Дисертації з теми "Aérosols organiques secondaires – Toxicologie"
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Jacob, Florence. "Génération contrôlée et détermination de l'impact toxicologique des aérosols organiques secondaires." Electronic Thesis or Diss., Université de Lille (2022-....), 2023. http://www.theses.fr/2023ULILS078.
Chronic exposure to atmospheric particles with a diameter less than 2.5 μm (PM2.5) at concentrations exceeding the levels recommended by the World Health Organization is responsible for the onset and/or exacerbation of respiratory, cardiovascular, neurological, and even cancer-related diseases. Regulatory threshold values have been defined regarding the ambient mass concentration of PM2.5, but these values do not take into account the impact of variations in the chemical composition of particles on induced biological effects. Special attention has been given in the literature to certain recognized harmful compounds such as metals and polycyclic aromatic hydrocarbons, some of which have been regulated. Nevertheless, other compounds are still poorly studied to date, even though they could also play an important role in particulate toxicity. This includes secondary organic aerosols (SOA), which constitute a major chemical fraction of PM2.5 and can represent up to 90% of their organic matter mass. They are formed through the reaction/oxidation/condensation of volatile organic compounds (VOCs) in the atmosphere. A rise in ambient SOA concentration is expected in the future due to the simultaneous increase in VOC precursor emissions and the oxidizing capacity of the atmosphere related to climate change. In this context, the present project first consisted in generating model SOA resulting from the oxidation of two VOCs that are widely present in the atmosphere, one of biogenic origin, limonene, and the other of anthropogenic origin, m-xylene. Limonene ozonolysis and m-xylene photooxidation were respectively carried out in a flow reactor and a simulation chamber. Two types of oxidations were tested for biogenic SOA synthesis: one with low ozone concentration and the other with high ozone concentration. The particulate phases were then characterized in terms of size (few hundred nm), mass, and chemical composition (hydroxyl, carbonyl, carboxylic acid functions, oligomers for limonene; nitrophenols, dimers for xylene). In a second step, the intrinsic oxidative potential (OP) of the generated biogenic and anthropogenic SOA was evaluated, as well as their toxicological impact in terms of oxidative stress and inflammatory effects on a model of immortalized human bronchial epithelial cells (BEAS-2B). The results obtained showed that among the biogenic SOA, those produced with low ozone concentration exhibit a more pronounced OP and antioxidant response. Furthermore, our results also indicate that, compared to these biogenic SOA, SOA resulting from m-xylene photooxidation have a higher OP and display greater cytotoxicity and activation of antioxidant defenses. In addition, oxidative damage to proteins and DNA was also detected in cells exposed to these SOA. Overall, the results from this project contribute to improving our knowledge on the chemical composition of SOA particulate phase and provide new insights into the mechanisms involved in their pulmonary toxicity
Guillaume, Bruno. "Les aérosols : émissions, formation d'aérosols organiques secondaires, transport longue distance, zoom sur les aérosols carbonés en Europe." Toulouse 3, 2006. http://www.theses.fr/2006TOU30260.
Kammer, Julien. "LANDEX : étude des aérosols organiques secondaires (AOS) générés par la forêt des Landes." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0402/document.
Forest ecosystems affect air quality and climate, especially through the emissions and the reactions of biogenic volatile organic compounds (BVOCs) with the atmospheric oxidants, known to generate Secondary Organic Aerosols (SOAs). This work aims to improve our knowledge on the processes involved in biogenic SOA formation and fate. Two field campaigns have been conducted in the Landes forest. In a first step, the measurement site was characterized by a statistical study of local meteorological conditions. During these campaigns, complementary physical and chemical measurements have been carried out, implying measurements of fluxes and concentrations of particles, BVOCs and oxidants. The results evidenced nocturnal new particle formation, which is an original result as this process was usually only reported during daytime. The strong contribution of BVOCs (dominated by α- and β-pinene) ozonolysis to nocturnal new particle formation has been demonstated. Particle flux measurements suggested that particles are transfered from the canopy to the higher atmospheric surface layer. The comparison between ozone fluxes and a physical ozone deposition model also highlighted an ozone production source. This ozone production might be related to BVOC photooxidation
Leglise, Joris. "Etude de la formation d'aérosols organiques secondaires par spectométrie de masse lors de l'ozonolyse de composés organiques volatils insatures." Thesis, Orléans, 2019. http://www.theses.fr/2019ORLE3013.
The understanding of secondary organic aerosols (SOA) is still incomplete, especially from the ozonolysis of unsaturated volatile organic compounds (VOC). The measurement of low volatility compounds involved in SOA formation is a challenge that the scientific community attempts to address. One of the objectives of this thesis work was the installation and use of a system for sampling and measuring the chemical composition of the aerosol by chemical ionization mass spectrometry (FIGAERO-CI-ToF-MS). This instrument has been used in the ozonolysis of unsaturated VOCs in the atmospheric simulation chamber HELIOS and the conditions for the formation of carboxylic acids and organosulfur compounds has been evaluated. The specific formation pathways of organosulfates (OS) have in addition been studied by injecting acidified seed particles. This study confirmed the low efficiency of the esterification of hydroxyl groups. Conversely, OS formation by epoxide ring opening is more efficient and increases with more acidic pH. In addition, the increase in relative humidity has a positive impact on the generation of carboxylic acids in the particulate phase.A second objective was the characterization of a system coupled to a proton transfer mass spectrometer (CHARON-PTR-ToF-MS) for collecting aerosols and measuring its chemical composition. The measurement of the fragmentation of 26 pure compounds in particulate phase allowed the development of a corrective procedure taking into account fragmentation process. This procedure was applied to the measurement of SOA generated by the ozonolysis of biogenic VOCs in an aerosol flow reactor. The volatility of the aerosol has been estimated using a thermodenuder installed downstream of the reactor. Taking into account fragmentation has greatly improved the agreement between the measured and the calculated volatility by several parametric equations
Guillaume, Bruno. "Les aérosols:émissions, formation d'aérosols organiques secondaires, transport longue distance- Zoom sur les aérosols carbonés en Europe -." Phd thesis, Université Paul Sabatier - Toulouse III, 2006. http://tel.archives-ouvertes.fr/tel-00145318.
- une meilleure caractérisation des inventaires d'émissions de BC et OCp, en développant un nouvel inventaire des sources principales que sont les combustions de fuels fossiles et de biofuels (secteur industriel, secteur domestique, trafic). Cet inventaire, de résolution 25kmx25km, fournit les émissions de BC et OCp pour 1995, 2000, 2005, 2010 et comporte deux zooms régionaux : sur la France à la résolution 10kmx10km et sur la région de la campagne Escompte à la résolution 1kmx1km,
- le développement d'un nouvel outil de modélisation globale de BC et OC (primaire et secondaire) par couplage du module d'aérosol ORISAM (module sectionnel) (LA/INERIS/ADEME) avec le modèle global de chimie-transport TM4 (collaboration LA/KNMI), qui permet à la fois la prise en compte d'une distribution des aérosols suivant 8 classes de taille (0.04µm-10 µm) et la prise en compte d'une composition chimique détaillée des aérosols (BC et OCp constituant le noyau de la particule sur lequel condensent plus de 6 réactifs chimiques organiques/inorganiques),
- des simulations avec ce nouveau modèle global baptisé ORISAM-TM4, des confrontations de résultats avec les mesures de BC et OC et l'étude du transport longue distance des aérosols,
- des tests de sensibilité sur la formation des aérosols organiques secondaires (SOA) portant sur différentes familles de composés organiques volatils (COV) précurseurs de SOA et portant également sur l'hygroscopicité des SOA (caractère hydrophile/hydrophobe),
- enfin, j'ai couplé ce nouvel outil ORISAM-TM4 à un module radiatif pour déterminer les propriétés optiques des aérosols (épaisseur optique, albédo de simple diffusion) en mélange interne à l'échelle globale.
Martin, Emmanuel. "Etude et modélisation de la formation et de la croissance des aérosols organiques secondaires d'origine biogène." Université Louis Pasteur (Strasbourg) (1971-2008), 2001. http://www.theses.fr/2001STR13195.
Martinez, Alvaro. "Contribution des composés organiques volatils (COVs) provenant des émissions des véhicules aux aérosols organiques secondaires (AOS) et à la pollution urbaine." Thesis, Lyon, 2019. http://www.theses.fr/2019LYSE1041.
The transport sector is fundamental to the economic development of a country and to ensure communication and a good quality of life. However, road transport contributes significantly to global warming and leads to serious degradation of the air quality. Among all pollutants, fine and ultrafine particles, emitted by vehicles but also formed in the atmosphere are considered as potentially toxic. Many studies show that chronic exposure to fine particles promotes the development of respiratory and cardiovascular diseases. The main gaseous precursors, the atmospheric chemical pathways as well as the chemical composition and the physical transformations that secondary organic aerosol (SOA) undergo in the atmosphere, remain poorly understood. The main aim of this work was on one side to improve the knowledge about primary pollutants emitted from Euro 5 and Euro 6 diesel and gasoline passenger cars and on the other side to investigate the photochemical transformations of the VOCs/IVOCs emitted from these cars. Passenger car emissions have been evaluated on a chassis dynamometer test bench at the IFSTTAR laboratory. Particle number measurements were carried out directly at the tailpipe. For GDI vehicles PN0.23 (< 23 nm) represented on average 20 -30 % of total particle number emitted, while for diesel cars, this fraction was considerably lower (≈10-15%). During high speed regimes (Artemis motorway) of diesel passenger cars Diesel Particulate Filter (DPF) passive regeneration was observed. These periods were characterized by a high particle number concentration; their composition was mainly soot, bisulfate and some organic material. PM emitted from gasoline DI passenger cars was mainly composed by BC and some organic droplets containing traces of other elements. During cold start GDI cars do emit important concentrations of BC and organic material. Emission of hydrocarbons has also been investigated. Gasoline DI emitted important concentration of THCs during cold start. Among the aliphatic compounds, families until C15 have been identified, confirming emission of heavier HCs from diesel cars. The second aim of this work was the study of atmospheric degradation of selected VOCs (toluene, naphthalene, cyclohexane, nonane) emitted from Euro 5 and Euro 6 vehicles and to determine the SOA formation potential of these compounds under different environmental conditions. The chosen compounds have been photoxidized (alone and in mixture) in an Aerosol Flow Tube (AFT) reactor in order to simulate VOCs atmospheric aging. The results suggest: (1) aromatic and PAHs compounds, own highest potential to form SOA; (2) the temperature has an important impact on SOA formation and yield; (3) the presence of pre-existing seed particles has, in general, a positive effect on SOA formation and (4) NOx has been found to negatively affect SOA formation; (5) SOA potential formation of VOC mixtures is highly influenced by the fraction of aromatics. Some of the products identified in the particle phase have never been previously reported. Degradation of aromatic compounds under medium NOx regime produced nitro-aromatic compounds identified both in the gas and particle phase. This PhD contributes to enrich vehicle emissions database, still limited for Euro 5 and Euro 6 cars. Speciation of non-regulated compound will help to better understand atmospheric SOA budget and car emissions air quality impacts. By last, the photoxidation study of primary VOCs (alone, mixture and full emissions) will lead to a better comprehension of SOA formation from vehicles
Riva, Matthieu. "Caractérisation d'une nouvelle voie de formation des aérosols organiques secondaires (AOS) dans l'atmosphère : rôle des précurseurs polyaromatiques." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2013. http://tel.archives-ouvertes.fr/tel-00952636.
Riva, Matthieu. "Caractérisation d’une nouvelle voie de formation des aérosols organiques secondaires (AOS) dans l’atmosphère : rôle des précurseurs polyaromatiques." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14942/document.
This work deals with the secondary organic aerosol (SOA) formation from gas phase oxidation of volatile organic compounds in the presence of atmospheric oxidants (ozone, hydroxyl radical, chlorine and nitrate radical). Among them, polycyclic aromatic hydrocarbons (PAHs) have been proposed as an important potential source of anthropogenic SOA. The oxidation of 4 main gaseous PAHs (naphthalene, acenaphthylene, acenaphthene and phenanthrene) in the presence of main atmospheric oxidants has been performed in order to investigate the SOA formation. Characterization of both gas and particulate phases has been carried out using mass spectrometry and optical spectroscopy allowing the identification of products in both phases. Then, chemical mechanisms have been proposed in order to explain SOA formation. SOA yields have been also determined to evaluate the impact of the gas phase oxidation of PAHs in SOA formation. Experiments have been carried out using flow tube and atmospheric simulation chambers. SOA fate has been investigated to determine the different oxidation processes involved in SOA aging
Braure, Tristan. "Etude en réacteurs à écoulement de cinétiques et mécanismes d'oxydation de composés organiques volatils." Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10033/document.
This work aimed at improving our knowledge on the first steps of secondary organic aerosol (SOA) formation through the study of some biogenic volatile organic compounds (bVOC) oxidation reactions. Criegee intermediates which are formed in ozonolysis reactions are suspected to be involved in SOA formation and thus, their fate has first been studied through ozonolysis reactions of methylated alkenes in the gas phase. Rate coefficients and yields of the primary carbonyl and Criegee rearrangement products were determined for the ozonolysis reactions of 4-methyl-1-pentene, trans-2,2-dimethyl-3-hexene and trans-2,5-dimethyl-3-hexene at ambient temperature and pressure. Besides, limonene oxidation reactions by °OH radicals and ozone have been studied by determining their rate coefficients and by characterizing the particulate phase (nucleation thresholds; size distribution; aerosol yield) in the case of ozonolysis.The experimental setups consisted of laminar flow reactors which enable to study the first reaction steps (reaction times ranging from a few milliseconds to a few minutes) coupled with several analytical techniques for both the gas and particulate phases. In particular, the indirect detection of a Criegee intermediate was evidenced by the use of an organic scavenger ; rate coefficient and branching ratios for the limonene oxidation by °OH were studied over an extended temperatures range compared to literature data ; and the first steps of SOA formation during limonene ozonolysis were characterized
Camredon, Marie. "Développement d'un modèle déterministe pour la formation des aérosols organiques secondaires : application à la sensibilité du système AOS/COV/NOx." Paris 12, 2007. https://athena.u-pec.fr/primo-explore/search?query=any,exact,990004071120204611&vid=upec.
Progressive gas-phase oxidation of volatile organic compounds (VOC) leads to the formation of a myriad of intermediate species. These secondary organics are more functionalized than their parent compounds, and the numbe of functions typically increases as oxidation preceeds. Highly functionalized species have lower vapour pressures and/or higher polarities, allowing substantial gas/particle partioning, thus leading to secondary organic aerosol (SOA) formation. This organic particulate matter constitutes a large and variable fraction of fine particles (Dp <1 μm). Therefore SOA is suspected to modify significantly physical and chemical aerosol properties, such as mass distribution, acidity, reactivity, hygroscopic and optical properties. . . Despite the impacts of SOA on climate, our current understanding of SOA formation, composition and evolution remains incomplete. We develop in thisstudy an explicit SOA formation model enabling (i) to evaluate our understanding of mechanisms involved in SOA formation, (ii) to explore the sensitivity of SOA production to external parameters and (iii) to serve as a benchmark for the systematic development and testing of simplified chemical mechanisms for use in three-dimensional models. The explicit SOA formation model has been used to explore the evolution of the SOA/VOC/NOx system
Berger, Alexandre. "Modélisation multi-échelles de la composition chimique des aérosols : impacts des processus physico-chimiques sur la formation d'aérosols organiques secondaires dans les nuages." Toulouse 3, 2014. http://thesesups.ups-tlse.fr/3060/.
Atmospheric aerosols play a major role in environmental issues related to climate, air quality and human health. Organic aerosols (OA) are an important fraction of total particulate mass. However, formation mechanisms of OA are poorly understood. In particular, a current challenge remains the definition of semi-volatile organic compounds (SVOC) from atmospheric oxidation of volatile organic compounds (VOC) that will condense on or within existing aerosols to form secondary organic aerosols (SOA). Recent studies in laboratory have shown the contribution of oxygenated VOC (OVOC) in the formation of low volatile organic compounds in aqueous phase. However, these studies still incomplete and there is an urgent need for better understanding photochemistry in aqueous phase of polyfunctional species and to study the influence of the relevant parameters for the atmosphere (pH, initial concentrations, the presence of inorganic compounds) on SOA processes. Moreover, these pathways of SOA formation should be taken into account in atmospheric models. The objective of this thesis is to evaluate the potential SOA production during a cloud event observed at the puy-de-Dôme station with simulations performed using the Meso-NH model. The realism of these simulations for forming SOA depends on the integration, in the chemical gaseous phase scheme, of the relevant chemical species including VOC and their products. The ReLACS2 mechanism meets this requirement and takes into account both ozone precursors and formation of SOA. This latter mechanism is coupled with the ORILAM-SOA module that integrates gas/particle partitionning of inorganic and organic species, and nucleation, evaporation/condensation, activation and dynamic aerosol processes. Firstly, this coupling is tested on three real cases over Europe in contrasted standart meteorological conditions. An exercise of inter-comparison of Meso-NH and WRF/CHEM models and a comparison of these models with in-situ observations over Europe are performed. Secondly, a first work consists in including COVO, short and soluble (up to 4 carbons), and the associated aqueous phase reactivity, in the ReLACS2 mechanism, in order to consider SOA formation in aqueous phase. A new chemical mechanism, ReLACS3, is created. In parallel, a second work consists in including the part of cloud condensation nuclei (CCN) into the chemistry of the water droplets for a complete coupling between the gas, aqueous and particulate phases. To test these developments, an 2D idealized simulation of an orographic cloud, observed during an intensive campaign at the puy-de-Dôme station which occured in summer 2011, is performed. This study highlighted the potential impact of the aqueous phase reactivity and activation of CCN on SOA formation
La, Yuyi. "Formation des aérosols organiques secondaires : évaluation d'un modèle explicite par la comparaison à des observations de chambre de simulation atmosphérique." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1129.
Secondary organic aerosols (SOAs) represent a large fraction of fine particle matter, and contribute therefore to their impacts on human health, environment and climate. Understanding the sources, the evolution and the properties of SOAs is a challenge for the scientific community. These SOAs are produced by condensation onto preexisting aerosols of low volatility compounds formed during the progressive oxidation of gaseous organic matter. The objective of this thesis is to assess our knowledge of SOA formation processes. The methodology aims at (i) representing the processes in a deterministic and explicit model, (ii) comparing the modeling results with SOA measurements performed in controlled environments and (iii) examining the sensitivity of simulated results to poorly constrained parameters. The GECKO-A model (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere) developed at LISA generates explicit chemical schemes on the basis of fundamental principles and provides the related kinetic and thermodynamic constants. Its ability to represent SOA formation was evaluated by comparisons with experiments performed in environmental chambers. The comparisons between modeled and measured final SOA yields show that the GECKO-A tool accurately reproduces the influence of molecular structure on the SOA formation. However, quantitative analysis shows that these yields are systematically overestimated. This suggests that processes are missing or misrepresented in the model, in particular the loss of gaseous organic compounds on the chamber walls. The implementation of this process into the model leads to (i) a decrease of the simulated final yields up to a factor 2, (ii) a change on SOA composition with a high sensitivity for the first generation species (nitrates, hydroxynitrates and carbonylesters) and (iii) a decrease in the SOA production rate when the mass transfer rate to the wall is increased. The model fails however to reproduce the dynamic of SOA formation. The results show that the uncertainties on particle surface accommodation and wall losses allow to encompass the experimental data. However, no unique configuration of these two parameters can be selected for all of the experiments
Duncianu, Marius. "Réacteur à écoulement pour l’étude de la formation des aérosols organiques secondaires par ozonolyse de composés organiques volatils : développement analytique, validation cinétique et ozonolyse d’un composé biogénique." Thesis, Lille 1, 2012. http://www.theses.fr/2012LIL10039/document.
A steady flow reactor equipped with a mobile injection head was developed at the Chemistry and Environment Department, Ecole des Mines de Douai, to better understand the formation processes of secondary organic aerosols (SOA) following the gas phase oxidation of certain species particularly reactive and/or abundant in the atmosphere. In contrast to atmospheric simulation chambers the flow reactor allows to observe in stationary conditions the product formation in the early stages of the reaction at ambient pressure and temperature.The foremost part of this work was to characterize the reactor flow, and to develop and optimize the methods used for the gas phase analysis. In a second stage a kinetic study of the ozonolysis of methylated pentenes and α-pinene was performed to validate the system. The rate coefficients were determined in pseudo first order conditions with excess alkene and showed a good agreement with literature values. The expected oxidation pathways were identified and quantified for one alkene (in good agreement with the only study available), and a nonoxidized intermediate coming from the rearrangement of a Criegee biradical, has been found for short reaction times. Finally, the SOA formation from α-pinene ozonolysis was investigated with simultaneous characterization of the gas phase concentrations of reactants and products (by ozone analyzer and TD/GC/FID-MS), of the particle size distribution (by SMPS and HR-ToF-AMS), and of the average chemical composition of particles (HR-ToF-AMS)
Aregahegn, Kifle Zeleke. "Réactions photosensibilisées contribuant à la croissance et au vieillissement des aérosols atmosphériques organiques." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10266/document.
Aerosols are important constituents of the atmosphere and secondary organic aerosols (SOA) represent a main fraction of the organic aerosols in the total budget. This thesis mainly reports the investigation of three aspects of the growth and aging of SOA: the photosensitized SOA growth ; the mechanistic investigation of SOA aging and of the photochemistry of photosensitizers ; the analysis of the chemical composition of aged SOA. The photosensitized growth and aging processes of SOA were investigated using an aerosol flow tube coupled with various aerosol and gas sensing instruments. For further analysis of the aerosol composition and a better understanding of the formation and growth of SOA in these experiments the aerosols produced in the dark and in the light were sampled on filters at the exit of the flow tube
Brégonzio, Lola. "Formation d'aérosols organiques secondaires au cours de la photooxydation multiphasique de l'isoprène." Thesis, Paris Est, 2013. http://www.theses.fr/2013PEST1182/document.
Isoprene is the most abundant volatile organic compound in global scale. Despite its low secondary organic aerosol (SOA) yields, it has been recently shown that isoprene can significantly contribute to total particulate organic mass due to its large emissions. SOA are known to have various impacts on the environment, especially on climate. However, lacks in the comprehension of the SOA formation pathways, particularly via cloud droplets, are still important. The aim of the present work is to study SOA formation from isoprene (or methacrolein, one of isoprene major oxidation products) photooxidation, in dry condition, as well as in the presence of cloud. The chemistry occurring in the gaseous, particulate and aqueous phases, and the exchange between these phases were investigated through an original multiphase approach in the CESAM simulation chamber. Gaseous and particulate phases during isoprene photooxidation without hydrometeor were first characterized. While the SOA yields in the literature exhibit a general dispersion, the SOA yields obtained during the experiments are consistent with the lowest values found in the literature. This characterization in dry condition was completed by a simulation approach using a 0D photochemical box model. SOA yields obtained from explicit and detailed models show important disagreement with those measured: an incompatibility of the chemical codes with the isoprene chemistry cannot be dismissed. For the first time, protocols have been developed to study photochemistry in cloud phase in a simulation chamber. A specific methodology allowing the production of a cloud with an important lifetime was set up. The impact of cloud evapo-condensation cycles on the photooxidation of isoprene and its oxidation products was finally investigated. The impact of the cloud generation on the gaseous and particulate phases has been highlighted, suggesting a significant production of SOA from isoprene photooxidation by interactions with cloud droplets
Fotsing, Kwetche Césaire Rostand. "Modélisation à l’échelle moléculaire de la réactivité des aérosols atmosphériques." Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1R058/document.
This thesis contributes to the molecular level understanding of atmospheric aerosol chemistry. The objective is to set up an hybrid classical/quantum methodology to treat the heterogeneous chemical mechanisms occurring at the surface of model aerosols attacked by various reactive species, either radicals (Cl, OH or RO2 peroxyl) or saturated (oxygen, ozone). Firstly, the quantum approach used to treat the reactivity between chlorine and a carboxylic acid molecule (valeric acid) or fatty acid (palmitic acid) has been validated in the gas phase. These calculations made it possible, on the one hand, to highlight the spontaneity of the abstraction of the hydrogen atoms of the acid by the chlorine radical and, on the other hand, the increase of the reaction rate constant as the chain of the acid molecule gets longer. In the second part dedicated to the simulation of a model submicrometer aerosol, we have built an aggregate of palmitic acid using classical molecular dynamics and analysed its structural and energetic properties. Then, addition of water molecules leads to the formation of water islands at the surface of the aggregate. Finally, we studied the heterogeneous reactivity at the surface of the aerosol by dividing the system into two regions treated differently (QM/MM approach, Quantum Mechanics/Molecular Mechanics). We have identified a sample of hydrogen atoms at the surface of the aggregate that can be captured by chlorine and calculated for each of them the reaction rate constant within the QM/MM scheme. We have finally been able to determine for the first time a theoretical value of the reactive uptake coefficient, which can be in principle compared to experimental data
Roig, Rodelas Roger. "Chemical characterization, sources and origins of secondary inorganic aerosols measured at a suburban site in Northern France." Thesis, Lille 1, 2018. http://www.theses.fr/2018LIL1R017/document.
Tropospheric fine particles with aerodynamic diameters less than 2.5 µm (PM2.5) may impact health, climate and ecosystems. Secondary inorganic (SIA) and organic aerosols (OA) contribute largely to PM2.5. To understand their formation and origin, a 1-year campaign (August 2015 to July 2016) of inorganic precursor gases and PM2.5 water-soluble ions was performed at an hourly resolution at a suburban site in northern France using a MARGA 1S, complemented by mass concentrations of PM2.5, Black Carbon, nitrogen oxides and trace elements. The highest levels of ammonium nitrate (AN) and sulfate were observed at night in spring and during daytime in summer, respectively. A source apportionment study performed by positive matrix factorization (PMF) determined 8 source factors, 3 having a regional origin (sulfate-rich, nitrate-rich, marine) contributing to PM2.5 mass for 73-78%; and 5 a local one (road traffic, biomass combustion, metal industry background, local industry and dust) (22-27%). In addition, a HR-ToF-AMS (aerosol mass spectrometer) and a SMPS (particle sizer) were deployed during an intensive winter campaign, to gain further insight on OA composition and new particle formation, respectively. The application of PMF to the AMS OA mass spectra allowed identifying 5 source factors: hydrocarbon-like (15%), cooking-like (11%), oxidized biomass burning (25%), less- and more-oxidized oxygenated factors (16% and 33%, respectively). Combining the SMPS size distribution with the chemical speciation of the aerosols and precursor gases allowed the identification of nocturnal new particle formation (NPF) events associated to the formation of SIA, in particular AN
Liu, Yao. "Etudes des impacts de la réactivité en phase aqueuse atmosphérique sur la formation et le vieillissement des Aérosols Organiques Secondaires sous conditions simulées." Thesis, Aix-Marseille 1, 2011. http://www.theses.fr/2011AIX10030/document.
This work focused on the impacts of aqueous phase OH-oxidation of methacrolein, methyl vinyl ketone on the SOA formation, and impacts of aqueous phase OH-oxidation on aging of SOA that are formed by isoprene, -pinene and 1,3,5-trimethylbenzene in gas phase. The chemical characterization of aqueous phase was performed by different analytical techniques. The results show the formation of small primary and secondary reaction products that were explained by suitable chemical reaction mechanisms. The formation of oligomers with high molecular mass (compared with their precursors) has also been observed during the OH-oxidation. These oligomers might be low volatile compounds that induce the formation of SOA during water evaporation. Their capacity to form SOA was experimentally demonstrated by nebulizing the aqueous phase solution at different reaction times. The results show that at least a part of oligomers remains in the particle phase during water evaporation, and contributes to the SOA formation. All of these results highlight that aqueous phase reactivity could induce important effects on the formation and aging of atmospheric SOA, which can induce modification of physico-chemical properties of SOA
Ait-Helal, Warda. "Les composés organiques gazeux en périphérie de deux mégapoles, Paris et Los Angeles : sources, variabilité et impact sur l'aérosol organique secondaire." Thesis, Lille 1, 2013. http://www.theses.fr/2013LIL10173/document.
Secondary Organic Aerosol (SOA) impacts air quality and climate change. However, its ambient concentrations are still underestimated. A large discrepancy has been observed between estimations and observations of SOA in urban areas as well as in remote areas, since the sources and the nature of the SOA precursors, the Gaseous Organic Compounds (GOCs), and the SOA formation mechanisms remain unclear. The studies presented here aim (1) to characterize the GOCs, including important SOA precursors, in urban area by studying their determinants and their sources, and (2) to study the GOCs impact on the SOA formation in urban area. To answer these objectives, we studied GOCs measured at suburban sites of Paris and Los Angeles megacities, as part of the MEGAPOLI (summer 2009 and winter 2010) and CalNex (spring 2010) programs, respectively. From the study of the organic fractions of the particulate- and the gas-phases with air quality indicators and meteorological data, (1) we identified the GOCs determinants, (2) we identified their sources and quantified their relative contribution to the GOCs emissions according to the season, by implementing the source receptor model PMF, and (3) we estimated the impact of the GOCs on the SOA formation. In summer and in winter, the GOCs measured in Paris are strongly associated with the “remote” and “OVOCs” source profiles. The highest contributions to the emissions of GOCs measured in Los Angeles are associated to the anthropogenic source profiles. As for the SOA formation, these studies highlighted for the first time the importance of the Intermediate Volatility Organic Compounds (I-VOCs) in the SOA formation from their measurements in Paris
Valorso, Richard. "Développement et évaluation d’un modèle explicite de formation d’aérosols organiques secondaires : sensibilité aux paramètres physico-chimiques." Thesis, Paris Est, 2011. http://www.theses.fr/2011PEST1126/document.
Fine aerosols have an important impact on health, visibility and climate. Secondary Organic Aerosols (SOA) represent an important fraction of fine aerosol composition. SOA are formed by nucleation or condensation onto pre-existing particles of gaseous species formed during the oxidation of emitted volatile organic compounds (VOC). VOC oxidation implies a huge number of secondary intermediates which are potentially involved in SOA formation. In order to study SOA formation, it is necessary to develop chemical schemes describing explicitly the formation and condensation of the gaseous secondary intermediates. The LISA has thus developed in collaboration with NCAR (National Center of Atmospheric Research) a generator of explicit chemical schemes : GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere). This work aims at testing (i) the reliability of GECKO-A to simulate observed SOA concentrations in Atmospheric Simulation Chamber (ASC) and (ii) exploring the SOA sensitivity to physico-chemical parameters such as saturation vapour pressures, chamber walls effects or kinetics rate constants. In order to assess GECKO-A's chemical schemes, the model has been confronted to chamber experiments performed to study SOA. Saturation vapour pressure (Pvap) is the key parameter controlling the gas/particles partitioning of organic compounds The three Pvap estimation methods considered as the more reliable in the literature have been implemented in GECKO-A. Pvap estimated by the three methods differs highly, up to several orders of magnitude. Despite of these discrepancies, simulated SOA concentration and speciation show a low sensitivity to the method used to estimate the Pvap. Moreover, none of the methods were able to make the model fit the observations. SOA concentration is systematically overestimated of a factor 2. Semi volatile organic compounds deposition on a chamber walls has been investigated. The implementation of this process in the model leads to a significant decrease of the simulated SOA concentrations, up to factor of 2. Simulated SOA yields are in good agreement with measured SOA yields. The hypothesis of a misrepresentation of some gaseous processes has then been investigated through sensitivity tests. SOA formation sensitivity to COV+ OH reactions rate constants has been explored. Results exhibited a high sensitivity to the rate constants estimations (regarding the rate constants values estimation, as well as the determination of the OH attack sites). The estimated alkoxy radicals decomposition rate constants have also been tested. This test showed however no significant impact on the simulated SOA yields
Couvidat, Florian. "Modélisation des particules organiques dans l'atmosphère." Phd thesis, Université Paris-Est, 2012. http://pastel.archives-ouvertes.fr/pastel-00778086.
Boulon, Julien. "Approche multi-échelle de la formation des particules secondaires." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2011. http://tel.archives-ouvertes.fr/tel-00697022.
Simon, Leïla. "Détermination des sources de composés organiques (gazeux et particulaires) en Ile-de-France." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASJ011.
To refine the knowledge on air quality and atmospheric chemistry in the Paris region, it is essential to document the nature and variability of atmospheric pollutants on the long term. The suburban SIRTA station (integrated to the European infrastructure ACTRIS) has been hosting instruments for the continuous measurement of physicochemical properties of suspended particles and of some inorganic reactive gases for a decade. Nonetheless, questions remain open on the origins of secondary organic aerosol and more specifically the link with its precursor gases, volatile organic compounds (VOC). Although their play an important role in atmospheric chemistry, VOC were hitherto not measured on the long term at SIRTA.In this context, this thesis aims at better characterizing organic pollution in the Paris region. This involves the measurement of VOC in real time to complete the panel of existing measurements, as well as the application and evaluation of methods for the source apportionment of organic pollutants adapted to long term studies.For this purpose, measurements using mass spectrometry (PTR-MS), still very little used within ACTRIS, were setup at SIRTA as part of this thesis. Automated data treatment was improved and adapted for the long term and a rigorous quality control was applied to 2020 and 2021. These first two years of measurements were then studied in terms of diel and seasonal variabilities. The role played by meteorological conditions and air masses was particularly illustrated by results obtained during the lockdowns in 2020. An influence of anthropogenic sources was observed for monoterpenes, compounds usually identified as biogenic in suburban sites.The Positive Matrix Factorization (PMF) source-receptor model is classically used for the source apportionment of atmospheric pollutants (aerosol or VOC), but some limits exist for its long-term application. To overcome these limitations, new options exist and were tested during this thesis. Particularly, VOC were used as organic markers for the analysis of organic aerosol sources in summer, by creating a unified combined dataset. This complex methodology was implemented here for the first time with this type of instruments. It was adapted to the SIRTA dataset, allowing a better deconvolution of oxygenated organic aerosol compared to a classical method, and consequently to link it to its respective sources/processes, especially by distinguishing daytime and nighttime processes
Ahmad, Waed. "Formation d'aérosols organiques secondaires dans l'oxydation du limonène et des méthoxyphénols : Etude de l'influence des conditions environnementales." Thesis, Littoral, 2017. http://www.theses.fr/2017DUNK0441/document.
Atmospheric chemistry models frequently diverge from measurements of secondary organic aerosol (SOA) concentrations by a factor ranging from 8 to 100 in different environments. The gap between measured and modeled SOA could be explained by many formation processes that are still not well understood nor well incorporated into the models as well as the influence of environmental parameters on these processes. In this context, this research work focuses primarily on the formation of SOA in the ozonolysis of limonene through experiments carried out in a flow reactor (SAGE) and in a simulation chamber (LPCA). The particulate phase was characterized in terms of aerosol yield, size distribution, mass and nucleation threshold. The influence of the presence of different compounds : butanol, toluene, acetone, acetic acid and methylamine on these parameters has been described and reported and thus, the role of Criegee intermediates and OH radicals in SOA formation process is investigated. The second part consist of studying the SOA generated during the OH oxidation of 2-methoxyphenol (guaiacol) and 2,6-dymethoxyphenol (syringol). The IR spectra of these two methoxyphenols, the SOA formed through their oxidation and the nitro compounds derived from guaiacol and syringol have been studied experimentally by IRTF-RTA spectroscopy and/or theoretically by anharmonic DFT calculations. Finally, the hygroscopic character of these aerosols has been reported for the first time in a hydration cell
Zhang, Yunjiang. "Estimation multi-annuelle des sources d’aérosols organiques et de leurs propriétés d’absorption de la lumière en région Parisienne." Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLV013.
Carbonaceous aerosols, including organic aerosols (OA) and black carbon (BC), are playing important roles on air quality and climate change. Therefore, quantifying contribution of their emission sources, as well as the sources of their gaseous precursors, is needed to implement efficient mitigation measures. Investigating trends in atmospheric composition is also essential to a better knowledge of present and future impacts of airborne particles on global warming. This work aimed at investigating on-line and in situ carbonaceous aerosol measurements performed for more than 6 years at the SIRTA facility (Site Instrumental de Recherche par Télédétection Atmosphérique). This observatory platform is part of the ACTRIS (Aerosols, Clouds, Trace gases Research InfraStructure). It is located 25 km southwest of Paris city center and is representative of background air quality in the Ile de France region. The main sources of submicron OA were discriminated through Positive Matrix Factorization applied to Aerosol Chemical Speciation Monitor (ACSM) data. Light absorption properties of BC and brown carbon (BrC) were obtained from multi-wavelength Aethalometer measurements. Converging results illustrated well-marked seasonal, weekly, and diel cycles of the various primary and secondary carbonaceous aerosol fractions. Primary OA (POA), mainly from wood burning and traffic emissions, were confirmed to dominate submicron OA concentrations during the coldest months (November to February), while Oxygenated OA (OOA) were shown as the major contributors during the rest of the year. Less Oxidized OOA (LO-OOA), possibly with predominant biogenic origins, were found to contribute up to about 60% of total submicron OA on average in summer. Trend analyses indicated slight decreasing features (in the range of 0.05-0.20 µg m-3 yr-1) for every OA fractions over the 6+-year investigated period, except for this LO-OOA factor which showed no significant trend. Regarding absorption properties, BrC - with overwhelming biomass burning origin - was found to have equivalent light absorption impact than BC at near-ultraviolet wavelengths during the winter season. In summer, a mean value of 1.6 was obtained for BC absorption enhancement (Eabs) due to secondary aerosol lensing effect, supporting possible higher BC-related radiative impact than currently expected. Last but not least, More Oxidized OOA (MO-OOA) were shown as the main agent for this Eabs and then appeared as one of the most critical aerosol fraction to be considered within near-future climate models
Zhang, Yunjiang. "Estimation multi-annuelle des sources d’aérosols organiques et de leurs propriétés d’absorption de la lumière en région Parisienne." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLV013.
Carbonaceous aerosols, including organic aerosols (OA) and black carbon (BC), are playing important roles on air quality and climate change. Therefore, quantifying contribution of their emission sources, as well as the sources of their gaseous precursors, is needed to implement efficient mitigation measures. Investigating trends in atmospheric composition is also essential to a better knowledge of present and future impacts of airborne particles on global warming. This work aimed at investigating on-line and in situ carbonaceous aerosol measurements performed for more than 6 years at the SIRTA facility (Site Instrumental de Recherche par Télédétection Atmosphérique). This observatory platform is part of the ACTRIS (Aerosols, Clouds, Trace gases Research InfraStructure). It is located 25 km southwest of Paris city center and is representative of background air quality in the Ile de France region. The main sources of submicron OA were discriminated through Positive Matrix Factorization applied to Aerosol Chemical Speciation Monitor (ACSM) data. Light absorption properties of BC and brown carbon (BrC) were obtained from multi-wavelength Aethalometer measurements. Converging results illustrated well-marked seasonal, weekly, and diel cycles of the various primary and secondary carbonaceous aerosol fractions. Primary OA (POA), mainly from wood burning and traffic emissions, were confirmed to dominate submicron OA concentrations during the coldest months (November to February), while Oxygenated OA (OOA) were shown as the major contributors during the rest of the year. Less Oxidized OOA (LO-OOA), possibly with predominant biogenic origins, were found to contribute up to about 60% of total submicron OA on average in summer. Trend analyses indicated slight decreasing features (in the range of 0.05-0.20 µg m-3 yr-1) for every OA fractions over the 6+-year investigated period, except for this LO-OOA factor which showed no significant trend. Regarding absorption properties, BrC - with overwhelming biomass burning origin - was found to have equivalent light absorption impact than BC at near-ultraviolet wavelengths during the winter season. In summer, a mean value of 1.6 was obtained for BC absorption enhancement (Eabs) due to secondary aerosol lensing effect, supporting possible higher BC-related radiative impact than currently expected. Last but not least, More Oxidized OOA (MO-OOA) were shown as the main agent for this Eabs and then appeared as one of the most critical aerosol fraction to be considered within near-future climate models
Debevec, Cécile. "Identification des déterminants de la concentration en polluants organiques gazeux dans le bassin méditerranéen Est." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10138/document.
Volatile organic compounds (VOCs) play a key role within the atmospheric system acting as precursors of ozone and secondary organic aerosols (OA). In the Mediterranean region, particulate and gaseous concentrations are usually higher than in most continental European regions especially during summertime. However, air pollution in this region remains difficult to characterize because of a lack of atmospheric measurements. This thesis provides a better understanding of the sources and fate of VOCs in the Eastern Mediterranean region. During the intensive field campaign held in March 2015 at a background site of Cyprus, real-time measurements of a large number of VOCs have been performed, allowing the evaluation of their concentration levels in ambient air, improving the understanding of their major sources in the area, and describing their variabilities and their potential origins. A factorial analysis (PMF) showed that the local biogenic sources and the regional background were found to be the largest contributors to the VOC concentrations observed at this site. Benefiting from real-time OA measurements, a parallel between organic aerosol and gas phase composition was conducted. Biogenic VOC interactions with anthropogenic compounds can influence formation and growth of newly particles, inducing a reinforcement of secondary OA fraction. Finally, on-line measurements of primary VOCs were performed from January 2015 to February 2016 to provide a better characterization of the seasonal variation in VOCs and their sources impacting the Eastern Mediterranean region
Ait-Helal, Warda. "Les composés organiques gazeux en périphérie de deux mégapoles, Paris et Los Angeles : sources, variabilité et impact sur l'aérosol organique secondaire." Electronic Thesis or Diss., Lille 1, 2013. http://www.theses.fr/2013LIL10173.
Secondary Organic Aerosol (SOA) impacts air quality and climate change. However, its ambient concentrations are still underestimated. A large discrepancy has been observed between estimations and observations of SOA in urban areas as well as in remote areas, since the sources and the nature of the SOA precursors, the Gaseous Organic Compounds (GOCs), and the SOA formation mechanisms remain unclear. The studies presented here aim (1) to characterize the GOCs, including important SOA precursors, in urban area by studying their determinants and their sources, and (2) to study the GOCs impact on the SOA formation in urban area. To answer these objectives, we studied GOCs measured at suburban sites of Paris and Los Angeles megacities, as part of the MEGAPOLI (summer 2009 and winter 2010) and CalNex (spring 2010) programs, respectively. From the study of the organic fractions of the particulate- and the gas-phases with air quality indicators and meteorological data, (1) we identified the GOCs determinants, (2) we identified their sources and quantified their relative contribution to the GOCs emissions according to the season, by implementing the source receptor model PMF, and (3) we estimated the impact of the GOCs on the SOA formation. In summer and in winter, the GOCs measured in Paris are strongly associated with the “remote” and “OVOCs” source profiles. The highest contributions to the emissions of GOCs measured in Los Angeles are associated to the anthropogenic source profiles. As for the SOA formation, these studies highlighted for the first time the importance of the Intermediate Volatility Organic Compounds (I-VOCs) in the SOA formation from their measurements in Paris
Cholakian, Arineh. "Evolution de la composition chimique de l’atmosphère au-dessus du bassin Méditerranéen : forçages, mécanismes et scénarios." Electronic Thesis or Diss., Sorbonne Paris Cité, 2018. https://wo.app.u-paris.fr/cgi-bin/WebObjects/TheseWeb.woa/wa/show?t=5441&f=39753.
Subject to numerous anthropogenic (gaseous and particulate atmospheric pollution burden) and natural (desert dust events ...) forcings, but also heavily populated on its shores, the Mediterranean is recognized as a region particularly sensitive to the evolution of atmospheric pollutants and climate change. Today, the assessment of the future composition of the atmosphere in the Mediterranean is a major environmental and health issue. In particular, the simulation of the secondary organic aerosol (SOA) in the western basin remains little discussed in the literature, particularly because of the complexity of the subject. The ChArMEx (Chemistry-Aerosol MEditerranean Experiment) intensive campaign, which aims to scientifically evaluate the current and future state of the Mediterranean atmospheric environment, has given us the opportunity to improve our understanding of the organic fraction as well as total aerosols over the Mediterranean, using a 3D modeling approach. As a first step, different simulation schemes of organic aerosols (OA) taking into account the evolution of the semi-volatile organic compounds in the atmosphere (functionalization versus fragmentation), as well as the formation of the non-volatile SOA, have been implemented in the CHIMERE model. The comparison of these schemes with the measurements make it possible to highlight the main sources of OA formation in the western basin of the Mediterranean and to define the configuration of the most appropriate scheme for the simulation of this aerosol. We found that the scheme that takes into account the non-volatile SOA fragmentation and formation processes fits best to the mass cocnentration, oxidation state, and origin of the OA measured in the ChArMEx project, especially in Cap Corse and Mallorca. Subsequently, we utilized the CHIMERE model in order to present a detailed look at the future conditions of the Mediterranean basin. Future scenarios proposing different intensities for climate change have been investigated. In particular, the isolated effects of different drivers (regional climate, anthropogenic emissions and long-distance transport) have been identified, and the share of each in the evolution of the composition of the atmosphere for the main components of particulate matter has been estimated. In order to quantify the effect of the change of the scheme used for the simulation of the OA on future scenarios, 15 years of historic simulations and 15 years of future simulations were performed with three different OA simulation schemes. The results show that the percentage change in biogenic SOA can be underestimated by a factor of 2 in a simple scheme for the simulation of the SOA, compared to a scheme taking into account the functionalization, fragmentation and formation of non-volatile SOA. In order to bring a more regional perspective on the Mediterranean coasts, 5 years of simulations have been carried out on the PACA region on the south-eastern coasts of France, in order to study the exposure of the population to atmospheric pollutants, as well as the combined impact of demographic evolution (population change) and future atmospheric scenarios on this exposure in two case studies at the 2030 and 2050 horizons. The results show that the individual exposure as well as the cumulative exposure of the population decreases for most atmospheric compounds. On the other hand, the risk associated with the exposure of the entire population to ozone, biogenic SOA and desert dust could increase over large parts of the region, particularly in urban areas with high levels of population growth
Renard, Pascal. "Photochimie et oligomérisation des composés organiques biogéniques en phase aqueuse atmosphérique." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4748.
Air pollution caused by secondary organic aerosol (SOA) is one of the major challenges of this century. We focus this thesis on SOA , through an innovative approach, i.e. multiphase photochemistry.The photochemical reactor allows to simulate in laboratory, the atmospheric aqueous phase oxidation of biogenic volatile organic compounds (BVOC) and in particular, methyl vinyl ketone (MVK), and thus, to study SOA.We study the reactivity of MVK in the presence of ●OH and its ability to oligomerize under various initial concentrations of oxygen, MVK and ●OH. A wide analytical strategy based on liquid chromatography-mass spectrometry is used to identify the reaction products, and establish a chemical mechanism. We focus on these oligomers systems, formation, yield and aging. Collected data are used as inputs to a multiphase box model to explore the sensitivity of oligomerization to the variations of physical and chemical atmospheric parameters. The photochemistry of pyruvic acid generates radical chemistry and initiates MVK oligomerization. We closely compare this reaction to MVK ●OH oxidation. Then, we measure the surface activity of both systems. The ability of oligomers to partition to the interface could affect the climate. Finally, we used ion mobility - mass spectrometry to observe ●OH co-oligomerization of a mixture of organic compounds most representative of the atmosphere.Atmospheric oligomerization implies (i) a minimal concentration of precursors that could be reached in wet aerosol via the co-oligomerization; (ii) a reactivity in competition with the addition of the dissolved oxygen, whose the atmospheric relevance remains to be explored
Roose, Antoine. "Experimental and theoretical study of the uptake of peroxy radicals by organic aerosol surfaces." Thesis, Lille 1, 2019. http://www.theses.fr/2019LIL1R069.
Many uncertainties are still associated to chemical reaction mechanisms implemented in atmospheric models, especially for ROx radicals (OH, HO2, RO2). Of particular interest, heterogeneous processes (uptake of radicals) occurring at the aerosol surface have yet to be better described in models. The objective of this work is to investigate the peroxy radical uptake onto organic aerosol surfaces. The uptake is investigated both experimentally (macroscale observation) and theoretically (molecular level description).In the first part of this thesis an aerosol flow tube coupled to a peroxy radical measurement system (chemical amplification) has been developed and characterized. This system allows the measurement of HO2 uptake onto organic aerosols and could be used to measure RO2 uptakes as well. In this work, the uptake coefficient of HO2 onto glutaric acid particles has been measured and compared to conflicting literature data.The second part of this work consisted in the computation of fundamental processes driving the HO2 uptake onto glutaric acid model particles, using molecular modelling tools (molecular dynamics (MM) and/or quantum mechanics (QM)). The accommodation coefficient has been determined and a preliminary investigation of heterogeneous reactions has been carried out using the hybrid QM/MM ONIOM method
Lovrić, Josip. "Molecular modeling of aerosols." Thesis, Lille 1, 2017. http://www.theses.fr/2017LIL10080/document.
In this thesis numerical methods are used to study the properties, described at the molecular level, of organic aerosols, especially marine aerosols, and their interaction with species in the atmosphere. The organisation of the organic matter in these aerosols plays a key role for their optical, chemical properties, and their ability to act as a cloud condensation nuclei.The first part reviews atmospheric context and the methods (classical molecular dynamics and hybrid quantum/classical approaches) used in this thesis. Then applications to three cases are detailed.Firstly, the organization, more particularly the orientation, of palmitic acid molecules adsorbed on a salt (NaCl) surface as a function of the fatty acid coverage and temperature has been studied using classical molecular dynamics (Gromacs package). The impact of the humidity on the structuration of this organic coating has been described in details, showing the existence of structured fatty acid island-like monolayers on NaCl surface.In a second study, the reactivity of NO2 with these heterogeneous marine aerosols has been investigated by a hybrid quantum/classical method (CP2K package), with taking into account the effect of the humidity.The last study is a classical molecular dynamics of n-butanol crystal, water accommodation at these surfaces and simulation of water jet collision with n-butanol surface. These simulations, complementary to experiments, were performed to better understand the fundamental role of the water-organic matter interaction on the properties of the aerosols and clouds
Fayad, Layal. "Caractérisation de la nouvelle chambre de simulation atmosphérique CHARME et étude de la réaction d’ozonolyse d’un COV biogénique, le γ-terpinène". Thesis, Littoral, 2019. https://documents.univ-littoral.fr/access/content/group/50b76a52-4e4b-4ade-a198-f84bc4e1bc3c/BULCO/Th%C3%A8ses/LPCA/These_Fayad_Layal.pdf.
The study of atmospheric processes is among the central topics of current environmental research. The most direct and significant way to investigate the transformation of pollutants and the formation of aerosols in the atmosphere, is to simulate these processes under controlled and simplified conditions. In this regard, a new simulation chamber, CHARME (CHamber for the Atmospheric Reactivity and the Metrology of the Environment) has been designed in the Laboratory of Physico-Chemistry of the Atmosphere (LPCA) in the University of Littoral Côte d’Opale (ULCO). CHAE is also dedicated to the development and validation of new spectroscopic approaches for the metrology of atmospheric species including gases, particles and radicals.The first aim of this research was to characterize all the technical, physical and chemical parameters of this new chamber and to optimize the methods for studying the atmospheric reactivity of volatile organic compounds (VOCs) and simulating the formation of secondary organic aerosols (SOA). The results of numerous experiments and tests show that CHARME is a convenient tool to reproduce chemical reactions occurring in the troposphere. The second research objective was to investigate the reaction of the biogenic VOC, γ-terpinene, with ozone. The rate coefficient at (294 ± 2) K and atmospheric pressure was determined and the gas-phase oxidation products were identified. The physical state and hygroscopicity of the secondary organic aerosols was also studied. To our knowledge, this work represents the first study on SOA formation from the ozonolysis of γ-terpinene
Osseiran, Noureddin. "Spectroscopic characterization of molecules of atmospheric interest : internal dynamics and microsolvation with hydrogen sulfide (H2S)." Electronic Thesis or Diss., Université de Lille (2018-2021), 2021. http://www.theses.fr/2021LILUR062.
Biogenic volatile organic compounds (BVOCs), and especially monoterpenes (C10H16), are molecules naturally occurring in the atmosphere, which have been linked to the formation of secondary organic aerosol (SOA). They can alter the physical and chemical properties in the atmosphere, have negative effects on human health and contribute to climate change. There exists a strong relationship between the structure of a molecular system and the inter- and intramolecular interactions present on the molecular scale.Hence, having in-depth information about the gas phase structure and internal dynamics of these molecules, or their molecular complexes, is important to better understand their reaction pathways and complexation patterns.The synergic combination of quantum chemical calculations and Fourier transform microwave (FTMW) spectroscopy has been shown to be a reliable approach to examine the conformational landscape, structure and internal dynamics of several types of molecules of atmospheric interest, their oxidation products and their complexes. In the framework of this thesis, we have applied this theoretical-experimental approach to characterize the complexes of two monoterpenoids: fenchol (C10H18O) and fenchone (C10H16O) with another atmospheric contaminant: the H2S molecule. The gas phase stable conformations were identified in the pure rotational spectrum with the supportof ab initio and DFT calculations. A comparative analysis of the observed complexes with their water analogues confirmed the presence of weaker hydrogen bonds. On top of that, we observed a large amplitude motion, that was qualitatively described. The stabilizing non-covalent interactions of the two complexes were also evaluated.In a similar manner, and within the same general context, we also characterized the conformational landscape and methyl internal rotation in the case of limona ketone (C9H14O), which is a biogenic volatile organic compounds (BVOC) originating from the oxidation limonene. The experimental barrier height of the methyl torsion showed some deviation from the calculated values, which pushed toward a more thorough examination, that revealed the presence of an intermolecular interaction.The second part of this thesis was dedicated to the construction and evaluation of a broadband chirped pulse FTMW spectrometer, operating in the range 6-18 GHz. A detailed technical description of the spectrometer is given herein. Moreover, the preliminary tests performed to evaluate the performance of the spectrometer are reported
Srivastava, Deepchandra. "Improving the discrimination of primary and secondary sources of organic aerosol : use of molecular markers and different approaches." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0055/document.
Organic aerosols (OAs), originating from a wide variety of sources and atmospheric processes, have strong impacts on air quality and climate change. The present PhD thesis aimed to get a better understanding of OA origins using specific organic molecular markers together with their input into source-receptor model such as positive matrix factorization (PMF). This experimental work was based on two field campaigns, conducted in Grenoble (urban site) over the 2013 year and in the Paris region (suburban site of SIRTA, 25 km southwest of Paris) during an intense PM pollution event in March 2015. Following an extended chemical characterization (from 139 to 216 species quantified), the use of key primary and secondary organic molecular markers within the standard filter-based PMF model allowed to deconvolve 9 and 11 PM10 sources (Grenoble and SIRTA, respectively). These included common ones (biomass burning, traffic, dust, sea salt, secondary inorganics and nitrate), as well as uncommon resolved sources such as primary biogenic OA (fungal spores and plant debris), biogenic secondary AO (SOA) (marine, isoprene oxidation) and anthropogenic SOA (polycyclic aromatic hydrocarbons (PAHs) and/or phenolic compounds oxidation). In addition, high time-resolution filter dataset (4h-timebase) available for the Paris region also illustrated a better understanding of the diurnal profiles and the involved chemical processes. These results could be compared to outputs from other measurement techniques (online ACSM (aerosol chemical speciation monitor), offline AMS (aerosol mass spectrometer) analyses), and/or to other data treatment methodologies (EC (elemental carbon) tracer method and SOA tracer method). A good agreement was obtained between all the methods in terms of separation between primary and secondary OA fractions. Nevertheless, and whatever the method used, still about half of the SOA mass was not fully described. Therefore, a novel OA source apportionment approach has finally been developed by combining online (ACSM) and offline (organic molecular markers) measurements and using a time synchronization script. This combined PMF analysis was performed on the unified matrix. It revealed 10 OA factors, including 4 different biomass burning-related chemical profiles. Compared to conventional approaches, this new methodology provided a more comprehensive description of the atmospheric processes related to the different OA sources
Hallemans, Elise. "Étude de la formation, du vieillissement et de la composition chimique de l'aérosol organique secondaire dans le bassin méditerranéen." Thesis, Paris Est, 2016. http://www.theses.fr/2016PESC1122/document.
Secondary Organic Aerosol or « SOA » is formed in the atmosphere by oxidative process of volatile organic compounds (VOC). Gaps in knowledge of SOA formation and evolution pathways and of molecular characterization still exist. These aspects are an important source of uncertainties and can explain the underestimation of SOA budget calculated by models. In order to give new insights on these issues, the Mediterranean basin appears like an ideal area to study SOA. Actually, this region is characterized by high photochemistry, above all during summer season, and by intense VOC biogenic and anthropogenic emissions implying the formation of SOA in the atmosphere. In this context, two field campaigns have been performed in the frame of Canopée and ChArMEx projects.Thanks to a sampling and analyzing method by TD-GC/MS, the characterization of organic fraction enables one to determine more than one hundred compounds from C2 to C18 in gaseous and particulate phases. In combination with traditional datasets (PTR-MS, AMS), new insights were brought in reactivity of gaseous oxygenated compounds with OH radical, in chemical composition of organic material in particulate phase and about the contribution of various precursors to the capacity to form SOA. The determination of experimental and theoretical partitioning coefficients gives new information on SOA representation in models
Bertrand, Amélie. "Vieillissement atmosphérique de l'aérosol de combustion de biomasse : du potentiel de formation d'aérosol organique secondaire à la modification de l'empreinte chimique à l'échelle moléculaire." Thesis, Aix-Marseille, 2017. http://www.theses.fr/2017AIXM0149/document.
Biomass burning is in winter a main source of air pollution by particulate matter, especially in France. While primary emissions have been characterized extensively before, few studies have addressed the aging of these emissions in the atmosphere and large uncertainties remain. Therefore, the objectives of this thesis was to study in a smog chamber the aging of the aerosol emitted by 3 different woodstoves used for residential heating (fabricated from between 2000 and 2010, and representative of the policy engaged by the French environmental agency to renew the appliances across the country), with a specific focus on the Secondary Organic Aerosol (SOA) production potential and the modification of the chemical fingerprint of the emissions at the molecular level during their transport in the atmosphere. The experiments showed the SOA production potential can be significant. The OA concentration can be increased by up to a factor of 7 (1.5 – 7.1) after being aged in the smog chamber with a time equivalent to 5 hours in the atmosphere. The study also further demonstrated the influence of the combustion efficiency on the emissions and implicitly the role of the operator. The study of the composition of the aerosol at the molecular level showed the formation of compounds, likely to serve as markers for aged biomass burning, mainly nitrocatechols. Finally, the work also illustrates the influence of the volatilization of levoglucosan, main marker of biomass burning, during the dilution process occurring in the atmosphere, and challenge the pertinence of the degradation rate constant determined previously in smog chamber
Ma, Prettiny. "Modélisation de la formation des aérosols organiques secondaires dans les régions polluées." Thèse, 2016. http://hdl.handle.net/1866/18657.
Atmospheric aerosols (i.e. particulate matter or PM) are a major source of uncertainty in climate models. Many studies have also shown that elevated concentrations of PM reduce life expectancies. Secondary organic aerosol (SOA) is formed in the atmosphere from gaseous precursors through chemical reactions and SOA represents a major component of PM mass globally. To better understand the chemical pathways responsible for SOA formation, a box model is designed to simulate dynamically the evolution of organic species in an air parcel as it undergoes photochemical oxidation producing SOA. The model incorporates recently published parameterizations for the formation of SOA from volatile organic compounds (VOCs), as well as from semi-volatile and intermediate-volatility organic compounds (SVOCs and IVOCs). The model is constrained by several measurements of precursors, including recently developed measurements that provide greatly improved constraints on precursor concentrations, and the predications are compared against measurements of SOA taken during the CalNex campaign. When accounting for the effect of chamber wall-losses on VOC yields, the amount and rate of SOA formation in the model is more consistent with observations. The results of this study also indicate that the primary SVOCs and IVOCs are responsible for a majority (70 – 86 %) of the model SOA mass, emphasizing their high contribution as SOA precursors. However, the SOA mass predicted is underestimated at shorter photochemical ages when compared to field measurements, but at longer ages, model/measurement agreement is observed. This bias may be due to low IVOC/CO emissions ratios or low estimated IVOC oxidation rate constants, which highlights the need for further field and laboratory studies of these compounds.