The main aim of this study was to investigate the effects of water availability and SO2 pollution, imposed separately or simultaneously, on the photosynthetic metabolism of Augea capensis Thunb., a succulent of the Namib Desert in the region of Skorpion Zinc mine, Namibia. The main driver for this investigation was the need to distinguish between the effects of water availability on plants native to a desert environment, where water availability dominates plant response, but where the possibility of anthropogenic SO2 pollution poses a new threat to the unique succulent vegetation. Fifteen measuring sites were selected in the vicinity of the mine to determine how rainfall influenced the physiological status of the vegetation. Chlorophyll a fluorescence measurements, and analysis of recorded OJlP fluorescence transients with the JIP-test, were used for this purpose. A series of laboratory experiments were also conducted on A. capensis to determine the precise physiological response that water deprivation and SO2 pollution had under controlled growth conditions. Potted plants were exposed to water deprivation or SO2 fumigation in the light or dark. Besides chlorophyll a fluorescence, photosynthetic gas exchange and Rubisco activity were also measured. Changes in fast fluorescence rise kinetics observed under field conditions suggest considerable modulation of photosystem II function by rainfall with concomitant involvement of a heat stress component as well. In both the field and laboratory experiments, one of the JIP-test parameters, the so-called performance index (PIABS), was identified as a very sensitive indicator of the physiological status of the test plants. Moreover, under laboratory conditions, a good correlation existed between the water deprivation-induced decline in CO2 assimilation rates and the decline in PIABS values. The JIP-test in general, and the PIABS in particular, shows considerable potential for application in the investigation of water availability influences on desert ecosystems. In the laboratory experiments, water deprivation caused stomatal closure but also a slight elevation in intercellular C02 concentration and inhibition of Rubisco activity, suggesting that mesophyll limitation was the dominant factor contributing to the decrease in C02 assimilation rates. Following re-watering, A. capensis showed remarkable recovery capacity. Fumigation of A. capensis with 1.2 ppm SO2 in the dark or light revealed relatively small effects on C02 assimilation. The inhibitory effects on photosynthesis were also fully reversible, indicating no permanent metabolic/structural damage. The effects on photosynthesis were more pronounced when fumigation occurred in the dark. This phenomenon might be related to diurnal differences in cellular capacity for SO2 detoxification. When long-term moderate water deprivation was combined with simultaneous SO2 fumigation, there was no additional inhibitory effect on photosynthesis. These findings suggest that water deprivation do not increase sensitivity towards SO2 pollution in A. capensis. Fumigation with SO2, singly or in combination with water deprivation also had no major effect on chloroplast ultrastructure. It appears that A. capensis is remarkably resistant to SO2 pollution even in the presence of low water availability, which is a common phenomenon in desert ecosystems. Since A, capensis seems to be highly tolerant to S02, its suitability as an indicator species for the detection of SO2 pollution effects at Skorpion Zinc mine is questionable. Because water availability dominates the physiological/biochemical response in this species, subtle SO2 pollution effects might be difficult to detect against this dominant background. The high water content of A. capensis and similar succulents might act as a substantial sink for SO2 and could convey considerable tolerance against this form of air pollution. / Thesis (M.Sc. (Botany))--North-West University, Potchefstroom Campus, 2006.

Single stage and two-stage sodium sulfite cooking were carried out on either spruce, pine or pure pine heartwood chips to investigate the influence of several process parameters on the initial phase of such a cook down to about 60 % pulp yield. The cooking experiments were carried out in the laboratory with either a lab-prepared or a mill-prepared cooking acid and the temperature and time were varied. The influences of dissolved organic and inorganic components in the cooking liquor on the final pulp composition and on the extent of side reactions were investigated. Kinetic equations were developed and the activation energies for delignification and carbohydrate dissolution were calculated using the Arrhenius equation. A better understanding of the delignification mechanisms during bisulfite and acid sulfite cooking was obtained by analyzing the lignin carbohydrate complexes (LCC) present in the pulp when different cooking conditions were used. It was found that using a mill-prepared cooking acid beneficial effect with respect to side reactions, extractives removal and higher stability in pH during the cook were observed compared to a lab-prepared cooking acid. However, no significant difference in degrees of delignification or carbohydrate degradation was seen.  The cellulose yield was not affected in the initial phase of the cook however; temperature had an influence on the rates of both delignification and hemicellulose removal. It was also found that the  corresponding activation energies increased in the order:  xylan, glucomannan, lignin and cellulose. The cooking temperature could thus be used to control the cook to a given carbohydrate composition in the final pulp. Lignin condensation reactions were observed during acid sulfite cooking, especially at higher temperatures. The LCC studies indicated the existence of covalent bonds between lignin and hemicellulose components with respect to xylan and glucomannan. LCC in native wood showed the presence of phenyl glycosides, ϒ-esters and α-ethers; whereas the α-ethers  were affected during sulfite pulping. The existence of covalent bonds between lignin and wood polysaccharides might be the rate-limiting factor in sulfite pulping. / The sulfite pulping process is today practised in only a small number of pulp mills around the globe and the number of sulfite mills that use sodium as the base (cation) is less than five. However, due to the increasing interest in the wood based biorefinery concept, the benefits of sulfite pulping and especially the sodium based variety, has recently gained a lot of interest. It was therefore considered to be of high importance to further study the sodium based sulfite process to investigate if its benefits could be better utilized in the future in the production of dissolving pulps. Of specific interest was to investigate how the pulping conditions in the initial part of the cook (≥ 60 % pulp yield) should be performed in the best way. Thus, this thesis is focused on the initial phase of sodium based single stage bisulfite, acid sulfite and two-stage sulfite cooking of either 100 % spruce, 100 % pine or 100 % pine heartwood chips. The cooking experiments were carried out with either a lab prepared or a mill prepared cooking acid and the temperature and cooking time were varied. Activation energies for different wood components were investigated as well as side reactions concerning the formation of thiosulfate. LCC (Lignin carbohydrates complexes) studies were carried out to investigate the influence of different cooking conditions on lignin carbohydrate linkages.

A novel study on the investigation of three very common atmospheric sulphur species relevant to the Mpumalanga Highveld subregion was conducted. Long-term in situ measurements were applied in the diurnal and seasonal evaluation of the observed sulphur species. Ambient pollutant concentrations and surface meteorological data were collected at an air quality monitoring station at Elandsfontein. Elandsfontein air quality monitoring station was ideal for the observations due to its high elevation within the Mpumalanga Province surrounded by few rolling hills and negligible windbreaks which easily allows for extensive plume-contact with the surface during convective daytime mixing. The temporal characteristics of the sulphur species have been assessed relative to one another with varying meteorological conditions. The diurnal and seasonal concentration variations were used to describe the physical characteristics exhibited by the compounds over Elandsfontein. Pollution roses were used to target the source of the major release points and areas of these sulphur species relative to the Elandsfontein monitoring station. Gas and particle concentrations were analysed in relation to varying meteorological parameters with a view to ascertaining the sulphur transformation and concentration distribution in the planetary boundary layer. Particulate sulphate distribution has been modelled through multivariate regression analyses in relation to three meteorological parameters, namely, wind speed, relative humidity and ambient temperature for the various seasons observed over southern Africa. This study has shown that hydrogen sulphide, sulphur dioxide and sulphate species are present throughout the year in the Mpumalanga Highveld at notably significant levels. The presence of ambient particulate sulphate has been shown to result from the combination of chemical interactions during long-range aerosol transport; atmospheric recirculation processes shown from back trajectories over the southern Africa sub-region, as well as the variation in the removal mechanisms and rates for the different seasons throughout the year. These transport and removal processes all contribute to the overall sulphur mass balance in the planetary boundary layer. Dosage of the three sulphur species was evaluated to provide data for sulphur pollution loading that could form a basis for health and vii environmental impact assessments over the area. In view of the characteristic patterns displayed by particulate sulphate, multivariate mathematical models have been developed on a seasonal basis with variations in meteorological parameters. This was seen to predict an accuracy of up to 70 % of the particulate sulphate loading for different seasons over the South African Highveld. In order to understand the chemical interactions of atmospheric sulphur species, it is important to be able to predict the route taken and expected products of transformation on any given condition. Theoretical analyses of the chemical thermodynamic properties of the known reacting species and a well-established approach were used in predicting reaction paths and establishing the possible and feasible products of chemical transformation in relation to the ambient temperature. The determination of reaction paths and possible products of chemical transformation provides a measure of the relative importance of the reacting species and the mechanism of reaction. Gas-, aqueous-phase and radical reactions involving sulphur (IV) were investigated with a view to establishing their relative importances. Thermochemical properties of several sulphur-containing compounds not available in the literature have been generated for evaluation of Gibbs free energy (ΔG) and enthalpy (ΔH). An electronic energy structural approach has been applied to model for ΔG and ΔH of 88 sulphur species in 90 chemical reactions comprising gas-phase, aqueousphase and radical reactions. Modelling was evaluated for their relative importances over a temperature range of –100 °C to +100 °C. The temperature range is well above the known tropospheric temperature range to account for variations in the atmospheric environment. To further comprehend the chemistry of sulphur with regards to distribution of the species in the atmosphere, a kinetic model is developed and incorporated into a dispersion model. The kinetic evaluation of the oxidation rate of SO2 to sulphate has been determined with advection and dispersion over the Elandsfontein area. Gas-phase transformation with advection and dispersion has been used to evaluate the extent of the distribution of SO2 relative to the major contributing sources. The dry deposition was considered to be the dominant removal mechanism. It was assumed that the reaction rate was second order in concentration and that the rate of deposition was first order. The oxidation rates obtained for the seasons were 10.9 % h-1 for summer; 8.83 % h-1 for autumn; 6.56 % h-1 for winter; viii 10.8 % h-1 for spring, while an overall rate of 9.6 % h-1 was obtained for the one year study period. The transformation rate model produced a reaction constant and an activation energy of 4.92 x 10-6 μg m-3 s-1 and 36.54 kJ kg-1 for summer; 3.939 x 10-6 μg m-3 s-1 and 43.89 kJ kg-1 for autumn; 2.90 x 10-6 μg m-3 s-1 and 115.69 kJ kg-1 for winter; 4.82 x 10-6 μg m-3 s-1 and 43.29 kJ kg-1 for spring, while for the year 4.29 x 10-6 μg m-3 s-1 and 34.31 kJ kg-1. A Gaussian puff unsteady state Lagrangian dispersion model with reflection at the surface and inversion layer was applied for concentration diffusion. The Lagrangian dispersion model with dry deposition was a better prediction of the observed data than the models from previous studies using a first order rate constant with or without deposition rate.

