The ever-changing industrial processes which are becoming more globalised as well as the merging of markets in different economies, led to an increased focus on the health and safety of workers in the industries and the mining sector over the past decades. Occupational exposure limits (OELs) have been used for more than half a century as a risk management tool for the prevention of work-related illnesses which may arise from the exposure to a wide variety of hazardous chemical substances in the working environment. Aim: The aim of this study is to analyse comparatively occupational exposure limits (OELs) of hazardous chemical substances from selected groups contained in the Hazardous Chemical Substance Regulations (HCSR) and the Mine Health and Safety Regulations (MHSR) with those of selected developed countries and organisations. Method: The two lists of OELs from South Africa – HCSR and MHSR – were compared with 11 different developed countries and/or organisations namely: Canada (British Colombia), United Kingdom (Health and Safety Executive, HSE), Australia (National Occupational Health and Safety Commission, NOHSC), New Zealand (Ministry of Business, Innovation and Employment), Japan (Japan Society for Occupational Health, JSOH), Finland (Ministry of Social Affairs and Health), Germany (Deutsche Forschungsgemeinschaft-DFG), Sweden (Swedish Work Environment Authority) and United States of America (American Conference of Governmental Industrial Hygienists, ACGIH, Occupational Safety and Health Administration, OSHA and National Institute for Occupational Safety and Health, NIOSH). The selection of these countries and organisations was done on the basis of their dominance in the literature as well as the availability of the lists containing OELs. The OELs from each country and/or organisation, depending on the nature and characteristics of the said element and/or compound, were categorised into one of four groups, namely: pesticides, metals, dusts and fibres. The geometric means of each country and/or organisation were calculated from the ratios of each list by using the HCSR and MHSR as the denominator respectively. Results: It became evident that South Africa performed poorly when compared to other countries and/or organisations, indicated in this study. OSHA overall had the highest set OELs, in five out of the six comparisons that could be made, thus being less stringent than South Africa’s. Countries and organisations such as Sweden, Japan and Finland have the lowest overall set OELs for the different groups respectively. Conclusion: South African OELs legislated by both the HCSR and MHSR, are overall higher (less stringent) when compared to those of developed countries and/or organisations. The less stringent nature of South African OELs may be attributed to infrequent rate at which they are updated. The failure to incorporate recent scientific knowledge into OELs may impact on the health of workers. South Africa should follow international best practice and increase the frequency at which OELs are updated. Recommendations: The effectiveness of having two sets of OELs within a country; each applicable to its own industry should be investigated. Attention with regards to the groups lacking attention, i.e. fibres and pesticides should be given priority when revised. Although the other groups should not be disregarded. Duplicate OELs identified in the HCSR should be removed. To prevent duplicate OELs from being established it would be prudent to utilise CAS numbers when referring to substances in addition to their common and chemical names, thus this supports the recommendations made in an earlier study. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2015

