Organic aerosols are ubiquitous to the lower atmosphere and there is growing concern about their impact on climate and human health. These aerosols typically have multicomponent compositions that change over time in part due to oxidation by reactive trace gases, such as ozone. A current challenge to the atmospheric research community is to develop better methods of analysis of these particles. Photoelectron resonance capture ionization aerosol mass spectrometry (PERCI-AMS) is an online mass spectrometric method that has been applied to the analysis of organic aerosols. One of its key advantages is that it employs low energy (~ 0 eV) photoelectrons in the ion forming process, which has been shown to minimize fragmentation in the organic analytes, thus simplifying mass spectral interpretation. This dissertation focuses on the application of PERCI-AMS to the analysis of organic particles. Initial emphasis is placed on the heterogeneous reaction of gas phase ozone with liquid oleic acid particles. Products identified included carboxylic acids, aldehydes, and peroxides including alpha-acyloxyalkyl hydroperoxides polymers. The evidence of peroxidic products suggested the stabilization of carbonyl oxide intermediates (i.e. Criegee intermediates) that are formed during ozonolysis. Subsequent PERCI-AMS experiments investigated the reactivity of the stabilized Criegee intermediates. This included investigating the reaction of Criegee intermediates with unsaturated fatty acids and methyl esters. A novel ketone-forming reaction is described in these systems, suggesting the Criegee intermediates can react at a carbon-carbon double bond. Further PERCI-AMS experiments investigated the oxidative processing of particulate amines including octadecylamine and hexadecylamine. Ozonolysis of these amines resulted in strong NO2 - and NO3 - ion signals that increased with the ozone exposure and suggested a mechanism of progressive oxidation. Additionally, a strong ion signal was detected for NO3 -(HNO3), which is the ion core of the most important ion cluster series in the troposphere, NO3 -(HNO3)n(H2O)m. PERCI-AMS was applied to the analysis of ozonized mixed particles of amines with oleic acid or dioctyl sebacate. In the ozonolysis of the amines with oleic acid, products included imines and amides. The routes to the amides were shown to most likely arise from the reactivity of stabilized Criegee intermediates and/or secondary ozonides with the amines. There was also direct evidence of the formation of a surface barrier in the octadecylamine and oleic acid reaction system, which resulted in the retention of oleic acid at high ozone exposures. These experiments have fostered a better understanding of the analytical capacity of PERCI-AMS in assaying the reactivity of organic aerosols as well as giving a more accurate description of the heterogeneous chemistry of these challenging reaction systems. Suggestions for adaptations to PERCI-AMS and future experiments on

Pharmaceutical aerosols provide a number of advantages for treating respiratory diseases that include targeting high doses directly to the lungs and reducing exposure of other organs to the medication, which improve effectiveness and minimize side effects. However, difficulties associated with aerosolized drug delivery to the lungs include drug losses in delivery devices and in the extrathoracic region of human upper airways. Intersubject variability of extrathoracic and thoracic drug deposition is a key issue as well and should be minimized. Improvements to respiratory drug delivery efficiency have been recently proposed by Dr. P. Worth Longest and Dr. Michael Hindle through the use controlled condensational growth methods, which include enhanced condensational growth (ECG) and excipient enhanced growth (EEG). These methods reduce inhaled drug loss through the introduction of an aerosol with an initial submicrometer aerodynamic diameter, which then experiences condensational growth to increase droplet size and enhance thoracic deposition. Tracheobronchial and nasal human airway computational models were developed for this study to assess drug delivery using conventional and EEG methods. Computational versions of these models are used to assess drug delivery and variability with computational fluid dynamics (CFD) simulations, which are validated with experimental data where possible. Using CFD, steady state delivery of albuterol sulfate (AS) during high flow therapy (HFT) through a nasal cannula was characterized with four nasal models developed for this study, with results indicating an increase in average delivered dose from 24.0% with a conventional method to 82.2% with the EEG technique and an initially sized 0.9 µm aerosol, with a corresponding decrease in the coefficient of variation from 15% to 3%. Transient CFD simulations of nebulized AS administration through a mask during noninvasive positive pressure ventilation (NPPV) were performed and validated with experimental data, which resulted in 40.5% delivered dose with the EEG method as compared with 19.5% for a conventional method and a common inhalation profile. Using two newly created face-nose-mouth-throat models, dry powder delivery of ciprofloxacin during NPPV was assessed for the first time with steady state CFD predictions, which showed an increase in average delivered lung dose through a new mask design of 78.2% for the EEG method as compared with 36.2% for conventional delivery, while corresponding differences in delivered dose between the two models were reduced from 45.4% to 12.8% with EEG. In conclusion, results of this study demonstrate (i) the use of highly realistic in silico and in vitro models to predict the lung delivery of inhaled pharmaceutical aerosols, (ii) indicate that the EEG approach can reduce variability in nose-to-lung aerosol delivery through a nasal cannula by a factor of five, and (iii) introduce new high efficiency methods for administering aerosols during NPPV, which represents an area of current clinical need.

