Emissions from natural ecosystems, broadly classified as biogenic volatile organic compounds (BVOCs), contribute 90\% to the VOC budget. Individual BVOCs vary widely in their reaction rates with atmospheric oxidants, making their atmospheric impact highly dependent on VOC composition. Their emissions are also dependent on vegetative make up and a number of meteorological and ecological variables. However, the ecological and physical drivers of their emissions is becoming more variable in a changing climate, leading to greater uncertainties in models. Increasing the monitoring of individual compounds can improve our understanding of the drivers of these emissions and the impact of individual chemical species on atmospheric composition. Improved understanding of BVOC composition can better emission models and, SOA and ozone formation predictions. To study the atmospheric impacts and physical drivers of BVOCs, a GC-FID was adapted for automated hourly sampling and analysis. The details of the hardware and software used for the system are described in detail to enable future long-term BVOC measurements in additional locations. The instrument was deployed at a measurement tower in a forest in central Virginia for year-round collection of BVOC concentrations. Using two years of collected hourly data, this work assesses the chemical impacts of individual BVOCs on time scales ranging from hour to year. This work identifies the importance of both concentration and chemical structure in determining atmospheric impacts. Additionally, seasonality in the concentration of some biogenic species has large implications for atmospheric reactivity in the warmest months of the year, particularly ozone reactivity. Using ecological and meteorological data collected at the site in conjunction with the BVOC data, the drivers of BVOC concentrations and their seasonality are identified. Comparison between this data and current models, reveal important deviations which may lead to large modeled uncertainties. Furthermore, the collected data has been made publicly available to aid in future research regarding BVOCs. / Doctor of Philosophy / The earth hosts a number of sources of atmospheric emissions. These range from human-driven sources such as vehicles and factories, to natural sources such as trees and grass. The content of these emissions, amongst others, become a part of a large reactor (the atmosphere), that interact with each other. The interaction of these emissions with atmospheric oxidants forms a gas (ozone) with implications for human and ecosystem health, and secondary organic aerosol (the leading component to smog). However, the extent to which these emissions react with atmospheric oxidants is largely dependent on the structure of individual compounds. A major focus of this dissertation is to show that compounds with reactive structures can have a large impact on atmospheric composition, and that the quantity of emissions can be as important as compound structure. Understanding the impact of individual compounds in the atmosphere requires improved measurement techniques, capable of detecting the compounds of interest over long time periods. Therefore, another focus of this work was the adaptation and deployment of an instrument capable of detecting some of the most reactive species in the atmosphere, volatile organic compounds emitted from forests. The instrument deployed in this work was a gas chromatography flame ionization detector (GC-FID), which detects compounds largely composed of carbon and hydrogen. The instrument was adapted to run automatically through the development of an electronics box and software program interfaced with the GC-FID. Following development, the instrument was deployed to a remote forest research site for two years. The data collected from this work was used to determine the impact of individual compounds on atmospheric composition. Findings from this work could be used to improve a range of atmospheric models. Small changes in emissions (human or plant) contribute to the total VOC budget which can have large implications for the formation of ozone and SOA. Therefore, increased understanding of the BVOC concentrations and emission driver will aid in predicting these atmospheric components.

