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1
Leather, Kimberley. "Tropospheric ozone and photochemical processing of hydrocarbons : laboratory based kinetic and product studies." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/tropospheric-ozone-and-photochemical-processing-of-hydrocarbons-laboratory-based-kinetic-and-product-studies(39b76a99-2358-4db2-be58-baa75d18efea).html.
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Laboratory based temperature-dependent kinetics and product yields for alkene ozonolysis and the reaction of CH3O2 with ClO and BrO have been measured via chamber studies and a turbulent flow tube coupled to CIMS (Chemical Ionisation Mass Spectrometry). In order to gain a better understanding of the fate of the products formed during hydrocarbon oxidation and their subsequent impact on the ozone budget (and so the oxidising capacity of the atmosphere) it is imperative to know the rate at which these reactions proceed and to identify their product yields. As tropospheric temperature varies, Arrhenius parameters were determined during the ozonolysis of selected alkenes. The temperature dependent kinetic database was extended and the activation energies for the ozonolysis of selected alkenes were correlated with an existing SAR (Structure Activity Relationship). Given the myriad organic species in the atmosphere, SARs are useful tools for the prediction of rate coefficients. Inclusion of Arrhenius parameters into the SAR allows for prediction over a range of temperatures, improving the conditions reflected in models. Achieving mass balance for alkene ozonolysis has proven to be a difficult challenge considering the numerous pathways of the Criegee Intermediate (CI). The product yield of formic acid – an organic acid with significant atmospheric implications which is under predicted by models – was determined as a function of relative humidity during ethene ozonolysis. This reaction exhibited a strong water dependence which lead to the prediction of the reaction rate of the CI with water which ranges between 1 × 10-12 – 1 × 10-15 cm3 molecule-1 s-1 and will therefore dominate its loss with respect to bimolecular processes in the atmosphere. Peroxy radicals, strongly influence the total oxidising capacity of the troposphere. The reaction of peroxy radicals with halogen oxides is recognised to be responsible for considerable ozone depletion in the atmosphere, exacerbated by reactive halogens (X, XO) taking part in catalytic cycles. Arrhenius parameters were determined for ClO + CH3O2 and BrO + CH3O2. Temperature is an important parameter affecting rate, exemplified here as the reaction involving ClO exhibited a positive temperature dependence whereas for BrO a negative temperature dependence was evident. As a consequence, the impact of ClO + CH3O2 with respect to ozone loss is diminished. Global modelling predicts a reduction in ozone loss by a factor of around 1.5 and implicates regions such as clean marine environments rather than the polar stratosphere. Conversely, a more pronounced temperature dependence for the reaction of BrO with CH3O2 placed particular importance on lower stratospheric chemistry where the modelled CH3O2 oxidation is doubled. The main products for this reaction were identified to be HOBr and CH2O2. The decomposition of CH2O2 could enhance HOx in the lower and middle stratosphere and contribute to a significant source of HOx in the upper troposphere. Bimolecular reaction of CH2O2 with water could also provide a none negligible source HC(O)OH in the upper troposphere. Alkenes and peroxy radicals undergo chemical processing in the atmosphere whilst acting as a source and sink of ozone and thus can impose detrimental effects on the biosphere, climate and air quality of the Earth.
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Atkinson, Roger John. "An observational study of the austral spring statosphere : dynamics, ozone transport, and the "ozone dilution effect"." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12448.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1993.Includes bibliographical references (p. 367-385).
by Roger John Atkinson.
Sc.D.
3
Clay, Emlyn Robert. "Validation and comparison of ozone-induced hypertussive responses in the rabbit and guinea-pig." Thesis, King's College London (University of London), 2015. http://kclpure.kcl.ac.uk/portal/en/theses/validation-and-comparison-of-ozoneinduced-hypertussive-responses-in-the-rabbit-and-guineapig(82b1fc29-9290-48b6-aeec-d34a20beafbe).html.
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The thesis investigates establishing a hypertussive model of cough primarily in the rabbit and with comparative experiments conducted in the guinea pig. These models were then used to investigate the effectiveness of various antitussives such as codeine and levodropropizine, as well as, putative antitussives such as anticholinergics, PDE inhibitors, bronchodilators and drugs affecting targets on sensory nerves. “Hypertussive” is a poorly recognised term and it is defined in the context of this thesis to describe an inappropriately frequent and/or loud cough response when compared to normative cough responses for the same given dose and route of a given tussive stimuli. A novel model of hypertussive cough responses was established and validated in the rabbit and guinea pig using ozone as a sensitising agent. Primary measures include cough frequency, cough magnitude, time to first cough and cough duration. In further experiments lung function parameters such as dynamic compliance and total lung resistance, and total and differential cell counts, as well as pilot experiments involving analyzing categories of cough “sounds” were measured. The thesis was also concerned with the measurement and classification of cough events and in particular the discrimination of cough events from sneeze events. Two commercially available systems and ad hoc approaches were used to evaluate how best to describe, count and classify the cough response and qualitative and quantitative judgement have been made to assess a best approach. In summary, the data in this thesis suggests that ozone is a particularly effective acutely-acting non-allergic sensitising agent capable of shifting the dose response curve of the cough response to citric acid leftward by 0.5 to 1 log units. Sensitization of the cough reflex overcame desensitization of rabbits and guinea pigs to citric acid, allowing cross-over designs to be employed. Ozone appears to act via sensitization of the peripheral airway sensory input, but I found no evidence that this was via an action on Transient Receptor Potential Ankyrin 1 (TRPA1), which has previously been suggested to be an important target for ozone. Codeine and levodropropizine were effective against hypertussive responses, but did not block the normotussive cough. Anticholinergic drugs were not effective against ozone sensitised cough nor normotussive cough responses in the rabbit, but significantly inhibited sensitised cough responses and normotussive cough responses in guinea pigs. However, salbutamol demonstrated a similar treatment profile to the anticholinergic drugs implying that bronchodilation is an important mechanism to reduce the cough response in guinea pigs. Thus, these data suggest that drug candidates that cause bronchodilation may falsely identify as antitussives in the guinea pig model. Phosphodiesterase inhibitors were effective at blocking the infiltration of leukocytes in both guinea pigs and rabbits, but did not effect the acutely sensitised cough, suggesting that in this model ozone is inducing hypertussive responses independently of leukocyte infiltration.
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Sloan, Daniela. "Effects Of Ozone On Blood Components." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1772.
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Previous studies on the medical use of ozone therapies show a very diverse array of results, from ozone reducing the amount of HIV virus in the blood, to no effect, to causing the death of several patients due to pulmonary embolism and infections. However, ozone therapies are widely used in Europe and considered medically safe. In the U.S., doctors in 28 states use ozone therapies.
The objectives of this study were to investigate the effects of medical grade ozone at varying concentrations used in ozone therapies. These were achieved by evaluating the C-reactive protein, erythrocyte sedimentation rate, total reduced and oxidized glutathione content of erythrocytes which were all markers used to determine ozone injury/inflammation.
Despite the fact that ozone is a very strong oxidant, previous research indicates that depending on the dose and the health status of the biological system, sometimes ozone can act as an antioxidant.
The medical exposure range for ozone is between 20-80 mg/ml with an average of 50 mg/ml. The concentrations used in this study were 20, 40, 80 and 160 mg/ml. Ozone was generated in the "Breath Lab" at USF from medical grade oxygen obtained through electrical corona arc discharge using an OL80C ozone generator. De-identified blood samples of 10 ml blood/sample containing EDTA as anticoagulant were obtained from the James A. Haley VA Hospital patients. Equal volumes of blood and ozone gas mixture were allowed to mix in ozone-resistant syringes prior to dividing each sample into three parts, one for each corresponding parameter to be studied. The C-reactive protein was analyzed through ELISA using the colorimetric method available from Helica Biosystems; erythrocyte sedimentation rate was measured in graduated sedimentation tubes; the total reduced glutathione (GSH) and oxidized glutathione (GSSG) content of erythrocytes was determined according to the colorimetric method developed by the Oxford Biomedical Research.
Overall, the concentrations of ozone used did not have a statistically significant effect on the parameters investigated. However, a small percentage of the blood samples showed an improvement in the parameters studied, especially at the highest ozone concentration.
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Lasry, Fanny. "Analyse par modélisation tridimentionnelle des processus physico-chimiques déterminant la production d'ozone : évaluation de l'impact de scénarios d'émissions prospectifs : application au site ESCOMPTE." Paris 12, 2006. https://athena.u-pec.fr/primo-explore/search?query=any,exact,990002346940204611&vid=upec.
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L'étude a visé à étudier les processus physico-chimiques déterminant la production d'ozone sur le site de Berre-Marseille, ainsi qu'à évaluer l'impact des scénarios d'émissions prospectifs. Pour cela, nous avons utilisé un modèle eulérien de chimie-transport pour simuler 24 journées de pollution à l'ozone. Ce modèle a dans un premier temps été adapté afin de restituer la dynamique de petite échelle ainsi que la chimie complexe du site. L'analyse des sorties du modèle nous a permis d'identifier les différents composés primaires et secondaires en présence durant un épisode ainsi que de localiser les sites de production d'O3. Un volet du rapport est consacré à l'étude des régimes chimiques et à l'identification des composés et secteurs d'activités participant le plus à la formation d'O3. Enfin, la mise en oeuvre de scénarios 2010 est exposée. Nous présentons un bilan de la qualité de l'air et discutons des effets d'une régulation des émissions aux échelles régionales et continentalesThis work aimed to study the physical and chemical processes determining ozone production on the Berre-Marseille area, and to evaluate the impact of prospectives emissions scenarios. In this purpose, we used a chemistry-transport eulerian model to simulate 24 ozone episodes. In a first step, this model has been adapted in order to restitute the small scale dynamic and the complex chemistry of the site. The model outputs analysis allowed us to identify the different primary and secondary compounds present during a photochemical episode, and to localize the ozone production sites. A section of the manuscript is dedicated to the study of the chemical regimes and to the identification of the compounds ans category of emitters which are the most invoved in ozone formation. Last, we expose the elaboration of emissions scenarios for the year 2010. We have drawn up an air quality balance sheet and we discuss the effects of emissions regulations at regional versus continental scales
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Hsiang, Solomon M. "Ozone chemistry during global glaciations : a possible climate feedback." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/114119.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2006.Cataloged from PDF version of thesis. Pages 77-78 missing from original thesis.
Includes bibliographical references (pages 76-84).
A theory for changes in ozone chemistry during late Proterozoic global glaciations is developed. The possible significance of temperature, humidity, nitrogen oxides, reactive chlorine, lightning frequency, surface deposition and albedo as altered constraints on ozone processes is discussed. An elementary box model is developed by the author to make first order judgments regarding the significance of chemistry changes on ozone concentrations and its climactic effect. A one dimensional photochemical-transport model (Kasting, 1995) was used to more precisely determine the effects of global glaciations on ozone concentrations up to 5 hPa in several latitude bands. Reduced NO₂ availability in the stratosphere seems to dominate ozone's response (positive anomalies) in the stratosphere. Low temperatures, low humidity, reduced lighting frequency and altered chlorine and nitrogen chemistry collectively reduce ozone presence in the troposphere, however the overall sign of the tropospheric ozone anomaly depends heavily on poorly characterized deposition rates. With output from the one-dimensional photochemistry model, a time-varying ozone concentration field was assembled for the entire planet and used in snowball runs of the General Circulation Model (NCAR Community Atmosphere Model 3.0). These runs were compared to a controlled snowball run with a modern ozone field to discern the climactic significance of altered ozone. Results suggest that ozone concentrations during global glaciations might directly produce global average surface radiation anomalies of -1.5 ~ 1.5 W/m² , resulting in global average surface temperature anomalies of -0.5 ~ 0.5°K. Magnitude and sign uncertainties result from poorly known deposition rates for ozone over frozen surfaces and the simplicity of the modeling technique. The indirect effect of increasing stratospheric ozone, i.e. a reduction in atmospheric oxidative capacity, may result in positive anomalies of other green house gasses and is discussed as an area for further research.
by Solomon M. Hsiang.
S.B.
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Bandoro, Justin. "Attribution of stratospheric ozone change and associated climate impacts." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/115780.
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Thesis: Ph. D. in Climate Science, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references.
Recognition of stratospheric ozone depletion as a significant global danger sparked the landmark international agreement of the Montreal Protocol to control the production of ozone depleting substances (ODSs). There are now signs of stratospheric ozone recovery, and it is essential to understand whether the observed historical changes, during both the depletion and recovery eras, are directly the result of secular changes in ODSs, or influenced by other anthropogenic and natural forcings such as greenhouse gases (GHGs) and solar variability. This thesis explores the climate impacts of stratospheric ozone depletion, and how we can attribute, with high confidence, the causes of observed changes in stratospheric ozone. First, the linkages between Antarctic ozone loss and midlatitude surface climate changes are investigated. Unusually hot summer extremes in Australia, South America and Africa were found to be associated with elevated levels of ozone the previous November, and that this link has only emerged in the era of the Antarctic ozone hole. This study provides motivation for understanding the causes of ozone changes, showing direct impacts to regions where humans live. Second, a formal detection and attribution study of stratospheric ozone change is presented. A multi-satellite observational dataset and simulations from a chemistry climate model are analyzed. An improvement to conventional fingerprint attribution methodology is presented that accounts for nonlinearities in the temporal evolution of anthropogenic forcings. High confidence in the detection of ODSs upon observed stratospheric ozone change is shown. Detection of a GHG signal, in stratospheric ozone, is projected to emerge in the mid-21st century. Third, the improved attribution methodology is applied to seasonal atmospheric circulation changes. Reanalysis products and simulations from a multimodel assessment are used. Positive detection of both ODS and GHG fingerprints is found during the months of December- May, with the ODS signal dominating in the Southern Hemisphere. Ultimately, the results of this thesis further our scientific understanding of the role of ODSs in climate change, and provide new steps for future detection and attribution studies of the climate system.
by Justin Bandoro.
Ph. D. in Climate Science
8
Guthrey, Delparde Raleigh. "Time series analysis of ozone data." CSUSB ScholarWorks, 1998. https://scholarworks.lib.csusb.edu/etd-project/1788.
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Haskins, Jessica D. "The effects of volcanic aerosols on mid-latitude ozone recovery." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90662.
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Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 30-31).
In this paper, comparisons between the derived Chemistry Climate Model Initiative aerosol data set to balloon sonde measurements of aerosols made in Laramie, Wyoming are made between 1979- 2012. Using the derived CCMI aerosol data set as the input for surface area density of aerosols in the Specified Dynamics-Whole Atmosphere Climate Community Model (SD-WACCM), the impacts of volcanic aerosols on mid-latitude ozone loss are investigated. These results are compared to the ozone column expected recovery from a run of SD-WACCM with no volcanic eruptions in the same period. Particular emphasis is placed on the last decade to investigate how the small volcanic eruptions that have characterized the period of 2008-2012 have impacted the ozone column recovery during this time at northern mid-latitudes as atmospheric chlorine levels decrease from regulation. It is found that the CCMI aerosol data set underestimates aerosol surface area density between the local tropopause and approximately 70mbar in the lower stratosphere. This underestimation is corrected and the resulting change in the ozone column is compared to the initial model output with no volcanic aerosols. Using the correct aerosol values, it is shown that ozone loss in the lower stratosphere after these small, recent volcanoes rivals that of the post-Pinatubo years around 1995-1996.
by Jessica D. Haskins.
S.B.
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Kim, Judy E. (Judy Eunhee). "Physical chemistry of acid systems relevant to stratospheric ozone depletion." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/54401.
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Paode, Rajendra 1961. "Ozone and peroxone induced particle destabilization, microflocculation and coagulant savings." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/278116.
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This research addressed the role of ozone and peroxone (ozone plus hydrogen peroxide) in particle destabilization, microflocculation, and as a coagulation aid at a pilot scale water treatment facility for Colorado River Water and State Project Water. Different treatment scenarios included: (i) alum, (ii) ozone/peroxone with alum, and (iii) ozone/peroxone with ferrous sulfate. While particle destabilization was observed at all dosages of ozone and peroxone, microflocculation was observed only at lower ozone dosages and the peroxone treatments. Ozone/peroxone plus alum treatments gave improved flocculation and overall filtered water quality. Pre-oxidation with 2.5 mg/L of ozone reduces alum requirements by 50 percent. Overall, in terms of particle destabilization and microflocculation and as a coagulation aid, peroxone performed better than ozone. FeSO4 appeared to be a more effective flocculant that alum.
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Nzotungicimpaye, Claude-Michel. "Local variation and regional transport of tropospheric ozone over Cape Town." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/12862.
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Includes bibliographical references.[Fix subscripts in abstract.] The attractive image of Cape Town is threatened by periods of poor air quality occurring most often between April and September, during episodes of brown haze. When this haze occurs, it appears in the morning as a layer of concentrated pollution, likely to be associated with photochemical pollutants such as tropospheric ozone (O3) and some of its precursors. Previous studies have identified local emission sources and meteorological conditions associated with both the air pollution and the brown haze in Cape Town. However, due to the transport of air pollutants, emissions from remote sources may also contribute to air pollution levels in Cape Town. This dissertation investigates the local variation and the regional-scale transport of atmospheric pollution over Cape Town, with a focus on O3 pollution. The study analyses O3 observations from local air quality stations and uses two atmospheric chemistry-transport models to simulate the photochemical pollution over southern Africa.
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Carlson, Jodi A. "Procerum root disease physiology and disease interactions with ozone." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/37445.
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Zhang, Renyi. "Laboratory investigations of heterogeneous chemistry important to ozone depletion in the stratosphere." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/12219.
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Kin, Kon-Tsu 1964. "Oxidation of trace organic impurities in ultrapure water by UV and ozone." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282177.
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In this dissertation, the chemical oxidation of trace organic impurities by the treatment of UV light alone, ozone alone, and the combination of UV light and ozone in ultrapure water is discussed. Eighteen model compounds are chosen as the representative organic contaminants. Significant synergistic removal effect by the oxidation of the combination of UV light and ozone has been observed on all model compounds except for trichloroethylene, benzoic acid, and methionine. The removal efficiency by the oxidation of the combined treatment is observed to be greater than that by the oxidation of UV light alone or ozone alone for all model organics. Based on the same injected amount of contaminants over a given period of time, it is shown that the amount of leftover material after one cycle in the loop in a run with ozone injection is lower than that in a run without ozone injection for most compounds. The photolytic ozonation improves the TOC removal efficiency not only on the UV unit, but also on the loop removal performance. The chemistry, advantages and disadvantages of all those three oxidative methods are discussed. The mechanisms of oxidative reaction for the UV/ozone interactions and of ion exchange in the deionized tank are proposed. The rate coefficient of each reaction for model compound is determined by fitting the model prediction to the experimental data. The metrology for modeling the whole ultrapure water system has been established. The mathematical derivations for that metrology are given. For the purpose of paving the road for the reuse of rinsing wastewater, three cases simulating TOC dynamic responses are discussed, and the chemistry between HCl and organics under the treatment of UV light alone is studied. The combined UV/ozone reaction has been proven to be a better way in removing organic contaminants in terms of particles population number density. The mathematical equation of particle size reduction with its breakage rate and fragmentation distribution function is proposed and validated with the experimental data. It is concluded that the surface erosion is the pathway of size reduction when organic particles are oxidized.
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Niedfeldt, Emily. "Efficacy of treating waterborne pathogens with the antimicrobials ozone and trichloromelamine." Thesis, The University of Arizona, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1563207.
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There has been a recent surge in the number of people using reclaimed water systems for personal use. Because of this, it is getting more and more important for easy-to-use and cost effective disinfectants on the market for consumer application. This study looked at the efficacy of three disinfectants, trichloromelamine, ozone and acetic acid, for their ability to reduce the number of waterborne pathogens. Four samples of TCM were tested in a 10mL contaminated water:1mL TCM solution ratio and plated for both total plate counts and to check for generic E.coli. It was found that one of the four samples of TCM (TCM 3) was able to not only give a percent reduction of 92.54%, but it also killed the E.coli that was present in the water. TCM1 had an average percent reduction of 98.77, TCM2's percent reduction was 97.34, and TCM4's: 87.64. This was not the most effective disinfectant, however. Similar tests were done with ozone, ozone that was mixed with brine water, and ozone that was mixed with acetic acid, as well as pure acetic acid. Ozonated brine water, and ozone mixed with acetic acid were both nearly 100% effective at reducing bacterial load in the water samples (99.989 and 100%, respectively). The pure ozone was not nearly as effective, with a percent reduction of 85.7%. These results indicate that TCM and ozone could possibly be effective tools for the consumer to use to disinfect water holding tanks, however, more testing needs to be done in order to find out exactly how effective these products are in the long term, as well as to find the contact time needed for effective kill by TCM.
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Kargiolaki, Hariklia. "The response of poplar clones to atmospheric pollution by ozone and sulphur dioxide." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253283.
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Alvarado, Matthew James. "Formation of ozone and growth of aerosols in young smoke plumes from biomass burning." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45606.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 272-291).
The combustion of biomass is a major source of atmospheric trace gases and aerosols. Regional and global-scale models of atmospheric chemistry and climate take estimates for these emissions and arbitrarily "mix" them into grid boxes with horizontal scales of 10-200 km. This procedure ignores the complex non-linear chemical and physical transformations that take place in the highly concentrated environment of the young smoke plumes. In addition, the observations of the smoke plume from the Timbavati savannah fire [Hobbs et al., 2003] show much higher concentrations of ozone and secondary aerosol matter (nitrate, sulfate, and organic carbon [OC]) in the smoke plume than are predicted by current atmospheric chemistry models. To address these issues, we developed a new model of the gas- and aerosol-phase chemistry of biomass burning smoke plumes called ASP (Aerosol Simulation Program). Here we use ASP to simulate the gas-phase chemistry and particle dynamics of young biomass burning smoke plumes and to estimate the errors introduced by the artificial mixing of biomass burning emissions into large-scale grid boxes. This work is the first known attempt to simultaneously simulate the dynamics, gas-phase chemistry, aerosol-phase chemistry, and radiative transfer in a young biomass burning smoke plume. We simulated smoke plumes from three fires using ASP combined with a Lagrangian parcel model. We found that our model explained the formation of ozone in the Otavi and Alaska plumes fairly well but that our initial model simulation of the Timbavati smoke plume underestimated the formation of ozone and secondary aerosol matter. The initial model simulation for Timbavati appears to be missing a source of OH. Heterogeneous reactions of NO2 and SO2 could explain the high concentrations of OH and the rapid formation of ozone, nitrate and sulfate in the smoke plume if the uptake coefficients on smoke aerosols are large [O(10-3) and O(10-4), respectively]. Uncharacterized organic species in the smoke plume were likely responsible for the rapid formation of aerosol OC. The changes in the aerosol size distribution in our model simulations were dominated by plume dilution and condensational growth, with coagulation and nucleation having only a minor effect.
(cont.) We used ASP and a 3D Eulerian model to simulate the Timbavati smoke plume. We ran two test cases. In the reference chemistry case, the uncharacterized organic species were assumed to be unreactive and heterogeneous chemistry was not included. In the expanded chemistry case, the uncharacterized organic compounds were included, as were heterogeneous reactions of NO2 and SO2 with uptake coefficients of 10-3 and 2x10-4, respectively. The 3D Eulerian model matched the observed plume injection height, but required a large minimum horizontal diffusion coefficient to match the observed horizontal dispersion of the plume. Smoke aerosols reduced the modeled photolysis rates within and beneath the plume by 10%-20%. The expanded chemistry case provided a better match with observations of ozone, OH, and secondary aerosol matter than the reference chemistry case, but still underestimated the observed concentrations. We find that direct measurements of OH in the young smoke plumes would be the best way to determine if heterogeneous production of HONO from NO2 is taking place, and that these measurements should be a priority for future field campaigns. Using ASP within an Eulerian box model to evaluate the errors that can be caused by the automatic dilution of biomass burning emissions into global model grid boxes, we found that even if the chemical models for smoke plume chemistry are improved, the automatic dilution of smoke plume emissions in global models could result in large errors in predicted concentrations of O3, NOx and aerosol species downwind of biomass burning sources. The thesis discusses several potential approaches that could reduce these errors, such as the use of higher resolution grids over regions of intense biomass burning, the use of a plume-in-grid model, or the use of a computationally- efficient parameterization of a 3D Eulerian plume chemistry model.
by Matthew James Alvarado.
Ph.D.
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Beddows, Andrew Victor. "Sensitivity and uncertainty analysis of episodic ozone predictions from the community multiscale air quality model." Thesis, King's College London (University of London), 2016. https://kclpure.kcl.ac.uk/portal/en/theses/sensitivity-and-uncertainty-analysis-of-episodic-ozone-predictions-from-the-community-multiscale-air-quality-model(bc02e41c-3024-4c1d-a440-adee0d18e836).html.
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The first global variance-based sensitivity analysis of ozone and NO2 concentrations produced by the CMAQ model during the July 2006 ozone pollution episode over the UK has been performed. Gaussian process emulation methods have been employed to overcome the problems caused by long model run times which have previously prevented such analyses being undertaken. The computationally efficient Morris' method was used to rank the effect of perturbations in 223 model input variables, including all of the gas-phase species in the model domain chemical boundary conditions and emissions, and all of the reaction rates in the carbon bond five core chemical mechanism. The 30 most influential variables were combined with ozone deposition velocity to emulate the effects of perturbations in 31 input variables on the modelled concentrations of ozone and NO2. These emulators were then used in place of CMAQ in Fourier amplitude sensitivity tests, which decompose the variance induced in model output when all of the inputs are perturbed together into contributions from each of those inputs. These tests were performed for every hour of a 21 day time series spanning the episode and several days either side, for a number of locations around the UK. The results reveal a complex spatio-temporal pattern of model sensitivities, with NO and isoprene emissions, NO2 photolysis and ozone deposition velocity and boundary conditions being amongst the most inuential input uncertainties. The same emulators were used in a Monte Carlo uncertainty analysis of modelled ozone concentrations. The results of this analysis were used with a simple Bayesian weighting procedure to calibrate the model inputs, which led to a significant improvement in peak afternoon ozone predictions. Calibrated UK and EU NO and NO2 emissions were between 1.27 and 1.38 times the baseline values, suggesting that official NOx emissions totals may be substantially underestimated.
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Kuttippurath, Jayanarayanan. "Physics and chemistry of stratospheric ozone and interactions with climate change." Habilitation à diriger des recherches, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00920539.
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L'ozone est un constituant important dans la chimie de l'atmosphère, cela malgré sa faible concentration. L'ozone stratoshérique joue un rôle essentiel à la fois dans la régulation des radiations ultraviolettes du soleil connues pour être dangereuses aux différentes formes de vie sur Terre et également dans l'équilibre radiatif influençant le climat global. Cette thèse est consacrée à l'étude de l'évolution temporelle et spatiale de l'ozone stratosphérique polaire entre 1979 et 2012, ainsi qu'à son interaction avec le changement climatique, avec une attention particulière pour les années après 2000. L'analyse de la dynamique des hivers arctiques révèle une augmentation des évènements de forts réchauffements (EFR) ces dernières années (comparaisons faites entre les hivers 1998/99 et 2009/10). Alors qu'on compte 13 EFRs lors des 12 derniers hivers (soit 11EFR/décennie), le nombre moyen entre les hivers 1957/58 et 2009/10 s'élève à 7 EFR/décennie. Une étude chimique de la destruction de l'ozone lors des 17 derniers hivers (1993/94-2009/10) montre que celle-ci est inversement proportionnelle à l'intensité des EFRs. De même, il semble que, pour chaque hiver, plus l'EFR se produit tôt dans l'année (Décembre-Janvier), plus la perte d'ozone enregistrée est faible. Ainsi la fréquence des EFRs lors des récents hivers arctiques joue un rôle significatif sur la concentration moyenne d'ozone stratospherique dans l'hémisphère Nord et par conséquent également sur le climat arctique et global. Une analyse détaillée de la destruction d'ozone lors des hivers arctiques 1996/97 et 2002/03-2010/11 montre que l'hiver 2002/03 a subit un EFR et trois réchauffements mineurs. Pourtant, lors de cet hiver, une grande quantité d'ozone a été détruite à la fin du mois de mars. Environ 1.5 ppmv détruit entre 450 et 500 K, ou 65 DU entre 400 et 550 K qui s'ajoutent aux 0.7 ppmv détruit au mois de décembre (il s'agit de la plus forte perte d'ozone enregistrée au mois de décembre entre les hivers 1988/89 et 2010/11). La plus forte perte d'ozone enregistrée sur un hiver entier lors de cette décennie a été observée en 2010/11 (soit environ 2.5ppmv entre 400-500K ou 140DU entre 350-550K). L'étude montre également que, pour la première fois depuis que nous observons l'ozone, la quantité d'ozone détruite lors de cet hiver est comparable à celle détruite lors de certains hivers en Antarctique. Nous montrons que cette destruction d'ozone record est due à une activation des chlorines et une denitrification importante et prolongée lors de cet hiver. La perte d'ozone lors des autres hivers est de l'ordre de 0.7 à 1.6 ppmv autour de 475 K ou 40 à 115 DU entre 350 et 550 K (la plus petite destruction d'ozone ayant été mesurée lors de l'hiver 2005/06, particulièrement chaud). Pour l'Antarctique, une méthode est proposée pour estimer la tendance à long terme de la destruction chimique de l'ozone. Cette méthode est utilisée sur la période 1989-2012 pour estimer, en colonne totale, les tendances d'ozone à partir d'observations au sol et satellitaires. A l'intérieur du vortex polaire, nous montrons que la perte moyenne d'ozone se situe entre 33-50% pendant la période 1989-1992. Cette valeur est en accord avec l'augmentation de la concentration d'halogène lors de cette même période. Après cette période, la perte moyenne d'ozone semble atteindre une valeur de saturation aux alentours de 48%. La destruction d'ozone lors des hivers les plus chauds (e.g. 2002 et 2004) est légèrement inférieure (37-46%) et celle des hivers les plus froids (e.g. 2003 et 2006), légèrement supérieure (52-55%). La perte maximum d'ozone en Antarctique est observée entre le milieu du mois de septembre et le milieu du mois d'octobre, et la plus forte valeur de perte d'ozone est observée entre fin août et début septembre, atteignant en moyenne 0.5%/jr. Des analyses basées à la fois sur des profils d'ozone simulés grâce à un modèle haute résolution et sur des profils observés par instrument satellitaire lors des 7 hivers antarctiques entre 2004 et 2010, montrent également que les plus fortes pertes d'ozone coincident avec les hivers les plus froids de 2005 et 2006. Lors de ces deux hivers, la perte d'ozone a atteint 3.5 ppmv entre 450 et 550 K, ou 180 DU entre 350 et 850 K. Les deux hivers les plus chauds (2004 et 2010) ont connu les plus faibles pertes d'ozone (environ 2.5 ppmv entre 450 et 550 K, ou 160 DU entre 350 et 850 K). En Antarctique, l'altitude du maximum de destruction d'ozone est 500 K, cependant, pendant les hivers les plus froids et les hivers les plus chauds, ce maximum est 25 K plus haut (respectivement plus bas). Ce déplacement du maximum de perte permettant ainsi clairement de distinguer les hivers froids des hivers chauds. Cette étude montre également que la relative faible perte d'ozone ainsi que le trou d'ozone des récents hivers antarctiques (2004-2010) sont due à des phénomènes de réchauffement moindre.
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Valuntaitė, Vaida. "The Investigation and Assessment of the Man-made Ozone Formation and Dispersion." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090608_190741-86415.
Full textAbstract:
The dissertation comprises the general characteristic of the work,
5 chapters, conclusions and recommendations, references and list of published works on the topic of the dissertation. The dissertation covers 149 pages,
78 illustrations, 17 tables.
In introduction chapter the problem topicality is considered, the aims and tasks of the work are formulated, the novelty of the research is described, the author’s reports and publications as well as the dissertation structure are presented. Chapter 1 is intended for the review of literature. The survey of ozone sources in working premises and the environment air is presented as well as methods of the ozone concentration determination and its dispersion simulation are discussed. At the end of the chapter conclusions are formulated and the dissertation tasks are concretized. In chapter 2 the methodology of the ozone concentration determination with the ozone analyzer and passive samplers as well as the measurement methods of aerosol particles and meteorological, microclimatic parameters are described. In chapter 3 the results obtained during experimental investigations are discussed: the ozone concentration changes near technogenic sources of this pollutant, the influence of meteorological and microclimatic parameters on the ozone concentrations changes, the relation of aerosol particles with the ozone concentration. Ozone concentrations measured by different methods are compared and the results of comparative measurements are... [to full text]Disertaciją sudaro įvadas, 5 pagrindiniai skyriai, darbo išvados ir rekomendacijos, literatūros sąrašas, publikacijų sąrašas. Bendra disertacijos apimtis – 149 puslapiai, 80 iliustracijų, 17 lentelių. Įvadiniame skyriuje nagrinėjamas problemos aktualumas, formuluojamas darbo tikslas bei uždaviniai, aprašomas mokslinis darbo naujumas, pristatomi autoriaus pranešimai ir publikacijos, disertacijos struktūra. Pirmasis skyrius skirtas literatūros apžvalgai. Jame pateikta ozono šaltinių darbo patalpose ir aplinkos ore apžvalga, aptariami ozono koncentracijos nustatymo ir jos sklaidos modeliavimo metodai. Skyriaus pabaigoje formuluojamos išvados ir konkretinami disertacijos uždaviniai. Antrajame skyriuje aprašomi ozono koncentracijos nustatymo ozono analizatoriumi ir pasyviaisiais kaupikliais metodika bei aerozolio dalelių ir meteorologinių, mikroklimato parametrų matavimo metodai. Trečiajame skyriuje aptariami eksperimentinių tyrimų metu gauti rezultatai apie: ozono koncentracijos kitimą prie technogeninių šio teršalo šaltinių, meteorologinių ir mikroklimato parametrų įtaką ozono koncentracijos pokyčiams, aerozolio dalelių sąryšį su ozono koncentracija. Lyginamos ozono koncentracijos matuotos skirtingais metodais ir aptariami lyginamųjų matavimų rezultatai. Ketvirtajame skyriuje pateikti RISK programa sumodeliuoti ozono sklaidos nuo šaltinio rezultatai. Penktajame skyriuje pasiūlytas technologinis sprendimo variantas, leidžiantis sumažinti ozono koncentracijas prie technogeninių... [toliau žr. visą tekstą]
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Chittrakorn, Sasivimon. "Use of ozone as an alternative to chlorine for treatment of soft wheat flours." Diss., Manhattan, Kan. : Kansas State University, 2008. http://hdl.handle.net/2097/575.
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Goldman, Jeffrey Scott. "Time and place specific policies for controlling ozone precursor nitrogen oxides in New England's electric power sector." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/35422.
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Colette, Augustin. "Etude expérimentale et numérique de l' influence des processus de transport depuis la couche-limite sur la variabilité et le bilan d' ozone troposphérique." Paris 6, 2005. https://tel.archives-ouvertes.fr/tel-00011438.
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Robson, Thomas Matthew. "Response of a peatland ecosystem to stratospheric ozone reduction in Tierra del Fuego." DigitalCommons@USU, 2004. https://digitalcommons.usu.edu/etd/6605.
Full textAbstract:
Tierra del Fuego, at the southernmost tip of South America, is influenced by ozone depletion. The landscape of southern and western Tierra de! Fuego is dominated by peatlands; they are important locally and in the context of global climate change, because they store large quantities of organic carbon.
To determine the influence of solar ultraviolet-B radiation (UV-B) on a Tierra de! Fuego peatland, we selectively filtered solar UV-Bin ten pairs of plots. Polyfluorine filters were used to create the Near-Ambient-UV-B Treatment ( 90% solar UV-B), and polyester filters to create the Reduced-UV-B Treatment ( 17% solar UV-B). These filters were first installed in October 1996, and were maintained, September-March, for six years. Following previous plant growth measurements and samples of selected microorganisms under the two UV-B treatments (1996-1999), this dissertation is an account of the more detailed measurements made during the second three-year period of treatments (1999-2001 ). Seasonal sampling of the plant community, microfungi, microfauna, and biogeochemistry of the water and nutrients held by the Sphagnum capitulum was introduced, in an attempt to better understand ecosystem function.
Solar UV-B reduced Sphagnum height growth, but this was compensated by more compressed and densely packed Sphagnum capitula. Emergent vascular plants, Nothofagus, Empetrum, and Tetroncium, were more affected than Sphagnum by nearambient UV-B. Solar UV-B altered the Sphagnum-capitulum microenvironment, resulting in: more dissolved organic carbon and phosphorous, higher electrical conductivity, and greater acidity under near-ambient UV-B. Additionally, the populations of testate amoebae and some species of fungi were consistently increased; however, microfungal diversity and rotifer, nematode, and mite populations decreased under near-ambient UV-B.
Generally, Sphagnum minimizes the leaching of nutrients by effectively holding water at the capitulum. Solar UV-B altered Sphagnum-capitulum morphology, increased the volume of water held, and made this water more acidic and richer in nutrients. Based on these results, if current trends in ozone depletion were to persist over several decades, a reduction in vascular plant growth, and changes in the trophic relationships of the microorganismal community of the Sphagnum capitulum, would be predicted. These responses have the potential to affect peatland carbon storage and nutrient cycling in Tierra del Fuego.
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Farhat, Nawal. "The association of ozone and fine particulate matter with mortality and hospital admissions in 12 Canadian cities." Thesis, University of Ottawa (Canada), 2009. http://hdl.handle.net/10393/28271.
Full textAbstract:
Many recent epidemiological studies have linked health effects with short-term exposure to air pollution levels commonly found in North America. The association of ozone and fine particulate matter with mortality and hospital admissions in 12 Canadian cities was explored in a time-series study. City-specific estimates were obtained by Poisson regression models adjusting for the confounding effects of seasonality and temperature. Estimates were then pooled across cities using the inverse variance method. Results suggest significant associations across all outcomes except cardiovascular hospital admissions. Generally, stronger associations were found among the elderly. Effect estimates were robust to adjustment for seasonality confounding but were sensitive to lag structures. Considering the large population exposed to air pollution, reductions in ozone and particulate matter would lead to considerable health benefits.
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Rider, Elizabeth Ndayu. "Air quality applications of extreme value theory : return levels of extreme ozone events in Chicago and surrounding areas." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/114094.
Full textAbstract:
Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 21-24).
To quantify the effects of the NO, SIP call in urban and rural locales, surface ozone data from the Air Quality System is analyzed. Methods from extreme value theory are applied to calculate and compare 20-year return levels at 5 urban and 17 rural/suburban sites in Illinois based upon maximum daily 8-. hour average ozone concentrations from summer (JJA) for two periods (1992- 2002 and 2003-2013) and a threshold of 70 (ppb). Between the two periods, 21 out of 22 sites experienced a decrease in 20-year return levels. The magnitude of these decreases does not indicate a strong correlation between population density and air quality improvements, however, further analysis is required.
by Elizabeth Ndayu Rider.
S.B.
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Hennessy, John 1980. "High mobility germanium MOSFETs : study of ozone surface passivation and n-type Dopant channel implants combined with ALD dielectrics." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/58174.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 107-111).
Germanium offers higher electron and hole mobility than silicon, making it an attractive option for future high-performance MOSFET applications. To date, Ge p-channel device behavior has shown promise, with many reports of measured hole mobilities exceeding that of Si. However, Ge n-channel devices have shown poor performance due to an asymmetric distribution of interface state density (Dit) that degrades electrostatic behavior and carrier mobility. In this work, two methods are investigated for improving the performance of Ge MOSFETs. First, the formation of an interfacial passivation layer via in-situ ozone oxidation is explored. Long channel Ge p- and n-MOSFETs are fabricated with A12 0 3 and HfO2 gate dielectrics deposited by atomic layer deposition (ALD). The ozone surface passivation is observed to result in significant mobility enhancement for all devices, with particularly dramatic improvement in the n-FETs compared to devices with no passivation layer. Measurements of interface state density show a reduction across the entire Ge bandgap. Further improvement of the interface quality has been observed to occur in the presence of n-type channel implants in Ge n-FETs and this effect is studied. All n-type species investigated in this work (P, As, Sb) are seen to result in significant electron mobility enhancement, particularly at low inversion densities. Ge n-FETs receiving channel implants of As or Sb along with the ozone surface passivation exhibit effective electron mobilities higher than Si electron mobility under some conditions of surface electric field for the first time. Substrate bias measurements and low temperature characterization both suggest a reduction in Dit, primarily of acceptor-like trap states near the conduction band.
by John J. Hennessy.
Ph.D.
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Kalapati, Raga S. "Analysis of Ozone Data Trends as an Effect of Meteorology and Development of Forecasting Models for Predicting Hourly Ozone Concentrations and Exceedances for Dayton, OH, Using MM5 Real-Time Forecasts." University of Toledo / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1091216133.
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Miller, Emily N. "Degradation of Emerging Contaminants by Advanced Oxidation Using Multi-Walled Carbon Nanotubes and Continuous Ozone Injection." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2094.
Full textAbstract:
With a growing population and continuous accumulation of pollutants, water resources worldwide are quickly being depleted. Drastic improvements need to be made in both water conservation and treatment. Advanced oxidation processes (AOPs) have been developed to go above and beyond the capabilities of traditional wastewater treatment facilities to eliminate emerging contaminants from our water systems. AOPs increase the generation of hydroxyl radicals (•OH) in oxidation reactions, which are less selective and more reactive than other oxidants, such as ozone, so they are more effective at degrading persistent compounds. This study explored an AOP that utilizes ozonated multi-walled carbon nanotubes (MWCNTs) to generate •OH; past research has proven the success of this method of water treatment, showing a significant decrease in the effluent concentration of the tested compounds. However, these previous studies used a batch system with an initial aliquot of ozone, which would not be a feasible option in a commercial application. This research compares results from a semi-batch system with a continuous injection of ozone to these previous batch system studies to determine if continuous ozonation improves •OH generation capability, contaminant degradation, and the associated reaction kinetics. Results from batch studies had shown limitations to both •OH generation and contaminant degradation which were suspected to be due to ozone degradation; however, these results suggest that ozone availability is in fact not a limiting factor to •OH or contaminant degradation, and another mechanism must be at play. Further, to advance the AOP toward a commercially feasible design, a continuous flow-through system with a MWCNT embedded membrane was explored. The continuous system achieved 80% contaminant degradation in some cases, however, with varying retention times and efficiencies over time, the results were inconclusive and additional experimentation is required.
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Lamoureux, Tara. "Ozone and GAC Treatment of a Central Florida Groundwater for Sulfide and Disinfectant By-Product Control." Master's thesis, University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5656.
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This study evaluated the combination of ozone and granular activated carbon (GAC) treatment for the removal of sulfide and disinfection byproduct (DBP) precursors in drinking water at the pilot-scale. The research conducted was performed at the Auxiliary (Aux) and Main Water Treatment Plants (WTPs) in Sanford, Florida. Both WTPs rely upon groundwater sources that contain total sulfide ranging from 0.02 to 2.35 mg/L and total organic carbon (TOC) ranging from 0.61 to 2.20 mg/L. The Aux WTP’s raw water contains, on average, 88% more sulfide and 24% more TOC than the Main WTP. Haloacetic acids (HAA5) and total trihalomethanes (TTHMs) comprise the regulated forms of DBPs. HAA5 are consistently below the maximum contaminant level (MCL) of 60 μg/L, while TTHM ranges from 70 to 110 μg/L, at times exceeding the MCL of 80 μg/L in the distribution system. Ozone alone removed total sulfide and reduced UV-254 by about 60% at the Aux Plant and 35% at the Main Plant. Producing an ozone residual of 0.50 mg/L prevented the formation of bromate while removing approximately 35 to 60% concentration of DBP precursors as measured by UV-254. Operating the GAC unit at an empty bed contact time (EBCT) of 10 minutes for the Aux Plant and 5.5 minutes for the Main Plant resulted in 75% and 53% of UV-254 reduction, respectively. The average 120 hour TTHM formation potential for the Aux and Main Plants were 66 μg/L and 52 μg/L, respectively, after treatment by ozone and GAC. GAC exhaustion was deemed to have occurred after seven weeks for the Aux Plant and eleven weeks for the Main Plant. The GAC columns operated in three phases: an adsorption phase, a transitional phase, and a biologically activated carbon (BAC) phase. The GAC adsorption phase was found to produce the lowest TTHMs; however, TTHMs remained less than 80 μg/L during the BAC stage at each plant. BAC exhaustion did not occur during the course of this study. Ozone-GAC reduced chlorine demand by 73% for the Aux Plant and 10% for the Main Plant.M.S.Env.E.
Masters
Civil, Environmental and Construction Engineering
Engineering and Computer Science
Environmental Engineering
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Gaudel, Audrey. "Variabilité inter-annuelle de 20 ans de mesure de l'ozone troposphérique par lidar et sondes électrochimiques à l'Observatoire de Haute Provence (OHP)." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://tel.archives-ouvertes.fr/tel-00943908.
Full textAbstract:
L'ozone est un constituant minoritaire secondaire de l'atmosphère. C'est un gaz à effet de serre et un polluant nocif pour la biodiversité dans la troposphère. Il peut être transporté de la stratosphère ou de la couche limite vers la troposphère libre et parcourir de longues distances au-dessus des continents et des océans. L'objectif de cette thèse est de contribuer à l'analyse des tendances à long terme des concentrations d'ozone dans la troposphère et à la compréhension des sources de cette variabilité temporelle. Pour cela, nous avons utilisé les mesures de deux instruments basés à l'Observatoire de Haute Provence (OHP) dans le sud de la France (44˚N, 6.7˚E), des sondes ECC (Electro-chemical Concentration Cell) embarquées sous ballon et un lidar UV DIAL. Les travaux menés au cours de cette thèse ont montré qu'il est indispensable de les combiner pour prendre en compte la diversité des conditions météorologiques. En effet, notre analyse montre un biais systématique d'environ 1.3 ppb entre les moyennes saisonnières obtenues avec chacun des instruments qui est compatible avec les résultats des campagnes d'inter-comparaison mais qui est beaucoup plus faible que les différences importantes (> 7 ppb) dues à la variabilité du transport du fait des différences d'échantillonnage. En combinant les deux jeux de données, le lien entre la variabilité de l'ozone et celle du transport (NAO, hauteur de la tropopause, origine des masses d'air) a été étudié. Dans la haute et moyenne troposphère aucune tendance significative n'est observée, malgré une corrélation significative avec la NAO et un changement pour la dernière décennie dans les apports d'ozone à 500 hPa pour certains régimes de transport. En revanche, une tendance négative après 2000 est observée dans les basses couches. Elle peut être expliquée par une augmentation de la couche de mélange accompagnée d'une augmentation des flux de sud et une diminution de l'apport en ozone pour ces régimes de transport. La caractérisation des masses d'air arrivant à l'OHP avec d'autres paramètres tels que l'humidité spécifique, la vorticité potentielle et les aérosols a permis d'expliquer certaines sources de variabilité des concentrations d'ozone. L'apport des mesures d'aérosol issues de deux ans d'observations du lidar spatial CALIOP reste cependant limité et d'autres mesures d'aérosols doivent être prises en compte.
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Mena, Marcelo Andrés. "Improving emissions inventories in North America through systematic analysis of model performance during ICARRT and MILAGRO." Diss., University of Iowa, 2007. https://ir.uiowa.edu/etd/153.
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During 2004 and 2006 the University of Iowa provided air quality forecast support for flight planning of the ICARTT and MILAGRO field campaigns. A method for improvement of model performance in comparison to observations is showed. The method allows identifying sources of model error from boundary conditions and emissions inventories. Simultaneous analysis of horizontal interpolation of model error and error covariance showed that error in ozone modeling is highly correlated to the error of its precursors, and that there is geographical correlation also. During ICARTT ozone modeling error was improved by updating from the National Emissions Inventory from 1999 and 2001, and furthermore by updating large point source emissions from continuous monitoring data. Further improvements were achieved by reducing area emissions of NOx y 60% for states in the Southeast United States. Ozone error was highly correlated to NOy error during this campaign. Also ozone production in the United States was most sensitive to NOx emissions. During MILAGRO model performance in terms of correlation coefficients was higher, but model error in ozone modeling was high due overestimation of NOx and VOC emissions in Mexico City during forecasting. Large model improvements were shown by decreasing NOx emissions in Mexico City by 50% and VOC by 60%. Recurring ozone error is spatially correlated to CO and NOy error. Sensitivity studies show that Mexico City aerosol can reduce regional photolysis rates by 40% and ozone formation by 5-10%. Mexico City emissions can enhance NOy and O3 concentrations over the Gulf of Mexico in up to 10-20%. Mexico City emissions can convert regional ozone production regimes from VOC to NOx limited. A method of interpolation of observations along flight tracks is shown, which can be used to infer on the direction of outflow plumes. The use of ratios such as O3/NOy and NOx/NOy can be used to provide information on chemical characteristics of the plume, such as age, and ozone production regime. Interpolated MTBE observations can be used as a tracer of urban mobile source emissions. Finally procedures for estimating and gridding emissions inventories in Brazil and Mexico are presented.
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Daudé, Barthélémy. "Développement d'un photomètre UV pour des mesures de référence de gaz d'intérêt atmosphérique : ozone et COVs." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00828177.
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La détermination de la section efficace d'absorption de composés atmosphériques est indispensable pour leurs mesures de concentration. Plus les valeurs de sections efficaces sont exactes, meilleure est la détermination des concentrations atmosphériques. À l'heure actuelle, la valeur de la section efficace d'absorption de l'ozone à 253,65 nm servant de standard pour la mesure de concentration de l'ozone est entachée d'une erreur de 2% et est controversée. Pour cette raison, nous avons développée un photomètre permettant d'obtenir des sections efficaces d'absorption avec une très bonne exactitude à 253,65 nm. Le but était d'atteindre une précision inférieure à 1 %. Le photomètre réalisé a été testé sur le styrène, un composé organique volatil (COV) aromatique. Les COVs comme l'ozone sont des polluants de la troposphère qui absorbent fortement dans l'UV. Outre son intérêt de molécule test, le styrène comme de nombreux COVs, a une section efficace d'absorption dans l'UV connue avec une mauvaise précision. La forte absorbance du styrène nous a obligé à travailler en basse pression (en dessous de 1 Torr). Dans ce domaine de pression, il apparaît une non-linéarité dans la mesure de pression que nous avons corrigée en mesurant la transpiration thermique du styrène. Nous avons donc obtenu la première mesure de transpiration thermique d'une molécule aromatique. Grâce à une estimation précise des erreurs et des corrections faites, nous avons montré que le photomètre réalisé atteignait bien une précision inférieure au %. Nous avons obtenu une section efficace absolue d'absorption du styrène de 1,521E−17 cm^2 avec une incertitude de 0,6 % pour un intervalle de confiance de 95 %.
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Neves, Neuza Maria Santos. "Formação e dispersão de ozônio na região do Recôncavo Baiano." reponame:Repositório Institucional da UFBA, 2009. http://www.repositorio.ufba.br/ri/handle/ri/11753.
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Ozônio pode afetar a saúde humana sendo a ele atribuída a responsabilidade por centenas de milhares de mortes prematuras a cada ano e por centenas de internações hospitalares adicionais, além da perda de milhões de dias de trabalho. Estes impactos na saúde são causados tanto por exposições a longo prazo (crônica) quanto a curto prazo (aguda). De forma semelhante a que ocorre atualmente próximo às grandes cidades do mundo e aos centros industriais, as concentrações ambientais de ozônio estavam ultrapassando o padrão de qualidade do ar estabelecido no Brasil, nas vizinhanças do Pólo Petroquímico de Camaçari, especialmente durante os anos de 2000 a 2003. Com o objetivo de avaliar a formação e dispersão de ozônio na região do Recôncavo Baiano, foi desenvolvido um estudo, usando modelagem matemática, para melhor compreender as principais fontes dos precursores de ozônio, bem como sua formação e dispersão na referida região. A metodologia adotada no estudo foi a elaboração de um inventário de emissões atmosféricas para as regiões urbanas e industriais e utilização do modelo matemático fotoquímico denominado STEM III – Sulfur Transport and Deposition Model, da Universidade de Iowa (USA), para simular a formação e dispersão deste poluente fotoquímico secundário na atmosfera na região do Recôncavo Baiano. Os resultados do modelo foram comparados com as concentrações medidas por uma rede de monitoramento contínuo da qualidade do ar do Pólo Petroquímico, referente a um período em abril de 2003. Concluiu-se que os resultados calculados para ozônio na região do Recôncavo Baiano, através do modelo matemático STEM são adequados, uma vez que há concordância satisfatória com os dados medidos. Os desvios encontrados ocorreram especificamente durante os episódios com baixas velocidades do vento, quando foram registrados picos de concentrações deste poluente próximo ao Pólo Petroquímico de Camaçari. Os modelos matemáticos meteorológicos não descrevem adequadamente a situação real quando a velocidade do vento é inferior a 1 m/s. ix Os resultados das simulações demonstram que a formação de ozônio ocorre em regiões situadas muito além dos locais onde estão situadas as estações de monitoramento do ar do Pólo, e atinge áreas distantes de Salvador e da região industrial, como Feira de Santana e Santo Estevão, situadas a jusante dos ventos que sopram do quadrante Este, predominantes na região. Todas as concentrações calculadas para ozônio foram inferiores ao limite de 160 µg/m3 estabelecidas pela Resolução CONAMA 003/90, para períodos horários e portanto, não deverão causar impactos na saúde humana. No entanto as concentrações encontradas até cerca de 100 a 150 Km das fontes consideradas podem afetar os ecossistemas pois as concentrações máximas simuladas estão próximas do limite de 40 ppb.h (do inglês:Accumulated Dose Over Threshold of 40 ppb.h - AOT40), na região Oeste e Noroeste do domínio estudado. O regime de formação de ozônio na região de Camaçari e de Candeias é limitado pelo NOx, e as reduções das emissões de NO2 efetuadas pelo Pólo Petroquímico à partir de 2004 resultaram na eliminação das violações dos limites de ozônio na sua região de influência. Considerando-se o atual cenário de desenvolvimento do Brasil, em dez anos as concentrações de ozônio nas áreas costeiras do Recôncavo poderão representar uma ameaça para a produtividade agrícola desenvolvida na região situada no interior da Bahia, e eventualmente poderão representar também uma ameaça para a saúde humana, a depender do aumento das emissões, particularmente veiculares.
Salvador
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Marston, Kathryn G. "Effect of sorghum flour treated with ozone and heat on the quality of gluten-free bread and cake." Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/2266.
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Sun, Lin S. M. Massachusetts Institute of Technology. "A cost-effectiveness analysis of alternative ozone control strategies : flexible nitrogen oxide (NOx) abatement from power plants in the eastern United States." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53060.
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Thesis (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2009.Includes bibliographical references (leaves 90-93).
Ozone formation is a complex, non-linear process that depends on the atmospheric concentrations of its precursors, nitrogen oxide (NOx) and Volatile Organic Compounds (VOC), as well as on temperature and the available amount of sunlight. The dependence of ozone formation on meteorology makes the timing of emissions important, suggesting the need for a temporally differentiated regulation for NOx emissions. Such a flexible NOx regulation policy, so-called "smart trading", which is designed to target ozone episodes by reducing NOx emissions prior to and during forecasted episodes, has the potential for reducing the compliance cost and helping to solve the persistent ozone non-attainment problem in the Eastern United States. However, the total compliance cost of this new policy depends critically on the accuracy of ozone forecasting. This thesis aims to address the question of whether a NOx trading program that differentiates across emissions by time could reduce ozone concentrations more cost-effectively than the conventional command-and-control method in the Eastern U.S. given the uncertainty in ozone forecasting. A cost-effectiveness analysis is conducted to compare the average cost for achieving a certain amount of ozone reduction under the proposed smart trading plan and the command-and-control policy. The probability distribution of the compliance cost under a smart trading policy is simulated using a stochastic decision model based on the simulated electricity generation and air quality data.
(cont.) This study demonstrates the scientific and economic feasibility of a time-differentiated trading scheme. I explore whether such a regulatory design is justifiable with respect to ozone forecast accuracy by conducting sensitivity analysis of ozone prediction errors and discover that uncertainty in ozone forecasting may not be a major limiting factor for the feasibility of a time-differentiated NOx cap-and-trade program.
by Lin Sun.
S.M.in Technology and Policy
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Craig, Michael T. (Michael Timothy). "Reducing the contribution of the power sector to ground-level ozone pollution : an assessment of time-differentiated pricing of nitrogen oxide emissions." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/90030.
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Thesis: S.M. in Technology and Policy, Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2014.Title as it appears in MIT commencement exercises program, June 2014: Reducing the contribution of the power sector to peak concentrations of ground-level ozone: an assessment of time-differentiated pricing of nitrogen oxide emissions. Cataloged from PDF version of thesis.
Includes bibliographical references (pages 95-102).
Nitrogen oxide (NOx) is a prevalent air pollutant across the United States and a requisite precursor for tropospheric (ground-level) ozone formation. Both pollutants significantly impact human health and welfare, so National Ambient Air Quality Standards (NAAQS) have been established for each. As of 2013, over 100 million people in the U.S. lived in areas with ozone concentrations above the NAAQS. NOx emissions from the power sector, roughly 12% of total NOx emissions, are and will be significant contributors to ozone concentrations in the U.S. As such, states have reduced peak ozone concentrations through technology-based standards and cap-and-trade programs on NOx emissions from the power sector. These policies have largely treated NOx emissions uniformly. But marginal damages from NOx emissions are greatest on hot sunny days when meteorological conditions favor high ozone formation rates and, consequently, peak ozone concentrations. This thesis informs what type of policy is the most efficient for reducing peak ozone concentrations on high ozone days by assessing the cost-effectiveness of three policies for reducing NOx emissions on high ozone days. Emissions and costs under a relatively-novel differentiated policy, time-differentiated pricing, are compared for the first time to two currently-implemented undifferentiated policies, cap-and-trade and technology-based standards. Two power systems are studied, Texas and the Mid-Atlantic. A unique two-phase model is developed to capture the short- (re-dispatching) and long-term (control technology installation) effects of pricing schemes on power plants. The two-phase model dispatches generators with a unit commitment model, which, unlike past studies, captures real-world operational constraints of generators that may strongly influence emissions and costs under time-differentiated pricing. Technology-based standards are simulated via Monte Carlo analysis to capture the uncertain rule-making process. For reducing NOx emissions on high ozone days in both power systems, time-differentiated pricing is shown to be the most cost-effective policy with regards to producer and consumer costs. Most emissions reductions are due to substitution of gas- for coal-fired generators, as control technology installations are only observed at very high time-differentiated prices. For reducing summer-wide NOx emissions, undifferentiated pricing is the most cost-effective. In a minority of allocations, technology-based standards also achieve more cost-effective summer-wide reductions than time-differentiated pricing, but such allocations cannot be guaranteed ex ante. These results suggest that time-differentiated pricing is the most efficient policy for reducing peak ozone concentrations, depending on ozone formation rates.
by Michael T. Craig.
S.M. in Technology and Policy
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Powell, William W. "The removal of color and DOC from segregated dye waste streams using ozone and Fenton's reagent followed by biotreatment." Thesis, Virginia Polytechnic Institute and State University, 1992. http://hdl.handle.net/10919/50105.
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The decolorization of reactive dye-containing waste streams using oxidizing chemicals and the determination of the effect of the oxidizing agents on the subsequent biotreatment of the streams was investigated. Three oxidizing schemes were chosen for study: molecular ozone, base-promoted ozonation, and Fenton’s reagent (Fe²⁺ and H₂O₂). The ADMI color value of the solutions was used as the primary parameter for color comparison and dissolved organic carbon (DOC) removal was the measure of the effect of biodegradation.
Three different waste streams from a textile dyeing facility were chosen: a Navy slack washer effluent from a pad-dyeing operation, a Navy dyebath effluent from a dyejet, and a Brilliant Blue dyejet effluent. Pure dye solutions were oxidized as well to determine the effect of interfering species in the waste streams.
The results demonstrated that base-promoted ozonation was more effective than molecular ozone for the decolorization of the Navy slack washer effluent. In both cases the ADMI color value could be decreased by 82% but almost half as much ozone was necessary for the high pH trials. The high pH ozonation proved more effective for the Navy jet-dye effluent, as well, achieving a much lower color value with less ozone. Greater decolorization (96%) of the Navy jet-dye effluent was achieved by Fenton’s reagent than for either of the ozonation schemes. Ozonation of the Brilliant Blue jet-dye bath showed no dependence on pH and the color value of the solution was reduced could be 63%.
The results indicate that the dyes were selectively oxidized by ozonation and the amount of ozone required for decolorization depended mainly the initial color of the dye waste stream. The amount of hydrogen peroxide required for Fenton’s reagent oxidation depended on the initial DOC of the dye waste stream.
Oxidation of the wastewater streams proved to neither enhance nor hinder the operation of the biological reactors. The color removals by biological activity were minimal for both control and experimental reactors. Dissolved carbon removal was not enhanced by oxidative pretreatment.Master of Science
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Karat, Irma. "Advanced Oxidation Processes for removal of COD from pulp and paper mill effluents : A Technical, Economical and Environmental Evaluation." Thesis, KTH, Industriell ekologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121350.
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In Sweden, the dominating source for emissions of degradable organic substances to water is the pulp and paper industry. The organic substances increase oxygen consumption in the recipient which subsequently threatens aquatic species. Improved process engineering, process closures and use of external treatments have in recent years drastically lowered the Biological Oxygen Demand (BOD). However, the Chemical Oxygen Demand (COD) has not been reduced to the same extent, as some organic substances are more persistent and must be treated with more advanced techniques. Chemical precipitation, which can bind large parts of the remaining COD into solid matter, making it possible to be removed from the effluent by various separation technologies, contributes to an efficient COD removal. However, the direct operating cost for the treatment is high as large amount of chemicals are used in the process, and large quantities of sludge generated. In the near future EU pulp and paper industry will have to meet new regulatory demands on COD discharges, and pulp mills in Asia, South-America and Oceania will meet stringent discharge demands. It is therefore of interest to review alternative treatments in regards to technical, environmental and economical feasibility in the treatment of pulp and paper mill wastewaters. Much interest has been shown for Advanced Oxidation Processes (AOP), which is why these techniques have been evaluated in this thesis. The first part of the report consists of a literature review where processes with the following oxidants have been reviewed: 1. Ozone (O3); 2. Ozone + Hydrogen peroxide (O3/H2O2); 3. Fenton’s reagent (Fe2+/ H2O2); 4. Ozone + Ultraviolet light (O3/UV); 5. Hydrogen peroxide + Ultraviolet light (H2O2/UV); 6. Photo-Fenton’s reagent (Fe2+/ H2O2/UV); 7. Titanium dioxide + Ultraviolet light (TiO2/UV). Ozone treatment (1) and ozone in combination with hydrogen peroxide (2) were chosen for further experimental studies. The experiments were conducted at Wedecos (Xylem Water Solutions) laboratory in Germany and tested on wastewater from three different Swedish mills: A, B and C. The experimental results indicate that treatment with ozone is an efficient method for elimination of COD from pulp and paper mill wastewaters. A relatively high COD reduction (41 % for Mill A, 31% for Mill B and 53% for Mill C) was achieved for all wastewaters with an applied ozone dosage of 0.2g O3/L, without an appreciable impact on other parameters such as pH, N-tot, NO2-, NO3-, NH4+, P-tot and PO43-. There are indications that the nature of the wastewater has an impact on the COD removal efficiency and that TMP wastewater is easier to oxidize in comparison to wastewater from sulphate mills. The combination with hydrogen peroxide did not show any further COD reduction compared to ozone treatment alone, thus confirming the results Ko et al. showed in their study in 2009. Oxidation with ozone is seen as more environmental alternative in comparison to chemical treatment (precipitation/flocculation) because contaminants in the wastewater are destructed rather than concentrated or transferred into a different phase, which leads to the decrease of COD, colour and toxicity without the need to handle large amounts of sludge. However, a subsequent biological treatment may be necessary for removal of BOD as a BOD increase is registered for all wastewater treated in this study. The costs are on the other hand higher in comparison to chemical treatment even though there are indications of cases when treatment with ozone can be profitable (e.g. if the cost for sludge handling increases in the future, price for chemicals increases and electricity price decreases). There are some uncertainties regarding the system and there is no clear evidence that toxic by-products are not formed. More research must be done and more full-scale installations must be reported before the pulp and paper industry is willing to invest in oxidation technology.I Sverige, är massa- och pappersindustrin den dominerande utsläppskällan av nedbrytbart organiskt material till vatten. När det organiska materialet når recipienten ökar syreförbrukningen eftersom stora mängder syre erfordras för nedbrytningen av materialet. Detta leder i sin tur till att de vattenlevande organismerna hotas och utsätts för syrebrist. Förbättrad processteknik, ökad processlutning och utbyggnad av extern avloppsvattenrening har under de senaste åren drastiskt sänkt den biokemiska syreförbrukningen (BOD). Däremot har den kemiska syreförbrukningen (COD) inte reducerats i samma utsträckning då delar av det organiska materialet är mer persistent och måste behandlas med mer avancerad teknik. Kemisk fällning kan idag binda stora delar av det kvarvarande COD till fast material som sedan kan avlägsnas via olika separationsmetoder. En stor nackdel med den här typen av rening är att stora mängder kemikalier används som i sin tur genererar stora mängder slam som måste tas om hand, vilket introducerar höga driftkostnader. Inom en snar framtid kommer massa- och pappersbruk inom EU att möta nya regulatoriska krav för COD utsläpp, och bruk i Asien, Sydamerika och Oceanien kommer även de att möta väldigt hårda utsläppskrav. Det är därför av intresse att granska alternativa reningsmetoder och utvärdera dess tekniska, miljömässiga och ekonomiska genomförbarhet vid behandling av avloppsvatten från massa- och pappersbruk. Mycket intresse har visats för Avancerade Oxidationsprocesser (AOP), varför dessa tekniker valts att utvärderas i detta examensarbete. Första delen av rapporten innefattar en litteraturstudie där processer med följande oxidanter studerats: 1. Ozon (O3); 2. Ozon + Väteperoxid (O3/H2O2); 3. Fenton’s reagens (Fe2+/ H2O2); 4. Ozon + Ultraviolett ljus (O3/UV); 5. Väteperoxid + Ultraviolett ljus (H2O2/UV); 6. Foto-Fenton’s reagens (Fe2+/ H2O2/UV); 7. Titaniumdioxid + Ultraviolett ljus (TiO2/UV). Utav dessa valdes ozon behandling (1) och ozon i kombination med väteperoxid (2) för vidare experimentella studier. Behandlingarna har utförts vid Wedecos (Xylem Water Solutions) laboratorium i Tyskland och undersökts på avloppsvatten från tre olika svenska bruk; A , B och C. Experimentella resultat tyder på att ozonering är effektiv behandlingsmetod för reducering av COD i avloppsvatten från massa- och pappersbruk. En relativt hög COD reducering (41% för bruk A, 31% för bruk B, och 53% för bruk C) uppvisades för samtliga avloppsvatten med en tillämpad ozondosering på 0.2 g O3/L, utan någon märkbar inverkan på andra parametrar så som pH, N-tot, NO2-, NO3-, NH4+, P-tot och PO43-. Det förekommer indikationer om att typ av avloppsvatten har en inverkan på COD reduktionen och att TMP avloppsvatten är lättare att oxidera i jämförelse mot avloppsvatten från sulfatmassabruk. Kombinationen av ozon och väteperoxid uppvisade ingen ytterligare COD reduktion i jämförelse mot ozon som enda oxidant, och bekräftade därmed de resultat Ko et al. uppvisade i sin studie 2009. Ozonering ses som ett miljövänligare alternativ till kemisk rening (fällning/flockning) eftersom föroreningarna i vattnet destrueras istället för att koncentreras, vilket innebär att COD, färg och toxicitet kan minskas utan att stora mängder slam genereras. Dock kan en efterföljande biologisk behandling vara nödvändig för avskiljning av BOD då en BOD ökning uppvisats för samtliga avloppsvatten i denna studie i takt med att COD brutits ned till lättnedbrytbart biologisk material. Kostnaderna är däremot höga i jämförelse mot kemisk fällning även om det förekommer indikationer på fall när behandlingen kan vara lönsam (t ex om slamhanteringskostnaderna blir högre i framtiden, inköpspriset för kemikalier ökar och elpriset sjunker). Det råder vissa tveksamheter gällande systemet och det finns inga konkreta bevis på att toxiska biprodukter inte bildas. Mer forskning måste utföras och fler fullskaliga installationer måste rapporteras och innan massa- och pappersindustrin är villig att investera i oxidationstekniken.
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Gopalapillai, Prijitha. "Evolution of stratospheric ozone in the mid-latitudes in connection with the abundances of halogen compounds." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2012. http://tel.archives-ouvertes.fr/tel-00733555.
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Cette thèse a pour objet l'étude de l'évolution à long terme de l'ozone stratosphérique, en liaison avec la variation de l'abondance des composés halogénés dans la moyenne atmosphère. Dans ce but, les longues séries de mesures sol et satellitaires de la distribution verticale d'ozone obtenues depuis les années 1980 sont évaluées dans six stations du Network for the Detection of Atmospheric Composition Changes (NDACC - réseau international de surveillance de la composition atmosphérique), pour déterminer les biais et dérives éventuelles entre les mesures. Les tendances d'ozone stratosphérique sont ensuite évaluées dans deux stations de moyenne latitude de l'hémisphère nord à l'aide d'un modèle statistique utilisant deux types d'indicateurs pour représenter l'évolution des substances destructrices d'ozone dans la stratosphère: (1) l'Equivalent Effective Stratospheric Chlorine (EESC - paramètre quantifiant l'effet des composés chlorés et bromés stratosphériques sur l'ozone) et (2) deux fonctions linéaires avec changement de pente en 1997. L'étude de tendance est effectuée pour les mesures du contenu intégré d'ozone dans les deux stations et les mesures de distribution verticale à l'Observatoire de Haute-Provence. L'étude utilise les mesures sol d'ozone obtenues par lidar (profil d'ozone), spectromètre Dobson (contenu intégré et profil d'ozone par la méthode Umkehr), ozonosondage (profil d'ozone) et spectromètre UV-Visible SAOZ (contenu intégré). Les observations satellitaires utilisées proviennent des instruments SBUV(/2), SAGE II, HALOE, UARS MLS, Aura MLS et GOMOS. Tout d'abord une étude de la sensibilité des mesures lidar aux sections efficaces d'ozone utilisées dans l'algorithme de restitution est effectuée. La différence relative d'ozone obtenue à partir des mesures restituées à l'aide de différents jeux de données de section efficace reconnues par les instances internationales, est inférieure à ±1% entre 10 et 35 km à toutes les latitudes (à l'exception de -1.5 % à 15 km aux tropiques). Au-dessus de 35 km, l'écart s'accroit, avec un maximum à 45 km de 1.7 % aux tropiques et un minimum de 1.4 % aux hautes latitudes. La stabilité des différentes séries de mesures satellitaires et sol de la distribution verticale d'ozone est ensuite évaluée à partir de la comparaison avec les mesures lidar dans les six stations NDACC considérées au cours de la thèse. Le meilleur accord (±3%) entre les mesures issues des différentes techniques et les mesures lidar est obtenu entre 20 et 40 km. Dans ce domaine d'altitude, la dérive entre les différentes mesures est inférieure à ±0.3%yr−1. Des dérives et des biais comparativement plus importants sont calculés en dessous de 20 km et au-dessus de 40 km. Par ailleurs, la stabilité à plus long terme des mesures d'ozone est étudiée à partir de séries temporelles combinant les différences relatives entre les mesures lidar et les mesures SAGE II et HALOE d'une part avec les différences relatives entre les mesures lidar et les les mesures Aura MLS d'autre part. Les dérives estimées à partir de ces séries composites couvrant 27 années de mesure sont très faibles, de l'ordre de ±0.2%yr−1. Enfin les tendances évolutives du contenu intégré d'ozone sont évaluées à l'Observatoire Météorologique de Hohenpeissenberg (MOHp - Allemagne) à partir des mesures du spectromètre Dobson et à l'Observatoire de Haute-Provence (OHP - France) à partir des mesures des spectromètres Dobson et SAOZ. A l'OHP, les tendances de la distribution verticale d'ozone sont calculées à partir des mesures obtenues par différentes techniques de mesures, sol et satellitaires. Pour ce faire, un modèle de régression multilinéaire est développé, fondé sur l'utilisation de différentes variables telles que l'oscillation quasi-biennale (QBO), l'oscillation Nord-Atlantique (NAO), le flux solaire, le flux de chaleur turbulent, l'épaisseur optique des aérosols stratosphériques et les tendances à long terme. L'estimation des tendances calculées à partir des mesures de contenu intégré d'ozone dans les deux stations fournit des valeurs significatives, de l'ordre de −1.4±0.29 DUyr−1) et 0.55±0.29 DUyr−1 respectivement avant et après 1997. Les valeurs positives de la tendance après 1997, significatives pour un intervalle de confiance de 95 %, montrent clairement un début de rétablissement de l'ozone stratosphérique à ces latitudes. Concernant la distribution verticale d'ozone, les tendances calculées à partir de la moyenne des différentes séries de données à l'OHP montrent des valeurs maximales en valeur absolue de l'ordre de −0.5±0.1 %yr−1 entre 16 et 22 km et de −0.8±0.2 %yr−1 entre 38 et 45 km avant 1997. Des tendances positives significatives (0.2±0.05-0.3±0.1 %yr−1) sont évaluées entre 15 et 45 km après 1996. Ces tendances significatives du profil vertical d'ozone avant et après 1997 corroborent les résultats obtenus à partir du contenu intégré d'ozone et confirment le début de rétablissement de l'ozone stratosphérique. Par ailleurs, dans les deux cas (contenu intégré d'ozone et distribution verticale), les tendances post-1997 restituées par le modèle utilisant les fonctions linéaires sont plus élevées que celles issues du modèle utilisant l'EESC, indiquant ainsi que d'autres paramètres contribuent à l'augmentation du contenu en ozone. Enfin, il a été constaté que les contenus intégrés élevés d'ozone observés ces dernières années étaient liés à l'influence de la QBO et des processus dynamiques. Ainsi la QBO, la NAO et le flux de chaleur turbulent expliquent environ 80 % de l'importante anomalie positive de 25 - 30 DU mesurée entre février et avril 2010.
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Penalver, Tatianne. "Etude d'un procédé de dépollution basé sur le couplage ozone/charbon actif pour l'élimination des phtalates en phase aqueuse." Phd thesis, Université d'Orléans, 2011. http://tel.archives-ouvertes.fr/tel-00674791.
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Le respect des normes de rejets aqueux industriels imposées par la directive cadre sur l'eau (échéances en 2021) concernant les micropolluants, et notamment les phtalates, nécessite la mise au point de procédés de traitement innovants. L'étude du procédé basé sur le couplage ozone/charbon actif a ainsi été effectuée. Après la détermination des propriétés chimiques et texturales des charbons actifs testés, l'efficacité de ce couplage pour l'élimination des phtalates a été éprouvée selon plusieurs critères : cinétique d'élimination des polluants cibles, évolution de la minéralisation et de la toxicité au cours du traitement. La comparaison des résultats obtenus avec ceux de méthodes classiques (ozonation et adsorption seules) a mis en évidence le fort potentiel du couplage ozone/charbon actif, qui permet d'obtenir une élimination rapide des polluants ainsi qu'une minéralisation et une détoxification avancées dans toutes les conditions expérimentales testées. Ce couplage c'est aussi révélé efficace lors du traitement de matrices plus complexes, telle qu'une eau de sortie de station d'épuration. En outre, cette étude a permis de déterminer les propriétés chimiques et texturales du charbon actif favorisant ce procédé. Il a aussi été montré que ce matériau joue un rôle d'initiateur et de promoteur de radicaux libres (les réactions sont très majoritairement de nature radicalaire) ainsi que de support réactionnel. Enfin, cette étude a montré qu'une régénération in situ du matériau, économiquement très intéressante, pourrait être obtenue au cours du traitement.
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Belova, Alla. "Studies of planetary waves in ozone and temperature fields as observed by the Odin satellite in 2002-2007." Doctoral thesis, Umeå University, Physics, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1819.
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The results presented in this PhD thesis are mainly based on measurements collected by the advanced sub-mm radiometer (SMR) aboard the Odin satellite in 2002-2007. The primary data are series of temperature and ozone profiles in the middle atmosphere up to 68 km. These data are used to estimate global properties of planetary wave propagation in both horizontal and vertical directions. As good-quality retrievals from Odin are not available above 68 km, additional data sources have been considered in order to extend coverage of planetary wave properties to higher levels. These sources are temperature observations at 85-90 km obtained by the ground-based meteor radars located in the polar region in the Northern Hemisphere in Scandinavia at Esrange and at Andenes, and in Canada at Resolute Bay and at Yellowknife. Also, the series of ozone profiles from the ground-based Kiruna mm-wave radiometer, KIMRA, are used in order to compare the wave properties in ozone fields measured globally by Odin and locally by KIMRA.
The main task of this PhD thesis is to study the 5-day planetary wave characteristics in the Earth’s atmosphere. The influence of waves on the atmospheric circulation causes, for example, substantial local departures from radiative equilibrium, observed in the winter stratosphere and close to the summer mesopause. Seasonal variations of the 5-day planetary wave properties and physical phenomena related to these variations are also studied in this thesis.
During winter, planetary waves propagate freely in the vertical direction, and maximal wave amplitudes are found in the extratropical stratosphere. The Northern Hemisphere (NH) winter periods of 2002-2003 and 2005 have been examined and a comparison has been carried out between the planetary wave properties in temperature and ozone variations. In general, the results show an expected in-phase behavior between the temperature and ozone fields in the lower stratosphere (due to dynamic effects) and an out-of-phase pattern in the upper stratosphere (which is expected as a result of photochemical effects).
Earlier theoretical and experimental studies have shown that, despite unfavourable summertime wind conditions, 5-day planetary waves can be registered not only in the stratosphere but also at higher altitudes in the mesosphere. The NH summers of 2003-2005 and 2007 have been considered and results have confirmed the existence of 5-day planetary waves up to the mesopause level (85-90 km). The results demonstrate that, for different periods, the possible source of the observed waves could be located at lower altitudes in both hemispheres with successive propagation into the summer mesosphere, or the waves could be generated in-situ as a result of the baroclinic instability of summer easterly jet.
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Johansson, Sara. "Coupling of the Weather Research and Forecasting model (WRF) with the Community Multiscale Air Qualitymodel (CMAQ), and analysing the forecasted ozone and nitrogendioxide concentrations." Thesis, Uppsala universitet, Luft-, vatten och landskapslära, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-303924.
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Air quality forecasts are of great value since several pollutants in our environment effect both human health, global climate, vegetation, crop yields, animals, materials and acidification of forests and lakes. Air-quality forecasts help to make people aware of the presence and the quantity of pollutants, and give them a chance to protect themselves, their business and the Earth. Many different air-quality models are in daily use all over the world, providing citizens with forecasts of air quality and warnings of unhealthy air quality if recommended highest concentrations are exceeded. This study adapts the WRF meteorological model (Weather research and Forecasting model) to be a driver of the CMAQ air-quality model (models-3 Community Multiscale Air Quality model). Forecasts of ozone and nitrogen dioxide concentrations from this coupled WRF/CMAQ modelling system are tested against observed data during a four-day period in May, 2006. The Lower Fraser Valley study area is a fertile valley surrounded by mountain chains in southwest British Columbia, Canada. The valley stretches from the Pacific coast eastwards towards the Rocky Mountains. This valley hosts more than 2 million people and it is west Canada’s fastest growing region. The Lower Fraser Valley holds a big city, Vancouver, several suburbs, numerous industries and a widespread agricultural production. During the analysed four-day period in May, a synoptic high-pressure built over the region, favoring high concentrations of pollutants as ozone and nitrogen dioxide. The created WRF/CMAQ model forecasted an acceptable magnitude of nitrogen dioxide but the daily variations are not recreated properly by the model. The WRF/CMAQ model forecasts the daily variation of ozone in a satisfying way, but the forecasted concentrations are overestimated by between 20 and 30 ppb throughout the study. Factors that could contribute to the elevated ozone concentrations were investigated, and it was found that the weather forecasting model WRF was not generating fully reliable meteorological values, which in turn hurt the air-quality forecasts. As the WRF model usually is a good weather forecasting model, the short spin-up time for the model could be a probable cause for its poor performance.Prognoser över luftkvaliteten är mycket värdefulla, då flera luftföroreningar i vår närmiljö påverkar människans hälsa, det globala klimatet, vegetation, djur, material och bidrar till försurning av skog och vattendrag. Luftkvalitetsprognoser gör människan mer medveten om närvaron av luftföroreningar och i vilken mängd de finns. De ger människan en chans att vidta skyddsåtgärder för att skydda sig själv, sitt eventuella levebröd, och Jorden. Många olika luftkvalitetsmodeller används idag dagligdags över hela världen och förser invånare med prognoser för luftkvaliteten och varningar om koncentrationerna av föroreningar överstiger rekommenderade värden. I denna studie används väderprognosmodellen WRF (Weather Research and Forecasting model) för att driva luftkvalitetsmodellen CMAQ (models-3 Community Multiscale Air Quality model). Prognoser av ozon- och kvävedioxidhalterna i luften från den kopplade WRF/CMAQ modellen analyseras mot observerade data under en fyra dagars period i maj, 2006. Studieområdet Lower Fraser Valley är en bördig dalgång som är omgiven av bergskedjor i sydvästra British Columbia, Kanada. Dalen sträcker sig från Stilla havskusten och österut mot Klippiga bergen. I denna dalgång bor mer än 2 miljoner människor och det är västra Kanadas snabbast växande region. Lower Fraser Valley rymmer en storstad, Vancouver, flera förorter, många industrier och även stora jordbruksområden. Den fyra dagars period i maj som analyseras karaktäriseras av ett högtrycksbetonat synoptiskt väderläge med lokala variationer, vilka tillsammans är gynnsamma för att uppmäta höga koncentrationer av luftföroreningar som ozon och kvävedioxid. Den skapade WRF/CMAQ modellen prognostiserar godtagbar magnitud hos kvävedioxid men den dagliga variationen återskapas inte av modellen. Modellen prognostiserar den dagliga variationen av ozonkoncentration på ett tillfredsställande sätt, men storleksmässigt ligger koncentrationerna en faktor 20-30 ppb för högt rakt av under hela studien. Kringliggande faktorer som kan påverka koncentrationen ozon studeras närmare och det framkommer att den meteorologiska prognosmodellen WRF inte genererar fullt tillförlitliga värden för en rättvisande luftkvalitetsprognos. Då WRF modellen vanligtvis är en bra prognosmodell kan den korta initialiseringstiden för modellen vara en trolig orsak till dess otillräckliga prestation.
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Scurich, Justin J. "STRAWBERRY GROWTH, YIELD, FRUIT NUTRITION, AND CONTROL OF VERTICILLIUM WILT WITH PRE-PLANT SOIL FUMIGANTS, OZONE, AND BIOLOGICAL CONTROL." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/714.
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Verticillium wilt is a widespread soilborne disease of strawberry historically controlled by soil fumigation with methyl bromide (MB). MB was banned by the United Nations in 1995 and will be completely phased out by 2015. Research has concentrated on alternative methods of disease control without finding a single alternative able to replace MB in widespread disease control and yield increase. For the current study, strawberries were greenhouse grown in container pots filled with soil from both infested and non-infested areas of a commercial strawberry field in Watsonville, CA. Treatments included pre-plant soil fumigation with commercially available formulations of methyl bromide, chloropicrin, and 1, 3-Dichloropropene. Additional treatments included ozone gas (six treatments) and biological control (three treatments). Collected data included total plant yield, individual berry weight, number of fruit produced per plant, plant vegetative weight, infection status, and mineral concentration of fruit (calcium, magnesium, potassium, iron, zinc, manganese, carbon, and nitrogen). Plants grown in ‘clean’ soil were less likely than plants grown in ‘infested’ soil to be infected with Verticillium. Plants grown in soil treated with MB had higher plant weight and yield than did non-treated control. Ozone and biological control treatments did not have statistically higher yield than non-treated control plants nor statistically lower yield than plants grown in soil treated with MB. Individual berry weights had a narrow range while the number of berries produced per treatment had a wide range. Data suggests strawberry yield is dependent on the number of berries produced per plant. Plants with high vegetative weight produced the highest yield suggesting large plants produce many berries resulting in higher yield.
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Brown, Amy Patricia. "Application of Ozone in Dissolved Air Flotation (DAF) for Enhanced Removal of TOC and Suspended Solids in Pulp and Paper Wastewaters." Master's thesis, Temple University Libraries, 2016. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/406436.
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Environmental EngineeringM.S.Env.E.
Pulp and paper mills are one of the top consumers of water related to industrial manufacturing, which ultimately leads to a large volume of heavily contaminated wastewater. This discharged effluent can have a harmful effect on the receiving aquatic environment and cause further ramifications downstream. Thus, a technically feasible and cost effective treatment solution for safe release from the mill is essential. Dissolved air flotation (DAF) has many applications and involves the formation of air microbubbles triggered by a drop to atmospheric pressure. When introduced into the wastewater, these microbubbles attach to the floc particles present and float to the surface. Another water treatment technology is ozone, a powerful oxidant, and has been widely used in water and wastewater treatment over recent decades, including color reduction in pulp and paper mill wastewater treatment. This thesis studied the effect pre-ozonation has on the DAF process in treating pulp and paper mill secondary effluent. Wastewaters from three mills with different initial water quality parameters were used, especially chemical oxygen demand (COD), turbidity, and color. The most suitable coagulant and coagulant aid, aluminum chlorohydrate and cationic polymer NS 4700P respectively, were selected, and an effective bench-scale experimental procedure was established. Pre-ozonation did not reduce the need for coagulant due to little change in the overall COD, color, or turbidity removal. However, ozonation did reduce color before coagulation, and the ultimate target removal of COD to 90 ppm was met with the conditions chosen.
Temple University--Theses
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Abdioskouei, Maryam. "Improving air quality prediction through characterizing the model errors using data from comprehensive field experiments." Diss., University of Iowa, 2018. https://ir.uiowa.edu/etd/6535.
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Uncertainty in the emission estimates is one the main reasons for shortcomings in the Chemistry Transport Models (CTMs) which can reduce the confidence level of impact assessment of anthropogenic activities on air quality and climate. This dissertation focuses on understating the uncertainties within the CTMs and reducing these uncertainties by improving emission estimates
The first part of this dissertation focuses on reducing the uncertainties around the emission estimates from oil and Natural Gas (NG) operations by using various observations and high-resolution CTMs. To achieve this goal, we used Weather Research and Forecasting with Chemistry (WRF-Chem) model in conjunction with extensive measurements from two major field campaigns in Colorado. Ethane was used as the indicator of oil and NG emissions to explore the sensitivity of ethane to different physical parametrizations and simulation set-ups in the WRF-Chem model using the U.S. EPA National Emission Inventory (NEI-2011). The sensitivity analysis shows up to 57.3% variability in the modeled ethane normalized mean bias (NMB) across the simulations, which highlights the important role of model configurations on the model performance.
Comparison between airborne measurements and the sensitivity simulations shows a model-measurement bias of ethane up to -15ppb (NMB of -80%) in regions close to oil and NG activities. Under-prediction of ethane concentration in all sensitivity runs suggests an actual under-estimation of the oil and NG emissions in the NEI-2011 in Colorado. To reduce the error in the emission inventory, we developed a three-dimensional variational inversion technique. Through this method, optimal scaling factors up to 6 for ethane emission rates were calculated. Overall, the inversion method estimated between 11% to 15% higher ethane emission rates in the Denver-Julesburg basin compared to the NEI-201. This method can be extended to constrain oil and NG emissions in other regions in the US using the available measurement datasets.
The second part of the dissertation discusses the University of Iowa high-resolution chemical weather forecast framework using WRF-Chem designed for the Lake Michigan Ozone Study (LMOS-2017). LMOS field campaign took place during summer 2017 to address high ozone episodes in coastal communities surrounding Lake Michigan. The model performance for clouds, on-shore flows, and surface and aircraft sampled ozone and NOx concentrations found that the model successfully captured much of the observed synoptic variability of onshore flows. Selection of High-Resolution Rapid Refresh (HRRR) model as initial and boundary condition, and the Noah land surface model, significantly improved comparison of meteorology variables to both ground-based and aircraft data. Model consistently underestimated the daily maximum concentration of ozone. Emission sensitivity analysis suggests that increase in Hydrocarbon (HC). Variational inversion method and measurements by GeoTAS and TROPOMI instruments and airborne and ground-based measurements can be used to constrain NOx emissions in the region.
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White, Madeleine Michael Isabella. "Optimization and Longevity of Functionalized Multi-Walled Carbon Nanotube-Enabled Membranes for Water Treatment." DigitalCommons@CalPoly, 2020. https://digitalcommons.calpoly.edu/theses/2174.
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Water scarcity is a growing concern at the global scale. Large scale water reuse is growing both in necessity and popularity. Before water reuse can be performed efficiently on a large scale or be used for potable supply, even indirectly, contaminants of emerging concern (CECs) will need to be treated at the full scale. Advanced oxidation processes (AOPs) are a form of advanced water treatment capable of treating a wide range of CECs. This study contributes to the growing field of AOPs and more specifically AOPs using ozone combined with functionalized multi-walled carbon nanotubes (MWCNTs). Ozonation of MWCNTs has been found to increase hydroxyl radical production and improve AOP treatment. Novel MWCNT-enabled membranes were used as catalysts for ozonation to degrade the CEC Atrazine. Atrazine is an ozone recalcitrant CEC that is commonly found in herbicides. Atrazine removal results, found using a high-performance liquid chromatograph (HPLC), were inconsistent between membranes constructed using identical procedures. Further analysis using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopes (SEM), and UV-Vis spectrophotometry was conducted to explore inconsistencies in construction of the membranes which might explain removal inconsistencies and predict membrane longevity. Removal was found to be influenced by filtration time and ozone exposure. Ozone exposure and filtration time influence percent removal because they both affect hydroxyl formation. The membrane test filtration duration, for equal filtered volumes, ranged from under 5 minutes to nearly an hour. It is believed that filtration time inconsistency was due to inconsistent MWCNT loading on the surface of the membranes. Extended exposure to ozone might change the surface chemistry of the MWCNTs on the membrane surface, affecting hydroxyl radical production. Additionally, repeated use of the membrane created surface defects that might reduce the membrane strength. This study found that the lifetime of the membrane is far past what was simulated in lab and further testing must be performed.
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Levermore, Thorpe Dianne Marie. "Design, construction and operation of an automated vapor pressure determination apparatus (I). II, Gas chromatography/mass spectrometry headspace analysis of engine oil, III, Design of a chemically selective layer for ozone detection." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/30491.
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Pletkutė, Lina. "Trumpalaikė ozono koncentracijos kaita atmosferos pažemio sluoksnyje." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20100701_092116-04961.
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Baigiamajame magistro darbe nagrinėjama trumpalaikė ozono koncentracijos kaita ir jos priklausomybė nuo meteorologinių parametrų. Literatūros apžvalgoje aptariama ozono susidarymas, cheminės savybės, poveikis žmogaus sveikatai ir augalams. Atlikta 2000-2009 metais Preilos monitoringo stotyje gautų duomenų (vienos valandos vidurkiai) analizė. 2009 metų šiltuoju sezonu atliktas eksperimentas, sudaryta dešimties ir dviejų minučių vidurkių ozono koncentracijos ir meteorologinių parametrų duomenų bazė. Parametrų tarpusavio priklausomybė nustatyta panaudojant tiesinės regresijos metodą, apskaičiuoti koreliacijos koeficientai. Pasinaudojant Furje metodu atlikta ozono bei meteorologinių parametrų spektrinė analizė. Buvo rasti pagrindiniai dažnių pikai, kurie labiausiai išryškėja. Darbą sudaro 6 dalys: įvadas, literatūros apžvalga, matavimo prietaisai ir metodika, eksperimentinių tyrimų rezultatai, išvados ir literatūros sąrašas. Darbo apimtis – 57 p. teksto be priedų, 38 paveikslai., 3 lentelės, 53 bibliografiniai šaltiniai. Atskirai pridedami darbo priedai.In master final work the variation of short-term ozone concentration variations were analyzed. Ozone formation, chemical characteristics, impact on human health and plants were described. The study of the short- and long-term ozone concentration variations dependence on meteorological parameters is presented. The data of hourly parameters obtained at the monitoring station Preila during 2000-2009 years were analyzed. The 2 and 10 minutes average values of the ozone concentration and meteorological parameters were collected during experiment in warm season of 2009 year. The regression analysis was applied for the determination of the correlation coefficients between variables. The strongest relationship from the long-term variations was found between ozone concentration and temperature. The strongest relationship from the short-term variations was found between ozone concentration and wind speed. Structure: introduction, literary review, measurements instruments and methodology, experimental research results, conclusions and references. Thesis consists of: 57 p. text without appendixes, 38 pictures, 3 tables, 53 bibliographical entries. Appendixes included.