In this work, an experimental method is developed to study the effects of particle size, flow rate, pulsation, particle/substrate material, and temperature on the short-term reentrainment of submicron particles. The particles tested are in the size range of 10-900 nm and are deposited by wetting the inside of capillary tubes with a liquid suspension. The tubes are then dried in a desiccator. The particles are reentrained under turbulent dry air flow conditions and a condensation particle counter is used to measure the number of entrained particles.There has been very limited work done with nanoscale particles in general and no previous experimental work has reported about this particular parameter set. In order to interpret the data, a bimodal lognormal probability density for the ratio of adhesion force to removal forces is suggested. The majority of particles is attached to the surface by strong forces and cannot be entrained. However, a small fraction of particles, called loose particles, is attached to the surface by much smaller forces. Based on experimental data, an analytical equation for the fraction of loose particles in terms of a dimensionless force is developed. This dimensionless force is a function of particle size and gas flow rate. The temporal variations of fraction of deposited particles are calculated by incorporating the fraction of loose particles with the model of Wen and Kasper (1989).The experimental data confirmed the theoretical expectation that entrainment strongly depends on particle size and decreases as the size of the particle decreases. Both higher flow rates and pulsation of the flow increase the entrainment. Pulsation causes the distribution of forces to broaden. It is shown that the effect of particle/substrate material on entrainment can be predicted by the compound Hamaker constant provided that the morphology and the roughness of the system remain the same. Otherwise, the effect of roughness or morphology may override the effect of Hamaker constant.

No description available.

A purpose-built cylindrical resuspension chamber (V=0.437 m3 , S=0.35 m2 , S/V=8.38) was used for the dispersion of samples of soil and various kinds of dust. The samples were studied from the point of view of the number and mass distribution of aerosol particles which could affect the concentration of atmospheric aerosol. The samples were taken from lignite, power plant flue ash and from overburden soil in the North Bohemian surface mine Nastup. The individual samples were pneumatically dispersed inside the chamber under defined temperature-humidity conditions (20řC and relative humidity (RH) 50 %). An APS (Aerodynamic Particle Sizer) processing provided us with average size distributions of particle mass and number. Lignite and flue ash probably have the greatest potential impact on the concentration of atmospheric aerosol in the studied locality. The amount of the resuspended mass of the samples varied between 0.001 % (overburden soil) and 0.32 % (mine road). The lignite and flue ash samples were then analyzed by gravimetric methods using the HI (Harvard Impactor) and the SCI (Sioutas Cascade Impactor). The flue ash contained higher amounts of fine particles than the lignite. Subsequent chemical analysis by electron microscope of the filters with deposits of power plant flue ash showed that the PM2.5...

Master of Science / Department of Chemical Engineering / Larry Erickson / Oxy-fired boilers are receiving increasing focus as a potential response to reduced boiler emissions limits and greenhouse gas legislation. Among the challenges in cleaning boiler gas for sequestration is attaining the necessary purity of the CO[subscript]2. A key component in the oxy-fired cleaning path is high purity SO[subscript]x and NO[subscript]x removal, often through absorption using the lead-chamber or similar process. Aerosol formation has been found to be a source of product contamination in many flue gas absorption processes. A number of authors presented simulation methods to determine the formation of aerosols in gas absorption. But these methods are numerically challenging and not suitable for day-to-day analysis of live processes in the field. The goal of this study is to devise a simple and practical method to predict the potential for and effect of aerosol formation in gas absorption using information from Aspen Plus, a commonly used process simulation tool. The NO[subscript]x absorber in an oxy-fired boiler CO[subscript]2 purification system is used as a basis for this investigation. A comprehensive review of available data suitable for simulating NO[subscript]x absorption in an oxy-fired boiler slipstream is presented. Reaction rates for eight reactions in both liquid and vapor phases are covered. These are entered into an Aspen Plus simulation using a RadFrac block for both rate-based and equilibrium reactions. A detailed description of the simulation format is given. The resulting simulation was compared to a previously published simulation and process data with good agreement. An overall description of the aerosol formation mechanism is presented, along with an estimate of expected aerosol nuclei reaching the NO[subscript]x absorption process. A method to estimate aerosol quantities produced based on inlet gas nuclei concentration and available condensable water vapor is presented. To estimate aerosol composition and emissions, an exit gas slipstream is used to equilibrate with a pure water aerosol using an Aspen Plus Equilibrium Reactor block. Changing the composition of the initial aerosol feed liquid suggests that the location of aerosol formation may influence the final composition and emissions.