Heterogeneous reactions between gas-phase oxidants and particulate-phase organic compounds impact many important atmospheric chemical processes. For example, little is known about the reaction dynamics of gaseous oxidants with organic compounds found in the atmosphere. The first step of the reaction between gaseous ozone and solid pentacene was investigated using Reflection Absorption Infrared Spectroscopy (RAIRS). Ozone was found to add to pentacene non-selectively and form a range of products after heavy ozone exposure. The rate limiting step had an activation energy of 17 kJ/mol, which is consistent with the findings of previous ozone oxidation studies for the cleavage of a carbon-carbon double bond. Unfortunately the products could not be used to distinguish between probable reaction mechanisms. Hydroxyl radicals (•OH) play a major role processing atmospheric hydrocarbons. Due to their short lifetimes, not much is known about the dynamics of the first steps of •OH reactions. To investigate these reactions, a rotational state-selector was constructed to filter a molecular beam of •OH for reaction dynamics investigations with organic surfaces. The rotational state-selector was designed to leverage the linear Stark effect to pass only suitable molecules in a particular rotational state and block the flow of any other atoms, molecules and ions in a molecular beam. The state-selector was validated and used to positively deflect molecular beams of methyl iodide and D₂O via the linear Stark effect. Future studies with the rotational state-selector will investigate the initial steps of •OH reactions with solid organic compounds. / Master of Science

Grafts were made using 2-0 rootstock and scion from 12 ortets of eastern white pine (Pinus strobus L.) growing at the Radford Army Ammunition Plant (RAAP). The 12 ortets represented 4 symptom severity classes (3 ortets/class) ranging from trees with > 25% of their crowns exhibiting necrotic tipburn (Class I) to those with healthy crowns (Class IV). Grafts were made in spring 1976 and ramets were grown in a greenhouse drawing charcoal filtered air. Each treatment was performed twice, on separate days for a total of 10 ramets/clone/ treatment. Five ramets/clone were used in each 6 hour treatment. The current years growth was 7-10 weeks old when treated. The treatments were as follows: 1) 0₃-10 pphm, 2) 0₃-30 pphm, 3) NO₂-10 pphm, 4) NO₂-30 pphm, 5) 0₃-10+NO₂ -10 pphm, 6) 0₃-10+NO₂ -30 pphm, 7) no pollutant. The fumigation chamber was a modified open-top field chamber located indoors. Environmental conditions during the 14 treatments averaged: 26 C, 64% RH, and 16 Klux. The ramets were evaluated prior to fumigation and then 2, 7, and 14 days thereafter for visible symptoms. The overall injury was generally light with only 11% of the clone treatment combinations exhibiting injury on > 25% of the needle fascicles. Clones I-1 and I-2 were the most sensitive clones while clones III-1, IV-2 and to a lesser degree clones III-3 and IV-1 were tolerant. These results agree with field ratings of eastern white pine sensitivity at the RAAP and provide the first step in the development of an air pollution bioindicator system at the installation. / Master of Science

Listeria monocytogenes represents a high risk for consumers, because it causes severe illness. This work studied in-vitro growth and survival of L. monocytogenes in media acidified with malic acid, lactic acid or blueberry extract. The growth of L. monocytogenes and shelf life extension of fresh blueberries were evaluated after storage at 4 deg C or 12 deg C under different controlled atmosphere conditions, including air (control); 5% O2 and 15% CO2, 80% N2 (CAS); or ozone gas (O3) 4ppm at 4 deg C or 2.5ppm at 12 deg C, at high relative humidity (90-95%) for a total of 10 days. L. monocytogenes growth in tryptic soy broth with yeast extract (TSB+YE) mixed with different acid solutions (malic acid, lactic acid and blueberry extract) and incubated at 25 deg C for 24h, was calculated measuring optical density. Complete inhibition occurred in the presence of treatments including malic acid pH 2.0 and pH 3.0; lactic acid pH 2.0, pH 3.0 and pH 4.0; and with blueberry extract pH 2.0 in the mixture. After 6h, there were significant differences among growing treatments. At 18h, there were no significant differences in turbidity among media mixed with blueberry extract at pH 3.0, 4.0 and 5.0, and their optical density values were higher than treatments including media mixed with malic acid 5.0 or lactic acid 5.0. Blueberry extract was not an effective acidifying media and acid adapted L. monocytogenes grew in acidified media. Fresh blueberries inoculated with L. monocytogenes were stored at 4 deg C or 12 deg C under different controlled atmosphere conditions (Air, CAS or O3 4ppm at 4 deg C or 2.5ppm at 12 deg C) and sampled on day 0, 1, 4, 7 and 10 for bacterial growth, weight loss, firmness and yeast and molds counts. CAS did not delay or inhibit Listeria monocytogenes, yeast, or molds by day 10. Storage at 4 deg C showed lower weight loss values compared to 12 deg C. Ozone controlled weight loss and firmness loss. Moreover, gaseous ozone achieved 3 and 2 log reductions when compared with air at 4 deg C and 12 deg C, respectively. / Ph. D.

Anaerobic digestion has been the preferred method for reducing and stabilizing waste sludge from biological wastewater treatment for over a century; however, as sludge volumes and disposal costs increase, there has been a desire to develop various methods for reducing the volume of sludge to be treated, improving the performance of the digesters, and increasing the energy value of the sludge. To this end, there have been numerous pretreatment and side-stream systems studied and developed over the past several decades with the overall goal of reducing the volume of biosolids to be disposed of in landfills or by land application. These technologies can be broken into four large groups: mechanical, thermal, chemical and biological, although there is often overlap between groups. This research approached the evaluations of these technologies through several methods in the hopes of developing effective tools for predicting the performance of each technology. Batch digestion studies mimicking several of these treatment methods and extensive analytical work on samples from full-scale installations were conducted to determine the effectiveness of each technology. From these studies a simple batch digestion methodology was developed to analyze the effectiveness of the Cannibal solids reduction process on wastewater streams that have never been exposed to it. Batch digestion of sludges pretreated with ozone, mechanical shear and sonication provided insight into the effectiveness of each technology. Extensive analytical work on samples collected from full-scale installations of thermal hydrolysis, mechanical shear and the Cannibal process provided some insight into the workings of each process and potential leads as to how to further characterize and evaluate each process. / Master of Science

This thesis describes the preparation and characterization of manganese oxide catalysts and their application in the oxidation of acetone, a typical volatile organic compound (VOC), and ozone decomposition. This topic is of great value because of environmental concerns of the elimination of the harmful VOCs and ozone. Manganese oxide was chosen because it is a well-known complete oxidation catalyst for VOCs and also an active catalyst for ozone decomposition. Two cases of studies were carried out in this work. The first study involved the oxidation of acetone using ozone on silica- and alumina-supported manganese oxide catalysts deposited on aluminum oxide foam substrates. The characteristics of the catalysts were determined through various techniques, including x-ray diffraction (XRD), x-ray absorption spectroscopy (XAS), Brunauer-Emmett-Teller (BET) surface area analysis, temperature-programmed reduction (TPR), and oxygen chemisorption. The use of these techniques allowed better understanding of the nature of the catalysts. Activity tests were carried out in the acetone oxidation reaction and it was found that the usage of ozone substantially reduced the oxidation temperature. Steady-state in situ Raman spectroscopy was also carried out to better understand the mechanism of the acetone oxidation reaction using ozone. The second study involved an investigation of structural and electronic properties of manganese centers of the MnOx/SiO2 and MnOx/Al2O3 catalysts during the ozone decomposition reaction using in situ x-ray absorption spectroscopy (XAS). The number of surface active sites was again determined through TPR and oxygen chemisorption measurements. The performance of the catalysts with different loadings and supports were also compared. / Master of Science

Les troubles reliés à la dépression, l’épuisement professionnel et l’anxiété sont de plus en plus répandus dans notre société moderne. La consommation croissante d’antidépresseurs dans les différents pays du monde est responsable de la récente détection de résidus à l’état de traces dans les rejets urbains municipaux. Ainsi, ces substances dites « émergentes » qui possèdent une activité pharmacologique destinée à la régulation de certains neurotransmetteurs dans le cerveau suscitent maintenant de nombreuses inquiétudes de la part de la communauté scientifique. L’objectif principal de ce projet de doctorat a été de mieux comprendre le devenir de plusieurs classes d’antidépresseurs présents dans diverses matrices environnementales (i.e. eaux de surfaces, eaux usées, boues de traitement, tissus biologiques) en développant de nouvelles méthodes analytiques fiables capables de les détecter, quantifier et confirmer par chromatographie liquide à haute performance couplée à la spectrométrie de masse en tandem (LC-QqQMS, LC-QqToFMS). Une première étude complétée à la station d’épuration de la ville de Montréal a permis de confirmer la présence de six antidépresseurs et quatre métabolites N-desmethyl dans les affluents (2 - 330 ng L-1). Pour ce traitement primaire (physico-chimique), de faibles taux d’enlèvement (≤ 15%) ont été obtenus. Des concentrations d’antidépresseurs atteignant près de 100 ng L-1 ont également été détectées dans le fleuve St-Laurent à 0.5 km du point de rejet de la station d’épuration. Une seconde étude menée à la même station a permis l’extraction sélective d’antidépresseurs dans trois tissus (i.e. foie, cerveau et filet) de truites mouchetées juvéniles exposées à différentes concentrations d’effluent dilué traité et non-traité à l’ozone. Un certain potentiel de bioaccumulation dans les tissus (0.08-10 ng g-1) a été observé pour les spécimens exposés à l’effluent non-traité (20% v/v) avec distribution majoritaire dans le foie et le cerveau. Une intéressante corrélation a été établie entre les concentrations de trois antidépresseurs dans le cerveau et l’activité d’un biomarqueur d’exposition (i.e. pompe N/K ATPase impliquée dans la régulation de la sérotonine) mesurée à partir de synaptosomes de truites exposées aux effluents. Une investigation de l’efficacité de plusieurs stations d’épuration canadiennes opérant différents types de traitements a permis de constater que les traitements secondaires (biologiques) étaient plus performants que ceux primaires (physico-chimiques) pour enlever les antidépresseurs (taux moyen d’enlèvement : 30%). Les teneurs les plus élevées dans les boues traitées (biosolides) ont été obtenues avec le citalopram (1033 ng g-1), la venlafaxine (833 ng g-1) et l’amitriptyline (78 ng g-1). Des coefficients de sorption expérimentaux (Kd) calculés pour chacun des antidépresseurs ont permis d’estimer une grande sorption des composés sertraline, desméthylsertraline, paroxetine et fluoxetine sur les solides (log Kd > 4). Finalement, un excellent taux d’enlèvement moyen de 88% a été obtenu après ozonation (5 mg L-1) d’un effluent primaire. Toutefois, la caractérisation de nouveaux sous-produits N-oxyde (venlafaxine, desmethylvenlafaxine) par spectrométrie de masse à haute résolution (LC-QqToFMS) dans l’effluent traité à l’ozone a mis en lumière la possibilité de formation de multiples composés polaires de toxicité inconnue. / Mood disorders such as depression, burn-out and anxiety have increased in our modern society. Increasing amounts of antidepressant prescriptions around the world are now suspected to be the main cause of the recent detection of traces of antidepressant residues within urban wastewaters. These so-called “emerging” substances that possess pharmacological activity towards neurotransmitter regulation in the brain have raised serious concerns from the scientific community. The initial goal of the study was to better understand the fate of various classes of antidepressants present in different environmental matrices (e.g. surface waters, wastewaters, treatment sludge, and biological tissues) by developing novel reliable analytical methods that can detect, quantify and confirm antidepressants using high performance liquid chromatography coupled to tandem-mass spectrometry (LC-QqQMS,LC- QqToFMS). A preliminary study completed at the Montreal sewage treatment plant (STP) confirmed the presence of six antidepressants and four N-desmethyl metabolites in raw sewage (2 – 330 ng L-1). For this primary treatment (physico-chemical), low removal rates (≤ 15%) were obtained. Concentrations of antidepressant close to 100 ng L-1 were also detected directly in the St. Lawrence River at 0.5 km of the effluent outfall. A second study conducted at the same STP allowed the selective extraction of antidepressants in three biological tissues (e.g. liver, brain, and filet) dissected from juvenile brook trouts previously exposed to diluted untreated and treated effluents with ozone. Bioaccumulation of antidepressants was readily observed in fish tissues (0.08-10 ng g-1) for the specimens exposed to untreated effluent (20% v/v), with major distribution in liver and brain. During experiments, a significant correlation was established between the concentrations of three antidepressant detected in brain tissues and the activity of a selected biomarker of exposition (e.g. an N/K ATPase pump involved in the serotonin regulation) measured within dissected synaptosomes from trout exposed to effluents. Investigation of estimated treatment removal efficiencies from various Canadian STPs operating different disinfection modes showed that secondary treatments (biological) were more efficient than primary (physico- chemical) to remove antidepressants (mean removal rates : 30%). The highest amounts detected in treated sludge (biosolids) were obtained respectively with citalopram (1033 ng g-1), venlafaxine (833 ng g-1), and amitriptyline (78 ng g-1). Experimental calculated sorption coefficients (Kd) of each antidepressant predicted fairly good sorption capacities for sertraline, desmethylsertraline, paroxetine, and fluoxetine to solid matters (log Kd > 4). Finally, an excellent mean removal rate of 88% was obtained after ozonation (5 mg L-1) of a primary effluent. However, the characterization of new N-oxide side-products (venlafaxine, desmethylvenlafaxine) in ozonized effluent by high-resolution mass spectrometry (LC-QqToFMS) highlighted the possibility of formation of multiple polar compounds with unknown toxicity.

107 Summary The Ozone layer of the Earth located in the stratosphere in an altitude of 20 to 50 kilometres is the important part of the gases surrounding the planet Earth. Its purpose is to absorb UV radiation that otherwise very negatively affects life on the Earth. During the twentieth century, this ability was weakened by the emission of substances proven much later to be very dangerous in this way. Until 1987, by various chemical reactions, in particular of chlorine atoms, the ozone hole has been formed over the South Pole of the Earth, not fully healed yet. In 1985, risk to human life led using the precautionary principle to the adoption of the Vienna Convention and subsequently of its implementing protocol including specific obligations especially the control measures of the production and consumption of ozone depleting substances and of the trade with them in 1987. The protocol was later modified by amendments and adjustments. This diploma thesis describes these acts with respect to their evolution and actual state of knowledge. At European level, it shows the evolution of the European environmental law in focus on the protection of the ozone layer and on the process of incorporation of international instruments in this area of environmental law. It describes these European acts and compares the...

Le stress oxydant est un acteur clé dans les réponses des plantes à des conditions contraignantes. En raison de la complexité de la régulation de l’état redox cellulaire, il reste beaucoup à élucider concernant les interactions entre différentes composantes dans ces conditions. Grâce à une approche de génétique inverse basée sur un mutant d’Arabidopsis déficient en catalase (cat2) qui présente des modifications d’état redox prévisibles et bien définies, cette étude a exploré les interactions entre le stress oxydant et (1) un gène spécifique impliqué dans la déphosphorylation des protéines, (2) des enzymes spécifiques impliquées dans les systèmes antioxydants réducteurs. Les résultats obtenus révèlent que la sous-unité B'γ de la protéine phosphatase de type 2A (PP2A-B'γ) est importante dans la détermination des phénotypes et des réponses de défense photopériode-dépendantes chez cat2. En conditions de jours courts (SD), un double cat2 pp2a-b'γ mutant montrait une gamme de réponses qui n’étaient pas observées chez cat2. Ces effets comprenaient l’apparition de lésions ainsi que l’accumulation de l’acide salicylique et d’autres composés de défense. Des analyses métabolomiques et protéomiques ont permis de démontrer que ces effets étaient accompagnés de modifications de l’abondance de métabolites et protéines spécifiques, ainsi que des changements dans le statut de phosphorylation de certains polypeptides. Dans un deuxième volet du travail, l’importance d’une enzyme productrice du NADPH a été évaluée en produisant des doubles cat2 nadp-me2 mutants chez lesquels l’isoforme majeure de l’enzyme malique cytosolique n’est plus exprimée. Malgré une induction de cette enzyme par le stress oxydant aux niveaux de transcrits et d’activité, et une diminution importante de l’activité foliaire associée aux mutations nadp-me2, peu de différence a été observée entre les lignées cat2 et cat2 nadp-me2. De même, la mutation nadp-me2 n’a pas affecté la réponse phénotypique de plantes exposées à l’ozone. Dans la troisième partie du travail, le couplage entre les pools ascorbate et glutathion lors du stress oxydant a été exploré par l’introduction de mutations pour la déshydroascorbate réductase (DHAR) dans le fond génétique cat2. L’activité extractible de cette enzyme a été diminuée à des niveaux très faibles chez des lignées portant à la fois les mutations dhar1 et dhar3. Cependant, peu de différence a été observée dans les phénotypes et les statuts d’ascorbate et de glutathion chez un triple mutant cat2 dhar1 dhar3 par rapport à cat2. Des analyses préliminaires d’un quadruple cat2 dhar1 dhar2 dhar3 mutant semblent pourtant indiquer que les trois DHARs jouent des rôles fonctionnellement redondants dans le stress oxydant. Dans son ensemble, ces travaux apportent des données nouvelles sur les enzymes qui régulent les réponses aux stress oxydants et ont généré des outils intéressants pour des études ultérieures. / Oxidative stress is a key player in plant responses to challenging environmental conditions. The intricate nature of the regulation of cellular redox state means that much remains to be elucidated on interactions between different components in these conditions. By using a genetic approach based on a catalase-deficient Arabidopsis mutant (cat2) that presents well-defined, predictable changes in redox state, this study explored interactions between oxidative stress and (1) a specific gene involved in protein dephosphorylation, and (2) specific enzymes involved in the antioxidative/reducing system. The results showed that protein phosphatase 2 subunit B'γ (PP2A-B'γ) is involved in determining day length-dependent phenotypes and related defense responses in cat2. A cat2 pp2A-B'γ double mutant showed a range of responses that were not observed in cat2 grown in short days, including lesion formation and accumulation of salicylic acid (SA) and related metabolites. Metabolomics and proteomics analyses showed that these effects were associated with altered abundance of specific metabolites and proteins, as well as changes in protein phosphorylation status. A second part of the study investigated the importance of NADP-generating enzymes in oxidative stress by production of cat2 nadp-me2 double mutants, in which the cytosolic isoform of NADP-malic enzyme is knocked out. Although NADP-ME2 was shown to be induced by oxidative stress, and mutants for this gene had much decreased leaf NADP-malic enzyme activity, no effects on cat2 phenotypes or redox profiles were apparent. Similarly, phenotypic responses to ozone were not affected in an nadp-me2 single mutant. In the third part, coupling between ascorbate and glutathione pools during oxidative stress was investigated by introduction of loss of function mutations for dehydroascorbate reductase (DHAR) into the cat2 background. In lines carrying a combination of dhar1 and dhar3 mutations, extractable leaf activity was decreased to very low levels. Despite this, cat2 dhar1 dhar3 and cat2 phenotypes and ascorbate and glutathione pools were similar. However, preliminary functional analysis of a cat2 dhar1 dhar2 dhar3 quadruple mutant suggested that the three DHARs play functionally redundant roles in oxidative stress. Overall, the work provides new data on enzymes that regulate responses to oxidative stress and has produced interesting genetic tools for further study.

L'influence des paramétrisations chimiques et météorologiques sur les concentrations de polluants calculées avec un modèle de qualité de l'air est étudiée. L'influence des différences entre deux mécanismes chimiques de la phase gazeuse sur la formation d'ozone et d'aérosols en Europe est faible en moyenne. Pour l'ozone, les fortes différences observées localement proviennent principalement de l'incertitude associée à la cinétique des réactions d'oxydation du monoxyde d'azote (NO) d'une part et de la représentation des différents chemins d'oxydation des composés aromatiques d'autre part. Les concentrations d'aérosols sont surtout influencées par la prise en compte des précurseurs majeurs d'aérosols secondaires et le traitement explicite des régimes chimiques correspondant au niveau d'oxydes d'azote (NOx). L'influence des paramétrisations météorologiques sur les concentrations d'aérosols et leur répartition verticale est évaluée sur l'Île de France par comparaison à des données lidar. L'influence de la paramétrisation de la dynamique de la couche limite atmosphérique est importante ; cependant, c'est l'utilisation d'un modèle de canopée urbaine qui permet d'améliorer considérablement la modélisation de la répartition verticale des polluants / The influence of chemical mechanisms and meteorological parameterizations on pollutant concentrations calculated with an air quality model is studied. The influence of the differences between two gas-phase chemical mechanisms on the formation of ozone and aerosols in Europe is low on average. For ozone, the large local differences are mainly due to the uncertainty associated with the kinetics of nitrogen monoxide (NO) oxidation reactions on the one hand and the representation of different pathways for the oxidation of aromatic compounds on the other hand. The aerosol concentrations are mainly influenced by the selection of all major precursors of secondary aerosols and the explicit treatment of chemical regimes corresponding to the nitrogen oxides (NOx) levels. The influence of the meteorological parameterizations on the concentrations of aerosols and their vertical distribution is evaluated over the Paris region in France by comparison to lidar data. The influence of the parameterization of the dynamics in the atmospheric boundary layer is important ; however, it is the use of an urban canopy model that improves significantly the modeling of the pollutant vertical distribution