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Data publikacji: 4 czerwca 2021
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1

Jansson, Stina. "Thermal formation and chlorination of dioxins and dioxin-like compounds". Doctoral thesis, Umeå universitet, Kemi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1881.

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This thesis contributes to an increased understanding of the formation of dioxins and dioxin-like compounds in combustion processes. Although emissions to air from waste incineration facilities have been greatly reduced by the use of efficient air pollution control measures, the resulting residues (ashes and filters) are highly toxic and are classified as hazardous waste. The main objective of the work underlying this thesis was to elucidate the formation and chlorination pathways of dioxins and dioxin-like compounds in waste combustion flue gases in the temperature range 640-200°C in a representative, well-controlled laboratory-scale reactor using artificial municipal solid waste. This could contribute to the reduction of harmful emissions to air and also reduce the toxicity of waste incineration residues, thus reducing or even eliminating the need for costly and potentially hazardous after-treatment. A comparison of four different quenching profiles showed that the formation of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) was rapid and mainly occurred in the 640-400°C temperature region, with high dependency on sufficient residence time within a specific temperature region. Prolonged residence time at high temperatures (450/460°C) reduced the PCDD yields, even at lower temperatures along the post-combustion zone. PCDD, PCDF and PCN (polychlorinated naphthalene) isomer distribution patterns indicated contributions from chlorophenol condensation as well as chlorination reactions for all three classes of compounds. The formation of PCDDs was largely influenced by chlorophenol condensation and to some extent by chlorination reactions. For the PCDFs, chlorine substitution adjacent to the oxygen bridges was unfavoured, as demonstrated by the notably lower abundance of 1,9-substituted congeners. This was supported by bidirectional orthogonal partial least squares (O2PLS) modelling. The variable with the greatest influence on the distribution of PCDD congeners was the relative free energy (RΔGf). The O2PLS models displayed distinct clusters, dividing most of the homologues into two or three sub-groups of congeners which seemed to correspond to the probability of origination from chlorophenol condensation. The effects of injection of aromatic structures into the flue gas differed for each class of compounds. Injection of naphthalene increased the formation of monochlorinated naphthalene but the remaining homologues appeared to be unaffected. This was probably due to insufficient residence time at temperatures necessary for further chlorination. Injected dibenzo-p-dioxin was decomposed, chlorinated and re-condensated into PCDDs and PCDFs, whereas injection of dibenzofuran and fluorene reduced the PCDD levels in the flue gas.
Denna avhandling fokuserar på olika aspekter som kan bidra till en ökad förståelse av bildning av dioxiner och dioxin-lika föreningar i förbränningsprocesser. Även om utsläppen till luft från sopförbränningsanläggningar har minskat kraftigt tack vare effektiva rökgasreningsmetoder, så återstår problemet med mycket giftiga rökgasreningsprodukter (askor och filter), vilka klassificeras som farligt avfall. Det huvudsakliga syftet med arbetet bakom denna avhandling var att klarlägga bildnings- och kloreringsvägarna för dioxiner och dioxin-lika föreningar i temperaturintervallet 640-200°C i rökgaser från sopförbränning. Detta kan möjliggöra lösningar för ytterligare emissionsminskningar och en avgiftning av biprodukterna från avfallsförbränning, vilket minskar eller till och med eliminerar behovet av kostsam och riskfylld efterbehandling. Realistiska och välkontrollerade försök har utförts i en lab-skalereaktor där en artificiell hushållssopa har förbränts. En jämförelse av fyra olika temperatur- och uppehållstidsprofiler visade att bildning av polyklorerade dibenso-p-dioxiner (PCDD) och dibensofuraner (PCDF) sker snabbt och huvudsakligen inom temperaturintervallet 640-400°C. Bildningen var starkt beroende av en tillräckligt lång uppehållstid inom ett visst temperaturområde. En förlängd uppehållstid vid höga temperaturer (>450°C) resulterade i minskade halter av PCDD, vilka förhöll sig låga även senare i efterförbränningszonen. Isomermönstren av PCDD, PCDF och PCN (polyklorerade naftalener) visade alla tecken på att härröra från både klorfenolkondensation och kloreringsreaktioner. PCDD-mönstret visade tydliga indikationer på bildning från klorfenoler, och till mindre grad bildning via klorering. För PCDF var klorsubstitution i positioner angränsande till syrebryggan missgynnad, vilket bekräftades av multivariat modellering (O2PLS). Den variabel som starkast påverkade bildningen av PCDD var relativa fria energin (RΔGf). Modellerna visade på en distinkt gruppering av PCDD- och PCDF-kongenerna i två eller tre grupper för varje kloreringsgrad, och föreslås vara relaterad till sannolikheten för respektive kongen att bildas via klorfenolkondensation. Injektion av aromatiska kolstrukturer i rökgaskanalen gav upphov till skilda effekter. Injektion av naftalen ökade bildningen av monoklorerad naftalen medan resterande homologer inte verkade påverkas, sannolikt på grund av för kort uppehållstid för ytterligare klorering. Dibenso-p-dioxin spjälkades sannolikt till fenoliska fragment som klorerades och sedan återkondenserades till PCDD och PCDF, medan dibensofuran och fluoren kraftigt reducerade PCDD-koncentrationerna.
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2

Furness, Sebastian George Barton. "Novel mechanisms for activation of the dioxin (Aryl-hydrocarbon) receptor /". Title page, table of contents and summary only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phf988.pdf.

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3

Gao, Qiuju. "Dioxins and dioxin-like compounds in thermochemical conversion of biomass : formation, distribution and fingerprints". Doctoral thesis, Umeå universitet, Kemiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-118861.

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In the transition to a sustainable energy supply there is an increasing need to use biomass for replacement of fossil fuel. A key challenge is to utilize biomass conversion technologies in an environmentally sound manner. Important aspects are to minimize potential formation of persistent organic pollutants (POPs) such as dioxins and dioxin-like compounds. This thesis involves studies of formation characteristics of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs) in microwave-assisted pyrolysis (MAP) and torrefaction using biomass as feedstock. The research focuses are on their levels, distributions, fingerprints (homologue profiles and isomer patterns) and the underlying formation pathways. The study also included efforts to optimize methods for extracting chlorinated aromatic compounds from thermally treated biomass. The overall objective was to contribute better understanding on the formation of dioxins and dioxin-like compounds in low temperature thermal processes. The main findings include the following: Pressurized liquid extraction (PLE) is applicable for simultaneous extraction of PCDDs, PCDFs, PCNs, polychlorinated phenols and benzenes from thermally treated wood. The choice of solvent for PLE is critical, and the extraction efficiency depends on the degrees of biomass carbonization. In MAP experiments PCDDs, PCDFs and PCNs were predominantly found in pyrolysis oils, while in torrefaction experiments they were mainly retained in solid chars with minor fractions in volatiles. In both cases, highly chlorinated congeners with low volatility tended to retain on particles whereas the less chlorinated congeners tended to volatize into the gas phase. Isomer patterns of PCDDs, PCDFs and PCNs generated in MAP were more selective than those reported in combustion processes. The presence of isomers with low thermodynamic stability suggests that the pathway of POPs formation in MAP may be governed not only by thermodynamic stabilities but also by kinetic factors. Formation of PCDDs, PCDFs and PCNs depends not only on the chlorine contents in biomass but also the presence of metal catalysts and organic/metal-based preservatives. Overall, the results provide information on the formation characteristics of PCDDs, PCDFs and PCNs in MAP and torrefaction. The obtained knowledge is useful regarding management and utilization of thermally treated biomass with minimum environmental impact.
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4

Prange, Joelle, i n/a. "Origin of Dioxins in Queensland: Investigations into the Distribution and Sources of Polychlorinated Dibenzo-P-Dioxins in the Queensland Terrestrial Environment". Griffith University. School of Public Health, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20040615.161651.

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Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are persistent organic pollutants of global concern as they are persistent, toxic and can biomagnify through the food chain. PCDD/Fs are generally regarded as trace contaminants in a number of chemical products and they are formed as by-products from various industrial, chemical and combustion processes. The pollution with PCDD/Fs occurs with the release of these chemicals into the environment, resulting in the contamination of various compartments including; air, soil, sediment and biota. Studies that have investigated the distribution of PCDD/Fs in the environment suggest that the highest concentrations of these pollutants are found in locations with a history of industrial or chemical PCDD/F sources. Queensland is the north-eastern state of Australia. Queensland has a low population density, few industrial activities and is considered predominantly rural. Therefore it was somewhat surprising that elevated concentrations of PCDD/Fs (in particular the higher chlorinated PCDDs) have been observed in soil and sediments samples collected from various locations along the Queensland coast. The concentrations of PCDDs in Queensland samples were comparable to or higher than concentrations in similar matrices from highly polluted regions elsewhere. To investigate the origin of PCDDs in Queensland, the geographical distribution of PCDD/Fs in topsoil was investigated in the coastal and inland environments to provide information on the potential sources and to estimate the extent of the PCDD contamination. Distinct east-west gradients were detected in topsoil collected from bushland areas across the state with elevated PCDD concentrations confined to the coastal region. Within the coastal region, the contamination could not be associated with specific land uses. In fact, the PCDD/F congener profile was similar in the majority of samples from the coastal region, with a dominance of the higher chlorinated PCDDs (in particular OCDD), whereas PCDFs were low or below the limit of detection. The similarity in the PCDD/F congener profiles in the soils along the coastal region indicated that a source of PCDDs of similar origin has resulted in the contamination of soil extending more than 3000 km and estimations suggest that more than 50 tonnes of OCDD is stored in the topsoil of Queensland.s coastal region. Investigation into the vertical distribution of PCDDs in Queensland coastal soils revealed elevated concentrations of PCDDs, (in particular OCDD) in soils to at least 3.5 m. These results indicated that the extent of the PCDD contamination is significantly greater than anticipated and it was estimated that there is in the order of 3 000 tonnes of OCDD stored in Queensland's coastal soils. The specific PCDD/F congener profile in Queensland coastal soils is unlike known PCDD/F source profiles which led to the suggestion that some yet unidentified formation mechanism may have resulted in the contamination. Potential natural sources of PCDD/Fs, including forest fires, geogenic and biogenic processes were assessed as possible origins for the PCDD contamination in Queensland. Elevated concentrations of PCDDs were detected in the atmosphere during a 'prescribed burn'. This study demonstrated that although forest fires influence atmospheric PCDD/F concentrations substantially, forest fires are not the source of PCDDs in Queensland; rather they are an important mechanism for the redistribution of PCDDs and may have attributed to the widespread PCDD contamination. In this study geological materials (oil shale and kaolin) were analysed as a proxy to assess a geogenic origin of PCDDs. Elevated concentrations of PCDDs were observed in the kaolin samples, however similar and higher concentrations were detected in surface and sub-surface soils, suggesting that specific geogenic formation processes investigated are not the source of PCDDs in Queensland. A preliminary indication for a biogenic origin of PCDDs was identified during the anaerobic incubation of sugarcane irrigation sediments. An increase in the concentration of OCDD in the anaerobic treatment, compared to the control was observed after incubation for 90 days. In these same experiments, a dechlorination of OCDD to lower chlorinated (1,4,6,9-substituted) PCDDs was also observed. Similar transformation processes were observed in other anaerobic environments in Queensland, which led to the suggestion that a biogenic formation of PCDDs (possibly from a precursor) may be responsible for the origin of PCDDs in Queensland.
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5

Prange, Joelle. "Origin of Dioxins in Queensland: Investigations into the Distribution and Sources of Polychlorinated Dibenzo-P-Dioxins in the Queensland Terrestrial Environment". Thesis, Griffith University, 2004. http://hdl.handle.net/10072/367289.

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Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) are persistent organic pollutants of global concern as they are persistent, toxic and can biomagnify through the food chain. PCDD/Fs are generally regarded as trace contaminants in a number of chemical products and they are formed as by-products from various industrial, chemical and combustion processes. The pollution with PCDD/Fs occurs with the release of these chemicals into the environment, resulting in the contamination of various compartments including; air, soil, sediment and biota. Studies that have investigated the distribution of PCDD/Fs in the environment suggest that the highest concentrations of these pollutants are found in locations with a history of industrial or chemical PCDD/F sources. Queensland is the north-eastern state of Australia. Queensland has a low population density, few industrial activities and is considered predominantly rural. Therefore it was somewhat surprising that elevated concentrations of PCDD/Fs (in particular the higher chlorinated PCDDs) have been observed in soil and sediments samples collected from various locations along the Queensland coast. The concentrations of PCDDs in Queensland samples were comparable to or higher than concentrations in similar matrices from highly polluted regions elsewhere. To investigate the origin of PCDDs in Queensland, the geographical distribution of PCDD/Fs in topsoil was investigated in the coastal and inland environments to provide information on the potential sources and to estimate the extent of the PCDD contamination. Distinct east-west gradients were detected in topsoil collected from bushland areas across the state with elevated PCDD concentrations confined to the coastal region. Within the coastal region, the contamination could not be associated with specific land uses. In fact, the PCDD/F congener profile was similar in the majority of samples from the coastal region, with a dominance of the higher chlorinated PCDDs (in particular OCDD), whereas PCDFs were low or below the limit of detection. The similarity in the PCDD/F congener profiles in the soils along the coastal region indicated that a source of PCDDs of similar origin has resulted in the contamination of soil extending more than 3000 km and estimations suggest that more than 50 tonnes of OCDD is stored in the topsoil of Queensland.s coastal region. Investigation into the vertical distribution of PCDDs in Queensland coastal soils revealed elevated concentrations of PCDDs, (in particular OCDD) in soils to at least 3.5 m. These results indicated that the extent of the PCDD contamination is significantly greater than anticipated and it was estimated that there is in the order of 3 000 tonnes of OCDD stored in Queensland.s coastal soils. The specific PCDD/F congener profile in Queensland coastal soils is unlike known PCDD/F source profiles which led to the suggestion that some yet unidentified formation mechanism may have resulted in the contamination. Potential natural sources of PCDD/Fs, including forest fires, geogenic and biogenic processes were assessed as possible origins for the PCDD contamination in Queensland. Elevated concentrations of PCDDs were detected in the atmosphere during a 'prescribed burn'. This study demonstrated that although forest fires influence atmospheric PCDD/F concentrations substantially, forest fires are not the source of PCDDs in Queensland; rather they are an important mechanism for the redistribution of PCDDs and may have attributed to the widespread PCDD contamination. In this study geological materials (oil shale and kaolin) were analysed as a proxy to assess a geogenic origin of PCDDs. Elevated concentrations of PCDDs were observed in the kaolin samples, however similar and higher concentrations were detected in surface and sub-surface soils, suggesting that specific geogenic formation processes investigated are not the source of PCDDs in Queensland. A preliminary indication for a biogenic origin of PCDDs was identified during the anaerobic incubation of sugarcane irrigation sediments. An increase in the concentration of OCDD in the anaerobic treatment, compared to the control was observed after incubation for 90 days. In these same experiments, a dechlorination of OCDD to lower chlorinated (1,4,6,9-substituted) PCDDs was also observed. Similar transformation processes were observed in other anaerobic environments in Queensland, which led to the suggestion that a biogenic formation of PCDDs (possibly from a precursor) may be responsible for the origin of PCDDs in Queensland.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Public Health
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6

Machado, Diego Henrique de Oliveira. "Investigação das propriedades ópticas, morfológicas e elétricas da heterojunção SnO2:Ce3+/GaAs /". Bauru, 2016. http://hdl.handle.net/11449/135900.

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Orientador: Luís Vicente de Andrade Scalvi
Banca: Dayse Iara dos Santos
Banca: Anrea Simone Stucchi de Camargo
O Programa em Pós Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi
Resumo: Este trabalho apresenta o desenvolvimento e algumas conclusões do estudo de heterojunção de filmes finos de SnO2 e GaAs. Os filmes de SnO2 dopados com Ce3+, foram depositados a partir do método sol-gel usando as técnicas de dip e spin coating; os filmes de GaAs foram depositadas por evaporação resistiva e por sputtering. As heterojunções foram constituídas de filmes de SnO2 sobre filmes de GaAs, e filmes de GaAs sobre filmes de SnO2. Foram investigadas as propriedades ópticas, estruturais, morfológicas e elétricas de filmes finos constituintes das heterojunções e também a influência do dopante Ce3+. Entre os experimentos realizados estão: transmitância óptica, difração de raios X, microscopia eletrônica de varredura (MEV), microscopia óptica, microscopia de força atômica (AFM), fotoluminescência e medidas elétricas na presença de excitações com diferentes fontes de luz monocromáticas (quarto harmônico do laser Nd:Y AG (266nm), laser He-Ne (628nm), LED InGaN (450nm)). Entre as principais conclusões, verificou-se: 1) em algumas situações, condutividade independente da temperatura, sugerindo a participação de um gás de elétrons bidimensional (2DEG) na interface SnO2/GaAs; 2) o tamanho dos cristalitos, calculado a partir das análises de difração de raios X, fornece valores da ordem de 10 nm tanto para filmes de SnO2 como para filmes de GaAs; 3) a energia de bandgap, avaliada com base em dados de medidas de absorbância, fornece um valor máximo de 3,6 eV para filmes de dióxido de estanho e 1,6eV para filmes de GaAs; 4) MEV e microscopia óptica de para filmes de GaAs (depositado por evaporação resistiva e sputtering) apresentam sua superfície heterogênea, com partículas de variados tamanhos. Além disso, a aderência de filmes de SnO2 sobre filmes de GaAs está relacionada com a técnica utilizada para depositar os filmes da camada de base, o melhor resultado foi obtido quando a camada é a GaAs...
Abstract: The aims of this work is to present the development and the main conclusion, related the investigation of thin film SnO2/GaAs. Os filmes de SnO2/GaAs heterojunction. Ce3+ - doped SnO2 thin films were deposited by the sol-gel-dip -spin coating techniques, whereas GaAs films were deposited by resistive evaporation and sputerring. Heterojunctions were deposited by SnO2 layer growth on the oppositive order: GaAs on top of SnO2 Optical, structural, morphologic and electrical properties of heterojunction films were investigated, as well as the influence of Ce-doping in these measurements. Experiments carried out include: optical transmission, X-ray diffraction, scanning eletron microscopy (SEM), optical microscopy, atomic force microscopy (AFM), photoluminescence and electrical measurement under optical excitation. In this last case the excitation sources are monochromatic light from the fouth harmonic of a Nd:YAG laser (266nm), a He-Ne laser (628nm) and a InGaN LED (450nm). Among the main conclusions, it was verified that: 1) in some situations, a temperature independent electrical resistivity was observed and attributed to the possible formation of a two-dimensional electron gas (2DEG) at SnO2/GaAs interface; 2) crystalline size was calculated from X-ray diffraction data, being about 10 nm either for SnO2 films as GaAs films; 3) bandgap energy, evaluated from absorbance data yield a maximum value of about 3.6eV for tin dioxide and 1.6eV for GaAs films; 4) SEM images, obtained for GaAs thin films deposited by resistive evaporation and for the heterojuntion SnO2/GaAs, and optical microscopy, for sputtering deposited GaAs films and heterojunction samples, show that GaAs films present an heterogeneous surface, with particles of several distinct sizes. Besides, the adherence of SnO2 films on the GaAs layer is related to the used technique for deposition the base layer, being better in the case of resistive evaporation deposited GaAs. This was...
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7

Gaus, Caroline, i n/a. "Dioxins in the Marine Environment: Sources, Pathways and Fate of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Queensland, Australia". Griffith University. School of Public Health, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030624.144111.

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Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans(PCDFs) are two groups of lipophilic, persistent organic pollutants that are produced as by-products of various anthropogenic and industrial processes. Due to their relatively high toxic potencies and potential to bioaccumulate and biomagnify in organisms and through the food chain, the contemporary widespread distribution of these compounds is a concern to the health of the environment, wildlife and humans. This study determined the distribution, pathways and fate of PCDD/Fs in the coastal zone of Queensland, Australia, including the inshore marine environment of the World Heritage Great Barrier Reef Marine Park. This ecosystem supports unique fauna and flora such as the marine herbivorous mammal dugong (Dugong dugon) and its food source, seagrass. Elevated PCDD/Fs were present in soils and sediments along the entire Queensland coastline. Highest concentrations were found in soil from agricultural irrigation drains and in sediments near the mouths of major rivers. Elevated concentrations were associated with rural and urban types of land-use, and PCDD/Fs were present even in locations remote from anthropogenic activities. PCDD/F congener-specific analysis revealed an unusual profile in all samples, dominated by OCDD, with PCDFs present in low concentrations or below the limit of detection. Distinct HxCDD isomer patterns were observed, with the 1,2,3,7,8,9-HxCDD/1,2,3,4,6,7-HxCDD isomer pair dominating the 2,3,7,8-substituted HxCDDs. Similar congener and isomer characteristics were reported in sediments, soil and clay samples from other continents, but could not be attributed to any known source. Possible PCDD/F sources in Queensland were assessed using segmented estuarine sediment cores, for which radiochemical chronologies were established for each depth. Variations of PCDD/F concentrations in the sediment cores over several centuries of depositional history were relatively small. Elevated PCDD levels were still present in sediment slices from the early 17th century. PCDD/F homologue profiles in sediments deposited during the last 350 years were almost identical and correlated well to the characteristic profiles observed in surface sediments and soils from the entire Queensland coastline. These results suggested the presence of an unidentified PCDD source prior to the production of commercial organochlorine products. To investigate the formation of the unusual PCDD/F profiles, congener and isomer specific analyses were undertaken in soils, sediments and dated sediment cores. The results demonstrated that specific transformation processes in the environment have resulted in the observed PCDD profile characteristics. Dechlorination of OCDD was proposed to result in distinct 1,4-pattern characteristics (i.e. formation of isomers chlorinated in the 1,4,6,9-positions). Consequently, the environmental samples do not reflect the signatures of the original source. An alternative hypothesis to natural formation is discussed evaluating these processes and their implications for possible source contributions. This hypothesis explores the potential for the influence of anthropogenic PCDD precursors (e.g. pentachlorophenol) during the 1940s to 1990s. Transport of PCDD/Fs from the land-based source via impacted tributary river systems, and subsequent deposition processes are proposed to result in PCDD/F accumulation in the inshore marine ecosystem. The extent of the sediment PCDD/F contamination governs the concentrations in the extensive inshore marine seagrass meadows of Queensland. Partitioning processes in the sediment-seagrass system lead to increased toxic equivalency (TEQ) in the seagrass, compared to sediment.The relationship between contaminated inshore sediments, seagrass and dugongs were evaluated using six dugong habitat regions along the coastline. PCDD/F body burdens in dugongs are governed by sediment (and seagrass) PCDD/F concentrations in their habitat. High seagrass (and incidental sediment) ingestion rates, selective retention of toxicologically potent congeners and relatively low PCDD/F elimination capacities in dugongs are proposed to result in elevated PCDD/F concentrations and TEQ levels in adult animals. Transfer efficiencies of 4 and 27% of maternal TEQ levels to foetuses and calves (respectively) during gestation and lactation result in relatively high exposure potentials to offspring. Compared to no-observed-adverse-effect-levels in other mammals, and based on the results of this study, a tolerable daily intake (TDI) of 10-24 pg TEQ kg-1 day-1 was estimated for dugongs. The results of the present study found that dugongs from some regions along the coastline of Queensland exceed this TDI by up to 20 fold, suggesting that these populations may be at risk from PCDD/F contamination in their habitat. These results have important implications for the health of the environment, wildlife and humans and were used to develop a conceptual understanding of the sources, pathways and fate of dioxins in Queensland, Australia.
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8

Gaus, Caroline. "Dioxins in the Marine Environment: Sources, Pathways and Fate of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Queensland, Australia". Thesis, Griffith University, 2003. http://hdl.handle.net/10072/367537.

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Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans(PCDFs) are two groups of lipophilic, persistent organic pollutants that are produced as by-products of various anthropogenic and industrial processes. Due to their relatively high toxic potencies and potential to bioaccumulate and biomagnify in organisms and through the food chain, the contemporary widespread distribution of these compounds is a concern to the health of the environment, wildlife and humans. This study determined the distribution, pathways and fate of PCDD/Fs in the coastal zone of Queensland, Australia, including the inshore marine environment of the World Heritage Great Barrier Reef Marine Park. This ecosystem supports unique fauna and flora such as the marine herbivorous mammal dugong (Dugong dugon) and its food source, seagrass. Elevated PCDD/Fs were present in soils and sediments along the entire Queensland coastline. Highest concentrations were found in soil from agricultural irrigation drains and in sediments near the mouths of major rivers. Elevated concentrations were associated with rural and urban types of land-use, and PCDD/Fs were present even in locations remote from anthropogenic activities. PCDD/F congener-specific analysis revealed an unusual profile in all samples, dominated by OCDD, with PCDFs present in low concentrations or below the limit of detection. Distinct HxCDD isomer patterns were observed, with the 1,2,3,7,8,9-HxCDD/1,2,3,4,6,7-HxCDD isomer pair dominating the 2,3,7,8-substituted HxCDDs. Similar congener and isomer characteristics were reported in sediments, soil and clay samples from other continents, but could not be attributed to any known source. Possible PCDD/F sources in Queensland were assessed using segmented estuarine sediment cores, for which radiochemical chronologies were established for each depth. Variations of PCDD/F concentrations in the sediment cores over several centuries of depositional history were relatively small. Elevated PCDD levels were still present in sediment slices from the early 17th century. PCDD/F homologue profiles in sediments deposited during the last 350 years were almost identical and correlated well to the characteristic profiles observed in surface sediments and soils from the entire Queensland coastline. These results suggested the presence of an unidentified PCDD source prior to the production of commercial organochlorine products. To investigate the formation of the unusual PCDD/F profiles, congener and isomer specific analyses were undertaken in soils, sediments and dated sediment cores. The results demonstrated that specific transformation processes in the environment have resulted in the observed PCDD profile characteristics. Dechlorination of OCDD was proposed to result in distinct 1,4-pattern characteristics (i.e. formation of isomers chlorinated in the 1,4,6,9-positions). Consequently, the environmental samples do not reflect the signatures of the original source. An alternative hypothesis to natural formation is discussed evaluating these processes and their implications for possible source contributions. This hypothesis explores the potential for the influence of anthropogenic PCDD precursors (e.g. pentachlorophenol) during the 1940s to 1990s. Transport of PCDD/Fs from the land-based source via impacted tributary river systems, and subsequent deposition processes are proposed to result in PCDD/F accumulation in the inshore marine ecosystem. The extent of the sediment PCDD/F contamination governs the concentrations in the extensive inshore marine seagrass meadows of Queensland. Partitioning processes in the sediment-seagrass system lead to increased toxic equivalency (TEQ) in the seagrass, compared to sediment.The relationship between contaminated inshore sediments, seagrass and dugongs were evaluated using six dugong habitat regions along the coastline. PCDD/F body burdens in dugongs are governed by sediment (and seagrass) PCDD/F concentrations in their habitat. High seagrass (and incidental sediment) ingestion rates, selective retention of toxicologically potent congeners and relatively low PCDD/F elimination capacities in dugongs are proposed to result in elevated PCDD/F concentrations and TEQ levels in adult animals. Transfer efficiencies of 4 and 27% of maternal TEQ levels to foetuses and calves (respectively) during gestation and lactation result in relatively high exposure potentials to offspring. Compared to no-observed-adverse-effect-levels in other mammals, and based on the results of this study, a tolerable daily intake (TDI) of 10-24 pg TEQ kg-1 day-1 was estimated for dugongs. The results of the present study found that dugongs from some regions along the coastline of Queensland exceed this TDI by up to 20 fold, suggesting that these populations may be at risk from PCDD/F contamination in their habitat. These results have important implications for the health of the environment, wildlife and humans and were used to develop a conceptual understanding of the sources, pathways and fate of dioxins in Queensland, Australia.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Public Health
Faculty of Health Sciences
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9

Cantrell, Susannah M. "Embryotoxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)". free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9924870.

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Le, Van Anh. "SOURCES OF DIOXINS TO BALTIC AIR Volatilization and Resuspension As Potential Secondary Sources of Dioxins to Air". Thesis, Umeå universitet, Kemiska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-56570.

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Persistent organic pollutants (POPs) are ubiquitous contaminants characterized by semi-volatility, low water solubility, high lipophilicity and inherent toxicity. A combination of these properties results in long-rang transport, bioaccumulation and biomagnification through food webs. Elimination of the production, use and emissions of these POPs has been ongoing since the 1970s. However, the levels of some POPs are still unacceptably high in some parts of the environment and due to their high persistence levels only decline very slowly over a long period of time. This is especially true for POPs in the Baltic Sea due to long water residence time of approximately 40 years. Numerous studies have been carried out to explore the behavior and fate of the POPs in Baltic regions using analytical methods or modeling approaches. Air-soil exchange plays an important role in controlling the environmental fate of POPs in surface media. Air is a transport medium, which spreads chemicals far away from sources. Soils have received an input of POPs from the atmosphere over a long time period. These chemicals have accumulated in soil solids and, as primary emissions are released, can potentially be rereleased to other environmental media. Therefore, soil could become a significant "secondary" source of some POPs to the air. In this study, the aim was to determine if volatilization and/or resuspension are potential sources of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) ("dioxins") to Baltic air. Sources of these compounds to Baltic air are particularly interesting because levels of dioxins in fatty fish in the Baltic exceed the levels that are considered fit for human consumption in the European Union guideline. The fugacity quotient approach has been previously shown to be a useful method for exploring the equilibrium status of two connected environmental compartments. Fugacity quotients between the atmosphere and soil are calculated for seventeenth toxic 2, 3, 7, 8,-substituted dioxin congeners . A multimedia mass balance model designed for the Baltic Sea region (POPCYCLING-Baltic) is also employed to study the long-term exchange between air and soil. Estimated fugacity ratios from model simulations are compared with calculated fugacity quotients. Moreover, sensitive analysis is undertaken in order to evaluate the relative effect of background concentration, resuspension and bioturbation transport to the transfer flux from soil to air. Master’s Thesis 2011 II Fugacities of dioxins in soil are additionally measured directly using equilibrium passive sampling devices. Among available passive samplers, polyoxymethylene 17 μm (POM-17) are chosen to absorb freely dissolved PCDD/Fs molecules in soil. Total soil concentrations are measured to provide input data for the POPCYCLING-Baltic multimedia fate and transport model. Estimated fugacities of dioxins will be compared with directly "measured" fugacities in soil. The predictive ability of the model is assesses by comparing estimated and "measured" fugacity. Calculated fugacity quotients showed that lower chlorinated dibenzofuran are close to equilibrium between soil and air while other congeners show disequilibrium. Estimated soil/air fugacity ratios are higher than one but soil still accumulates dioxins because transport process is very slow and non-equilibrium can be maintained for a long period of time. Due to the seasonal variation in concentration, volatilization is higher in summer than in winter. Therefore, net gaseous flux between soil and air can be observed in summer. Sensitivity analysis revealed that volatilization flux is proportional to background soil concentration. High background soil concentration results in high volatilization fluxes and vice versa. The simulation showed that the contribution of resuspension flux to air pollution levels is relatively small in comparison to the influence of variation in background soil concentration. If relatively high and unrealistic resuspension velocities are used as inputs in the model, resuspension is a significant source to the atmosphere. In contrast to background soil concentration and resuspension, bioturbation has no effect on volatilization flux even though high bioturbation rates are used as model inputs. In conclusion, except for light congeners, soil is still a sink of PCDD/Fs present in Baltic air. However, the increase in soil/air fugacity ratios suggest an increasing important of soil-to-air transport in the near future. Equilibrium passive samplers using POM strips are considered as a very simple, reproducible, and inexpensive partitioning method. However, the largest disadvantage of using passive samplers for dioxins is the long time to reach equilibrium. It takes 6 months for PCDD/Fs to obtain equilibrium between soil and POM strips, which exceeded the time for doing a 45 credit thesis. The analytical phase of the experiment is still on-going, and thus it was not possible to include the experimental results in this study.
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Shoven, Heather A. "Monitoring Dioxin Levels in Maine Rivers with Semipermeable Membrane Devices". Fogler Library, University of Maine, 2001. http://www.library.umaine.edu/theses/pdf/ShovenHA2001.pdf.

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Lees, Michael. "Characterising the mechanism of activation of the bHLH/PAS Dioxin Receptor /". Title page, summary and contents only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phl4873.pdf.

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Krivickas, Sara Jane. "Synthesis and transformation of 1,2-dioxines linked to aromatic systems : a thesis submitted in fulfilment of the requirements of the degree of Doctor of Philosophy /". Title page, contents and summary only, 2003. http://web4.library.adelaide.edu.au/theses/09PH/09phk9297.pdf.

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Thesis (Ph.D.)--University of Adelaide, School of Chemistry and Physics, Discipline of Chemistry, 2004.
"September 2003" Addendum inserted inside backcover. Include bibliographical references (leaves 165-177).
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Löthgren, Carl-Johan. "Mercury and dioxins in a MercOx-scrubber /". Örebro : Örebro universitetsbibliotek, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-825.

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Amoroso, Cathy Elizabeth. "The use of science in environmental policy decision making : a case study of dioxin standards in Georgia". Thesis, Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/29334.

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Gaus, Caroline. "Dioxins in the marine environment sources, pathways, and fate of polychlorinated dibenzo-p-dioxins and dibenzofurans in Queensland, Australia /". Connect to this title online, 2002. http://bibpurl.oclc.org/web/9765.

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Ploteau, Stéphane. "Etude du lien entre l’exposition aux polluants organiques persistants et l’endométriose". Thesis, Nantes, Ecole nationale vétérinaire, 2016. http://www.theses.fr/2016ONIR087F/document.

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L’endométriose est une maladie gynécologique pour laquelle l’exposition à certains contaminants chimiques environnementaux est évoquée parmi les facteurs de risque associés. Les conclusions des études épidémiologiques existantes restent toutefois non convergentes. Leur hétérogénéité en termes de lésions décrites, de méthodologie et d’effectifs contribuent à ce constat, de même que l’étendue limitée des marqueurs d’exposition considérés dans ces études. Nous avons réalisé une étude cas-témoins appariés à partir d’une bio-collection de 113 patientes réunissant68 cas de patientes opérées d’endométriose profonde et 45 patientes témoins. Un ensemble unique de 78 polluants organiques persistants a été recherché, incluant dioxines, polychlorobiphényles, retardateurs de flamme polybromés, et pesticides organochlorés. Les niveaux d’exposition interne des sujets ont été mesurés à la fois dans les tissus adipeux pariétal et épiploïque ainsi que dans le sérum. La distribution de ces différents polluants au sein de ces trois compartiments a tout d’abord été caractérisée. Celle-ci a permis la prise en compte encore très rare de l’équilibre entre compartiments de stockage et compartiment circulant, ce rapport de concentration apparaissant comme un potentiel indicateur additionnel permettant d’affiner d’éventuels liens de causalité entre exposition chronique à des dangers chimiques et pathologie chez l’homme. Certains des contaminants ciblés sont ensuite apparus significativement associés à l’endométriose profonde, la stratification plus fine de notre population de cas indiquant un lien d’autant plus significatif en présence d’endométriome. Les mécanismes sous-jacents de cette association restent toutefois à élucider
Endometriosis is a gynecological disease for whichexposure to some environmental chemicals is evocatedamong the associated risk factors. Epidemiological studies are however globally non convergent and finally fairly conclusive. Their heterogeneity in terms of lesion localization and sub-phenotype, methodology, size and nature of the populations studied, as well as the limited number of monitored markers of exposure contribute to this situation. We realized a matched case-control study based on a biocollection of 113 patients including 68 patients suffering of deep endometriosis and 45 controls. We characterized the internal exposure levels of an extended range of around 78 persistent organic pollutants (including dioxins, polychlorobiphenyls, brominated flame retardants and organochlorine pesticides). Internal level exposures were measured in three biological compartments (omental fat, subcutaneous fat and serum). First, the distribution of these chemicals was characterized within these compartments. These extended exposure data from deep infiltrating endometriosis patients are the first ones available for France and give a new insight about the equilibrium of chemicals between storage and circulating compartments that should be further considered as a potential indicator permitting to establish a possible association between a chronic exposure to chemical hazards and human pathology. Afterwards, some of the targeted chemicals appeared significantly associated with deep endometriosis. A sub-stratification of our case population indicated a more significant relationship with the presence of endometrioma. Underlying mechanisms remain to be determined
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Walsh, Peter J. J. "Dioxins and furans in the rural UK environment". Thesis, University of East Anglia, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365159.

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Arehart, Eric. "Dioxin Alters Human Low-Density and Very Low-Density Lipoprotein Structure with Evidence for Specific Quenching of TRP-48 in Apolipoprotein C-H". Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/ArehartES2003.pdf.

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Ryu, Jae-Yong. "Dioxin formation on copper (II) chloride from chlorinated phenol, dibenzo-p-dioxin and dibenzofuran precursors". Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/19050.

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21

Danielsson, Conny. "Trace analysis of dioxins and dioxin-like PCBs using comprehensive two-dimensional gas chromatography with electron capture detection". Doctoral thesis, Umeå universitet, Kemiska institutionen, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-963.

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Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), two groups of struc-turally related chlorinated aromatic hydrocarbons, generally referred to as “dioxins” are of great concern due to their extreme toxicity and presence in all compartments of the environment. Since they occur at very low levels, their analysis is complex and challenging, and there is a need for cost-efficient, reliable and rapid analytical alternatives to the expensive methods in-volving use of gas chromatography high-resolution mass spectrometry (GC-HRMS). It is im-portant to routinely monitor food and feed items to detect contaminations at an early stage. For the regulation of dioxins and dioxin-like PCBs in food and feed according to current legis-lation, large numbers of samples have to be analysed. Furthermore, soils at many industrial sites are also contaminated with dioxins and need remediation. In order to optimize the cost-efficiency of reclamation activities it is important to acquire information about the levels and distribution of dioxins in the contaminated areas. The aim of the studies underlying this thesis was to investigate the potential of comprehen-sive two-dimensional gas chromatography with a micro-electron capture detector (GC × GC-µECD) as a cost-effective method for analysing dioxins and dioxin-like PCBs in food, feed, fly ash and contaminated soils. Quantification studies of dioxins and dioxin-like PCBs were con-ducted and results were compared with GC-HRMS reference data. Generally, there was good agreement between both the congener-specific results and data expressed as total toxic equiva-lents (TEQs). The developed GC × GC-µECD method meets the European Community (EC) requirements for screening methods for control of dioxins and dioxin-like PCBs in food and feed. The presented results also indicate that GC × GC-µECD has potential to be used as a routine method for the congener-specific analysis of 2,3,7,8-PCDD/Fs and dioxin-like PCBs in matrices such as food and feed, fly ash and soil. However, to fully exploit the potential of the GC × GC-µECD technique, it should be combined with a fast and cost-efficient sample preparation procedure. Therefore, a number of certified reference materials (CRMs) were extracted using a new shape-selective pressurized liquid extraction technique with integrated carbon fractionation (PLE-C), and the purified extracts were analysed for PCDD/Fs using GC × GC-µECD. The results compared well with the certified values of a fly ash and a sandy soil CRM, but they were much too high for a com-plex clay soil CRM. It was concluded that this combination of techniques was very promising for screening ash and highly permeable soils. Further assessments and method revisions are still required before GC × GC-µECD can be used on a routine basis, and available software packages need to be refined in order to accelerate the data-handling procedures, which currently restrict the sample throughput.
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Danielsson, Conny. "Trace analysis of dioxins and dioxin-like PCBs using comprehensive two-dimensional gas chromatography with electron capture detection /". Umeå : Department of Chemistry, Environmental Chemistry, Umeå University, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-963.

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Maliji, Ghorban. "Immunotoxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin in the rat". Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319022.

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Liang, Ying, i 梁颖. "Association of diabetes mellitus and dioxins exposure : a systematic review". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/193792.

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Objective: To review in the literature on the association between diabetes and background exposure of dioxins among general population. Method: Systematic review on studies the association of background dioxin exposure and diabetes among general population, published from January 1960 to July 2013 in PubMed, and from January 1979 to July 2013 in China National Knowledge Infrastructure (CNKI). Result: A total of nine articles (including seven cross-sectional studies, one longitudinal study and one cohort study) out of 111 articles from PubMed and 5 articles from CNKI were included in the systematic review. Five out of nine studies found a positive association between background exposure to dioxins or dioxins-like compounds and the risk of diabetes whilst two studies reported an inverse association between dioxins and insulin concentrations or IGF-I serum levels. Two studies reported positive significant relation of dioxins and diabetes in women but not in men. Discussion: Based on this systematic review, the association of background dioxins exposure and diabetes among general population remains unclear. Given the crosssection design of the studies, causal relation between dioxin exposure and diabetic risks cannot be drawn.
published_or_final_version
Public Health
Master
Master of Public Health
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Okumura, Yutaka. "Mass Balance and Bioaccumulation of Major Dioxins in Sendai Bay". Kyoto University, 2011. http://hdl.handle.net/2433/135409.

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Breve, Joelma Cristina de Souza [UNESP]. "Síntese e caracterização do compósito SnO2/TiO2 nanoestruturado". Universidade Estadual Paulista (UNESP), 2014. http://hdl.handle.net/11449/115966.

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O nanocompósito faz parte de um tipo de material o qual, apesar de ser obtido pela junção de dois ou mais materiais, não possui simplesmente a união das propriedades individuais de cada componente, mas possuui novas propriedades resultantes da interação entre as fases, justificada pela enorme interface entre estes materiais. Neste trabalho o método Poliol foi utilizado para preparar nanocompósitos SnO2/TiO2, formados de óxidos semicondutores de grande interesse no cenário atual da tecnologia sendo ambos de grande versatilidade para aplicações. Estes óxidos podem apresentar-se com uma mesma estrutura cristalina, a tetragonal do tipo rutila. Porém, apresentam diferentes estruturas eletrônicas e band gaps de energia, conferindo propriedades diferenciadas relacionadas à absorção de luz e à aplicação como sensores de gás. O compósito nanoestruturado e os óxidos sintetizados isoladamente foram caracterizados estruturalmente (DRX, FEG-MEV), por meio de análises térmicas (TG/DTA) e por espectroscopia de absorção de luz na região do ultravioleta, visível e infravermelho. As análises térmicas aliadas à difração de raios X revelaram que a síntese conjunta dos óxidos modifica o precipitado reduzindo a proporção de compostos orgânicos e intermediários e antecipando a formação das fases cristalinas do dióxido de titânio. Na análise por FEG-MEV observou-se que o compósito formado no aquecimento a 500ºC é constituído de nanoportículas de SnO2 suportados por placas maiores de TiO2 e este material, quando submetido à espectroscopia na região UV-Vis, apresentou maior absorção na região do ultravioleta. Foram realizados ensaios fotocatalíticos de descoloração do corante Rodamina B, os quais indicaram que o nanocompósitos possui atividade catalítica intermediária quando comparada aos óxidos isolados. Essa mesma amostra foi submetida a caracterizações elétricas que levaram à proposta de um modelo...
The nanocomposite is part of a class of materials which, despite being obtained by joining two or more materials, it has not simply the sum of the individual properties of resulting from the interaction between the phases, justified by the enormous interface between these materials. In the present work Polyol method was used to prepare SnO2/TiO2 nanocomposites, formed of semiconductor oxides of great interest in today's technology being of great versatility for applications. These oxides may present the same crystal structure, the tetragonal rutile type. However, they present different electronic structures and energy band gaps, giving different properties related to light absorption and application as gas sensors. The synthesized nanostructured composite as well as the isolate oxides were structurally characterized (XRD, FEG-SEM), using thermal analysis (TG/DTA), and light absorption spectroscopy within ultraviolet, visible and infrared regions. The combination of thermal analysis and X ray diffraction revealed that the simulataneous synthesis of two metals modified the precipitate, reducing the proportion of organic and intermediates compounds and anticipating the formation of crystalline phases of titanium oxides. By FEG-SEM analysis it was found that te composite treated at 500ºC consists of SnO2 nanoparticles suported by large plates of TiO2 and this material present highest uptake in the ultraviolet region. Testing photocatalytic discoloration of the dye Rhodamine B indicated that the nanocomposite has an intermediate catalytic activity when compared to the isolate oxides. The same sample was subjected to electrical characterization which led to a simplified model of electron transport in which it is assumed that the existing barrier between TiO2 particles is reduced due to the presence of SnO2 on the their surfaces
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Breve, Joelma Cristina de Souza. "Síntese e caracterização do compósito SnO2/TiO2 nanoestruturado /". Bauru, 2014. http://hdl.handle.net/11449/115966.

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Orientador: Dayse Iara dos Santos
Banca: Luis Vicente de Andrade Scalvi
Banca: Luiz Henrique Dall'Antonia
O Programa em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi
Resumo: O nanocompósito faz parte de um tipo de material o qual, apesar de ser obtido pela junção de dois ou mais materiais, não possui simplesmente a união das propriedades individuais de cada componente, mas possuui novas propriedades resultantes da interação entre as fases, justificada pela enorme interface entre estes materiais. Neste trabalho o método Poliol foi utilizado para preparar nanocompósitos SnO2/TiO2, formados de óxidos semicondutores de grande interesse no cenário atual da tecnologia sendo ambos de grande versatilidade para aplicações. Estes óxidos podem apresentar-se com uma mesma estrutura cristalina, a tetragonal do tipo rutila. Porém, apresentam diferentes estruturas eletrônicas e band gaps de energia, conferindo propriedades diferenciadas relacionadas à absorção de luz e à aplicação como sensores de gás. O compósito nanoestruturado e os óxidos sintetizados isoladamente foram caracterizados estruturalmente (DRX, FEG-MEV), por meio de análises térmicas (TG/DTA) e por espectroscopia de absorção de luz na região do ultravioleta, visível e infravermelho. As análises térmicas aliadas à difração de raios X revelaram que a síntese conjunta dos óxidos modifica o precipitado reduzindo a proporção de compostos orgânicos e intermediários e antecipando a formação das fases cristalinas do dióxido de titânio. Na análise por FEG-MEV observou-se que o compósito formado no aquecimento a 500ºC é constituído de nanoportículas de SnO2 suportados por placas maiores de TiO2 e este material, quando submetido à espectroscopia na região UV-Vis, apresentou maior absorção na região do ultravioleta. Foram realizados ensaios fotocatalíticos de descoloração do corante Rodamina B, os quais indicaram que o nanocompósitos possui atividade catalítica intermediária quando comparada aos óxidos isolados. Essa mesma amostra foi submetida a caracterizações elétricas que levaram à proposta de um modelo...
Abstract: The nanocomposite is part of a class of materials which, despite being obtained by joining two or more materials, it has not simply the sum of the individual properties of resulting from the interaction between the phases, justified by the enormous interface between these materials. In the present work Polyol method was used to prepare SnO2/TiO2 nanocomposites, formed of semiconductor oxides of great interest in today's technology being of great versatility for applications. These oxides may present the same crystal structure, the tetragonal rutile type. However, they present different electronic structures and energy band gaps, giving different properties related to light absorption and application as gas sensors. The synthesized nanostructured composite as well as the isolate oxides were structurally characterized (XRD, FEG-SEM), using thermal analysis (TG/DTA), and light absorption spectroscopy within ultraviolet, visible and infrared regions. The combination of thermal analysis and X ray diffraction revealed that the simulataneous synthesis of two metals modified the precipitate, reducing the proportion of organic and intermediates compounds and anticipating the formation of crystalline phases of titanium oxides. By FEG-SEM analysis it was found that te composite treated at 500ºC consists of SnO2 nanoparticles suported by large plates of TiO2 and this material present highest uptake in the ultraviolet region. Testing photocatalytic discoloration of the dye Rhodamine B indicated that the nanocomposite has an intermediate catalytic activity when compared to the isolate oxides. The same sample was subjected to electrical characterization which led to a simplified model of electron transport in which it is assumed that the existing barrier between TiO2 particles is reduced due to the presence of SnO2 on the their surfaces
Mestre
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Agramunt, Garcia Sílvia. "Exposiciones ambientales durante el embarazo y eventos reproductivos". Doctoral thesis, Universitat Autònoma de Barcelona, 2016. http://hdl.handle.net/10803/392661.

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INTRODUCCIÓN: La exposición intra-útero a múltiples factores ambientales puede influenciar a varios parámetros tales como la edad gestacional, el peso o el perímetro cefálico. Cabe destacar la medida de la distancia anogenital en recién nacidos como marcador de exposición a disruptores endocrinológicos durante el embarazo, con consecuencias deletéreas reproductivas y de aumento de riesgo de càncer hormonodependiente en el individuo. En este trabajo hemos analizado diferentes tóxicos ambientales y los hemos relacionado con eventos reproductivos. MÉTODOS: En el marco del estudio de cohortes multicéntrico europeo NewGeneris, se han analizado más de 1000 muestras de sangre de cordón para estudiar la presencia de tóxicos ambientales como el grupo de substancias dioxinas (CALUX DR), óxido de etileno (FIRE) y acrilamida (FIRE). RESULTADOS: Se ha objetivado asociación entre niveles de dioxinas y disminución de la distancia anogenital en recién nacidos varones (n=237 bebés; -0,41mm, IC 95% -0,77; 0,66), dioxinas y disminución del peso al nacer (n=247 bebés, β =-82g/aumento en 10pg/TEQ-q lípido; IC 95% -264 a 100), dioxinas y disminución del perímetro cefálico (n=205 bebés, β = -0,4g/aumento en 10pg/TEQ-q lípido; IC 95% -7 a 7), y dioxinas y disminución de la edad gestacional (n=260 bebés, β = -0,8 semanas/aumento en 10pg/TEQ-q lípido; IC 95% -1,4 a 0,2). Se ha objetivado asociación entre niveles de óxido de etileno y disminución del peso al nacer (n=1094, β = -37,73g/aumento en 10pmol/g Hb; IC 95% -55,95 a -19,52), óxido de etileno y disminución del perímetro cefálico (n=963, β = -0,11cm/aumento en 10pmol/g Hb; IC 95% -0,18 a -0,04), pero no entre óxido de etileno y edad gestacional (n=1094, β = -0,001 semanas/aumento en 10pmol/g Hb; IC 95% -0,06 a 0,06). Se ha objetivado asociación entre niveles de acrilamida y disminución del peso al nacer (n=1101 bebés, β = -35g/aumento en 10pmol/g Hb; IC 95% -51 a -19), acrilamida y perímetro cefálico (n=1005 bebés, β = -0,06g/aumento en 10pmol/g Hb; IC 95% -0,12 a 0,00), pero no entre acrilamida y edad gestacional (no significativa). CONCLUSIÓN: La conclusión principal de la tesis es que la exposición intra-útero a compuestos con efecto disruptor endocrinológico causa disminución en la distancia anogenital en varones, menor peso al nacer, menor perímetro cefálico y menor edad gestacional; incluso en un contexto de baja exposición general. Nuestros hallazgos son consistentes con la evidencia hallada en estudios animales experimentales utilizados para las recomendaciones de límites de exposición elaboradas por la OMS.
INTRODUCTION: Prenatal exposure to various substances can influence reproductive outcomes such as birth weight, cranial perimetrum at birth or gestational age. Of special importance is the measure of anogenital distance in newborns, which would be related to the prenatal exposure to endocrinologic disruptors. In this PhD project we have analised some environmental substances and their association with reproductive outcomes. METHODS: The project has been developed in the multicentric cohort European study NewGeneris, with more than 1000 cord blood samples. We have analised the activity of dioxins (CALUX DR®), ethylene oxide (FIRE procedure) and acrylamide (FIRE procedure). RESULTS: We have observed an association between dioxins and a disminution on anogenital distance of male infants (n=237 newborns; -0.41mm, 95% CI -0.77; 0.66), dioxins and birth weight (n=247 newborns, β =-82g/10pg increase/TEQ-q lipid; 95% CI -264; 100), dioxins and head circumference at birth (n=205 newborns, β = -0,4g/10pg increase/TEQ-q lipid; 95% CI -7 to 7), and dioxins and gestational age (n=260 newborns, β = -0,8 weeks/10pg increase/TEQ-q lipid; 95% CI -1,4 to 0,2). Ethylene oxide has been associated to birth weight (n=1094, β = -37,73g/ 10pmol increase/g Hb; 95% CI -55,95 to -19,52), ethylene oxide and head circumference at birth (n=963, β = -0,11cm/10pmol increase/g Hb; 95% CI -0,18 to -0,04), ethylene oxide and gestational age (n=1094, β = -0,001 semanas/10pmol increase/g Hb; 95% CI -0,06 to 0,06). Acrylamide has been associated with birth weight (n=1101 newborns, β = -35g/10pmol increase/g Hb; 95% CI -51 to -19), acrylamide and head circumference at birth (n=1005 bebés, β = -0,06g/10pmol increase/g Hb; 95% CI -0,12 to 0,00), but not to gestational age. CONCLUSION: The PhD main conclusions that prenatal exposure to endocrine disruptors are associated to a decrease on anogenital distance in male newborns, as well as a decrease on birth weight, head circumference at birth and gestational age; even in a low level exposure setting. Our findings are consistent with the evidence found in experimental animals used for the WHO recommendations on exposure límits.
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GUILBOT, Kelly. "Determination of dioxins in Cretaceous strata from the South of Sweden. : Can the environmental anthropogenic pollutant dioxin be of natural origin ?" Thesis, Örebro universitet, Institutionen för naturvetenskap och teknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-25916.

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Eleven sediment samples from different geological layers and four fossils from the South of Sweden were collected and estimated to be 80 million years old (approximately late of Cretaceous period). The samples were analyzed for polychlorinated dibenzo-p dioxins (PCDD/Fs) to investigate whether these samples are likely to contain dioxins from a natural formation. For over thirty years, the scientific community has discussed the possibility of a natural formation of dioxins. Several hypothesis have been put forward, but often rejected by the evidence of a source of anthropogenic pollution in the samples. In order to answer this issue, two types of analyses have been performed : high resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS) and elemental analyzer-isotopic ratio mass spectrometry (EA-IRMS). HRGC/HRMS provides information about the source of dioxins comparing the distribution of all PCDD/Fs to experimental isotopic patterns from past publications. δ13C of organic carbon gives information about the nature of carbon present in soils and can be helpful to trace paleoclimates.
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Bell, Jon Grahame. "Adsorption characteristics of models for dioxins on modified nanoporous activated carbons". Thesis, University of Newcastle Upon Tyne, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.516433.

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Assefa, Anteneh. "Tracing and apportioning sources of dioxins using multivariate pattern recognition techniques". Doctoral thesis, Umeå universitet, Kemiska institutionen, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-102877.

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High levels of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in edible fish in the Baltic Sea have raised health concerns in the Baltic region and the rest of Europe. Thus, there are urgent needs to characterize sources in order to formulate effective mitigation strategies. The aim of this thesis is to contribute to a better understanding of past and present sources of PCDD/Fs in the Baltic Sea environment by exploring chemical fingerprints in sediments, air, and biota. The spatial and temporal patterns of PCDD/F distributions in the Baltic Sea during the 20th century were studied in Swedish coastal and offshore sediment cores. The results showed that PCDD/F levels peaked in 1975 (± 7 years) in coastal and 1991 (± 5 years) in offshore areas. The time trends of PCDD/Fs in the sediment cores also showed that environmental half-lives of these pollutants have been shorter in coastal than in offshore areas (15 ± 5 and 29 ± 14 years, respectively). Consequently, there have been remarkable recoveries in coastal areas, but slower recovery in offshore areas with 81 ± 12% and 38 ± 11% reductions from peak levels, respectively. Source-to-receptor multivariate modeling by Positive Matrix Factorization (PMF) showed that six types of PCDD/F sources are and have been important for the Baltic Sea environment: PCDD/Fs related to i) atmospheric background, ii) thermal processes, iii) manufacture and use of tetra-chlorophenol (TCP) and iv) penta-chlorophenol (PCP), v) industrial use of elementary chlo- rine and the chloralkali-process (Chl), and vi) hexa-CDD sources. The results showed that diffuse sources (i and ii) have consistently contributed >80% of the total amounts in the Southern Baltic Sea. In the Northern Baltic Sea, where the biota is most heavily contaminated, impacts of local sources (TCP, PCP and Chl) have been higher, contributing ca. 50% of total amounts. Among the six sources, only Thermal and chlorophenols (ii-iv) have had major impacts on biota. The impact of thermal sources has, however, been declining as shown from source apportioned time-trend data of PCDD/Fs in Baltic herring. In contrast, impacts of chlorophenol-associated sources generally increased, remained at steady-state or slowly decreased during 1990-2010, suggesting that these sources have substantially contributed to the persistently high levels of PCDD/Fs in Baltic biota. Atmospheric sources of PCDD/Fs for the Baltic region (Northern Europe) were also investigated, and specifically whether the inclusion of parallel measurements of metals in the analysis of air would help back-tracking sources. PCDD/Fs and metals in high-volume air samples from a rural field station near the shore of the central Baltic Sea were measured. The study focused on the winter season and air from the S and E sectors, as these samples showed elevated levels of PCDD/Fs, particularly PCDFs. Several metals were found to correlate significantly with the PCDFs. The wide range of candidate metals as source markers for PCDD/F emissions, and the lack of an up-to-date extensive compilation of source characteristics for metal emission from vari- ous sources, limited the use of the metals as source markers. The study was not able to pin-point primary PCDD/F sources for Baltic air, but it demonstrated a new promising approach for source tracing of air emissions. The best leads for back-tracking primary sources of atmospheric PCDD/Fs in Baltic air were seasonal trends and PCDD/F congener patterns, pointing at non-industrial related thermal sources related to heating. The non-localized natures of the sources raise challenges for managing the emissions and thus societal efforts are required to better control atmospheric emissions of PCDD/Fs.
EcoChange
BalticPOPs
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32

Wejheden, Carolina. "Studies on gender-specific disruption of bone tissue homeostasis by dioxins". Stockholm : Institutet of Environmental Medicine, Karolinska Institutet, 2010. http://diss.kib.ki.se/2010/978-91-7409-728-3/.

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Bastian, Lawin. "Waste management options associated with greenhouse gas emissions reduction and dioxins control". 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/174909.

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Lohmann, Rainer. "Studies on the atmospheric sources, fate and behaviour of dioxins and furans". Thesis, Lancaster University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.322093.

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Chatkittikunwong, Watcharee. "Analytical synthesis and stability studies of halogenated dibenzo-p-dioxins and dibenzofurans". Thesis, University of East Anglia, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335138.

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Shinkyo, Raku. "Structure-function analysis of mammalian cytochromes P450 involved in metabolism of dioxins". Kyoto University, 2006. http://hdl.handle.net/2433/144094.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(農学)
甲第12357号
農博第1538号
新制||農||923(附属図書館)
学位論文||H18||N4115(農学部図書室)
24193
UT51-2006-J349
京都大学大学院農学研究科食品生物科学専攻
(主査)教授 井上 國世, 教授 吉川 正明, 教授 村田 幸作
学位規則第4条第1項該当
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37

Palamede, Audrey. "Stabilization of chlorinated dibenzo-p-dioxins, dibenzofurans and chlordecone in soils from three former industrial areas. : Leaching behavior of chlorinated dibenzo-p-dioxins, dibenzofurans and chlordecone from three soils". Thesis, Umeå universitet, Kemiska institutionen, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-163550.

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38

Peña-Rey, Lorenzo Isabel. "Estudio bibliométrico de la producción científica sobre dioxinas a través de las bases de datos Pubmed e I.M.E. (1997-2003)". Doctoral thesis, Universidad de Murcia, 2004. http://hdl.handle.net/10803/10737.

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Introducción .Las dioxinas, son compuestos organoclorados que se acumulan en la cadena alimentaria, generando diversos problemas de salud. En el año 1997 fueron declarados carcinógenos humanos. Su principal fuente de producción son las incineradoras de residuos sólidos. Objetivos del estudio:Analizar la producción cientifica sobre dioxinas en los últimos 7 años; conocer la distribución de los articulos en las revistas, estudiar su distribución geográfica e idiomas, analizar la productividad de los autores, las pautas de firmas por autor y trabajo en equipo, la calidad de los articulos y el impacto de las revistas que publican sobre el tema, la existencia de los colegios invisibles y las enfermedades que más carga de enfermedad producen en los paises que publican sobre el tema. Material y método. Se utilizaron las bases de datos PubMed e Índice Médico Español (IME). Se crearon nuevas bases de datos en Reference Manager v.10 y se analizaron con SPSS v. 11.0 Se utilizó la base de datos Science Citation Index-Expanded para el estudio de las citas y Journal Citation Reports (JCR) para el estudio de la calidad de las revistas. Se aplicaron las leyes de Solla Price, la ley de Bradford y la ley de Lotka; se estudiaron el Índice de productividad y el de Transitoriedad de los autores, el Índice de Impacto y el Índice de Inmediatez de las revistas. Se hizo un control de la calidad de los articulos siguiendo los Requisitos de Uniformidad para Manuscritos enviados a Revistas Biomédicas del Comité Internacional de Directores de Revistas Médicas (CIDRM).Se analizaron y representaron los componentes de los colegios invisibles a través del estudio de las citas. Se estudió la morbi-mortalidad y la carga de enfermedad de las enfermedades que según la OMS existen en los paises más afectados por estos compuestos. Resultados Se encontraron 3.522 articulos. El número de articulos por año publicado se adecua a la Ley de Solla Price, con un coeficiente de correlación cercano a 1. De las 641 revistas que publican sobre el tema el núcleo de las zonas de Bradford lo compone la revista Chemosphere con 446 articulas, en el otro extremo hay 313 revistas que publican 1 solo articulo en los 7 años del estudio. El autor que más publica es Peterson con 42 artículos. La ecuación de Lotka se adapta a nuestro estudio. Las revistas que más publican tienen mayor factor de impacto. No hay diferencias en la calidad de los artículos publicados entre las que más y menos publican. Las tres enfermedades que producen mayor carga de enfermedad según la OMS en los paises productores de información sobre dioxinas son las enfermedades neuropsiquiátricas, cardiovasculares y neoplasias. Conclusiones: Se muestra la dispersión de la literatura cientifica en orden creciente. La mayoría de los artículos pertenecen a revistas publicadas en el pais de origen de la base de datos. Del análisis de los autores se reconocen grupos de investigación siendo los que más publican los que más se citan, y los que trabajan en conjunto. Los artículos con más de 7 autores son los que predominan al final del estudio. Las revistas que más artículos publican tienen con más frecuencia factor de impacto medido por JCR. La calidad de los artículos no difiere entre los autores más o menos prolíficos. No existe relación entre la publicación de artículos sobre dioxinas en los paises y una mayor prevalencia o incidencia de ciertos cánceres. Las enfermedades que más carga de enfermedad producen probablemente se deben a la presencia de otros factores más que a las dioxinas.
Introduction Dioxins were declared as human carcinogenic substances in 1997. They accumulate in food, and they can genera te health problems. The main dioxins producers are salid waste incinerators. Objectives: to analyse the scientific production about dioxins in the last 7 years, describing the distribution in journals, geographic distribution and the publication languages. To analyse the productivity of authors, the pattern of signatories / authors, the work teams and the relationship with burden of disease. Methods Sources of date: PubMed, I.M.E. (Spanish Medical Index) and Science Citation Index-Expanded databases. Data were analysed with SPSS 11.0 and Reference Manager 10.0 programs. Solla Price, Bradford and Lotka modeis were applied; the productivity index was computed; the Impact Factor and the Immediacy Index of journals were studied. A quality control of papers was done, taking into account the Uniform Requirements for Manuscript Submitted to Biomedical Journals of the International Commitee of Medical Journal Editors. Components of Invisible Colleges were assessed. Scientific production was linked to burden of disease produced by dioxins. Results 3522 articles were found. The number of articles published each year is fitted to Solla Price model, with a correlation coefficient clase to 1. The Bradford nucleus is the journal Chemosphere, with 446 articles. One author published 42 articles. The equation is fitted to Lotka's one, with an exponential change of -0.5. The most publisher journals have algo higher Impact Factor. No differences of quality of articles were founded among journals according to the number of published papers. Neuro-psychiatric and cardiovascular disorders and tumors were founded as the three groups that produce majar burden of disease in countries with higher information production on dioxins. Conclusions It has been shown the scientific literature dispersion. Majority of papers belong to journals edited in the origin country of database. Research groups of authors have be en found. Specialisation of some journals of Nucleus and 1st Bradford Zone has been shown. Burden of disease of some countries is not explained by contamination.
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Gripp, William Gomes. "Aspectos técnicos e ambientais da incineração de resíduos sólidos urbanos: considerações sobre a proposta para São Paulo". Universidade de São Paulo, 1998. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-10062016-122416/.

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A tecnologia de incineração no gerenciamento de resíduos sólidos urbanos é empregada de maneira intensa em diversos países do mundo. No Brasil, além da sua utilização eventual em resíduos de serviços de saúde, há uma proposta para implantação de duas usinas de grande porte visando ao tratamento térmico de resíduos sólidos domiciliares na cidade de São Paulo. Através de uma revisão bibliográfica sobre o tema, são apresentados os principais parâmetros técnicos e ambientais desta tecnologia, entre eles os mecanismos de combustão e de formação de poluentes, os tipos de equipamentos empregados, as formas de manejo e disposição de cinzas e escórias e os métodos de controle e redução de emissões atmosféricas como gases ácidos, material particulado e metais pesados. Também é feita uma revisão do atual conhecimento técnico-científico sobre dioxinas e furanos relativamente à incineração de resíduos sólidos urbanos. A partir desta base teórica pesquisada e da análise dos Estudos de Impacto Ambiental e dos Relatórios de Impacto Ambiental das usinas de incineração de Santo Amaro e Sapopemba, conclui-se que tais incineradores, na forma como são propostos, não apresentam o nível tecnológico necessário para atender às normas de operação e emissão de poluentes vigentes em países onde há legislação regulando esta atividade.
The incineration technique on the management of municipal solid waste is intensely used in several countries. In Brazil, besides an occasional utilization on medical services waste, there is a proposal for the implantation of two large facilities for the thermal treatment of domestic solid waste in São Paulo city. Through a review on this theme, we present here the main technical and environmental parameters on this technology, including the combustion and the pollutant generation mechanisms, types of equipment, management and disposition of fly and bottom ashes and the main control and reduction methods of atmospheric pollution like acid gases, particulates and heavy metals. The state of the art on the present technical-scientific knowledge on dioxins and furans connected to the incineration of urban solid waste is presented. On this theoretical basis and on the analysis of the environmental impact assessment and environmental impact report on the Santo Amaro and Sapopemba facilities, we conclude that the incineration systems, as in the proposal, do not present the technologic level necessary to obey the operation and pollutant emission rules on the countries where this activities are controlled.
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Akki, Umesh. "Gas phase formation pathways and mechanisms of polychlorinated dibenzo-p-dioxins and dibenzofurans". Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/23157.

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Do, Lan. "New tools for sample preparation and instrumental analysis of dioxins in environmental samples". Doctoral thesis, Umeå universitet, Kemiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-70218.

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Polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), two groups of structurally related chlorinated aromatic hydrocarbons, are of high concern due to their global distribution and extreme toxicity. Since they occur at very low levels, their analysis is complex, challenging and hence there is a need for efficient, reliable and rapid alternative analytical methods. Developing such methods was the aim of the project this thesis is based upon. During the first years of the project the focus was on the first parts of the analytical chain (extraction and clean-up). A selective pressurized liquid extraction (SPLE) procedure was developed, involving in-cell clean-up to remove bulk co-extracted matrix components from sample extracts. It was further streamlined by employing a modular pressurized liquid extraction (M-PLE) system, which simultaneously extracts, cleans up and isolates planar PCDD/Fs in a single step. Both methods were validated using a wide range of soil, sediment and sludge reference materials. Using dichloromethane/n-heptane (DCM/Hp; 1/1, v/v) as a solvent, results statistically equivalent to or higher than the reference values were obtained, while an alternative, less harmful non-chlorinated solvent mixture - diethyl ether/n-heptane (DEE/Hp; 1/2, v/v) – yielded data equivalent to those values. Later, the focus of the work shifted to the final instrumental analysis. Six gas chromatography (GC) phases were evaluated with respect to their chromatographic separation of not just the 17 most toxic congeners (2,3,7,8-substituted PCDD/Fs), but all 136 tetra- to octaCDD/Fs. Three novel ionic liquid columns performed much better than previously tested commercially available columns. Supelco SLB-IL61 offered the best overall performance, successfully resolving 106 out of the 136 compounds, and 16 out of the 17 2,3,7,8-substituted PCDD/Fs. Another ionic liquid (SLB-IL111) column provided complementary separation. Together, the two columns separated 128 congeners. The work also included characterization of 22 GC columns’ selectivity and solute-stationary phase interactions. The selectivities were mapped using Principal Component Analysis (PCA) of all 136 PCDD/F’s retention times on the columns, while the interactions were probed by analyzing both the retention times and the substances’ physicochemical properties.
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Eichbaum, Kathrin Verfasser], Henner [Akademischer Betreuer] [Hollert i Andreas [Akademischer Betreuer] Schäffer. "In vitro bioassay tools for the toxicological evaluation of dioxins and dioxin-like compounds in sediments and biota / Kathrin Eichbaum ; Henner Hollert, Andreas Schäffer". Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://d-nb.info/1130326551/34.

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Eichbaum, Kathrin [Verfasser], Henner [Akademischer Betreuer] Hollert i Andreas [Akademischer Betreuer] Schäffer. "In vitro bioassay tools for the toxicological evaluation of dioxins and dioxin-like compounds in sediments and biota / Kathrin Eichbaum ; Henner Hollert, Andreas Schäffer". Aachen : Universitätsbibliothek der RWTH Aachen, 2016. http://nbn-resolving.de/urn:nbn:de:hbz:82-rwth-2016-009703.

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Tsang, Jennifer Arr, i 曾昭雅. "Dioxin contamination in soil: remediation technology and environmental management". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31255644.

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PICCINELLI, ELSA. "Environmental impact of industrial plants combustion processes: kinetic and formation/destruction mechanisms of PolichlorinatedDibenzo-p-Dioxins and PolichlorinatedDibenzoFurans". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2009. http://hdl.handle.net/10281/10060.

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The aim of the project was to study the mechanism of formation and degradation of PolyChlorinatedDibenzo-p-Dioxins (PCDDs) and PolyChlorinatedDibenzoFurans (PCDFs) in combustion processes. Today the challenge is to demonstrate that the conclusion based on laboratory scale experiments and the models coming from the results are useful tools to estimate emissions and to prevent or reduce PCDD/F (sum of PCDDs and PCDFs) formation in the flue gas cleaning system of plants. Following this, the study was developed at two different scales: Laboratory scale. The native carbon oxidation and PCDD/F formation were simultaneously studied at different temperatures (230-350 °C) and times (0-1440 min) in order to establish a direct correlation between the disappearance of the reagents and the formation of the products. The kinetic runs were conducted in a experimental set up where conditions were chosen to gain information on the role of fly ash deposits in cold zone of the plant in PCCD/F formation reaction Real plant scale. An extensive experimental study of a secondary aluminium casting plant flue gas cleaning system was performed. In particular, on the strength of the knowledge obtained by laboratory studies and the results of the samplings, the best strategies to prevent PCDD/F formation were identify and Air Pollution Control Device (APCD) performance was improved.
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Saeed, Anam. "Studies on the Decomposition of Selected Brominated Flame Retardants (BFRs) and Formation of Polybrominated Dibenzo-p-dioxins and Dibenzofurans (PBDD/Fs) and Mixed Halogenated Dibenzo-p-dioxins and Dibenzofurans (PXDD/Fs)". Thesis, Saeed, Anam (2016) Studies on the Decomposition of Selected Brominated Flame Retardants (BFRs) and Formation of Polybrominated Dibenzo-p-dioxins and Dibenzofurans (PBDD/Fs) and Mixed Halogenated Dibenzo-p-dioxins and Dibenzofurans (PXDD/Fs). PhD thesis, Murdoch University, 2016. https://researchrepository.murdoch.edu.au/id/eprint/35843/.

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Brominated flame retardants (BFRs) are bromine-bearing hydrocarbons added or applied to materials to increase their fire resistance. As thermal treatment or recycling activities are common disposal methods for BFR-laden objects, it is essential to determine the precise decomposition chemistry of BFRs at elevated temperatures, and their transformation pathways into hazardous pollutants. Sunlight can trigger the photodecomposition of BFRs, either during the life cycle of treated objects, or when emitted to the environment after disposal. Therefore, knowledge of the geometric and electronic structures of BFRs is of chief importance when tracking their fate in the ambient environment. Although BFR decomposition mainly occurs in a condensed phase, gas phase reactions also contribute significantly to their overall decay and subsequent fragmentation into brominated pollutants. Thermal degradation of BFRs often proceeds in the presence of bromine atoms which inhibit complete combustion. Therefore, under thermal conditions such as smouldering, municipal waste incineration, pyrolysis, thermal recycling, uncontrolled burning and fires, BFRs degrade to form brominated products of incomplete combustion (BPICs). Thermal degradation of BFRs produces potent precursors to polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs). Co-combustion of BFR-containing objects with a chlorine source (e.g., polyvinyl chlorides) results in the emission of significant concentrations of mixed halogenated dibenzo-p-dioxins and dibenzofurans (i.e., PXDD/Fs; X = Br, Cl). In this thesis, we investigated the thermochemical parameters of bromochlorophenols (BCPhs) and the photodecomposition properties of major BFRs and their derived brominated phenols (BPhs). We scrutinised the formation of brominated and non-brominated products that evolved during the thermal decomposition of major BFR i.e., tetrabromobisphenol A (TBBA), through experimental measurements coupled with accurate quantum chemical calculations. We acquired thermo-kinetic parameters as well as mechanistic routes pertinent to the destruction of TBBA. We illustrated reaction networks for the synthesis of PXDD/Fs from BPhs and chlorinated phenols (CPhs). Similarly, we described pathways leading to the formation of PBDFs and polybrominated diphenylethers (PBDEs) from brominated benzenes (BBzs). We critically reviewed the literature on BFR thermal decomposition with specific foci on underlying mechanisms, decomposition products, the influence of the polymeric matrix, metallic content and operational conditions. As BCPhs are direct building blocks for the formation of PXDD/Fs, we computed the thermochemical parameters of their complete series. We calculated standard enthalpies of formation, entropies, heat capacities and bond dissociation enthalpies (BDHs) of O-H bonds for the complete series of BCPhs. Values of the acid dissociation constant (pKa) were estimated based on an accurate thermodynamic cycle incorporating solvation and protonation energies. Calculated values of BDHs of O-H bonds in BCPhs vary slightly with the change in degree and pattern of halogenation. Gibbs energies of solvation of BCPhs in water are highly exergonic, with their values increasing with the degree of halogen substitution. Values of pKa dictate that BCPhs characterised by high degrees of halogenation display stronger acidity and dissociate more easily in aqueous media (i.e., they are stronger acids than lower substituted phenols). Photolysis and photochemical decomposition are important channels for the degradation of halogenated organic pollutants in the environment. Therefore, we performed density functional theory (DFT) and time-dependent density functional theory (TDFT) calculations in order to derive the photodecomposition properties of major deployed BFRs and congeners of BPhs in both gaseous and aqueous media. We clarified the effect of degree and pattern of bromination on the photodebromination of selected brominated aromatic compounds based on several molecular descriptors; namely, geometries of the ground (S0) and electronically first excited (S1) states, values of the HOMO-LUMO energy gap (EH-L) and atomic charges on bromine atoms (qBr). Molecules exhibit different geometries in the S0 and S1 states and C-Br bonds elongate upon S0 → S1 transitions. In agreement with the recent findings on PBDEs, we found that the photoreactivity of bromine atoms in investigated BFRs and BPhs followed the sequence of ortho > meta > para. The bromine atom connected to the ortho-position holds the highest positive atomic charge and, thus, experiences the greatest lengthening of C-Br bonds in the S1 state, in both gaseous and an aqueous media, prompting their reductive debromination. Excitation energies decrease linearly with increasing numbers of bromine substituents, and congeners with a high degree of bromination photodecompose more readily than lower brominated isomers. Computed values of EH-L for major BFRs and their non-brominated molecules inferred that the number of bromine substituents and the nature of the structure (aromatic/non-aromatic) contributes significantly towards the photoreactivity of molecules. We conducted gas phase thermal decomposition of TBBA using a laboratory-scale tubular reactor. Our main focus was to identify pollutants arising in the temperature range of 673 – 1123 K following evaporation of TBBA in the gas phase. The identification and quantitation involved the use of a gas chromatograph – triple quadrupole mass spectrometer (GC-QQQMS) instrument, functioning in multiple reaction monitoring (MRM) and total ion current (TIC) modes. Product analysis revealed that thermal decomposition of TBBA commenced at 723 K. The major decomposition products were HBr, di-tribrominated bisphenols, benzene, phenol, mono-tribrominated congeners of benzene and phenol, brominated and non-brominated alkylated benzenes, benzofuran, bromobenzofuran, dibenzofuran, bromine substituted polyaromatic hydrocarbons (PAHs), biphenyl and biphenylene. We observed that, most of the decomposition products evolved in trivial concentrations at a temperature of 773 K and peaked at around 923 – 973 K. Higher temperatures favour the generation of non-brominated products. In this chapter, we have performed quantum chemical calculations to derive the degradation pathways of TBBA and to illustrate routes for the formation of brominated and non-brominated species. We constructed formation mechanisms related to the emission of PBDD/Fs in systems involving BFRs. In particular, we investigated formation corridors of (i) PXDD/Fs from the coupling reactions of 2-chlorophenoxy (2-CPhxy) and 2-bromophenoxy (2-BPhxy) radicals, (ii) PBDFs and PBDEs synthesis from the condensation reaction of monobromobenzene (MBBz) and a 2-BPhxy radical. The coupling reactions of 2-BPhxy and 2-CPhxy radicals produce keto-ether (through the additions of a phenoxy O at ortho C(H), C(Cl) and C(Br) sites) and diketo (at ortho positions to C–C bridges) structures. Keto-ethers act as direct intermediates for the formation of dioxin moieties such as dibenzo-p-dioxin (DD), 1-monochlorodibenzo-p-dioxin (1-MCDD), 1-monobromodibenzo-p-dioxin (1-MBDD), 1-bromo-6-chlorodibenzo-p-dioxin (1-B,6-CDD) and 1-bromo-9-chlorodibenzo-p-dioxin (1-B,9-CDD) molecules. Diketo adducts initiate the formation of furan species, i.e., 4-monochlorodibenzofuran (4-MCDF), 4-monobromodibenzofuran (4-MBDF) and 4-bromo-6-chlorodibenzofuran (4-B,6-CDF) compounds, through interconversion and rearrangement reactions. We found that, these mechanisms of formation, commencing from halogenated phenoxy radicals, are largely insensitive to patterns and degrees of halogenation on meta and para sites. It follows that, our developed mechanistic and kinetic factors of reactions involving 2-BPhxy and 2-CPhxy should also apply to higher halogenated phenoxy radicals. We explored the initial oxidative decomposition pathways of monobromobenzene (MBBz) in the generation of BPhxy radicals and examined the possible dimerisation reactions of MBBz and 2-BPhxy. It was found that, the coupling of MBBz and 2-BPhxy results in the generation of twelve pre-PBDF intermediates, of which four can also serve as building blocks for the synthesis of PBDEs. The resonance-stabilised structure of the o-BPhxy radical accumulates more spin density character on its phenoxy O atom (30.9 %) in reference to ortho-C and para-C sites. Thus, the formation of the pre-PBDE/pre-PBDF structures via O/o-C couplings advances faster, as it requires lower activation enthalpies (79.2 – 84.9 kJ mol-1) than the pre-PBDF moieties, which arise via pairing reactions involving o-C(H or Br)/o-C(H or Br) sites (97.2 – 180.2 kJ mol-1). Kinetic analysis indicates that the O/o-C pre-PBDE/pre-PBDF adducts self-eject the out-of-plane H atoms to produce PBDEs, rather than undergo a three-step mechanism that forms PBDFs. Since the formation mechanisms of PBDFs and PBDDs are typically only sensitive to the bromination at ortho positions, the results reported herein also apply to higher brominated isomers of BBzs. Overall, this thesis provides novel and comprehensive information on the thermochemical properties of the complete series of BCPhs (potential precursors to PXDD/Fs) and the electronic/structural characteristics of BFRs and their derived BPhs, with regards to their photodecomposition. To gain an insight into the degradation of TBBA once it has evaporated, this thesis examines the pure gas phase decomposition of TBBA and suggests mechanisms by which the experimentally-detected volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) are generated. Furthermore, this thesis explores the role of BPhs and CPhs as building blocks for the formation of PXDD/Fs, and computes their parameters. We also elucidate reaction pathways and thermo-kinetic parameters for PBDFs and PBDEs produced by the oxidation of BBzs.
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Rivera, Austrui Joan. "Estudi de les emissions de PCDD/F i altres contaminants orgànics persistents a l'atmosfera mitjançant l'ús de captadors en continu". Doctoral thesis, Universitat de Barcelona, 2016. http://hdl.handle.net/10803/400876.

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L’emissió a l’atmosfera de compostos orgànics persistents (COPs) vinculada als processos de combustió susciten un gran interès per la seva possible influència negativa sobre la salut humana i el medi ambient. La legislació europea obliga a les industries a realitzar controls periòdics de les seves emissions a l’atmosfera, amb l’objectiu de reduir-les al màxim. Entre els compostos orgànics que més preocupen per la seva toxicitat, es troben les dioxines i els furans (PCDD/Fs) i els bifenils policlorats (PCBs). La determinació de les emissions d’aquests compostos en fonts estacionàries es basa a Europa en la Norma EN1948, que preveu per a tal efecte, una presa de mostra de 6 a 8 hores i la posterior determinació del seu contingut al laboratori per GC/HRMS. No obstant, existeixen actualment equips de captació en continu que, permanentment instal·lats a la xemeneia, permeten la recol·lecció ininterrompuda de mostra durant llargs períodes de temps, amb la millora en la representativitat dels resultats que se n’obtenen, però manquen encara d’un marc normatiu que els reguli. En la present tesi doctoral s’han realitzat diversos estudis per a la determinació de les emissions de dioxines i furans (PCDD/Fs), bifenils policlorats tipus dioxina (dl-PCBs) i altres contaminants orgànics persistents en fonts estacionàries mitjançant l’ús de captadors en continu. Aquestes tasques s’han dut a terme en el marc de diferents projectes que han fet possible l’aplicació d’aquesta tècnica en diferents tipus de processos industrials. Els treballs han requerit d’una banda l’estudi previ de la aplicabilitat d’aquests sistemes de captació, i d’altra banda la adaptació del mètode d’anàlisi per a emissions puntuals al nou tipus de mostra. A mode de resum, s’ha modificat la metodologia analítica utilitzada anteriorment al nostre laboratori per a la determinació del contingut de PCDD/Fs i dl-PCBs en mostres procedents de captacions puntuals en xemeneia (de 6 a 8 hores), amb l’objectiu d’adaptar-la a l’anàlisi de mostres procedents de captacions en continu (vàries setmanes), molt més concentrades. Així mateix, s’ha procedit a realitzar un estudi de validació de la metodologia proposada i determinar la incertesa dels resultats obtinguts, fent especial èmfasi en els punts de la metodologia en què aquesta es diferencia del mètode convencional. D’altra banda, els extractes analitzats per GC/HRMS han estat també analitzats per un sistema GC-APCI-MS/MS(QqQ), per tal d’avaluar la idoneïtat d’aquesta nova tècnica, recentment acceptada com a mètode de confirmació per a l’anàlisi de COPs en aliments, per a la determinació en aquest cas, en mostres procedents de fonts estacionàries. La metodologia analítica proposada ha permès caracteritzar mostres procedents de diferents tipus d’activitats industrials. Concretament en el sector de la incineració de residus, s’ha realitzat un estudi al llarg de dos anys que ha permès la determinació de les emissions de PCDD/Fs i dl-PCBs amb un captador en continu en una planta incineradora de residus industrials i perillosos. Els altres estudis han estat desenvolupats en el sector de la fabricació del ciment, i han suposat la determinació de nous factors d’emissió per als processos estudiats, així com la caracterització dels perfils o ‘petjada química’ de les seves emissions. Així mateix, un dels estudis ha comportat l’anàlisi complementari d’altres compostos orgànics d’interès, com les dioxines i els furans polibromats (PBDD/Fs) o els hidrocarburs aromàtics policíclics (PAHs). A més, els treballs en el sector de la fabricació del ciment han permès aprofundir en l’estudi de la influència sobre els nivells de les emissions de compostos orgànics persistents dels processos de co-incineració, amb l’ús de diferents combustibles alternatius, arribant-se a la conclusió que aquesta pràctica no té perquè representar un increment de les emissions d’aquests compostos.
The release of Persistent Organic Pollutants (POP) to air from combustion processes is a matter of concern due to their toxic effect on human health and environment. European legislation obliges industrial plants to undertake periodic controls of their emission releases to air, with the aim to reduce them. In Europe, the determination of the mass concentrarion of dioxins and furans (PCDD/Fs) and polychlorinated biphenyls (PCBs) is regulated by Standard EN1948. This standard is based on the GC/HRMS analysis of a sample issued from a manual sampling train and taken in a range of time from 6 to 8 hours. New automatic sampling devices are available nowadays that allow sampling times up to several months. By extending the sampling coverage to the whole operation period, better results are achieved for the assessment of total pollutants emission release. The present thesis work includes several studies for the determination of the mass concentration of PCDD/Fs, PCBs and other POPs in stack gas emissions by means of long-term sampling systems, in different types of industrial plants. For this purpose a preliminary study of the applicability of long-term sampling systems has been necessary, as well as the modification of the analysis scheme applied to short-term samples, in order to adapt it to the characteristics of new samples. In summary, the methodology used for the analysis of PCDD/Fs and dl-PCBs from short-term samples was adapted to the analysis on these more concentrated samples issued from long-term sampling systems. The uncertainty of the method was assessed as well as the validation, with special emphasis on these points where the new methodology differs from the conventional one. On the other hand, the extracts determined by GC/HRMS were also analysed by means of a gas chromatograph coupled to a triple quadrupole with atmospheric pressure ionization (GC-APCI-MS/MS), for the evaluation of this novel technique performance in emission samples analysis. The proposed methodology was used for the determination of POPs emission in different type of industrial activities. From waste incineration field, with a two year project for the determination of POPs emissions in a hazardous waste plant incinerator, to cement plants with and without the use of alternative fuels. The studies contributed to the establishment of new emission factors for these plants and the characterization of the ‘footprint’ of their particular emissions. Moreover, one of the cement plants study included the simultaneous determination with dioxin-like compounds of polybrominated dioxins and furans (PBDD/Fs) and poly aromatic hydrocarbons (PAHs). The results of the studies in cement plants proved that, even if an influence of the ratio usage of alternative fuels results in some cases in changes on the emission profiles, co-incineration is a practice that is not necessarily related to higher persistent organic pollutants emission levels.
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Hu, Keke. "Structure-activity relationships for the metabolism of polychlorinated dibenzo-p-dioxins and related compounds". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ35799.pdf.

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JAMSHAID, ASHIQ MUHAMMAD. "Influence of alternative fuels on the formation of dioxins in a cement production plant". Thesis, Umeå universitet, Kemiska institutionen, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-89026.

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Cespedes, Miguel Angel. "Characterisation of the effects of dioxins on Ahr through its homologue in Drosophila spineless". Thesis, University of Sussex, 2010. http://sro.sussex.ac.uk/id/eprint/2359/.

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Dioxins are extremely widespread, toxic and persistent pollutants, as well as a major concern for human health. The Aryl hydrocarbon receptor (Ahr) is the key component in the metabolic response to dioxins. Ahr is a cytoplasmic bHLH-PAS transcription factor that, upon binding with dioxin, translocates to the nucleus. There it forms a complex with the Ah receptor nuclear transloator (Arnt), another bHLH-PAS protein, and binds to the eight-nucleotide XRE motif to control gene expression. Previous work with Ahr knock-out mice revealed the existence of dioxin-independent activity for Ahr in development, but the relationship between the two activities of Ahr remains unclear. Our work uses Drosophila to clarify this question, which is central for therapies seeking inactivation of Ahr. The Drosophila Ahr homologue, spineless(ss), does not bind dioxins, however, it physically interacts with Tango (Tgo), Arnt's fly homologue, and controls gene expression through the XRE motif during development. Here I show that, in the absence of dioxin, Ahr can still bind Tango and Arnt and rescues ss- phenotypes, indicating equivalent dioxin-independent activities. I next demonstrate that exposure to dioxin produces an in vivo hyperactivation of Ahr, which can also be achieved by increasing the dosage of either Tango or Arnt. Thus Ahr shows different levels of activity, from basal to toxic, depending on the presence of specific ligands and cofactors, and the toxic effects of dioxins represent an excess of the Ahr developmental function. I have also carried out a genetic screen in the search of genes that interact with ss. From this screen I have found that the genes that code for the Krüppel-type zinc-finger proteins Squeeze (Sqz) and Rotund (Rn) interact functionally with ss. I demonstrate that Rn and Ss interact physically in vivo. Ahr is also able to interact functionally with rn and sqz indicating that the interaction with zinc-finger proteins might be an ancestral feature of the dioxin receptor.
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