Für eine dauerhaft gesicherte und umweltgerechte Energieerzeugung kommt den erneuerbaren Energien in Zukunft eine immer größere Bedeutung zu. Dies stellt eine große Herausforderung für die Entwicklung zukünftiger Energiesysteme dar, da erneuerbare Energieträger zeitlich und räumlich zumeist hoch variabel zur Verfügung stehen. Eine effiziente Integration solar erzeugter Energie in das bestehende Energieversorgungsnetz ist daher nur möglich, wenn verlässliche Nahe-Echtzeit-Vorhersagen der am Erdboden verfügbaren Einstrahlung und ein- bis dreitägige Vorhersagen von Energieproduktion und -nachfrage zur Verfügung stehen. Die vorliegende Arbeit beschäftigt sich mit der Vorhersage der solaren Strahlung für die nächsten Tage und Stunden im Hinblick auf Anwendungen in der Energiewirtschaft. Der dominante Atmosphärenparameter für die Abschwächung der solaren Einstrahlung ist die Bewölkung. Das größte wirtschaftliche Potential der Solarenergie liegt jedoch in Zeiträumen und Regionen, in denen wenig Bewölkung auftritt. Im wolkenlosen Fall beeinflussen vor allem Aerosole, feste und flüssige Partikel in der Atmosphäre, die direkte und diffuse Strahlung am Erdboden. Aerosole sind durch eine hohe zeitliche und räumliche Variabilität gekennzeichnet, die die Bestimmung ihrer raumzeitlichen Verteilung und damit ihres Einflusses auf die Strahlung erschwert und einen hohen Aufwand zu ihrer Prognose erforderlich macht. Am Beispiel eines fünfmonatigen europäischen Datensatzes (Juli-November 2003) werden Prognosen der aerosoloptischen Tiefe bei 550 nm (AOT550) untersucht, die aus Aerosolvorhersagen eines Chemie-Transport-Modells stammen. Es zeigt sich, dass im Vergleich mit Bodenmessungen die Aerosolprognosen mit einer mittleren Unterschätzung von -0,11 und einem RMSE von 0,20 die geforderte Genauigkeit nicht ganz erreichen. Dabei stellen insbesondere die unregelmäßig auftretenden Saharastaubausbrüche über dem zentralen Mittelmeer eine im Modell bisher nicht erfassbare Quelle großer Ungenauigkeiten in der AOT- und damit auch in der Strahlungsvorhersage dar. Entsprechend der hohen regionalen Aerosol-Variabilität finden sich zudem signifikante Unterschiede zwischen den Regionen, zum Beispiel eine deutliche Unterschätzung des Aerosolaufkommens in der stark industriell belasteten Po-Ebene Norditaliens sowie gute Entsprechungen in abgelegenen Gegenden Nordeuropas. Basierend auf dieser Aerosol-Prognose und unter Einbeziehung weiterer Fernerkundungsdaten (Bodenalbedo, Ozon) und Parametern aus der numerischen Wetterprognose (Wasserdampf, Wolken) wird ein Prototyp für ein Vorhersagesystem der Solarstrahlung konzipiert und vorgestellt: das AFSOL-System (Aerosol-based Forecasts of Solar Irradiance for Energy Applications). An Hand der fünfmonatigen Testepisode wird das AFSOL-System mit Vorhersagen des Europäischen Zentrums für Mittelfrist-Wettervorhersage (ECMWF), mit satellitenbasierten Beobachtungen der Solarstrahlung (Meteosat-7) und mit Bodenmessungen der Solarstrahlung verglichen. Für den wolkenlosen Fall erzielt das AFSOL-Modellsystem eine deutliche Verbesserung der Direktstrahlungsprognosen gegenüber den ECMWF-Vorhersagen, mit einer Reduktion des relativen Bias von -26% auf +11% und des relativen RMSE von 31% auf 19%. Dies kann auf die verbesserte Beschreibung des atmosphärischen Aerosols zurückgeführt werden, die sich im Vergleich zu den am ECMWF genutzten AOT-Klimatologien ergibt, auch wenn insbesondere bei der Behandlung von Wüstenstaubepisoden weiterhin Probleme auftreten. Auch die Globalstrahlungsprognosen erreichen im wolkenlosen Fall eine höhere Genauigkeit als die operationell verfügbaren ECMWF-Vorhersagen, was sich in einer Verringerung des relativen Bias von -10% zu +5% sowie des relativen RMSE von 12% zu 7% zeigt. Im bewölkten Fall jedoch können die Vorhersagen des AFSOL-Systems erhebliche Ungenauigkeiten aufweisen, die sich auf Grund von Problemen bei der Wolkenprognose des zu Grunde liegenden numerischen Wettervorhersagemodells ergeben. Abschließend wird in einer Fallstudie zur Verwendung der Vorhersagen für die optimale Betriebsführung eines solarthermischen Kraftwerks in Spanien beispielhaft gezeigt, dass die Nutzung der AFSOL-Prognose im wolkenlosen Fall eine deutliche Gewinnsteigerung bei der Einspeisung ins öffentliche Stromnetz durch den Handel an der spanischen Strombörse ermöglicht. / Due to the limitation of fossil fuel resources and their impact on climate change, our future energy system will increasingly depend on growing shares of renewable energy sources. This poses a major challenge on the development of future energy systems, since energy production from most renewable resources is highly variable in space and time. Because of the high variability, an efficient integration of solar energy into the existing energy supply system will only be possible if reliable near real time forecasts of ground level solar irradiance as well as one to three day forecasts of energy production and demand are available. This study deals with solar irradiance forecasts of the next few days and hours with respect to their application in solar energy industries. The main atmospheric parameter responsible for the extinction of solar irradiance is clouds. However, a main focus and economic potential of the solar energy industry is situated in regions and time periods with minimal cloud cover. During these ”clear sky cases“ it is mainly aerosols, solid and liquid particles in the atmosphere, that influence the direct and diffuse irradiance at ground level. Aerosols are highly variable in space and time, which leads to difficulties in calculating and forecasting their spatio-temporal patterns and thus their influence on irradiance. For an episode of five months (July-November 2003) in Europe, forecasts of the aerosol optical depth at 550 nm (AOD550) based on particle forecasts of a chemistry transport model are analysed. It is shown that the aerosol forecasts underestimate ground based measurements by a mean -0.11 (RMSE 0.20), which is not within the accuracy required for input parameters of irradiance forecasts. In particular, sporadic Saharan dust storm events in the central Mediterranean region lead to large inaccuracies which at the moment cannot be accounted for in the model system. Due to the high regional variability of aerosol presence and type, also large differences in the representation accuracy for different European regions can be distinguished, e.g., severe underestimations of particle load in the highly industrialized Po Valley in northern Italy or small errors for remote continental areas in Northern Europe. Using these aerosol forecasts and other remote sensing data (ground albedo, ozone) as well as numerical weather prediction parameters (water vapor, clouds), a prototype for an irradiance forecasting system is set up: the AFSOL system (Aerosol-based Forecasts of Solar Irradiance for Energy Applications). Based on the five month dataset its results are compared to forecasts of the European Centre for Medium-Range Weather Forecasts (ECMWF), satellite based irradiance data from Meteosat-7 and ground measurements. It is demonstrated that for clear sky situations the AFSOL system significantly improves direct irradiance forecasts compared to ECMWF forecasts, with a reduction of relative bias from -26% to +11% and a reduction of relative RMSE from 31% to 19%. This can be attributed to the increased accuracy of atmospheric aerosol description compared to the climatological values used by the ECMWF, regardless if there are still deficiencies especially for desert dust situations. Global irradiance forecasts are also shown to have higher accuracies in comparison to the operationally available ECMWF forecasts, with a reduction of relative bias from -10% to +5% and a reduction of relative RMSE from 12% to 7%. However, for cloudy situations the AFSOL forecasts can lead to significant forecast errors due to cloud modelling deficiencies in the underlying mesoscale numerial weather model. Finally, a case study on the use of the AFSOL irradiance forecasts for optimizing operation strategies of a solar thermal power plant in Spain is presented. It is demonstrated that with the improved forecast in clear sky cases a significant rise in profit can be obtained when feeding the solar energy into the public Spanish electricity market by participating in the Spanish electricity stock exchange.

This thesis is concerned with the development of an on-line in-situ device for a chemical characterisation of flowing aerosols. The thesis describes the principles and most important features of such a system, allowing also on-line measurements using Raman spectroscopy as a diagnostic technique An analysis of the effect of forced oscillations on the motion of the particle dispersed in a gas flow is given in Chapter 2. Also the most important particle parameters are introduced. A review of the particle/fluid interaction in laminar air flows and the response of the particle is presented. In Chapter 3 the behaviour of the particle under different external conditions (ion bombardment and electric fields) is extended. A brief review of the most important particle charging theories (diffusion, field, and alternating potential charging) shows, that the effect of the electrical properties (represented by the dielectric constant) of the particles affects the charging process. A non-contact method for particle charge measurement was also presented. In the second part of the chapter, the interaction between the electric field and the charged particle for the purpose of particle trapping is illustrated. The most common systems like the two or four ring electrodynamic balance and the quadrupole trap are pointed out. In Chapter 4 a short review of the possibility of using scattered light to study aerosol particles is presented. First, the conditions and the facilities of using the Mie theory for particle size and refractive index determination are mentioned, then some features concerning the classical treatment of the Raman effect are presented Supported by the theoretical considerations exposed in Chapter 2, 3, and 4 the construction and the tests of different devices are presented in Chapter 5. Following the goal of the thesis, first an overview of the used materials and methods for particle generation is presented. Then, the constructed charging devices are described (from the mechanical and electrical point of view) and compared by measuring the acquired charge on the particle. Charged particles can be trapped in different containers. Two types of axially symmetric electrodynamic balances (two ring or an extended four ring configuration) were presented. For a deeper understanding these systems were studied using analytic and numerical methods. Considering the presented purpose of the work another type of trapping system has been developed, namely the quadrupole trap. A similar theoretical characterisation (in term’s of Mathieu equation) as for the electrodynamic balance was presented pointing out some specific features of this system. The incoming particle stream will be focused to the centre of the system simultaneously also the applied DC and AC potential onto the tube electrodes, yields a stable trapping of one or more particles. Chapter 6 consists of two parts: the system for single particle and for many particles investigation. The individual devices presented in Chapter 5 are now put together. The first part presents the method and the experimental realisation of a set-up for solid particle injection. In order to suppress the phase injection disadvantage found for the electrodynamic balance a developed program processes the information obtained from a particle cloud through an adequate electronic detection system, and reduces the number of particles until just one single particle is trapped. The method for one particle investigation can be extended for many particles. Using the presented set-up the particles are moved from one quadrupole to another and transformed from a particle cloud to a particle stream. A linearity between an external vertical mounted detector and the formed image of the particle stream on the CCD camera has been observed and used for simultaneous detection of many particles by Raman spectroscopy. For both methods Raman results are presented. One limitation of Raman Spectroscopy is the relatively long integration time needed for adequate signal-to-noise ratio. There are two factors which influence the integration time: first the incident radiation and the detector sensitivity, and second the intensity of the Raman bands. Using a CCD detector, the desired detector sensitivity should be achieved. So, the improvement of the signal-to-noise ratio should be the next goal in the system development. In order to reduce the integration time an optical system including optic fibres and the integration of an FT-Raman module operating in the visible region is planed. The goal of this work was to develop and construct an instrument for on-line in-situ single particle investigation by Raman spectroscopy. With the presented experimental set-up and the developed program the purpose of the work, the on-line in-situ near atmospheric pressure aerosol investigation was achieved. The Raman spectroscopy has been used successfully for a chemical characterisation of the aerosol particles. / Diese Arbeit beschäftigt sich mit dem Aufbau eines on-line in-situ Analysegerätes zur chemische Charakterisierung von Aerosolen in Luftströmungen. Die Arbeit beschreibt neben den Grundlagen die wichtigsten Eigenschaften eines solchen Systems für on-line Messungen, das die Raman-Spektroskopie als eine Diagnosetechnik einsetzt. Kapitel 2 beinhaltet eine Analyse der Effekte von erzwungenen Oszillationen auf die Bewegung dispergierter Teilchen im Gasfluss. Dort werden auch die wichtigsten Eigenschaften von Partikeln vorgestellt. Es wird ein Überblick über die Teilchen-Gas Wechselwirkungen in laminarer Strömung gegeben, und die Reaktion des Teilchens in Abhängigkeit von Veränderungen (Kräften) wird diskutiert. In Kapitel 3 wird das Verhalten von Teilchen unter verschiedenen externen Bedingungen (Ionenbeschuss oder elektrisches Feld) weiter erörtert. Ein kurzer Überblick über die wichtigsten Theorien zur Teilchenladung (Diffusions-, Feld-, und alternierende Potentialaufladung) zeigt, dass die elektrischen Eigenschaften (dargestellt durch die dielektrische Konstante) des Teilchens den Ladungsprozess beeinflussen. Darüber hinaus wird eine kontaktlose Messmethode für die Ladung der Teilchen diskutiert. Im zweiten Teil des Kapitels wird die Wechselwirkung zwischen dem elektrischen Feld und dem geladenen Teilchen erläutert, zu dem Zweck, dass man die Teilchen ’’einfängt’’. Die gängigen Systeme wie z.B. die elektrodynamische Waage mit zwei oder vier Ringen und die Quadrupolfalle werden ebenfalls diskutiert. In Kapitel 4 werden die Möglichkeiten zur Untersuchung von Teilchen durch um Analyse des gestreuten Lichts vorgestellt. Zunächst werden die Bedingungen und Möglichkeiten für die Eignung der Mie-Theorie zum Studium von Partikelgröße und Brechungskoeffizient diskutiert; des weiteren wird auf die Eigenschaften des klassischen Raman-Effektes eingegangen. In Kapitel 5 wird die Konstruktion und anschließende Erprobung von Geräten beschrieben. Der Aufbau dieser Geräte erfolgte mit Hilfe der theoretischen Erwägungen aus den Kapiteln 2, 3 und 4. Es wird ein Überblick über die verwendeten Materialien und Methoden für die Teilchenerzeugung gegeben. Dann werden die entwickelten Ladegeräte beschrieben (vom mechanischen und elektronischen Standpunkt aus gesehen), und sie werden untereinander verglichen, indem die erzielte Ladung auf den Teilchen gemessen wird. Geladene Teichen können in verschiedenen Anordnungen gefangen werden. Zwei Arten von achsensymmetrischen elektrodynamischen Waagen (Zwei-Ring- oder eine erweiterte Vier-Ring-Konfiguration) werden vorgestellt. Für ein besseres Verständnis wurden diese Systeme durch analytische und numerische Methoden untersucht. In Anbetracht der Ziele dieser Arbeit wurde eine andere Art von Fangsystem entwickelt, die sogenannte Quadrupolfalle. Eine ähnliche theoretische Charakterisierung wie im Falle der elektrodynamischen Waage wurde vorgenommen und verschiedene spezifische Eigenschaften des Systems dargelegt. Der ankommende Teilchenfluss wird in die Mitte des Systems fokussiert, und unter Berücksichtigung des DC-Potentials auf den Rohrelektroden erhält man ein stabiles „Trapping“ eines oder mehrerer Teilchen. Kapitel 6 beschreibt die Experimentalaufbauten für die Untersuchung von einem oder von mehreren Teilchen. Die einzelnen Geräte, die in Kapitel 5 vorgeführt wurden, werden jetzt zusammengesetzt. Der erste Teil des Kapitels stellt die Methode und den experimentellen Aufbau für die Injektion von Feststoffteilchen vor. Um dem Nachteil der Phaseninjektion im Falle der elektrodynamischen Waage entgegenzukommen, wurde ein Programm entwickelt, das die Informationen (aufgenommen durch ein elektronisches Detektionssystem) von einer Teilchenwolke verarbeitet und das die Zahl der Teilchen reduziert, bis nur ein einziges übrig bleibt. Die Methode für die Ein-Teilchen-Untersuchung kann auch für mehrere Teilchen erweitert werden. Unter Verwendung des beschriebenen Systems werden die Teilchen aus einem Quadrupol in einen anderen bewegt und von einer Teilchenwolke in einen Teilchenstrom umgewandelt. Es wurde eine Linearität zwischen einem extern montierten Detektor und der Abbildung des Teilchenflusses durch ein Spektrometer auf einer CCD-Kamera festgestellt, welche für die gleichzeitige Detektion von mehreren Teilchen mittels Raman-Spektroskopie genutzt wurde. Für beide Methoden werden Raman-Ergebnisse gezeigt. Eine Einschränkung bei der Anwendung der Raman-Spektroskopie besteht in den relativ langen Integrationszeiten, die für ein ausreichendes Signal-Rausch-Verhältnis gebraucht werden. Es gibt zwei Faktoren, die die Integrationszeit beeinflussen: (1) die einfallende Strahlung und die Detektorempfindlichkeit und (2) die Frequenz und die Intensität der Raman Banden. Durch Verwendung eines CCD-Detektors kann die gewünschte Detektorsensitivität erreicht werden. Der nächste Schritt in der Systementwicklung ist die Verbesserung des Signal-Rausch-Verhältnisses. Um die Integrationszeit zu verkürzen, ist für zukünftige Arbeiten ein optisches System geplant, das optische Fasern und den Einbau eines FT-Raman-Moduls im sichtbaren Bereich einschließt. Das Ziel dieser Arbeit war die Entwicklung und der Aufbau eines Geräts zur on-line in-situ Untersuchung eines einzelnen Teilchens mit Hilfe der Raman-Spektroskopie. Durch den vorgestellten experimentellen Aufbau und das entwickelte Steuerungsprogramm konnte das Ziel der Arbeit, die in-situ Untersuchung von Aerosolen bei normalem Luftdruck, erreicht werden. Die Raman-Spektroskopie wurde erfolgreich zur chemischen Charakterisierung von Aerosolen eingesetzt.

Le but de cette thèse est de comprendre les origines et les processus de formation des aérosols organiques (AO) et inorganiques (AI)en Méditerranée durant différentes saisons en utilisant le modèle de chimie-transport de la plateforme de la modélisation de la qualité de l'air Polyphemus. Dans le cadre du projet de recherche ChArMEx (Chemistry Aerosol Mediterranean Experiment), des mesures des concentrations des aérosols et de leurs propriétés ont été conduites à la station ERSA du Cap Corse (île de la Corse, France) dans le bassin ouest de la Méditerranée pendant les étés 2012 et 2013 et l'hiver2014. Ce travail de thèse a également bénéficié de mesures effectuées durant des vols avions au-dessus de la Méditerranée pendant l'été 2014.Le modèle est évalué pendant les différentes périodes simulées et des processus/paramétrisations ont été ajoutés ou modifiés afin d'avoir de bonnes comparaisons modèle/mesures pour les concentrations et les propriétés des aérosols. Des études de sensitivité à la météorologie, aux émissions anthropiques et aux émissions marines, en plus des différents paramètres d’entrée du modèle sont conduites pour comprendre les origines des aérosols. La paramétrisation des émissions de sels marins est choisie de manière à avoir de bonnes comparaisons aux mesures de sodium, qui est un composé non volatil émis principalement par les sels marins. Grâce à une paramétrisation qui estime la fraction organique des émissions marines à partir de la chlorophylle-a montre que les organiques marins contribuent à moins de 2% des AO. L'évaluation du modèle montre l'importance de la description des émissions des bateaux pour la modélisation des concentrations du sulfate et des AO. Cependant, les hypothèses faites dans la modélisation de la condensation/évaporation ont beaucoup d'impact sur les concentrations simulées de nitrate et d'ammonium (équilibre thermodynamique, état de mélange).Pendant les étés 2012 et 2013, les AO sont principalement d'origine biogénique, ce qui est bien reproduit par le modèle. Les mesures enregistrent d'importantes concentrations d'AO hautement oxydés et oxygénés. Pour que le modèle reproduire non seulement les concentrations, mais également les propriétés d’oxydation et d'hydrophilicité des AO, trois processus de formation d'aérosols organiques secondaires (AOS) à partir de monoterpènes sont ajoutés au modèle: l'autoxidation qui induit la formation de composés organiques d'extrêmement faible volatilité, un mécanisme de formation du nitrate organique, et un mécanisme de formation d'un produit d'oxydation de deuxième génération. Les états d'oxydation et d'oxygénation des AO à Ersa sont bien simulés en supposant de plus la formation d'organosulfates. Des simulations hivernales montrent que les AO y sont principalement d'origine anthropique. Bien que les émissions des composés organiques semi-volatils et de volatilité intermédiaire (COVIS) qui sont manquants dans les inventaires d'émissions influencent peu les AO en été, leur influence est dominante en hiver. La contribution du secteur du chauffage résidentiel pendant la saison froide s'avère très importante. Différentes descriptions et paramétrisations des émissions et des schémas de vieillissement des COVIS sont ajoutées au modèle, c-à-d distribution de volatilité à l'émission, schéma à une étape d'oxydation vs schéma à plusieurs étapes d'oxydation et la prise en compte de composés organiques volatils non-traditionnels(COVNT). Bien que le modèle reproduise bien les concentrations des AO, les études de sensibilité révèlent que la distribution de volatilité à l'émission influence beaucoup les concentrations des AO. Néanmoins, les états d'oxydation et d'oxygénation de ces derniers restent sous-estimés par le modèle pendant l'hiver quelque soit la paramétrisation utilisée, ce qui suggère la nécessité d'ajouter au modèle d'autres mécanismes de formation des AOS à partir des précurseurs anthropiques (autoxidation, formation du nitrate organique) / This work aims at understanding the origins and processes leading to the formation of organic aerosols (OA) and inorganic aerosols (IA) over the western Mediterranean Sea during different seasons, using the air-quality model Polyphemus. In the framework of ChArMEx (the Chemistry-Aerosol Mediterranean Experiment), measurements of both aerosol concentrations and properties are performed at a remote site (Ersa) on Corsica Island in the northwestern Mediterranean sea in the summers 2012, 2013 and the winter 2014. This thesis also benefits from measurements performed during flights above the western Mediterranean Sea in the summer 2014. The model is evaluated during these periods, and different processes/parameterizations are added or modified in order to have good model-to-measurements comparisons, not only of aerosol concentrations but also of their properties. Origins of aerosols are assessed through different sensitivity studies to the meteorological model, anthropogenic emissions inventory, sea-salt emissions and different input models. The contribution of marine emissions to inorganic aerosols (IA) is important, and the parameterization of sea-salt emissions is chosen such as having good comparisons to sodium measurements, which is a non-volatile compound emitted mainly by sea salts. Marine organic aerosols (OA), which are added to the model with a parameterization that uses the chlorophyll-a concentration as a proxy parameter to model the marine chemistry, contribute to OA by only 2% at the maximum. The ground-based and airborne model-to-measurements comparisons show the importance of an accurate description of shipping emissions to model sulfate and OA concentrations. However, this is not true for nitrate and ammonium concentrations, which are very dependent on the hypotheses used in the model for condensation/evaporation (thermodynamic equilibrium, mixing state).During the summers 2012 and 2013, OA concentrations are mostly of biogenic origin, which is well reproduced by the model. Measurements show important concentrations of highly oxidized and oxygenated OA. For the model to reproduce not only the concentrations but also the oxidation and hydrophilicity properties of OA, three processes to form secondary organic aerosols (SOA) from monoterpenes are added to the model : the autoxidation process leading to the formation of extremely low volatility organic compounds, the organic nitrate formation mechanism and the second generational ageing. The high oxidation and oxygenation states of OA at Ersa are well modeled when organosulfate formation is also assumed. Winter simulations show that OA are mainly of anthropogenic origin. The influence of the anthropogenic intermediate/semi-volatile organic compound (ISVOC) emissions, which are missing from emission inventories, is low in summer. Nonetheless, the role and the contribution of ISVOC appear very significant during the winter, with a large contribution from residential heating. Different parameterizations to represent the emissions and the ageing of IS-VOC are implemented in the model, namely the volatility distribution of emissions, single-step vs multi-step oxidation scheme and non-traditional volatile organic compounds (NTVOC) chemistry. Sensitivity studies show that the volatility distribution at the emission is a key parameter to improve the modeling of OA concentrations. The model reproduces well the observed concentrations, but the observed organic oxidation and oxygenation states are strongly under-estimated, stressing the potential role of autoxidation and organic nitrate from anthropogenic precursors

Norovirus is the most common pathogen to cause acute gastroenteritis in the world. Symptoms of acute gastroenteritis include vomiting and/or diarrhea, along with fever, abdominal pain, and malaise. Annually, norovirus causes 685 million cases of acute gastroenteritis and 200,000 deaths, worldwide. Among the 685 million cases occurring every year, 19-21 million occur in the United States. Norovirus can spread through direct or indirect contact (e.g., contaminated food or water). In addition, recent evidence has suggested that norovirus can also be spread via aerosolization. However, no study has determined an indoor generation source for aerosolized norovirus. Therefore, the goals of this study were to optimize sampling and quantification methods for the collection of aerosolized norovirus. Upon optimization, the last was to investigate a potential indoor generation source (i.e., toilet flushing) of aerosolized norovirus. To achieve this goal we devised three studies. In the first study, we optimized a sampling method for the collection of aerosolized norovirus using murine norovirus (MNV) as a surrogate. Optimization of the sampling method was performed using two bioaerosol samplers (SKC BioSampler and the National Institute for Occupational Safety and Health [NIOSH] Bioaerosol Cyclone Sampler 251) and two sampling media (Hanks Balanced Salt Solution [HBSS] and Phosphate Buffered Saline [PBS]). Murine norovirus was aerosolized in a bioaerosol chamber and later collected using the optimized sampler/media combination. After collection, viral RNA was extracted from MNV collected samples and quantified using quantitative polymerase chain reaction (qPCR). Intact capsids of MNV were assessed using propidium monoazide dye in combination with qPCR and confirmed with transmission electron microscopy. There were a total of 10 trials conducted, with each trial lasting for 30 minutes. The SKC BioSampler collected a significantly higher concentration of MNV than the NIOSH-251 sampler did (p-value < 0.0001). However, there were no significant differences in the relative percent of MNV that remained viable between both samplers (p-value = 0.2215). The use of HBSS sampling media yielded a higher concentration of MNV than PBS media (p-value = 0.0125). However, PBS media maintained viability at a significantly higher percentage than HBSS media (p-value < 0.0001). The results support the optimization of a sampling method for the collection of aerosolized MNV and possibly norovirus in different sampling environments. In the second study, we optimized the quantification method for MNV. A relatively new quantification system, droplet digital polymerase chain reaction (ddPCR), was evaluated using the same extracted samples collected in the first study to determine if the same overall outcome could be achieved. In addition, a MNV standard was directly compared between the qPCR and ddPCR. When comparing the same standard, the mean observed concentrations were similar to the nominal concentration. The limit of detection for both instruments was 5 copies per reaction. The coefficient of variation was lower across all ddPCR results than the qPCR results. The range of the R2 was larger for ddPCR compared to qPCR. As for the analysis of bioaerosol samples collected from the first study, the SKC BioSampler collected a significantly higher concentration of MNV compared to the NIOSH-251 sampler (p-value = 0.0002). However, there were no significant differences in the relative percent of MNV that remained viable in both samplers (p-value = 0.6734). The use of HBSS sampling media yielded a higher concentration of MNV than PBS media (p-value = 0.0190). However, PBS media maintained viability at a significantly higher percentage than HBSS media (p-value = 0.0004). The use of ddPCR allows for a simpler workflow and fewer samples and resources. These results support that both PCR systems yield similar results and overall outcomes, thus presenting an optimized quantification method for MNV. In the third study, we used the optimized sampling and quantification methods to conduct a field trial investigation of a potential indoor aerosolization source for norovirus (toilet flushing). To inform bioaerosol sampler placement, two optical particle counters monitored particle size and number distribution of aerosol produced from flushing a toilet across three variables (height, position, and side). The location with the highest mean particle concentration, and where bioaerosol sampling occurred, was behind the toilet and 0.15 m above the toilet bowl rim. A flushometer type toilet was seeded with 105 and 106 PFU/mL of MNV and then flushed. Upon flushing, a SKC BioSampler and Coriolis µ sampler were activated to collect aerosolized MNV. Samples were extracted and then quantified using RT-ddPCR, and viability was quantified using PMA: RT-ddPCR. The concentration of MNV collected after seeding the toilet water ranged from 2.18 x 105 – 9.65 x 106 total copies of MNV. Positive samples of airborne MNV were detected using the Coriolis µ sampler with collected concentrations ranging from 383 – 684 RNA copies/m3 of air. Sample viability for bioaerosol samples were unable to be quantified. The relative percent of MNV virions that remained intact in seeded toilet water was 37-79%. This study provides the first evidence that MNV, a NV surrogate, can be aerosolized when a toilet is flushed.