La pollution de l'environnement, sa remédiation et l'obtention de sources d'énergie plus propres et plus efficaces sont des problématiques difficiles auxquels les humains sont confrontés. Parmi les nombreux matériaux développés par les scientifiques, les polymères de coordination cristallins type MOFs sont de plus en plus développés dans plusieurs domaines, du fait de la facilité et la versatilité de leur synthèse. La recherche sur ces matériaux est récente, mais les possibilités qu’offrent ces matériaux pour différentes applications sont énormes.C'est dans ce cadre que nous avons travaillé sur la conception et la synthèse de différents MOF pour la récupération, le recyclage et/ou la dégradation de certains polluants. En utilisant différentes approches de synthèse, nous avons obtenu des matériaux efficaces pour les diffèrent applications ciblées de ces matériaux. Nous pensons que les MOF ont le potentiel pour solutionner certains problèmes cruciaux comme la décontamination de l'environnement. / The pollution of the environment, its remediation and to obtain a cleaner and more efficient energy sources are some of the most challenging topics that humans are now facing. Among the several materials that scientists have developed, Metal Organic Frameworks (MOFs) are gaining a lot of attention on several fields due to the easiness and the versatility in which these materials can be designed, synthesized and used. Even when research on these materials is still young, the possibilities that they offer are enormous.It is on this frame that our work group has worked on the design and the synthesis of different MOFs for the recovery, the recycling and/or the degradation of some pollutants of interest. By using different synthesis approaches we have tested the versatility in the synthesis and the possible applications of these materials. We believe that MOFs hold the potential to solve some crucial issues in the recovery of the environment.

Orientador: Li Li Min / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-16T04:54:04Z (GMT). No. of bitstreams: 1 Eid_NayeneLeocadiaManzutti_D.pdf: 3371365 bytes, checksum: c5958487d4a3f2d1c58e3f284b78b334 (MD5) Previous issue date: 2010 / Resumo: Embora o avanço tecnológico tenha viabilizado o uso dos sistemas digitais para a aquisição de imagens radiográficas, ainda hoje, no Brasil, os filmes radiográficos convencionais continuam sendo os tipos de receptores mais utilizados nos consultórios odontológicos. Deste modo, após a exposição aos raios X, os filmes radiográficos devem ser processados em soluções químicas a fim de que a imagem latente seja convertida em imagem real, passível de análise para diagnóstico. Sabe-se que, tanto o revelador quanto o fixador radiográfico contém em sua composição substâncias químicas altamente tóxicas, podendo apresentar risco à saúde de profissionais, que podem desenvolver lesões cutâneas e dermatites em decorrência do manuseio e manipulação destas soluções de processamento, além de apresentarem risco à saúde pública, caso ocorra a ingestão de produtos oriundos do meio ambiente previamente contaminado e ainda, sérios prejuízos ao meio ambiente, contaminação da fauna e flora, em virtude do descarte indevido destas soluções após seu uso. Tendo isto em vista, os objetivos deste trabalho foram: 1) Avaliar a eficácia de um novo modelo de recipiente para processamento radiográfico manual em câmara-escura portátil, para uso em consultórios odontológicos; 2) Avaliar qualitativamente e quantitativamente as imagens radiográficas obtidas por meio do processamento radiográfico nos diferentes recipientes; 3) Comparar os resultados obtidos em ambas as análises; sob a hipótese de que, devido às suas configurações geométricas, este novo modelo de recipiente propiciaria a economia de soluções químicas para que a execução do processamento radiográfico manual, reduziria os custos aos profissionais da área odontológica e, além disto, promoveria a redução do impacto ambiental devido à minimização da quantidade de químicos usados nestes recipientes. Para atender aos objetivos e conhecer sobre a aplicabilidade deste trabalho, realizou-se um outro estudo no qual se fez uma investigação sobre o descarte dos Resíduos de Serviço de Saúde produzidos em consultórios odontológicos localizados no Estado do Tocantins, Brasil. O estudo abordou aspectos relacionados ao conhecimento e atitudes dos cirurgiões dentistas frente aos resíduos gerados em seu ambiente de trabalho, e sua percepção sobre os resíduos gerados nos demais consultórios odontológicos. Um questionário foi aplicado a 239 cirurgiões-dentistas. Destes, 78,2% trabalhavam em clínica particular e 68,6% já haviam cursado alguma pós-graduação. Do total dos entrevistados, 87,9% afirmaram realizar exames radiográficos em seu consultório e estes foram unânimes em afirmar que o processamento das imagens era realizado manualmente em câmara-escura portátil e a maioria dos entrevistados (88,1%) afirmou que, em média, a cada 5 dias, descartava no esgoto as soluções químicas de processamento utilizadas. Ademais, 30,1% dos participantes acreditavam que os resíduos de amálgama eram descartados, por outros profissionais, em lixo comum e outros 8,8% supunham que o descarte era feito na pia dos consultórios; 61,9% acreditavam que o lixo contaminado (infectante) era disposto juntamente com o lixo comum e, em relação os resíduos perfurocortantes, 14,2% acreditavam que eram descartados em recipientes plásticos e 9,2% em lixo comum. Por meio deste trabalho, concluiu-se, que, em geral, os cirurgiões-dentistas entrevistados desconheciam sobre o correto descarte dos resíduos de serviço de saúde, uma vez que foi observada negligência desta prática por muitos deles, além da percepção de que outros profissionais também realizavam o descarte incorreto dos resíduos gerados em seu ambiente de trabalho. De posse destas informações, testou-se um novo modelo de recipiente para processamento radiográfico manual. Foram obtidas imagens radiográficas dos dentes posteriores de um phantom de mandíbula humana macerada e em seguida, estas imagens foram processadas em quatro câmaras-escuras portáteis. Em uma delas foram colocados dois recipientes convencionais (R1) abastecidos com 200ml das soluções de processamento e, em cada uma das demais câmaras-escuras, para este mesmo propósito, foi disposto um par de cada um dos três tipos de recipientes desenvolvidos pelos autores, R2, R3 e R4, abastecidos com 12, 19,2 e 24ml das soluções reveladora e fixadora respectivamente. Foram processadas 184 películas em R1, 40 em R2, 48 em R3 e 56 em R4. As películas radiográficas foram digitalizadas e posteriormente submetidas à análise objetiva no programa MaZda; em seguida, foram dispostas de maneira ordenadas, obedecendo a sequência do processamento, em papel cartão preto, para que pudessem ser submetidas à análise subjetiva. Os resultados da análise subjetiva mostraram que houve concordância dentre os cinco examinadores em relação às imagens consideradas aceitáveis para diagnóstico para os quatro recipientes estudados, e os resultados da análise objetiva mostraram que as imagens foram consideradas satisfatórias para diagnóstico até o 15º dia de pesquisa para R1, até o 4º dia para R2 e R3, e 5º dia para R4. A análise subjetiva mostrou-se menos sensível que a objetiva na avaliação da qualidade das imagens radiográficas processadas nos recipientes convencionais (R1), porém, mostrou grande correlação com a objetiva na avaliação da qualidade das imagens processadas nos demais recipientes (R2, R3 e R4). Deste modo, concluiu-se que o novo modelo de recipiente viabilizou o processamento de películas radiográficas em câmara-escura portátil, utilizando menor quantidade de soluções químicas para o processamento radiográfico manual, sendo que estas se apresentaram com qualidade satisfatória para diagnóstico. / Abstract: Even though the technological advances have allowed the utilization of digital systems for acquisition of radiographic images, conventional radiographic films are still the most used in dental offices in Brazil. Thus, after X-ray exposure, the radiographic films must be processed in chemical solutions to change the latent stored images into visible images for diagnostic purposes. Both the developer and fixer contain highly toxic chemical substances that may endanger the health of professionals, who may present skin lesions and dermatitis due to handling of these solutions. These chemicals may also constitute a public health problem if contaminated products of the environment are ingested, besides posing serious risks to the environment by contamination of the fauna and flora if these chemical solutions are improperly discarded after utilization. Therefore, this study aimed to: 1) evaluate the efficacy of a new container for manual radiographic processing in portable darkrooms for utilization in dental offices; 2) qualitatively and quantitatively evaluate the radiographic images obtained by radiographic processing in the different containers; 3) compare the results obtained in both analyses, considering that the design of the new container would allow dental professionals to save the chemical solutions used for manual radiographic processing, reducing the costs and also the environmental impact, considering the minimization of the quantity of chemical solutions used in these containers. To meet these objectives and know the applicability of this study, a previous study was conducted in which we investigated the discard of Health Service Wastes produced in dental offices of the state of Tocantins, Brazil. The study discussed the aspects related to the knowledge, perception and attitudes of dentists towards the waste generated in their work environment. We interviewed 239 dentists using a structured questionnaire, of whom 78.2% worked at private offices and 68.6% had post-graduate degree. From the total of respondents, 87.9% stated that they did perform intraoral radiographic exams in their offices, and these professionals unanimously used portable dark rooms from commercial brands for radiographic processing. Most dentists (88.1%) that perform radiographic exams in their offices declared that the mean period for changing the radiographic processing chemicals was 5 days. Conversely, 30.1% of participants believed that amalgam wastes were discarded in common garbage, and 8.8% believed that amalgam wastes were discarded in the offices' sink; 61.9% of them believed that the infectious waste were discarded together with the common garbage. Regarding the sharp objects, 14.2% believed that these were discard in plastic recipients, and 9.2% believed that the majority of dentists discarded sharp objects in the common garbage. The data obtained in this study revealed that, in general, the dentists interviewed were unaware of the correct procedures for the discard of health service waste, since there was both negligence in these practices by many of them and the perception that other professionals also performed incorrect discard of waste generated in their work environment. After achievement of these data, a new model of container for manual radiographic processing was tested. Radiographic images were obtained from the posterior teeth of a phantom dry human mandible and processed in four portable darkrooms. One darkroom had two conventional containers (R1) filled with 200ml of processing solutions. For the same purpose, each of the other darkrooms had one pair of the three types of containers designed by the authors, namely R2, R3 and R4, filled with 12, 19.2 and 24ml of developing and fixer solutions. A total of 184 films were processed in R1, 40 in R2, 48 in R3 and 56 in R4. The films were digitized and objectively analyzed using the software MaZda; following, they were arranged according to the sequence of processing in black cardboards for subjective analysis. The results of the subjective analysis revealed good agreement between the five examiners concerning the images considered acceptable for diagnosis for all four containers investigated. The results of the objective analysis demonstrated that the images were considered satisfactory for diagnosis until the 15th day of investigation for R1, fourth day for R2 and R3, and fifth day for R4. The subjective analysis was less sensitive than the objective analysis to evaluate the quality of radiographic images processed in the conventional containers (R1), yet presented high correlation with the objective analysis for evaluation of the quality of images processed in the other containers (R2, R3 and R4). Thus, it was concluded that the new model of container allowed processing of radiographic films in portable darkrooms using a smaller quantity of chemical solutions for manual radiographic processing and presenting satisfactory quality for diagnosis. / Doutorado / Neurocirugia / Doutor em Fisiopatologia Medica

Estrogens, alkylphenols and bisphenol-A, enter the environment through waste water systems and waste disposal of manufactured products e.g. detergents, paints, polycarbonates and flameretardants. These analytes disrupt the endocrine function of living organisms affecting their reproductive health and those of future generations. Gas phase low molecular- mass aldehydes and amines are typically eye, nose, and throat irritants. Formaldehyde is classified as a probable human carcinogen. Given their negative impact on human health it is urgent to monitor pollutants at extremely low levels in both air and water. The aqueous pollutants are often concentrated using solid phase extraction cartridges or liquid-liquid extraction followed by derivatization. Methods that can most effectively and selectively pre-concentrate aldehydes and amines involve in situ derivatization. Unfortunately, the derivatizing reagents as well as their associated solvents or adsorbents, are responsible for problems encountered with these methods. Polydimethylsiloxane (PDMS) has emerged as the ideal concentration and reaction medium for trace analysis. However the expensive commercial devices such as SPME and SBSE both require the samples to be returned to the laboratory for concentration. Due to the open tubular nature of the PDMS multichannel trap (MCT), developed in our laboratory, it is ideally suited for on-site and online sampling. The MCTs have a high analyte capacity owing to the large volume of PDMS available for concentration. The derivatization reaction can be performed in situ providing a “onepot concentration and reaction device”. This allows for reduced risk of contamination of / or losses of the sample and a sampling method that can cater for both air and water samples. To demonstrate the versatility of the PDMS MCT, two approaches for concentration in PDMS were investigated in this study, namely, 1) the on-line concentration and in situ derivatization of volatile polar analytes from air followed by REMPI-TOFMS detection, and 2) the concentration of phenolic lipophilic analytes from water requiring derivatization prior to analysis by GC/MS. 1) Analyte and derivatizing reagent were simultaneously introduced into the PDMS trap using a ypress- fit connector. The reaction occurs in situ followed by thermal desorption using a thermal modulator array alone or in conjunction with a thermal desorption unit. The aldehydes and amine derivatives were successfully detected by the REMPI-TOFMS. Reaction efficiencies were determined at room temperature without catalysts. Formaldehyde yielded a low reaction/concentration efficiency of 41 % with phenylhydrazine in PDMS, while acetaldehyde, acrolein and crotonal displayed much improved values of 92, 61 and 74 % respectively. Both propylamine and butylamine yielded 28 % reaction/concentration efficiency with benzaldehyde in the PDMS matrix. Detection limits obtained with this technique were significantly lower than the permissible exposure limits set by the Occupational Safety and Health Administration. It should be noted that the detection limits were not determined by actual measurement but by extrapolation from a larger signal. 2) Aqueous analytes were concentrated in the PDMS MCT using a gravity flow rate of ~50 ìl/min. The trap was dried and 5 ìl derivatizing reagent added. At room temperature and without the presence of a catalyst, the reaction of alkylphenols with trifluoroacetic acid anhydride in the PDMS matrix was 100% complete after 5 minutes. Bisphenol-A reacted less than 50 % to completion during this period, but the amount of derivative formed remained constant. This study revealed that extraction efficiencies of the alkylphenols and bisphenol-A off the PDMS trap have poor batch-tobatch repeatability indicating that the PDMS matrix was not homogenous. For two different PDMS batches: tert-octylphenol displayed an extraction efficiency of 70 and 79%, nonylphenol displayed 84 and 43% while Bisphenol-A displayed 10 and 26% respectively. The thermally desorbed derivatives were analysed by GC/MS. Despite background contamination in the desorption unit, detection limits were at the ppt level. Detection limits were not determined by actual measurement but by extrapolation from a larger signal. / Thesis (PhD)--University of Pretoria, 2009. / Chemistry / unrestricted

Stormwater is water that originates from snow or rainfall and that cannot naturally infiltrate the soil. When stormwater flows from hard surfaces it can transport different pollutants to watercourses. By measuring turbidity continuously and using the relationship between turbidity and pollutants the pollutant levels can be estimated. The aim of this study was partly to investigate the relationship between turbidity and phosphorus, metals and PAHs in stormwater in three catchment areas. This study also aimed to investigate how the distribution between dissolved and particulate bound concentrations of phosphorus and metals varied during different rain courses and at different catchment areas. The study was carried out in Uppsala and included continuous measurement of turbidity in three stormwater wells in three catchment areas. Seven samples were also taken at different precipitation occasions in both stormwater and in Fyrisån. In Svartbäcken there was a strong relationship between turbidity and phosphorus and metals. In Librobäck there was an indication that there was a strong relationship between turbidity and some metals and PAH:s. There was no relationship between turbidity and pollutants in Luthagen. Based on these samples, it is difficult to draw any conclusions about why the connections differed for certain pollutants and catchment areas. Due to the fact that the number of measuring points was too few the continuous measurement could not be used to estimate variations in pollution levels. To be able to use the continuous measurement, a longer sampling period and different precipitation occasions is needed. The continuous measurements were used to get an idea of when the samples were taken during the stormwater flow. The results also showed that all pollutants were mostly particulate bound for samples taken at the beginning of a precipitation occasion and with some precipitation during the sampling. For samples that did not take place in connection with stormwater runoff events, the distribution varied for the pollutants in the study. It has not been possible to see a clear trend for how the distribution between dissolved and particulate bound pollutants has varied between different catchment areas. / Dagvatten är vatten som uppkommer vid regn eller vid snösmältning och som inte kan infiltrera naturligt i marken. När dagvattnet avrinner ytligt på marken kan det föra med sig föroreningar till recipienten. Genom att mäta turbiditet kontinuerligt och utnyttja eventuella samband med föroreningar kan föroreningshalter i dagvatten uppskattas. Studien hade två huvudsakliga syften varav det ena var att undersöka samband mellan turbiditet och fosfor, metaller samt PAH:er i dagvatten i tre avrinningsområden. Detta för att se om sambanden kunde användas för att med hjälp av kontinuerlig mätning av turbiditet uppskatta föroreningshalter vid avrinningsområdena. Det andra syftet var att undersöka hur fördelningen mellan lösta och partikulärt bundna andelar fosfor och metaller varierade under olika regnförlopp och vid olika avrinningsområden.  Studien utfördes i Uppsala och innefattade delvis kontinuerlig mätning av turbiditet i tre dagvattenbrunnar i tre avrinningsområden. Det gjordes även sju stickprovtagningar vid olika nederbördstillfällen i både dagvatten och i Fyrisån. I Svartbäcken visade resultaten att det fanns starka samband mellan turbiditet och fosfor och metaller. I Librobäck fanns det en indikation för starka samband mellan turbiditet och fosfor samt vissa metaller och PAH:er. I Luthagen fanns det dock inga samband mellan turbiditet och undersökta föroreningarna. Utifrån dessa prover var det svårt att dra några slutsatser kring varför sambanden skilde sig åt för vissa föroreningar och avrinningsområden. På grund av att antalet mätpunkter var för få kunde inte den kontinuerliga mätningen användas för att uppskatta variationer av föroreningshalter. För att kunna använda den kontinuerliga mätningen behövs en längre provtagningsperiod med fler provtagningar.  Resultatet visade även att den partikulärt bundna andelen dominerade för alla föroreningar vid de provtagningar som togs i början på ett nederbördstillfälle och vid viss nederbörd. Vid provtagningar som utfördes senare under nederbördstillfället varierade fördelningen för de olika föroreningarna. Det har inte varit möjligt att se en tydlig trend för hur fördelningen mellan lösta och partikulärt bundna föroreningar varierade mellan olika avrinningsområden.

Les polluants organiques persistants (POPs) sont des substances toxiques ayant la capacité de se bioaccumuler le long de la chaîne alimentaire. Une fois émis dans l'atmosphère, ils sont dispersés par le vent puis se déposent au sol. Du fait de leur persistance, ils peuvent être réémis depuis le sol vers l'atmosphère et parcourir ainsi de longues distances. Ce processus est couramment appelé « effet saut de sauterelle ». On peut donc retrouver les POPs très loin de leurs sources d'émissions. Pour pouvoir prendre des décisions visant à réduire leur impact environnemental, il est nécessaire de comprendre leur comportement dans l'atmosphère mais également dans les autres milieux, tels que le sol, la végétation ou l'eau. De nombreux modèles numériques de complexité variable ont été développés dans le but de prédire le devenir des POPs dans l'environnement. La plupart d'entre eux considèrent le sol comme un compartiment homogène, pouvant ainsi mener à une sous-estimation des réémissions du sol vers l'atmosphère. Or, du fait de la mise en place de réglementations visant à réduire les émissions anthropiques des POPs, la concentration dans l'atmosphère tend à diminuer et le sol, qui semblait jusqu'alors être seulement un réservoir, devient une source potentielle de POPs pour l'atmosphère. Il apparaît donc nécessaire de coupler les modèles de dispersion atmosphérique à un modèle de sol réaliste. Mes recherches ont permis d'étudier l'impact des interactions entre le sol et l'atmosphère sur la concentration dans les différents milieux. Pour cela, nous avons développé un modèle de sol multi-couches permettant de mieux estimer le profil de concentration dans le sol et les échanges entre ces deux milieux. Une analyse de sensibilité a été effectuée afin d'identifier les paramètres clés dans la détermination des réémissions. Puis ce modèle a été couplé à un modèle 3D de chimie-transport atmosphérique. Une étude de cas à l'échelle européenne a alors été réalisée afin d'évaluer ce modèle et d'estimer l'impact des réémissions sur les concentrations de POPs dans l'environnement / Persitent Organic Pollutants (POPs) are toxic substances that bioaccumulate in the food chain. Once emitted in the atmosphere, they are transported by the wind and deposited on soil. Since they are persistent, they can be reemited from soil to atmosphere by volatilization and travel over very long distances. This process is called grasshopper effect. Thus, POPs may be found at significant levels far from their emission source. It is necessary to understand the transport and fate of these pollutants in order to support the decision making process and reduce human exposure to POPs. Regulations over the last decades lead to a decrease of anthropogenic emissions and subsequent decrease of atmospheric concentration. In this context, the soil is no longer a sink of POPs but can be a source to the atmosphere. Many numeric models aim to study the behavior of POPs in the environment. Most of them consider soil compartment as a homogeneous box, leading to an underestimation of reemissions. Then, it appears of great importance to develop more realistic soil models. The objective of my thesis was to develop such a model, with vertical transport within the soil. This model was evaluated against measured concentration soil profile. We also conducted a sensitivity analysis to identify the key parameters involved in the process of reemissions. Then, the soil model was coupled with an atmospheric transport model. A case study was finally undertaken to estimate the impacts of reemissions on global-mass balance of POPs at European scale

This research paper fulfills the requirements of Geography 4C6. / This paper is an introductory study on the ability of a detention pond to reduce pollutant loading to a receiving water body. Three forms of water pollution are analysed in this study, trace metal (V, Ti and Mn in the water and on suspended solids and bottom sediments), organic and bacterial (bacterial indicators of fecal coliform and fecal streptococci are utilized) pollutants. Each pollutant type requires a different form of analysis to obtain concentrations for targeted pollutants. V, Ti and Mn concentrations were obtained from Instrumental Neutron Activation Analysis (INAA), organic concentrations were acquired by Electron Capture Gas Chromatography (ECGC) and bacterial concentrations were obtained from various laboratory techniques performed by technicians in the Microbiology Lab at McMaster University and in the Provincial Health Laboratories in Hamilton, Ontario. Suspended solid concentration are also analysed to determine the pond's effectiveness in reducing suspended solids load and thus the pollutants they carry. The Storm Water Management Model was used to estimate total pollutant loading into the pond via a combined sewer overflow (CSO). The pollutant concentrations obtained were analysed spatially through the sampling network and temporally between sampled dry and wet weather periods. The result of this study has led to the disturbing conclusion that the detention pond appears to have little or no effect on enhancing water quality. / Thesis / Bachelor of Science (BSc)

Call number: LD2668 .T4 1984 K55 / Master of Science

Since 2008, large numbers of Nile crocodile (Crocodylus niloticus) carcasses were found in the Kruger National Park (KNP), South Africa. Most of the crocodile carcasses were found in the Olifants Gorge, which is situated below the Letaba and Olifants river confluence, before the Mozambique border and Massingir Dam. The Massingir Dam is an important resource and it plays a significant role in the welfare of the local Mozambican population. Autopsies performed on the crocodiles indicated that the adipose tissue colour changed from normal white to yellow and this is usually a sign of pansteatitis. Pansteatitis is caused by lipid peroxidation in an organism and it is characterised by the lack of vitamin E. This disease is recognisable by the hardening of the fatty tissue and yellow discolouration, and is mostly associated with aquatic organisms from polluted ecosystems. There are speculations that the crocodile fatalities may be associated with the Massingir Dam that backed up into the Olifants Gorge after flooding. After the dam was reconstructed, it flooded the Olifants Gorge, causing it to act like a localised sediment trap as the water flow slowed down and as a result, caused pollutants to build-up. Sediment samples were collected from selected rivers and ponds within the KNP. These samples were analysed for selected elements, persistent organic pollutants (POPs), and polycyclic aromatic hydrocarbons (PAHs). The sediment samples were analysed in Norway for POPs and PAHs with the use of a high-resolution gas chromatography/mass spectrometry (GC/MS) and the heavy metals were analysed in South Africa with the use of inductively-coupled plasma mass spectrometry (ICP/MS). In order to identify which elements may have affected the health of the crocodiles, a series of sediment quality indices were used. These indices made it possible to determine which elements may have been involved. The order of probability of heavy metals causing harm was Se>As>Ni>Cr>Cu>I>V>Mn>Co>Fe>Cd>Hg>Zn>Pb>Ba>U. The data was compared to selected international guidelines. All the information was used to determine which of the sampled sites had the highest contamination. The sites sampled with the highest concentrations were in the Crocodile, Nkomati, Olifants, and Letaba Rivers. Concentrations of the elements, POPs, and PAHs were also quantifiable in the Olifants Gorge. The following elements (Fe, Co, Cu, Cr, Pb, V, As, and Ni) were quantified at elevated levels and may therefore have caused negative effects on the crocodiles in the Olifants Gorge. These elevated concentrations, in combination with the dramatic change in the physical environment due to the dam, could have added additional stress that may have contributed to the observed crocodile mortalities in the Olifants Gorge. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

Since 2008, large numbers of Nile crocodile (Crocodylus niloticus) carcasses were found in the Kruger National Park (KNP), South Africa. Most of the crocodile carcasses were found in the Olifants Gorge, which is situated below the Letaba and Olifants river confluence, before the Mozambique border and Massingir Dam. The Massingir Dam is an important resource and it plays a significant role in the welfare of the local Mozambican population. Autopsies performed on the crocodiles indicated that the adipose tissue colour changed from normal white to yellow and this is usually a sign of pansteatitis. Pansteatitis is caused by lipid peroxidation in an organism and it is characterised by the lack of vitamin E. This disease is recognisable by the hardening of the fatty tissue and yellow discolouration, and is mostly associated with aquatic organisms from polluted ecosystems. There are speculations that the crocodile fatalities may be associated with the Massingir Dam that backed up into the Olifants Gorge after flooding. After the dam was reconstructed, it flooded the Olifants Gorge, causing it to act like a localised sediment trap as the water flow slowed down and as a result, caused pollutants to build-up. Sediment samples were collected from selected rivers and ponds within the KNP. These samples were analysed for selected elements, persistent organic pollutants (POPs), and polycyclic aromatic hydrocarbons (PAHs). The sediment samples were analysed in Norway for POPs and PAHs with the use of a high-resolution gas chromatography/mass spectrometry (GC/MS) and the heavy metals were analysed in South Africa with the use of inductively-coupled plasma mass spectrometry (ICP/MS). In order to identify which elements may have affected the health of the crocodiles, a series of sediment quality indices were used. These indices made it possible to determine which elements may have been involved. The order of probability of heavy metals causing harm was Se>As>Ni>Cr>Cu>I>V>Mn>Co>Fe>Cd>Hg>Zn>Pb>Ba>U. The data was compared to selected international guidelines. All the information was used to determine which of the sampled sites had the highest contamination. The sites sampled with the highest concentrations were in the Crocodile, Nkomati, Olifants, and Letaba Rivers. Concentrations of the elements, POPs, and PAHs were also quantifiable in the Olifants Gorge. The following elements (Fe, Co, Cu, Cr, Pb, V, As, and Ni) were quantified at elevated levels and may therefore have caused negative effects on the crocodiles in the Olifants Gorge. These elevated concentrations, in combination with the dramatic change in the physical environment due to the dam, could have added additional stress that may have contributed to the observed crocodile mortalities in the Olifants Gorge. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

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.