L'objectif du travail de thèse est d'étudier les effets de température et du dopage sur les caractéristiques de gravure du Si et des polymères : produits de réaction, cinétiques, énergie d'activation, anisotropie, et sélectivité. La gravure anisotrope des polymères est ensuite étudiée en fonction de la température en utilisant des mélanges de gaz permettant d'utiliser un procédé par passivation latérale. Les résultats expérimentaux obtenus sont discutés en tenant compte de l'étude thermodynamique des systèmes chimiques concernés. Le travail s'achève par l'étude de faisabilité de filtres pour microfiltration par perçage de pores à travers des films polymère.

In this study, flue gas emissions and combustion efficiencies during combustion and co-combustion of olive cake and coal are investigated in a bubbling fluidized bed with an inside diameter of 102 mm and a height of 900 mm and 1900 mm. Tun&ccedil / bilek lignite coal and Edremit olive cake were used in the experiments as fuels. Temperature distributions along the combustion column were continuously measured. Flue gas concentrations of O2, CO, SO2 and NOx were measured during combustion experiments. Four sets of experiments were performed in order to examine the effect of fuel composition, excess air ratio, freeboard extension and limestone addition on flue gas emissions and combustion efficiency. The olive cake addition to coal were 25, 50, 75 % by wt. The bed temperature on the average was 850 oC. The results of the experiments showed that coal combustion occurs at lower parts of the combustion column whereas olive cake combustion takes place more in the freeboard region. As olive cake percentage in the fuel mixture increased, CO emissions increased, SO2 and NOx emissions decreased. The reason for the decrease of NOx emissions with increasing percentage of olive cake in the fuel mixture was due to a reducing atmosphere created in the combustion column. Mostly combustion losses resulted mainly from the unburnt carbon in the fly ash. With the freeboard extension, noticeable decrease in CO emissions and slight increase in combustion efficiencies were observed. Among the limestones tested, &Ccedil / an limestone gave the best result with Ca/S = 3 at an optimum bed temperature of 850 oC. The SO2 reduction was 87% at this Ca/S ratio. For co-combustion experiments, it was observed that SO2 adsorption efficiency of limestone increased with the addition of olive cake to the fuel mixture.

Molten Carbonate Fuel cells are high temperature fuel cells suitable for distributed generation and combined heat and power, and are today being installed on commercial basis in sizes from 100kW to several MW. Novel applications for MCFC which have attracted interest lately are MCFC used for CO2 separation from combustion flue gas, and high temperature electrolysis with reversible fuel cells. In the first application, the intrinsic capability of the MCFC to concentrate CO2 from the cathode to the anode side through the cell reaction is utilized. In the second application, the high operating temperature and relatively simple design of the MCFC is utilized in electrolysis, with the aim to produce a syngas mix which can be further processed into hydrogen of synthetic fuels. In this thesis, the effect on fuel cell performance of operating a small lab-scale molten carbonate fuel cell in conditions which simulate those that would apply if the fuel cell was used for CO2 separation in combustion flue gas was studied. Such operating conditions are characterized especially by a low CO2 concentration at the cathode compared to normal operating conditions. Sulfur contaminants in fuel gas, especially H2S, are known poisoning agents which cause premature degradation of the MCFC. Furthermore, combustion flue gas often contains sulfur dioxide which, if entering the cathode, causes performance degradation by corrosion and by poisoning of the fuel cell. This makes poisoning by sulfur contaminants of great concern for MCFC development. In this thesis, the effect of sulfur contaminants at both anode and cathode on fuel cell degradation was evaluated in both normal and in low CO2 simulated flue gas conditions.      The results suggested that the poisoning effect of SO2 at the cathode is similar to that of H2S at the anode, and that it is possibly due to a transfer of sulfur from cathode to anode. Furthermore, in combination with low CO2 conditions at the cathode, SO2 contaminants cause fuel cell poisoning and electrolyte degradation, causing high internal resistance. By using a small lab-scale MCFC with commercial materials and standard fuel cell operating conditions, the reversible MCFC was demonstrated to be feasible. The electrochemical performance was investigated in both fuel cell (MCFC) and electrolysis cell (MCEC) modes. The separate electrodes were studied in fuel cell and electrolysis modes under different operating conditions. It was shown that the fuel cell exhibited lower polarization in MCEC mode than in MCFC mode, and a high CO2 concentration at the fuel cell anode reduced the polarization in electrolysis mode, which suggested that CO2 is reduced to produce CO or carbonate. / Smältkarbonatbränsleceller (MCFC) är en typ av högtemperaturbränsleceller som är anpassade för kombinerad el- och värmeproduktion i mellan-till stor skala. Idag installeras MCFC på kommersiell basis i storlekar mellan 100kW och flera MW. En ny typ av tillämpning för MCFC som har väckt intresse på senare tid är användandet av MCFC för CO2-avskiljning i kombination med konventionell elproduktion genom förbränning. En annan ny tillämpning är högtemperaturelektrolys genom användandet av reversibla bränsleceller. I det första fallet utnyttjas att CO2 kan koncentreras från katod- till anodsidan, vilket sker genom cellreaktionen för MCFC. I det andra fallet utnyttjas den höga arbetstemperaturen och den relativt enkla cell-designen för att använda reversibla MCFC till elektrolys, med syfte att producera en syngas-blandning som kan förädlas till vätgas eller till syntetiskt bränsle. I denna avhandling studeras effekten på bränslecellens prestanda genom att operera en MCFC i lab-skala med driftförhållanden som simulerar de som förväntas uppkomma om bränslecellen användes för CO2-avskiljning ur rökgaser från förbränning. Dessa driftförhållanden karaktäriseras av låg CO2-koncentration på katodsidan jämfört med normal drift. Svavelföroreningar i bränsle, speciellt H2S, är kända för att orsaka förgiftning av anoden, vilket i sin tur försämrar bränslecellens prestanda. Dessutom innehåller rökgaser ofta SO2, vilket antas orsaka korrosion och förgiftning av katoden. Detta gör effekten av svavelföroreningar till ett prioriterat ämne för utvecklingen av MCFC. I denna avhandling undersöks effekten av svavelföroreningar på både anod- och katodsidan, i normala driftförhållanden och i förhållanden med låg CO2 som simulerar användandet av rökgaser för CO2-avskiljning. Resultaten tyder på att effekten av förgiftning med SO2 på katoden liknar den med H2S på anoden, och att detta kan vara orsakat av en transport av svavel från katod till anod. Vidare, i kombination med låg CO2 koncentration på katoden så orsakar SO2-föroreningar elektrolytdegradering, vilket orsakar hög inre resistans. Genom att använda en liten MCFC i lab-skala med kommersiella material och standardförhållanden för MCFC påvisades att reversibla smältkarbonatbränsleceller kan vara ett lovande koncept. Den elektrokemiska prestandan av både cell och separata elektroder undersöktes både som bränslecell (MCFC)och vid elektrolys (MCEC). Resultaten visade att cellen uppvisade lägre polarisation vid elektrolys än som bränslecell, och att ten hög CO2-koncentration på det som är bränslecellens anodsida gav upphov till en minskad elektrodpolarisation, vilket indikerar att CO2 reduceras för att producera CO eller karbonat. / <p>QC 20141028</p>

The main aim of this study was to investigate the effects of water availability and SO2 pollution, imposed separately or simultaneously, on the photosynthetic metabolism of Augea capensis Thunb., a succulent of the Namib Desert in the region of Skorpion Zinc mine, Namibia. The main driver for this investigation was the need to distinguish between the effects of water availability on plants native to a desert environment, where water availability dominates plant response, but where the possibility of anthropogenic SO2 pollution poses a new threat to the unique succulent vegetation. Fifteen measuring sites were selected in the vicinity of the mine to determine how rainfall influenced the physiological status of the vegetation. Chlorophyll a fluorescence measurements, and analysis of recorded OJlP fluorescence transients with the JIP-test, were used for this purpose. A series of laboratory experiments were also conducted on A. capensis to determine the precise physiological response that water deprivation and SO2 pollution had under controlled growth conditions. Potted plants were exposed to water deprivation or SO2 fumigation in the light or dark. Besides chlorophyll a fluorescence, photosynthetic gas exchange and Rubisco activity were also measured. Changes in fast fluorescence rise kinetics observed under field conditions suggest considerable modulation of photosystem II function by rainfall with concomitant involvement of a heat stress component as well. In both the field and laboratory experiments, one of the JIP-test parameters, the so-called performance index (PIABS), was identified as a very sensitive indicator of the physiological status of the test plants. Moreover, under laboratory conditions, a good correlation existed between the water deprivation-induced decline in CO2 assimilation rates and the decline in PIABS values. The JIP-test in general, and the PIABS in particular, shows considerable potential for application in the investigation of water availability influences on desert ecosystems. In the laboratory experiments, water deprivation caused stomatal closure but also a slight elevation in intercellular C02 concentration and inhibition of Rubisco activity, suggesting that mesophyll limitation was the dominant factor contributing to the decrease in C02 assimilation rates. Following re-watering, A. capensis showed remarkable recovery capacity. Fumigation of A. capensis with 1.2 ppm SO2 in the dark or light revealed relatively small effects on C02 assimilation. The inhibitory effects on photosynthesis were also fully reversible, indicating no permanent metabolic/structural damage. The effects on photosynthesis were more pronounced when fumigation occurred in the dark. This phenomenon might be related to diurnal differences in cellular capacity for SO2 detoxification. When long-term moderate water deprivation was combined with simultaneous SO2 fumigation, there was no additional inhibitory effect on photosynthesis. These findings suggest that water deprivation do not increase sensitivity towards SO2 pollution in A. capensis. Fumigation with SO2, singly or in combination with water deprivation also had no major effect on chloroplast ultrastructure. It appears that A. capensis is remarkably resistant to SO2 pollution even in the presence of low water availability, which is a common phenomenon in desert ecosystems. Since A, capensis seems to be highly tolerant to S02, its suitability as an indicator species for the detection of SO2 pollution effects at Skorpion Zinc mine is questionable. Because water availability dominates the physiological/biochemical response in this species, subtle SO2 pollution effects might be difficult to detect against this dominant background. The high water content of A. capensis and similar succulents might act as a substantial sink for SO2 and could convey considerable tolerance against this form of air pollution. / Thesis (M.Sc. (Botany))--North-West University, Potchefstroom Campus, 2006.

Concentrations of elements and ions measured in samples collected between February 1993 and December 2000 at a rural site in central Anatolia were investigated to evaluate the chemical composition of atmosphere at central Anatolia, to determine pollution level of the region, to study temporal variability of the pollutants and to investigate the sources and source regions of air pollutants in the region. Level of pollution at central Anatolia was found to be lower than the pollution level at other European countries and Mediterranean and Black Sea regions of Turkey. Enrichment factor calculations revealed that SO42-, Pb and Ca are highly enriched in the aerosol / whereas, soil component has dominating contribution on observed concentrations of V, Mg, Ca and K. SO42-/(SO2+SO42-) ratio observed in &Ccedil / ubuk station indicates that contribution of distant sources is more important than the contribution of local sources on observed SO42- levels. SO42-/NO3- ratio calculations showed that Central Anatolia is receipt of SO42- from Eastern European countries. Positive Matrix Factorization (PMF) analysis revealed 6 source groups, namely motor vehicle source, mixed urban factor, long range transport factor, soil factor, NO3- factor and Cd factor. Distribution of Potential Source Contribution Function (PSCF) values showed that main source areas of SO42-, NH4+ and Cd are western parts of Turkey, Balkan countries, central and western Europe, central Russian Federation and north of Sweden and Finland / NO3- are the regions located around the Mediterranean Sea / and there is no very strong potential source area observed for NH3 and Pb.

Η ατμοσφαιρική ρύπανση επηρεάζει την δημόσια υγεία, το φυσικό οικοσύστημα και επιφέρει μεταβολές στις κλιματικές συνθήκες. Το πρόβλημα της αέριας ρύπανσης παρουσιάζεται εντονότερο σε αστικές περιοχές, όπου η συσσώρευση ανθρωπίνων δραστηριοτήτων οδηγεί κατά κανόνα σε αυξημένες εκπομπές αερίων. Κάτω από την επήρεια δυσμενών μετεωρολογικών συνθηκών, τα επίπεδα συγκεντρώσεων των ρύπων μπορούν να ξεπεράσουν τα όρια της Παγκόσμιας Οργάνωσης Υγείας. Για την αποτελεσματική αντιμετώπιση του προβλήματος είναι απαραίτητη η ανάλυση και η σωστή περιγραφή όλων των φαινομένων και παραγόντων που καθορίζουν τις σχέσεις πηγής – αποδέκτη και ατμοσφαιρικών ρύπων. Για το σκοπό αυτό ενδείκνυνται κυρίως μαθηματικά μοντέλα προσομοίωσης μετεωρολογικών φαινομένων και φαινομένων διασποράς και μετασχηματισμού ρύπων. Η έντονη ευαισθητοποίηση της κοινής γνώμης σε θέματα σχετικά με την προστασία του περιβάλλοντος αναγκάζει τις κυβερνήσεις των χωρών να επιβάλλουν την διερεύνηση των συνεπειών έργων και δραστηριοτήτων στο ατμοσφαιρικό περιβάλλον. Τα μοντέλα διασποράς ατμοσφαιρικών ρύπων είναι εύχρηστα εργαλεία που μπορούν να εκτιμήσουν συγκεντρώσεις ρύπων, έτσι ώστε αυτές να είναι αντιπροσωπευτικές στο χώρο και στον χρόνο. Οι μετρήσεις ρύπων με όργανα λαμβάνονται σε συγκεκριμένες θέσεις και ως εκ τούτου δεν είναι αντιπροσωπευτικές για μεγαλύτερες περιοχές. Μέσες τιμές ρύπων για μεγαλύτερες περιοχές υπολογίζονται εύκολα με μοντέλα ατμοσφαιρικής ρύπανσης. Σκοπός αυτής της εργασίας, είναι η πρόβλεψη των συγκεντρώσεων των ρύπων διοξειδίου του θείου SO2, ολικών οξειδίων του αζώτου NOx και της ποσοστιαίας κατανομής της συνεισφοράς των πηγών ρύπανσης στις συγκεντρώσεις των ρύπων που καταγράφονται στις θέσεις των αποδεκτών με την χρήση του λογισμικού AERMOD της Εταιρίας Περιβαλλοντικής Προστασίας (EPA) των ΗΠΑ. Το AERMOD χρησιμοποιεί γκαουσιανά μοντέλα διασποράς. Για τον σκοπό αυτό συγκεντρώνονται και χρησιμοποιούνται πολλά και διαφορετικού τύπου δεδομένα, όπως μετεωρολογικά, γεωγραφικά, κυκλοφορίας αυτοκινήτων και πλοίων, εκπομπές ρύπων κ.α. Επίσης γίνεται η υπόθεση, ότι οι μεγαλύτερες συνεισφορές στην ατμοσφαιρική ρύπανση της Πάτρας γίνονται από την κυκλοφορία των αυτοκινήτων, από τα πλοία του λιμανιού και τις κεντρικές θερμάνσεις των κατοικιών. Η πρόβλεψη που προκύπτει μετά από την επεξεργασία των παραπάνω δεδομένων από το πρόγραμμα AERMOD συγκρίνεται με τα διαθέσιμα αποτελέσματα των μετρήσεων για ατμοσφαιρικούς ρύπους από το Εργαστήριο Τεχνολογίας του Περιβάλλοντος, που έγιναν στην Πάτρα στο διάστημα από τις 13 Νοεμβρίου του 1997 έως τις 23 Ιανουαρίου του 1998, κατά τις πρωινές (8:30 – 9:30) και βραδινές ώρες (20:30 – 21:30) στα πλαίσια διπλωματικής εργασίας υπό την επίβλεψη του κ. Π. Γιαννόπουλου. Στο Κεφάλαιο 1 αναφέρονται γενικές πληροφορίες για την ατμοσφαιρική ρύπανση, την πόλη της Πάτρας, για τους σημαντικότερους ρύπους της ατμόσφαιρας, αλλά και το πώς τα μετεωρολογικά φαινόμενα επηρεάζουν την διασπορά των ρύπων. Στο 2ο Κεφάλαιο αναφέρονται γενικές πληροφορίες για τα σημαντικότερα μαθηματικά μοντέλα ατμοσφαιρικής διασποράς, ενώ στο 3ο κεφάλαιο γίνεται μία γενική περιγραφή του θεωρητικού υπόβαθρου του προγράμματος AERMOD και του Προγράμματος AERMET. Στο Κεφάλαιο 4 παρουσιάζονται τα γεωγραφικά και μετεωρολογικά δεδομένα, τα δεδομένα για τους φόρτους κυκλοφορίας των οχημάτων στην πόλη της Πάτρας αλλά και πληροφορίες για την κίνηση των πλοίων στο παλιό λιμάνι της Πάτρας. Στο 4ο κεφάλαιο παρουσιάζονται οι υπολογισμοί των εκπομπών των ρύπων από τα αυτοκίνητα, τα πλοία και τις κεντρικές θερμάνσεις των κατοικιών. Επίσης παρουσιάζεται η ποσοστιαία κατανομή των εκπομπών από τις πηγές ατμοσφαρικής ρύπανσης και η συνεισφορά της κάθε μιας στην ρύπανση της ατμόσφαιρας. Τέλος παρουσιάζονται οι προβλέψεις που προκύπτουν για τις συγκεντρώσεις των ρύπων στις θέσεις των αποδεκτών και η σύγκριση αυτών με τις μετρήσεις για ατμοσφαιρικούς ρύπους που είχαν γίνει από το Νοέμβριο του 97 έως τον Ιανουάριο του 98. Στο Κεφάλαιο 5 παρουσιάζονται τα συμπεράσματα της εργασίας. Σαν συμπέρασμα της εργασίας προκύπτει ότι τα γκαουσιανά μοντέλα ατμοσφαιρικής διασποράς είναι χρήσιμα εργαλεία για την βραχυπρόθεσμη πρόγνωση των επιπέδων ρύπανσης, την εκτίμηση της συνεισφοράς των επί μέρους πηγών στην ποιότητα του αέρα και τη βελτιστοποίηση των στρατηγικών αντιρρύπανσης. Επισημαίνεται ότι τα μοντέλα προσομοίωσης αποτελούν την μοναδική μεθοδολογία αναφορικά με την δυνατότητα εκτίμησης της συνεισφοράς των επιμέρους πηγών. Επίσης, από τα αποτελέσματα αυτής της εργασίας προκύπτουν χρήσιμα συμπεράσματα για την προέλευση της ατμοσφαιρικής ρύπανσης στην πόλη της Πάτρας, όπως το ότι το μεγαλύτερο ποσοστό της (65 – 76% για το SO2 και 85 – 92% για NOx) προέρχεται από την κυκλοφορία των οχημάτων, ενώ αξιοσημείωτα είναι και τα ποσοστά των ρύπων που προέρχονται από τις κεντρικές θερμάνσεις (17 – 29% για το SO2 και 7,5 – 14,2% για NOx). Επίσης από τα αποτελέσματα φαίνεται ότι τα ποσοστά των ΝΟx που προέρχονται από τα πλοία είναι πολύ μικρά (0,3% - 0,4%), ενώ αντίθετα τα αντίστοιχα ποσοστά του SO2 (6% – 7%) είναι αξιοσημείωτα. Τέλος, άξιο αναφοράς είναι ότι όπως προκύπτει από τις συγκεντρώσεις των ρύπων που προβλέπει το AERMOD, φαίνεται ότι σε μία ζώνη πλάτους 400 m γύρω από το λιμάνι το ποσοστό της συγκέντρωσης του SO2 είναι αυξημένο (8% – 9%). / Air pollution affects public health, natural ecosystem and bring changes in climatic conditions. The problem of air pollution are most marked in urban areas, where the accumulation of human activities should lead to increased greenhouse gases. Under the influence of adverse weather conditions, the concentration levels of pollutants can overcome the limits of the World Health Organization. For the effective address of this problem is necessary to analyze all phenomena and factors that define the relationship source - receptor and atmospheric pollutants. For this purpose are suitable mathematical models simulating weather patterns and phenomena of dispersion and transformation of pollutants. The intense public awareness on issues related to the protection of the environment forces governments to impose the investigation of the effects of projects to the atmosphere. The air pollutant dispersion models are handy tools that can estimate pollutant concentrations, so that they are representative in space and time. The measurements of pollutants with instruments done at specific locations and therefore they are not representative for larger areas. Mean values for pollutants at larger areas easily calculated with models of atmospheric pollution. The aim of this work is the prediction of pollutant concentrations of sulfur dioxide SO2, total nitrogen oxides NOx and the percentage distribution of the contribution of pollution sources in pollutant concentrations recorded at the locations of receptors with the use of the software AERMOD. AERMOD belongs to the Environmental Protection Company (EPA) in the USA. AERMOD uses Gaussian dispersion models. For this purpose collected and used many different types of data, such as meteorological, geographical, automobile traffic and ship emissions, etc. Also it is assumed that the greatest contributions to air pollution of Patras come from the circulation of cars, from the port's ships and from the heating installations. The prediction obtained after processing the above data from the AERMOD program comes in comparison with the available results of measurements of air pollutants from the Laboratory of Environmental Engineering, held in Patras in the period from 13 November 1997 until 23 January 1998 in the morning (8:30 - 9:30) and evening (20:30 - 21:30) in the thesis under the supervision of Mr. P. Giannopoulos. In Chapter 1 reported general information on air pollution, about the significant atmospheric pollutants, and how weather conditions affect the dispersion of pollutants. In the second chapter reported general information about the most important mathematical atmospheric dispersion models, while in the third chapter gives a general description for the theoretical background of the programs AERMOD and AERMET. In Chapter 4 presents the geographical and meteorological data, data on motor vehicle traffic volumes in the city of Patras and information on the movement of ships in the old harbor of Patras. In the fourth chapter presented calculations of emissions of pollutants from cars, ships and central heating of homes. Also in the fourth chapter reported the percentage distribution of emissions from sources of atmospheric pollution and contribution of each in the pollution. Finally in the fourth chapter presented the forecasts for the concentrations of pollutants in the positions of the receptors and compare them with measurements for atmospheric pollutants that were made from November 97 until January 98. In Chapter 5 presented the conclusions of the work. As a conclusion of this study shows that the Gaussian atmospheric dispersion models are useful tools for short-term forecasting of pollution levels, and for the assessment of the contribution of individual sources on air quality. Noted that the simulation models are the unique methodology regarding the possibility of assessing the contribution of individual sources. Also, from the results of this work resulting conclusions about the origin of air pollution in the city of Patras, such that the highest percentage (65 - 76% for SO2 and 85 to 92% for NOx) comes from traffic vehicles, while noteworthy are the percentages of pollutants from central heating (17 - 29% for SO2 and 7.5 to 14.2% for NOx). Also, from the results it appears that rates of NOx from ships are very small (0.3% - 0.4%), while the corresponding percentages of SO2 (6% - 7%) is remarkable. Finally, it is worth mentioning that as indicated by the concentrations of pollutants that AERMOD calculates , it seems that in a zone extending 400 m around the harbor, the percentage of the concentration of SO2 is increased (8% - 9%).

Measuring the composition of the planetary boundary layer is essential for monitoring pollutants and for understanding their impact on environment and health. Nadir satellite remote sensing is particularly appealing to sound this part of the atmosphere, but is however challenging because pollutants concentrations are generally weak and confined in a small part of the atmospheric column. Among the sounders currently in orbit, those operating in the thermal infrared have usually their maximum sensitivity in the mid-troposphere, and are thought to be inadequate to measure the near-surface atmospheric composition. Their sensitivity to this part of the atmosphere is indeed generally limited by low temperature contrast (called thermal contrast) between the ground and the air above it. Shortly before the beginning of this PhD, this has however been challenged with different studies, which have shown the possibility to measure air pollution with thermal infrared sounders in case of high thermal contrast conditions. This was especially demonstrated with the measurement of ammonia global distribution using the Infrared Atmospheric Sounding Interferometer (IASI). This work aims at fully exploring the capabilities of thermal infrared sounders to sound the near-surface atmospheric composition. It mainly focuses on the observations of the IASI instrument, and addresses the following questions: where and when is IASI sensitive to the near-surface atmosphere? How large and how variable is the sensitivity to near-surface pollutants? What are the parameters that drive this variability? The answers to these questions are looked at for two pollutants: sulphur dioxide (SO2) and carbon monoxide (CO), and are obtained through a series of different analyses. SO2 is the first constituent on which this work focuses. The retrieval of its near-surface concentration is first of all attempted in an area surrounding the industrial area of Norilsk. This region, well-known for the extraction of heavy metals and its extremely high levels of pollution, encounters large temperature inversions in winter, which trap SO2 close to the ground. By exploiting these (corresponding to high negative thermal contrast), we show that it is possible to retrieve the surface SO2 concentrations in the region. This is done using a simplified version of the optimal estimation method, based on the use of a total measurement error covariance matrix. Further, we show that the surface SO2 concentration retrieval using the ν3 band is limited, in addition to thermal contrast, by the strong water (H2O) absorption, which renders the lowest atmosphere opaque in this spectral range in case of large humidity. Two conditions are therefore shown to be required to monitor near-surface SO2 in the ν3 band: large thermal contrast and low surface humidity. These findings are confirmed with the retrieval of SO2 at global scale, performed using a newly developed retrieval scheme based on the conversion of radiance indexes into SO2 columns using look-up-tables. It is composed of two successive steps: 1) the determination of the altitude of SO2 and the selection of low plumes (below 4 km), 2) for the selected observations, the conversion of radiance indexes into integrated SO2 0–4 km columns. The distributions and time series so obtained are used to better characterise the variability of IASI sensitivity to surface SO2 in the ν3 band at the global scale, and more particularly, in terms of thermal contrast strength and total column of H2O.The characterisation of IASI sensitivity to CO is realised in a second part of the work. Radiative transfer simulations are conducted first to determine the possibility to detect enhancement in CO near-surface concentrations with IASI. The framework of the optimal estimation is then used to investigate the capability of IASI to decorrelate, as a function of thermal contrast, the CO concentration in the low troposphere from that in the high troposphere. Finally, comparisons of IASI CO observations with co-located aircraft and ground-based measurements are shown to confirm with real data how IASI sensitivity to near-surface CO varies in terms of thermal contrast conditions, and to which extent it allows determining the CO abundance in case of high pollution. / Mesurer la composition de la couche limite atmosphérique depuis les satellites est essentiel pour comprendre l’impact des polluants sur l’environnement global et sur la santé. Parmi les sondeurs actuellement en orbite, ceux opérant dans l’infrarouge thermique sont souvent considérés comme inadéquats pour cet objectif, leur sensibilité à l’atmosphère de surface étant généralement limitée par de faibles contrastes de température (appelés contrastes thermiques, TC) entre le sol et l’air au-dessus. Différentes études récentes ont cependant montré la possibilité de mesurer la pollution de l’air avec ce type de sondeur dans des conditions de TC élevé.Ce travail a pour objectif de redéfinir la capacité des sondeurs opérant dans l’infrarouge thermique à mesurer la composition de l’atmosphère de surface. Il se focalise sur les observations de l’instrument IASI (Interféromètre Atmosphérique de Sondage Infrarouge), et tente de répondre, pour les deux polluants que sont le dioxyde de soufre (SO2) et le monoxyde de carbone (CO), aux questions suivantes :Où et quand IASI est-il sensible à l’atmosphère de surface ?Quels sont les paramètres qui influencent cette sensibilité et dans quelle mesure?Dans une première partie, la thèse se focalise sur l’ajustement des concentrations de SO2 de surface pour la région industrielle de Norilsk, connue pour son niveau de pollution élevé. Nous montrons qu’il y est possible de restituer les concentrations de surface de SO2 en hiver, en exploitant les larges inversions de température (TC négatifs) qui s’y développent. Les restitutions reposent sur une version simplifiée de la méthode de l’estimation optimale, utilisant une matrice complète de l’erreur de mesure. En plus du TC, nous montrons que l’ajustement dans la bande ν3 du SO2 est également limité par la forte absorption de la vapeur d’eau (H2O), qui rend les basses couches de l’atmosphère opaques. La nécessité de combiner des TCs élevés et une faible humidité pour permettre la mesure du SO2 en surface est confirmée par une analyse à l’échelle globale, utilisant une méthode basée sur la mesure d’indices de radiance et leur conversion en colonnes de SO2 à l’aide de tables pré-calculées. Composée de 2 étapes, cette méthode identifie et sélectionne d’abord les panaches situés sous 4 km ;elle convertit ensuite les indices de radiance en colonnes de SO2 intégrées entre 0 et 4 km. Les distributions et séries temporelles obtenues sont utilisées pour caractériser, en termes de valeurs de TC et de colonnes totales d’H2O, la variabilité de la sensibilité de IASI au SO2 de surface dans la bande ν3.Dans la seconde partie du travail, des simulations de transfert radiatif sont entreprises pour déterminer la possibilité de détecter avec IASI des augmentations de la concentration de CO dans l’atmosphère de surface. Le formalisme de l’estimation optimale est aussi utilisé pour analyser l’influence du TC sur la capacité de IASI à décorreler les concentrations du CO dans la basse et la haute troposphère. Finalement, des comparaisons entre les concentrations de CO restituées des mesures IASI sous différentes conditions de TC et de pollution et celles mesurées par avions et par des stations au sol complètent la caractérisation. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished