging as they travel through the atmosphere, by interactions with sunlight and exposure to atmospheric gases, other particles, and humidity, modifying their physicochemical characteristics. In depth-study of particles in the laboratory is of crucial importance for understanding the physicochemical processes of aerosols in the atmosphere.In this thesis, we studied the phase behavior and photodegradation of aerosols formed from internal mixtures of organic and inorganic compounds analogous to the species found in fresh and polluted marine aerosols from anthropogenic emissions. The studies were conducted on individual particles suspended in air and deposited on hydrophobic substrates. The Raman micro-spectrometry technique coupled to an acoustic levitation chamber was fundamental for understanding in-situ the state of mixing of the particles during their exposure to light and humidity, through the acquisition of spatially resolved spectra. The direct photolysis of malonic acid particles in levitation, in the absence of an oxidant, has been demonstrated, as well as the effect of the presence of NaCl salt on the photodegradation products. The impact of the photoproducts on the hygroscopic properties of the particles has also been highlighted. Studies carried out on complex droplets containing an oligomer, ammonium sulfate, and glycolic acid revealed the coexistence of three liquid phases in the droplet, as well as the premature crystallization of the inorganic salt at high relative humidity. The effect of the UV-Visible light on the hygroscopic properties and the phase separation of levitated particles has been demonstrated
Delmas, Stéphane. "Caractérisation organique et minérale des particules individuelles (aérosols) de l'environnement sidérurgique : étude des synergies entre la matière organique et la nature des espèces minérales en présence". Metz, 1991. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1991/Delmas.Stephane.SMZ920.pdf.
Testo completoThe aim of our work is organic and inorganic characterization of particular pollutants, mainly polycyclic aromatic hydrocarbons adsorbed on complex particles, released in the environment during the various stages of steel manufacturing. In the first part of this work, we describe the experimental methodology used to conduct this study. The basic methods used are gas chromatography with or not mass spectrometry and LAMMA 500 laser microprobe connected to a tunable dye laser. Using this last instrument, the analysis is carried out in two stages : a first laser shot with a very low energy desorbs the PAHs from its support. Then, a second high energy laser impact pulverizes the particle, giving organic or inorganic chemical informations on the nature of adsorption substrate. The results obtained reveal both the organic compounds desorbed from the particles as well as their constituant organic and (or) inorganic chemical components. These are essentially carbon matrices in samples collected in coke ovens and iron oxides in samples collected from blast furnaces. In the second part of this work, we tried to simulate the reactions of atmospheric transformations of solid PAHs adsorbed on various substrates using NO2 as the atmospheric polluant. The objective of this part of the ewperiment was to enable a greater understanding of the mechanisms involved in nitro-PAHs formation during its stay in the atmosphere or during collecting step. The results suggest than FTMS 2000 laser microprobe analysis, used in the desorption mode could detect high molecular weight compounds which are only partially recoverable using conventional analytical methods. In the last section, a theorical approach using semi-empirical calculations was conducted in order to confirm the experimental results regarding the reactions of some kind of PAHs with NO2. A good correlation between reactivity and electronic density was obtained for the two molecules studied : benzo(a)pyrene and dibenzo(a,h)pyrene
Choël, Marie. "Analyse quantitative des particules atmosphériques par microscopie électronique à balayage couplée à la spectrométrie d'émission X". Phd thesis, Université du Littoral Côte d'Opale, 2005. http://tel.archives-ouvertes.fr/tel-00011532.
Testo completoRimetz, Juliette. "Les aérosols de pollution en zone urbaine et industrielle sous influence marine : physico-chimie des particules". Phd thesis, Université des Sciences et Technologie de Lille - Lille I, 2007. http://tel.archives-ouvertes.fr/tel-00282543.
Testo completoRimetz, Juliette. "Les aérosols de pollution en zone urbaine et industrielle sous influence marine : physico-chimie des particules". Phd thesis, Lille 1, 2007. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/2007/50376-2007-247.pdf.
Testo completo