The ever-changing industrial processes which are becoming more globalised as well as the merging of markets in different economies, led to an increased focus on the health and safety of workers in the industries and the mining sector over the past decades. Occupational exposure limits (OELs) have been used for more than half a century as a risk management tool for the prevention of work-related illnesses which may arise from the exposure to a wide variety of hazardous chemical substances in the working environment. Aim: The aim of this study is to analyse comparatively occupational exposure limits (OELs) of hazardous chemical substances from selected groups contained in the Hazardous Chemical Substance Regulations (HCSR) and the Mine Health and Safety Regulations (MHSR) with those of selected developed countries and organisations. Method: The two lists of OELs from South Africa – HCSR and MHSR – were compared with 11 different developed countries and/or organisations namely: Canada (British Colombia), United Kingdom (Health and Safety Executive, HSE), Australia (National Occupational Health and Safety Commission, NOHSC), New Zealand (Ministry of Business, Innovation and Employment), Japan (Japan Society for Occupational Health, JSOH), Finland (Ministry of Social Affairs and Health), Germany (Deutsche Forschungsgemeinschaft-DFG), Sweden (Swedish Work Environment Authority) and United States of America (American Conference of Governmental Industrial Hygienists, ACGIH, Occupational Safety and Health Administration, OSHA and National Institute for Occupational Safety and Health, NIOSH). The selection of these countries and organisations was done on the basis of their dominance in the literature as well as the availability of the lists containing OELs. The OELs from each country and/or organisation, depending on the nature and characteristics of the said element and/or compound, were categorised into one of four groups, namely: pesticides, metals, dusts and fibres. The geometric means of each country and/or organisation were calculated from the ratios of each list by using the HCSR and MHSR as the denominator respectively. Results: It became evident that South Africa performed poorly when compared to other countries and/or organisations, indicated in this study. OSHA overall had the highest set OELs, in five out of the six comparisons that could be made, thus being less stringent than South Africa’s. Countries and organisations such as Sweden, Japan and Finland have the lowest overall set OELs for the different groups respectively. Conclusion: South African OELs legislated by both the HCSR and MHSR, are overall higher (less stringent) when compared to those of developed countries and/or organisations. The less stringent nature of South African OELs may be attributed to infrequent rate at which they are updated. The failure to incorporate recent scientific knowledge into OELs may impact on the health of workers. South Africa should follow international best practice and increase the frequency at which OELs are updated. Recommendations: The effectiveness of having two sets of OELs within a country; each applicable to its own industry should be investigated. Attention with regards to the groups lacking attention, i.e. fibres and pesticides should be given priority when revised. Although the other groups should not be disregarded. Duplicate OELs identified in the HCSR should be removed. To prevent duplicate OELs from being established it would be prudent to utilise CAS numbers when referring to substances in addition to their common and chemical names, thus this supports the recommendations made in an earlier study. / MSc (Occupational Hygiene), North-West University, Potchefstroom Campus, 2015

No description available.

Thesis (M.Sc. (Engineering))--University of the Witwatersrand, Faculty of Engineering, 1987.

[pt] O presente estudo foca o comportamento da redução da ferrita de zinco produzida em laboratório e a contida nos pós de aciaria elétrica (PAE) pelo CO puro e misturas COCO2, esta última tomada como exemplo de um caso real. Este trabalho se iniciou com a caracterização dos principais compostos presentes no PAE (óxido de ferro (III), óxido de zinco e ferrita de zinco) usando técnicas, metodologias e equipamentos para caracterizações térmica (ATD-ATG), estrutural (DRX), microscópica (MEV-MET analise de EDS), física (porosidade do briquete, massa especifica, tamanho médio e área superficial específica das partículas) e química. Constatou-se que as partículas dos materiais estudados são predominantemente de geometria esférica e, em particular o estudo via MET da ferrita de zinco, revelou aglomerados micrométricos e homogêneos tipo clusters, formados por partículas arredondadas e constituídas por alguns monocristais com tamanhos da ordem de 100 nm. Com a finalidade de estudar a cinética de redução da ferrita de zinco, foram realizados ensaios de redução por CO puro e misturas gasosas formadas por: 75 por cento CO-25 por cento CO2 e 50 por cento CO-50 por cento CO2 nas temperaturas de 1073, 1173, 1223, 1273 e 1373K. O tempo máximo de redução foi de 105 min. Os resultados obtidos permitiram propor uma sequência cinética de redução, ao longo da qual os principais produtos de redução da ferrita de zinco foram caracterizados via MEV, visando estabelecer a fenomenologia/morfologia da redução. Conclui-se que a fenomenologia morfológica e cinética da redução da ferrita de zinco, embora complexa, é similar a da redução dos óxidos de ferro, dependendo das composições gasosas, temperatura e tempo de reação. O estudo morfológico permitiu constatar que a redução da ferrita de zinco evidencia sua decomposição nos óxidos constituintes (ZnO e Fe2O3), na faixa de 1073 a 1273K e a redução sequencial do óxido de zinco e dos óxidos de ferro. Os típicos produtos sólidos da redução são: óxido de zinco (ZnO), wüstita (FeO), óxidos mistos do tipo (Zn, Fe)O e ferro metálico. O estudo cinético estabeleceu ainda que ocorre uma rápida redução do óxido de zinco, liberando zinco gasoso, evidenciando a seguinte sequência de redução: primeiramente, o óxido de zinco se reduz, seguido dos óxidos de ferro. Isto ocorre significativamente nas temperaturas entre 1223 e 1373K. Estabeleceu-se um modelo geral de redução da ferrita de zinco usando a metodologia de superfície resposta (RSM), que envolveu o planejamento estatístico fatorial 3(4) para avaliar a influência dos fatores preestabelecidos sobre a (porcentagem) Redução (temperatura e tempo de reação, composição gasosa, e massa da amostra). Os modelos cinéticos que melhor ajustaram os mecanismos de redução foram: o modelo de reação química de interface-simetria esférica, seguido pelo modelo exponencial de reação contínua, representados por: [1 - raiz cúbica de (1 -alfa)] = kt e −ln(1 -alfa) igual a kt , respectivamente. O modelo de reação química de interface - simetria esférica, representado por: [1 - raiz cúbica de (1 - alfa)] = kt foi o que melhor adequou-se à redução da ferrita de zinco sintética. Os parâmetros cinéticos obtidos foram: (a) 100 por cento CO: Ea de 55,60 kJ/mol e A igual a 8,833 mHz; (b) 75 por cento CO-25 por cento CO2: Ea igual a 88,21 kJ/mol e A igual a 127,74 mHz; (c) 50 por cento CO-50 por cento CO2: Ea igual a 95,21 kJ/mol e A igual a 193,37 mHz; De maneira similar, no caso da redução da ferrita de zinco presente no PAE, o modelo que melhor representou o processo, também foi o modelo de reação química de interface - simetria esférica, representado por: [1 - raiz cúbica de (1 - alfa)] igual a kt , sendo, Ea (energia de ativação aparente) e A (constante pré-exponencial de Arrhenius), os parâmetros cinéticos obtidos: (d) 100 por cento CO: Ea igual a 52,34 kJ/mol, e A igual a 4,98 mHz; (b) 75 por cento CO-25 por cento CO2: Ea igual a 66,70 kJ/mol e A igual a 76,06 mHz; (c) 50 por cento CO-50 por cento CO2: Ea igual a 86,28 kJ/mol e A igual a 289,59 mHz. A comparação entre as energias de ativação aparente, permitiu concluir que tanto a redução da ferrita de zinco sintética como a redução dos Pós de Aciaria Elétrica-PAE, tiveram como etapa controladora da reação global a redução dos óxidos de ferro, particularmente para a redução com 100 por cento CO. No caso da redução com misturas COCO2, isto não foi observado para a ferrita de zinco sintética, embora possa ser válida para os Pós de Aciaria Elétrica-PAE, considerando seu baixo teor de zinco. Assim, para o caso da redução da ferrita de zinco por misturas CO-CO2, propõe-se como etapa controladora a redução simultânea do óxido de zinco e dos óxidos de ferro. / [en] This work deals with the behavior of the synthetic zinc ferrite reduction as well as a case study for the same process using electric arc furnace dusts (EAFD). These processes were conducted under pure CO atmosphere and CO-CO2 gas mixtures. The research here reported onsets with the characterization of the compounds present in EAFD - Iron (III) oxide, zinc oxide and zinc ferrite - using techniques, methodologies and equipments for thermal characterization (DTA-TGA), structural (XRD), microscopic (SEM-TEM coupled to EDS), physical (briquette porosity, specific gravity, average size and particle specific surface) and chemical analysis. It was found that the studied materials particles showed predominantly spherical geometry and in particular, the TEM scans in the zinc ferrite, reveled cluster type micrometric and homogeneous agglomerates formed from single crystal round particles having the size of circa 100 nm. Aiming at the study of the kinetics of the zinc ferrite reduction experiments were conducted using synthetic and EAFD materials submitted to pure CO gas and mixtures of it with CO2 in the following proportions: 75 per cent CO-25 per cent CO2 e 50 per cent CO-50 per cent CO2. The runs were conducted at the temperatures 1073, 1173, 1223, 1273 e 1373K and the maximum reaction time was 105 min. The obtained results permitted the proposal of a kinetic reduction reaction chain. In the course of the study, also, the main zinc ferrite reduction products were characterized by the SEM analysis. This analysis also permitted the observation of phenomenological and morphological correlations during the process. It was concluded that the morphological and kinetic zinc ferrite reduction, in spite being a complex process, it is similar to iron oxides reduction, meaning, dependent on the gaseous compositions, temperature and reaction times. The morphological prism permitted to propose that the zinc ferrite reduction denounces its instantaneous decomposition in their constituent oxides (ZnO and Fe2O3) when submitted to temperatures in the range of 1073 to 1273K and also the sequential reduction of zinc and iron oxides. The typical reduction products were zinc oxide (ZnO), wüstite (FeO) and mix oxides type (Zn, Fe) O and metallic iron. Again, the kinetic study established that a rapid reduction of the zinc oxide occurs, as compared to the other present oxides, through the sequence: firstly the zinc oxide reduction takes place, and this is followed by the iron oxides reduction. The last processes occur significantly for temperatures in the range of circa 1223 to 1373K. A general model of the zinc ferrite reduction by the gaseous mixture of CO-CO2 was proposed using the response surface methodology (RSM) for the factorial analysis 3(4). This was done evaluating the effect of the following variables: temperature, reducing atmosphere composition, specimen mass and reaction time over the (percentage)Reduction. The kinetic models that presented the better adjustment for the reduction were the boundary chemical reaction model for spherical symmetry (BCRM ss) with the equation [1 - cubic root (1 - alfa)] equal kt and the model of simple exponential continuous reaction obeying the relation: − ln(1 - alfa) equal kt . The kinetic parameters obtained (Ea, apparent activation energy, and A, Arrhenius preexponential frequency fator) were for the first model, that is synthetic zinc ferrite: (a) 100 per cent CO gas: Ea equal 55,60 kJ/mol & A equal 8,83 mHz; (b) 75 per cent CO-25 per cent CO2: Ea equal 88,21 kJ/mol and Aequal 127,74 mHz; (c) 50 per cent CO-50 per cent CO2: Ea equal 95,21 kJ/mol and A equal 193,37 mHz. And for the second material, zinc ferrite contained in the EAF dusts: (a) 100 per cent CO gas: Ea equal 52,34 kJ/mol and A equal 4,98 mHz; (b) 75 per cent CO-25 per cent CO2: Ea equal 66,70 kJ/mol and A equal 76,06 mHz; (c) 50 per cent CO-50 per cent CO2: Ea equal 86,28 kJ/mol and A equal 289,59 mHz. The comparison between the apparent activation energy obtained from the best fitting kinetic models permitted to conclude that the zinc ferrite reduction as well as the electric arc furnace dusts reduction global reactions rates are controlled by iron oxides reduction, this in particular for the case of the reduction with 100 per cent CO. As for the reduction with the CO-CO2 gas mixtures, this was not observed for the synthetic zinc ferrite, although, for the reduction of the electric arc furnace dust, this could be the case due to their low zinc content. Considering these facts and the experimental results of this work, it is suggested that the zinc ferrite reduction by CO-CO2 gas mixtures has the global reaction rate controlled simultaneously by the reduction of both zinc and iron oxides.

Ce travail de thèse traite de l'application d'outils de diagnostics optiques et électriques aux poussières formées dans des plasmas micro-ondes, magnétisé ou non , en vue d'élucider à la fois leur cinétique de formation , et leur dynamique dans ces milieux. Après des premiers chapitres (1 à 3) introductifs qui ont vocation à décrire l'état de l'art récent concernant les plasmas poussiéreux, la démarche de ce travail ainsi que les principaux outils diagnostics utilisés ou mis en place durant cette thèse (spectroscopie d'absorption infrarouge, extinction / diffusion laser entre autres), ce manuscrit peut être scindé en deux parties. La première traite de l'étude fondamentale de poussières de carbone formées à partir de gaz hydrocarbonées tels que CH 4 et C2H2 (Chap.4/ 5), et la seconde d'une étude orientée sur la formation de poussières de tungstène par pulvérisation d'une cible massive exposée à des plasmas d'hydrogène et d'argon (Chap.6). Cette dernière partie vise à appréhender certains processus menant à la formation de poussières dans des conditions proches des machines de fusion thermonucléaire. De l'ensemble de ces travaux ressortent certains résultats importants liés au caractère magnétisé de la décharge, mais également aux types de source plasma utilisées. En effet, il a été montré que l 'utilisation de source micro-onde ponctuelle induit de fort gradient de température au sein du milieu conduisant à une prépondérance de la force de thermophorèse sur la dynamique des poussières par rapport aux autres forces (électrique, ionique) considérées habituellement comme les forces dominantes dans les plasmas poussiéreux usuels (RF, DC). De plus, il a été montré que la formation de poussières était possible dans des conditions peu propice à leur création (très basse pression) grâce à l'action du champ magnétique qui permet aux ions d'être confinés dans la décharge sur des temps assez long pour être à même d'amorcer des processus de nucléation. Ainsi, les ions positifs joueraient un rôle clé dans la formation de précurseurs de poussières dans des plasmas magnétisés (très basse pression). Enfin, il a été montré que l'interaction d'un plasma d'hydrogène avec une cible massive de tungstène pouvait non seulement conduire à la formation de poussières par processus de pulvérisation mais également par des processus d'explosion de cloques formées à la surface du tungstène après diffusion de l'hydrogène dans la surface. / This work deals with the application of diagnostics tools to study dust formed in magnetized and non­ magnetized microwave plasma in order to elucidate kinetics processes, and dynamic in these medium. After first chapters (1-3) that are introductory and are intended to describe: (i) the state of the art regarding recent dusty plasmas work; (ii) the approach of this work and (iii) the main diagnostic tools used or developed during this thesis (infrared absorption spectroscopy, extinction / scattering laser method and others), the manuscript can be divided into two part s. The first one deals with the fundamental study of carbon dust created by the use of hydrocarbon gases such as CH 4 and C2H2 (chapter 4 and 5) and the second deals with the study of tungsten dusts formed by the interaction of a solid target exposed to H2 and Ar plasmas thanks to physical sputtering process (Chapter 6) . The latter seeks to understand some of the processes leading to the formation of dust in close conditions of edge fusion plasmas of thermonuclear machines. This work stand out some important results related to the magnetized character of the discharge but also to the plasma source types used. lndeed, it was shown that the use of a local microwave source induces strong temperature gradient in the medium resulting in a preponderance of thermophoresis force on the dynamics of dust compared to other forces (electric, ion dragg) usually considered as dominant forces in well studied dusty plasmas (RF , DC). In addition, it was shown that dust formation was possible in less suitable creation conditions (very low pressure) through the action of the magnetic field which allows ions to be confined longtime enough in the discharge to be able to initiate nucleation processes. Thus, positive ions play a key role in the formation of dust precursors in magnetized plasmas (very low pressure). Finally, it has been shown that the interaction of a hydrogen plasma tungsten target could not only lead to dust formation by sputtering process but also by blistering burst process.

Abstract This study investigated the optimal operating parameters on road dust removal by a flusher. It aimed at enhancing road flushing efficiency, analyzing particle size range, and establishing a flushing model. This study explored main roads by collecting road dusts in Kaohsiung metropolitan area in October 2001. The roads were classified by road dust loading (RDL) as follows: level A (minor, RDL<1g/m2), level B (normal, RDL=1~5g/m2), level C (abnormal, RDL=5~11g/m2), and level D (serious, RDL= 11~25g/m2). The frequency of road flushing was recommended as follows: Level D roads were flushed every day to maintain RDL≤20g/m2. Level C roads were flushed every day, while level B roads were flushed every two days, to keep RDL≤10g/m2. Level A roads were flushed every week to maintain RDL≤5g/m2. A pilot-scale road-flush testing field was designed for this particular study to investigate the influence of operating parameters on road flushing efficiency. The findings indicated that flat-fan type nozzle demonstrated higher flushing efficiency than hollow-cone type nozzle, and that the flushing speed and the distance of the nozzle away from the ground were correlated negatively with the road flushing efficiency, whereas the pressure of nozzle and RDL was correlated with the road flushing efficiency. The results suggested that, in the condition of eighty percent of flushing efficiency, the optimal operating parameters were flushing speed of 15km/hr, the pressure of nozzle of 2.0kg/cm2, the distance away from the ground of 30cm, the angle of 40o, and the particle size less than 150£gm. The results showed that particle size was correlated negatively with the road flushing efficiency under various operating parameters of flushing for different road levels. Beside, the road flushing efficiency was above 80% for silt with particle size less than 75£gm. However, for particle size larger than 850£gm, the road flushing efficiency was up to 40%. It concluded that the road flushing efficiency of fine particles was better than that of coarse particles. After conducting dimensionless analysis and multiple regression analysis, the model of road flushing efficiency can be shown as follows, ¡]R¡×0.8276¡^ where £b is the road flushing efficiency, U is the flusher speed (m/s), P is the water injecting pressure (N/m2), W is the road dust loading (kg/cm2), H is the distance of nozzle away from the ground (m), q is the amount of water per square meter (m3/m2), and £c is the angle of nozzle spread. In this model, RDL is negatively correlated with U, W and H. Moreover, the road flushing efficiency increases with water injection pressure and flow rate. On the basis of the above model, the average percentage of error was approximately 0.28%. In this study, the optimal operating parameters of a flusher were that the flushing speed of 10km/hr, water injecting pressure of 2.0kg/cm2, the distance of nozzle away from the ground of 20cm, and the water injecting angle of 45o. However, depending upon the road cleanness levels, the optimal operating parameters could be varied. For instance, the distance of the nozzle away from the ground should be increased up to 30cm in order to prevent the damage from uneven roads or cavities. The experiments showed that 30cm of the height was a better option due to the road flushing efficiency was only 2% lower while compared with that of 20cm. After the analysis of experimental data, the results can serve as the operation condition for road flushing practice as authorities concerned. The operating parameters proposed in this study could be useful for basic design of a high-efficiency flusher. Moreover, the model of road flushing efficiency can be further applied to predict the road flushing efficiency.

Kasmet vidutiniškai šalyje užauginama 3 – 4 milijonai tonų javų. Juos pristatant į grūdų apdorojimo įmones nustatyta, kad grūdų vidutinis šiukšlingumas siekia 4 – 7%. Dalis mažųjų šiukšlių gali patekti į darbo vietą grūdų apdorojimo patalpose. Grūdų apdorojimo technologijose dirbantiems žmonėms dulkės kenkia sveikatai ir ilgainiui gali tapti rimtos profesinės ligos priežastimi. Dulkėtumo tyrimai grūdų sandėliuose yra aktuali, mažai tyrinėta problema. Darbe ištirti dulkių koncentracijos lygiai grūdų sandėlyje technologinėse operacijose. Nustatyta, kad dulkių koncentracijos matavimų maksimali paklaida neviršytų 0,35 mg/m3, imties tūris turėtų būti ne mažiau, kaip 31 matavimai (bandymuose pasirinkta ne mažiau 33). Bandymų metu nustatyta maksimali dulkių koncentracija (6,17 mg/m3), kuri yra potencialiai pavojinga aptarnaujamo personalo sveikatai, todėl rekomenduotina darbuotojams naudoti asmenines apsaugos priemones. Nustatyta vidutinė dulkių koncentracija (2,16 mg/m3) neviršija HN 23:2011 ilgalaikio poveikio ribinio dydžio 5 mg/m3. / Each year, the national average and producing 3-4 million tonnes of cereals. Delivery to the grain-processing companies showed that the average grain impurities to 4-7%. Some small debris can enter the work area of grain handling facilities. Grain processing technology for people working in the dust is harmful and may eventually become a serious cause of occupational disease. Dust grain storage research is relevant, a little research on the problem. Work to investigate the concentration levels of dust grain warehouse technological operations. There were found that it has been not less as 31 measurement off amount (in experimentations there were chosen not less than 33), that the maximum concentrations of dusts bias won’t go off 0,35 mg/m³. During the tests, the maximum concentration of dust (6,17 mg/m³), which is potentially dangerous to the health personnel served, therefore, recommended that employees wear personal protective equipment. Estimated the average dust concentration (2,16 mg/m³), does not exceed the long-term exposure limit value of 5 mg/m³ with HN 23:2011.

To this date, estimates of the climate response to mineral dust remain largely uncertain because of our limited capability to quantify dust distribution in the atmosphere. Focusing on the Central and East Asian dust source regions, this thesis aims to develop a coupled regional dust modeling system to provide an improved modeling capability of atmospheric dust as well as to aid the integration of ground-based and satellite observations. The objectives of this study are as follows: 1) evaluate the capabilities of the available data to detect and quantify mineral dust in the atmosphere; 2) develop and test a coupled regional dust modeling system able to simulate size resolved dust concentrations accounting for the regional specifics of Central and East Asia; and 3) outline a methodology for data and modeling integration. The capabilities of ground-based and satellite data to characterize dust in the atmosphere are examined in great details. Based on analysis of MODIS data reflectance and radiances, we found evidence for regional signature of dust in near-IR and proposed a new probabilistic dust-cloud mask that explicitly takes into account the spatial variability characteristics of dust aerosols. We developed a coupled regional dust modeling system (WRF-DuMo) by incorporating a dust emission module (DuMo) into the NCAR WRF model. The WRF-DuMo unique capabilities include explicit treatment of land surface properties in Central and East Asia, a suite of dust emission schemes with different levels of complexity, multiple options for dust injection in the atmosphere and flexible parameters of the initial size distribution of emitted dust. Two representative dust events that originated in East Asia in the springs of 2001 and 2007 have been modeled with WRF-DuMo. Simulations with different initial size distribution of dust, injection and emission parameterizations have been performed to investigate their relative role on the modeled dust fields. We performed an integrated analysis of modeled dust fields and satellite observations by introducing an ensemble model dust index, which used in conjunction with satellite dust retrievals improves the capability to characterize dust fields. Finally, we provide recommendations for the development of an integrated observational and modeling dust framework.

Made available in DSpace on 2014-10-09T12:27:18Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:59:13Z (GMT). No. of bitstreams: 0 / A poeira doméstica tem sido identificada como um importante vetor de exposição por substâncias inorgânicas e orgânicas, potencialmente tóxicas, em crianças e adultos. A composição da poeira tem uma forte influência de contaminantes provenientes de ambientes internos e externos. Durante o uso normal ou por intempéries, de uma variedade de artefatos e materiais, as substâncias químicas são desincorporadas para o meio ambiente. Uma vez liberadas, elas tendem a se acumular e enriquecer na poeira doméstica; e por meio de exposição contínua (mecanismos de inalação, ingestão e contato direto com a pele) afeta a saúde humana. Neste trabalho, foi realizada uma avaliação da contaminação por constituintes inorgânicos e ésteres ftálicos em poeira doméstica; e a correlação com as prováveis fontes antropogênicas. As amostras de poeira foram coletadas de 69 residências, nos bairros Pirituba, Freguesia do Ó, Jaraguá e Perus, da região metropolitana de São Paulo, entre 2006 e 2008. As amostras foram separadas nas frações: 850, 850-300, 300-150, 150-75, 75- 63 e <63 &mu;m. A análise por fluorescência de raios X (WDXRF) mostrou a presença de Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Br, Rb, Sr, Zr e Pb. A análise por cromatografia de fase gasosa acoplada o espectrômetro de massa (GCMS) a presença de ésteres ftálicos (DEHP, DnBP, DEP, DEHA, BBP e DMP). A partir do fator de enriquecimento (FE), os elementos P, S, Cr, Ni, Cu, Zn e Pb foram classificados como sendo significantemente e extremamente enriquecidos na poeira. As contribuições naturais e antropogênicas foram identificadas por meio de ferramentas estatísticas como análise de fatores (AF) e cluster (AC). Os elementos Cr, Ni, Cu, Zn e Pb foram encontrados em concentrações significativamente elevadas com relação aos valores de exposição total (ingestão, inalação e contato dérmico) e de risco. / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP