Silicic magmas pose threats to society in the form of explosive volcanism. Understanding silicic magmatism is thus crucial for evaluating eruption-related risks, but numerous questions are unresolved: How are silicic magmas generated and how do they evolve? Over what timescales? What are the connections between shallow silicic magma reservoirs, their associated volcanic centers, and tectonic setting? This study uses petrography, whole rock and zircon elemental and isotopic geochemistry, and U-Pb zircon geochronology to investigate these questions in ancient silicic volcanic centers of the western U.S. and southern Brazil. The Silver Creek caldera in the Miocene southern Black Mountains volcanic center (SBMVC) of western Arizona produced the 18.8 Ma, ~1000 km3 Peach Spring Tuff (PST) supereruption. The PST was bracketed by 2 million years (19 17 Ma) of compositionally diverse intrusive and volcanic magmatic activity. Analysis of pre- and post-PST SBMVC units reveal that 1) the SBMVC experienced ~200 k.y. (19 18.8 Ma) of localized high-temperature magmatism (≥900 °C), coincident with the PST eruption; 2) SBMVC magmas were derived from Precambrian Mojave crust and enriched lithospheric mantle; 3) pre- and post-PST magmas are isotopically more diverse and have stronger mantle fingerprints than the PST, suggesting they were less homogeneous and less crustal than the PST magma body; and 4) mantle input into the SBMVC increased following the PST eruption. Late Proterozoic to early Cambrian silicic intrusions, lavas, and pyroclastic flows are sporadically exposed for ~1500 km throughout northern Uruguay and southern Brazil and are associated with a series of 600 530 Ma rift-generated basins. Zircon geochemistry and U-Pb geochronology of silicic units associated with the two largest basins, the Camaquã and Itajaí basins, indicate that 1) Neoproterozoic-Cambrian silicic magmatism in the region was episodic, occurring at ~520 Ma in the Itajaí basin and ~540 Ma and ~580 Ma in the Camaquã basin; 2) ~580 Ma magmatism was widespread, extending from the Graciosa region at the northern extent of the magmatic system to the Camaquã basin in the south; and 3) ~580 Ma magmatism is coincident with the proposed widespread rifting event that was responsible for basin development.

Icelands great abundance of silicic rock (10-13% of subaerial exposures), coupled with the unusual thickness of the islands crust, hints at continental nucleation and permanent crust construction in an oceanic environment. This phenomenon is rare on modern Earth, but it is often postulated that Icelandic magmatism is a modern analogue for ancient (Hadean) crustal construction. Understanding the processes that form abundant, juvenile, silicic crust in oceanic Iceland has important implications for understanding Earths early, and ongoing, history. The Icelandic crust is juvenile; there is neither ancient nor appreciable felsic crust nor sediments to complicate the magmatic history. Investigations into the origins of Icelandic silicic magma are therefore more focused than the global approach to the issue. Despite this, the issue remains highly contentions and hotly debated. Studies of zircon have elsewhere underpinned understanding of silicic magma processes and crustal evolution, but no such research has been carried out in Iceland until now. This investigation into the origins and evolution of Icelands silicic crust is the first comprehensive study of Icelandic zircons. Elemental and isotopic geochemistry and U-Th-Pb geochronology of zircon from intrusive and extrusive rocks and sediments, coupled with supporting bulk-rock elemental and isotope geochemistry and petrography, reveal that: (1) very low 18O/16O supports partial melting of crust hydrothermally altered by meteoric water as a primary driver of Icelandic felsic petrogenesis; (2) uniformity of O isotopic compositions demonstrates neither a change in magmatic processes nor a change in the meteoric-water composition imprinted on magmas throughout Icelands history, despite extreme climate variability; (3) increased variability in Hf isotope ratios suggest changes to Icelands mantle source with time, (4) Iceland is not an appropriate modern analogue for the Hadean, as their zircon records are quite distinct; (5) zircons reflect tens of thousands of years of activity preceding individual rhyolitic eruptions, and indicate the longevity of silicic magma systems at individual central volcanoes may reach three million years; (6) Icelandic zircons form a compositional category that is distinguishable from typical continental and oceanic zircon populations.

Climate change mitigation will require extensive decarbonization of the electricity sector. This thesis addresses both large-scale wind integration (Papers 1-3) and development of new energy technologies (Paper 4) in service of this goal. Compressed air energy storage (CAES) could be paired with a wind farm to provide firm, dispatchable baseload power, or serve as a peaking plant and capture upswings in electricity prices. Paper 1 presents a firm-level engineering-economic analysis of a wind/CAES system with a wind farm in central Texas, load in either Dallas or Houston, and a CAES plant whose location is profit-optimized. Of a range of market scenarios considered, the CAES plant is found to be profitable only given the existence of large and infrequent price spikes. Social benefits of wind/CAES include avoided construction of new generation capacity, improved air quality during peak demand, and increased economic surplus, but may not outweigh the private cost of the CAES system nor justify a subsidy. Like CAES, pumped hydropower storage (PHS) ramps quickly enough to smooth wind power and could profit from arbitrage on short-term price fluctuations exacerbated by large-scale wind. Germany has aggressive plans for wind power expansion, and Paper 2 analyzes an investment opportunity in a PHS facility in Norway that practices arbitrage in the German spot market. Price forecasts given increased wind capacity are used to calculate profit-maximizing production schedules and annual revenue streams. Real options theory is used to value the investment opportunity, since unlike net present value, it accounts for uncertainty and intertemporal choice. Results show that the optimal investment strategy under the base scenario is to wait approximately eight years then invest in the largest available plant. Paper 3 examines long-distance interconnection as an alternate method of wind power smoothing. Frequency-domain analysis indicates that interconnection of aggregate regional wind plants across much of the western and mid-western U.S. would not result in significantly greater smoothing than interconnection within a single region. Time-domain analysis shows that interconnection across regions reduces the magnitude of low-probability step changes and doubles firm power output (capacity available at least 92 % of the time) compared with a single region. An approximate cost analysis indicates that despite these benefits, balancing wind and providing firm power with local natural gas turbines would be more cost-effective than with transmission interconnection. Papers 1 and 3 demonstrate the need for further RD&D (research, development, and deployment) of low-carbon energy technologies. Energy technology development is highly uncertain but most often modeled as deterministic, which neglects the ability both to adapt RD&D strategy to changing conditions and to invest in initially high-cost technologies with small breakthrough probabilities. Paper 4 develops an analytical stochastic dynamic programming framework in which RD&D spending decreases the expected value of the stochastic cost of a technology. Results for a two-factor cost model (which separates RD&D into R&D and learning-by-doing) applied to carbon capture and sequestration (CCS) indicate that given 15 years until large-scale deployment, investment in the RD&D program is optimal over a very broad range of initial mitigation costs ($10-$380/tCO2). While the NPV of the program is zero if initial mitigation cost is $100/tCO2, under uncertainty the program is worth about $7 billion. If initial mitigation cost is high, the program is worth most if cost reductions exogenous to the program (e.g. due to private sector activity) are also high. Factors that promote R&D spending over learning-by-doing include more imminent deployment, high initial cost, lower exogenous cost reductions, and lower program funds available.

Prioritizing the finite resources available to advance research, development and demonstration of the nuclear industry requires a comprehensive evaluation of potential advanced nuclear technologies to inform decision making. A number of advanced nuclear technologies and fuel cycle options present promising improvements that are only realized when deployed and running at steady-state. However, an advanced nuclear fuel cycle will not be implemented all at once. Moreover, there is little work to understand how transitioning to new nuclear energy systems could affect waste management and human health, when compared to the presently deployed, once-through nuclear fuel cycle. A potential transition from the U.S. once-through nuclear fuel cycle to a modified-open nuclear fuel cycle has been modeled, using a phased approach, including reprocessing of both plutonium and uranium within a simplified dynamic energy demand scenario. Low-radioactivity waste generated and worker collective doses were estimated based on data from industry experience and then these metrics were compared to the baseline U.S. once-through nuclear fuel cycle. Overall observations regarding the comparison between the two nuclear fuel cycles were that worker collective doses were not significantly different but a significant amount of radioactive waste was avoided by using recycled uranium and plutonium from used nuclear fuel. Important outcomes of this work were that the once-through nuclear fuel cycle, as implemented in the U.S., is not as simple as depicted in textbooks and fuel cycle evaluations and must be updated to serve as an accurate baseline against which to measure performance of future potential advanced nuclear fuel cycles. It was also concluded that the two major contributions to occupational radiological impacts in the once-through nuclear fuel cycle, from uranium recovery operations through reactor operations, had reversed in recent years; this is different from historical data and conventional wisdom which says that impacts from the front-end of the once-through nuclear fuel cycle are dominant.

The purpose of this study was to determine the views of educators regarding integration of environmental education into the school curriculum in the Mafikeng District of the North-West Province. The survey population was drawn from the Mafikeng District of the North West Province. The respondents for this study were drawn from the six education circuits in the Mafikeng District. There are 1 02 primary schools in the Mafikeng District. Out of I 02 primary schools, fifty-two (n =52) were randomly selected. In each circuit, fifty percent (50%) of the primary schools were randomly selected to participate in the · study. In each school, six educators were also randomly selected to participate in the study. A total number of participants for this study was 312 (n = 312). A questionnaire was the primary tool used for collecting data for this study. Both open and closed-ended questions were used. The aim of the questionnaire was to obtain information on issues and challenges facing educators in integrating environmental education into the outcomes-based education curriculum. The questionnaire was administered to 312 (n = 312) educators. Out of the total sample, 219 (70%) respondents returned usable questionnaires. For data analysis, content analysis method was employed. Frequencies, percentages and tables were also used in the analysis of data. The findings revealed that respondents were aware of the importance of incorporating environmental learning into school curriculum. However some of them stated that integration of environmental education should only happen in certain learning areas such as Human and Social Sciences and Natural Sciences where environmental aspects are self-evident and obvious. The study also revealed that some educators struggle to integrate environmental education into their learning areas because they still encounter problems in implementing the present curriculum, that is Outcomes-Based Education (OBE). Furthermore, it was revealed that the challenges facing integration of environmental education into the school curriculum included lack of both physical and human resources and lack of knowledge and understanding of environmental education. It was concluded that the success of integration of environmental education into the school curriculum would depend on a number factors. The most pressing one was better access to resources, especially learning support materials and more in-service training for more knowledge and information about environmental education. Furthermore, putting in place school-based support services to conduct workshops regularly, will enhance the integration processs of environmental education into the school curriculum as this will minimise the gap between in-service training and long waited periods for follow-ups, are recommended. / Thesis (M.A.) North-West University, Mafikeng Campus, 2003

The Public Trust Doctrine placed wildlife in trust, via state control and regulation, for the benefit of the people. Managing agencies that lose sight of the importance of public acceptance of predator policies and management actions may find themselves legislatively or judicially subverted. This study examines how the Montana public wolf hunting and trapping seasons have affected tolerance and acceptance of gray wolves (Canis lupus) among rural resident ranchers, hunters, and trappers. Twenty residents from the Blackfoot, Bitterroot, and Ninemile Valleys were qualitatively interviewed over the summer and fall of 2013. Potential participants were initially identified using purposive sampling, with subsequent interviewees located through snowball sampling. The presence or absence of the public wolf hunting and trapping seasons is not the sole determining factor of tolerance or intolerance of wolves in this sample population. The pattern of determinant factors instead more closely represents a web of influence than a direct line of cause and effect. Eight main nodes, or themes, were identified in interview transcription data identified based on frequency of occurrence in interview data and how essential they seemed in shaping attitudes of interviewees: 1) the consequences of political maneuvering (frustration, perceived inequity, and mistrust); 2) the need for management and control of the wolf population; 3) wolf-related impacts to interviewees livelihood and way of life; 4) personal beliefs, affects, and attitudes; 5) previous interactions with predators; 6) cultural influences; 7) the place and impact of wolves in the ecosystem; and 8) noted changes in opinion. Most themes were further divided into subthemes, and the connections between all themes and subthemes were examined from there. While the impacts of the seasons have not yet been great or entirely consistent across the sample population, statements made by interviewees suggest that removal of public wolf hunting and trapping liberties would greatly reduce tolerance and acceptance in these interest groups and increase an overall polarization of public opinions. Interview data reveal complex relationships between stakeholders, interest groups, and impacts from wolf re-establishment, as well as complex attitudes towards wolves that often incorporate some level of awe and admiration. Individuals trust in managing agencies may be critical in moving forward. Data also shows that there will likely be more changes to come in this sample populations acceptance and tolerance of wolves. Wolf tolerance and acceptance levels should be further monitored in Montana rural resident ranchers, trappers, and big game hunters, the stakeholder groups that are the most directly impacted by and most necessary for continued wolf management and recovery.

Womens presence in agriculture as farmers, consumers, advocates, and activists has become ever more apparent over the last two decades as census data, popular media, and academic literature increasingly reflect their work. Many of the farmers in western Montana practicing sustainable agriculture are women and have built relationships with other women farmers in the region through existing agriculture-focused organizations like Homegrown and the Western Montana Growers Cooperative. Even with the strong presence of these organizations, some women farmers feel there is potential for the formalization of a women farmer network in western Montana that would increase the opportunities for socialization among farmers and provide space to discuss gender-specific experiences of farming. This project describes interviewees experiences as women in agriculture, existing communication among women farmers, and explores the potential for a women farmer network in western Montana.

Biosolids being recycled to the land for agriculture is not only cost-effective for municipalities but it is also beneficial to the environment. To protect public and environmental health, however, land application of biosolids is regulated for concentrations of pathogens and chemical contaminants, and for production of odours. Electro-dewatering (ED) of residual biosolids from wastewater treatment is a newly commercialized technology which can produce a drier biosolids cake compared to other advanced dewatering technologies. Additionally, it has been demonstrated that ED inactivates pathogen indicators below the detection limit and reduces the regrowth potential. In the current study, using olfactometry and headspace gas chromatography - mass spectrometry (GC/MS), reduced production of odours during storage of dewatered biosolids was documented, and possible mechanisms leading to this reduction were examined.The study compared centrifuged secondary biosolids as the untreated sample control with the same biosolids that had been either electro-dewatered for 10 min or simply heat-treated for 10 min as a secondary control. These samples were incubated at room temperature under anaerobic conditions. Qualitative analysis of the head space by a trained olfactometric panel showed that ED biosolids possessed lower perceived odour concentrations when characterized by detection threshold and recognition threshold compared to the untreated and the heat-treated biosolids (detection thresholds were 13,000 for ED biosolids, 25,000 for untreated biosolids, and 18,000 for heat-treated biosolids). Quantitative analysis by GC/MS of reduced sulphur compounds (methanethiol, dimethyl sulphide and dimethyl disulphide) showed relatively high concentrations for the untreated and heat treated samples, but these compounds remained below the detection limit (78 ppmv for methanethiol, 59 ppmv for dimethyl sulphide and 8 ppmv for dimethyl disulphide) for the ED samples during 14 days of anaerobic incubation. To investigate the reason for the lower odour production by ED biosolids, several factors were examined: (1) the lower pH of the electro-dewatered biosolids (pH 4.5-4.8 vs. pH 6.8-7.5 for the untreated and heat-treated biosolids), (2) the removal of odour precursors by ED, (3) the production of inhibitory compounds during ED. The low pH hypothesis was tested by increasing the pH of the ED biosolids to the level found in the untreated biosolids before anaerobic incubation. Increasing the pH of ED biosolids led to an increase in methanethiol generation. This suggests that lowering the pH of biosolids is one of the main factors causing the abatement of odour production by ED. The removal of odour precursor hypothesis was tested by adding back the filtrate extracted by ED. As the filtrate had a very high pH of 12.8, which also changed the pH of the ED biosolids, the filtrate pH was manipulated such that the pH of the resulting biosolids would be either ~4.5 or ~7. As in the pH-specific experiments, methanethiol emissions were not detected for all samples with a low pH, whereas methanethiol emissions from the high pH samples were increased in the ED biosolids with added filtrate. These methanethiol emissions were above those of the untreated, ED biosolids without filtrate and the heat-treated biosolids. These final results indicate that the dominant factor responsible for reduced odours in ED biosolids is the low pH, but that the removal of precursors may also contribute to lowering odour production. Once these factors were taken into account, there was no clear evidence that ED produced inhibitory compounds. Finally, these experiments confirmed that bacterial pathogen indicators did not regrow under the conditions tested. Therefore, it can be concluded that, under the conditions tested, ED achieved irreversible inactivation of pathogen indicator organisms and reduced odour production by lowering the pH. / L'électro-déshydratation (ED) des biosolides résiduels découlant du traitement des eaux usées est une technologie nouvellement commercialisée qui peut produire des biosolides plus secs que d'autres technologies de déshydratation avancées. Dans l'étude présentée dans ce mémoire, la réduction de la production d'odeurs durant l'entreposage des biosolides déshydratés a été documentée et les mécanismes possibles conduisant à cette réduction ont été examinés en utilisant l'olfactométrie et la spectrométrie de masse (GC/MS) en phase gazeuse de l'espace de tête. L'étude a comparé des biosolides secondaires centrifugés en tant que contrôle (échantillons non traité) avec les mêmes biosolides qui avaient été soit électro-déshydratées pendant 10 min, soit simplement traité à la chaleur pendant 10 min comme un contrôle secondaire. L'analyse qualitative de l'espace gazeux au-dessus des échantillons par un panel olfactométrique a montré que les biosolides électro-déshydratés produisaient des concentrations perçus d'odeurs inférieure selon les seuils de détection et de reconnaissance des odeurs par rapport aux échantillons non traités ou traités à la chaleur (seuils de détection étaient 13 000 pour les biosolides électro-déshydratés, 25 000 pour les biosolides non traités, et 18 000 pour les biosolides traités à la chaleur). L'analyse de GC/MS des composés soufrés réduits (méthanethiol, sulfure de diméthyle et le disulfure de diméthyle) a montré des concentrations relativement élevées pour les échantillons non traités et traités à la chaleur, mais ces composés sont restés sous la limite de détection pour les échantillons électro-déshydratés et incubés en anaérobie pendant 14 jours.Pour determiner la cause de la réduction de la production d'odeur par les biosolides électro-déshydratés, plusieurs hypothèses ont été émises: (1) le pH inférieur des biosolides électro-déshydratée (pH 4,5-4,8 vs pH 6.8 à 7.5 pour les biosolides non-traités et traités thermiquement), (2) l'élimination des précurseurs d'odeur par le processus d'électro-déshydratation, (3) la production de composés inhibiteurs au cours de l'électro-déshydratation. L'hypothèse d'un pH faible a été testée en augmentant le pH des biosolides électro-déshydratées au niveau des biosolides non traitées avant l'incubation anaérobie. L'augmentation du pH des boues électro-déshydratées a conduit à une augmentation de la production méthanethiol. Ceci suggère que l'abaissement du pH des boues est l'un des principaux facteurs responsables de la réduction de la production d'odeur par électro- déshydratation. L'hypothèse de la suppression du précurseur d'odeur a été testée en rajoutant le filtrat extrait par l'électro-déshydratation. Comme le filtrat présente un pH très élevé (12.8), le filtrat pH a été manipulé de telle sorte que le pH des biosolides résultant serait soit de ~ 4.5 ou de ~ 7. Comme dans les expériences spécifiques au pH, les émissions de méthanethiol n'ont pas été détectées pour les échantillons dont le pH était bas, alors que les émissions méthanethiol à partir des échantillons à pH élevé ont augmentés dans les biosolides électro-déshydratées avec filtrat ajoutée. Ces émissions de méthanethiol étaient supérieures à ceux des biosolides électro-déshydratées sans filtrat, des biosolids non traités et des biosolides traités à la chaleur. Ces derniers résultats indiquent que le facteur dominant responsable de la réduction des odeurs dans les biosolides électro-déshydratées est le faible pH, mais que l'élimination des précurseurs peut également contribuer à réduire la production d'odeurs. Une fois que ces facteurs eurent été pris en compte, il n'y avait pas de preuve claire que l'électro-déshydratation produit des composés inhibiteurs. Par conséquent, on peut conclure que, dans les conditions testées, l'électro-déshydratation atteint une inactivation irréversible d'organisme indicateur d'agent pathogène et a réduit la production d'odeur par abaissement du pH.

The treatment and disposal of waste biosolids from activated sludge wastewater treatment plants can contribute a large portion of the total operation costs. Many technologies are being explored to address this issue, and ozonation of return activated sludge (RAS) has been shown to economically reduce waste biosolids production in Europe. However, as European winter temperatures rarely fall below 12 °C, little research has been done on biosolids reduction by ozonation at cold temperatures like during Canadian winters. A previously performed global sensitivity of a model describing ozone transformations suggested that, below 12 °C, the nitrification and other processes in a treatment plant could be less stable in the plant with RAS ozonation than without. Thus, the objective of this research was to experimentally determine the behaviour at cold temperatures of RAS ozonation for the reduction of biosolids production, and the effects of the process on treatment performances. Four 2-L sequencing batch reactors (SBRs) were designed and built, and the operation was optimized. The SBRs were fed a synthetic municipal wastewater, and operated at 0.5-day hydraulic retention times (HRTs) and 15-day solids retention times (SRTs). One SBR pair was maintained at 8 °C while the other pair was kept at room temperature (~20 °C). Within each pair, one reactor was operated as a non-ozonated control, while a portion of the suspended solids of the other was periodically ozonated such as to reach a biosolids reduction target of 40%. Analyses of chemical oxygen demand (COD), suspended solids, and ammonium concentrations were performed and tracked over a 6-month period. It was found that after an initial adaptation phase, biosolids inventory in the ozonated reactor remained similar to the control and maintained an acceptable COD conversion at both temperatures. The ammonium removal in the cold ozonated reactor did not recover once ozonation began, as it did in the warm reactor, and full nitrification was lost in both cold reactors when the nitrogen concentration was increased. A preliminary computer model of the cold SBRs was developed. The calibrated model satisfactorily predicted the solids inventory and effluent soluble COD. Therefore, while biosolids and COD conversion with ozonation can be maintained at a temperature of 8 °C, reactor nitrification performance was found to be unstable so far at that temperature, but further research is needed to fully understand this unexpected result. / Le traitement et l'élimination des biosolides produits aux usines d'épuration par boues activées peuvent contribuer à une grande partie des frais de fonctionnement. À travers le monde, de nombreuses technologies sont examinées pour résoudre ce problème. En Europe, l'ozonation des boues activées recirculées (return activated sludge [RAS] en anglais) peut réduire économiquement la production de biosolides. Cependant, les températures hivernales d'Europe tombent rarement en dessous de 12 °C, donc peu de recherches ont exploré la réduction des biosolides par ozonation à des températures froides, comme celles des hivers canadiens. Une analyse de sensibilité globale réalisée précédemment sur un modèle décrivant les transformations de l'ozone a suggéré qu'en dessous de 12 °C la nitrification et d'autres processus d'une usine d'épuration pourraient être moins stable si un système d'ozonation des RAS est installé. Ainsi, l'objectif de cette recherche était de déterminer expérimentalement le comportement à des températures froides de l'ozonation des RAS sur la réduction de production de biosolides, ainsi que l'effet de ce processus sur les performances du traitement biologique. Quatre réacteurs biologiques séquentiels (RBS) de 2 L ont été conçus et construits, et l'opération a été optimisée. Les RBS ont été alimenté par de l'eau usée municipale synthétique. Ils étaient opérés avec un temps de rétention hydraulique de 0,5 jour et un temps de rétention des solides de 15 jours. Une des paires de RBS fut maintenue à 8 °C tandis que l'autre paire fut opérée à température ambiante (~20 °C). Dans chaque paire, un des réacteurs était le réacteur contrôle (c'est-à-dire non traité à l'ozone), tandis qu'une partie des matières en suspension (MES) de l'autre réacteur était périodiquement exposée à l'ozone pour atteindre un objectif de réduction de la production de biosolides de 40%. Les analyses de la demande chimique en oxygène (DCO), des matières en suspension et des concentrations d'ammonium ont été effectuées et suivies sur une période de 6 mois. Après la phase initiale d'adaptation, l'inventaire des biosolides dans le réacteur ozoné était comparable à celui du réacteur contrôle. De plus, l'enlèvement de la DCO fut maintenue à des niveaux acceptables aux deux températures d'opération pour tous les réacteurs. Une fois que l'ozonation a commencé, l'enlèvement de l'ammonium dans le réacteur ozoné à température froide ne s'est pas rétabli à un niveau similaire à celui avant l'ozonation malgré que le réacteur à température ambiante ait bien réussi le rétablissement. Cependant, la nitrification complète a été perdue dans les deux réacteurs à température froide lorsque la concentration d'azote a augmenté. Un modèle informatique préliminaire des RBS à température froide a été calibré. Le modèle calibré a pu prédire la quantité de matières solides et la concentration de DCO soluble dans l'effluent, avec une marge d'erreur acceptable. Par conséquent, tandis que l'inventaire des biosolides et la conversion de DCO avec l'ozonation peuvent être maintenus à une température de 8 °C, les performances de nitrification du réacteur étaient instables à cette température. Des recherches supplémentaires sont nécessaires pour comprendre pleinement ce résultat inattendu.

The presence of metal ions, especially heavy metals, in various waters at elevated levels can pose a high risk to the environment and human health. Drinking water is one of the major sources that contributes to the daily intake of heavy metals by humans, and thus a rapid, low-cost and sensitive method for detection of heavy metal content in water is desirable. The goals of this study are to develop a chemical method for rapid testing of lead (PbII) ion in water solutions and to incorporate the method into a portable device for potential onsite applications. First, a rapid and sensitive colorimetric method for lead detection has been developed in this study by utilizing the unique optical properties and surface chemistry of gold nanoparticles (GNPs) and glutathione (GSH), which is a peptide used for lead recognition. In the reaction, GSH molecules serve as linkers to coordinate with both PbII and GNPs so as to aggregate the GNPs and thereby change the colour of the assay solution. The colour changes as measured by absorbance at selected wavelengths using UV-Vis spectrometry are proportional to the levels of PbII in aqueous samples, and thus quantification of PbII can be realized. As the reaction is based on label-free GNPs, no pre-modification is required. The limit of detection (LOD) of 6.0 ppb achieved by the method is lower than the maximum acceptable PbII concentrations (10 -15 ppb) in drinking water, indicating its high sensitivity and potential applicability in drinking water testing. The high selectivity for PbII against 10 metal ions has been demonstrated, and several masking agents were evaluated for their effectiveness in reducing potential inferences for an additional four metals. Second, a polydimethylsiloxane (PDMS) microfluidic chip was fabricated and coupled with a portable optical reader specifically designed for GNP probes. This device was first tested for detection of aluminum (AlIII) as a model compound by GNP probes to examine the compatibility of the microfluidic chip with the GNP probes and the sensitivity to the corresponding colour changes of the GNPs. It showed an LOD (1.2 ppm) comparable with that of UV-Vis Spectrometry (1.3 ppm) and operations were simple since only pipetting was required. The prominent feature of the device is that PDMS microfluidic chips are disposable and can be redesigned for other assays as well, such that the label-free GNP probes developed in this study for PbII detection can be possibly integrated in those microfluidic chips in the near future. The use of LED array light sources with controllable wavelengths is another feature to enable multi-analyte capability, which could be examined in the near future. / La présence d'ions métalliques en particulier les métaux lourds dans différents types d'eau à des niveaux élevés peut présenter un risque important pour l'environnement et la santé humaine. L'eau potable est l'une des principales sources qui contribuent à l'apport quotidien en métaux lourds chez l'humain, et donc une méthode rapide, peu coûteuse et sensible à la détection des métaux lourds dans l'eau est en grande demande. Les objectifs de cette étude est de développer une méthode chimique pour un dépistage rapide d'ion de plomb (PbII) en phase aqueuse et d'intégrer la méthode dans un dispositif portable à des fins d'applications potentielles sur place. Premièrement, une méthode colorimétrique rapide et sensible à la détection de plomb a été développée dans cette étude en utilisant les propriétés optiques uniques et la chimie de surface des nanoparticules d'or (GNPs) et le glutathion (GSH), qui est un peptide utilisé pour la reconnaissance de plomb. En réaction, les molécules de GSH servent de relieurs à fin de coordonner avec le PbII ainsi que le GNPs de manière à regrouper les sondes GNPs et ainsi changer la couleur du dosage. Les changements de couleur mesurée par absorption à des longueurs d'onde sélectionnées en utilisant la spectrométrie d'UV-Vis sont proportionnels au niveau du PbII dans des échantillons aqueux, permettant ainsi la quantification de PbII. Comme la réaction est basée sur l'utilisation des GNPs non-libellés, pas de pré-modification est requise. La limite de détection (LOD) de 6,0 ppb réalisée par la méthode est inférieure aux concentrations maximales de PbII acceptable (10 à 15 ppb) dans l'eau potable, ce qui indique sa haute sensibilité et applicabilité potentielle en analyse d'eau potable. Une haute sélectivité pour le PbII contre 10 ions métalliques a été démontrée, et plusieurs agents masquant ont été évalués pour leur efficacité dans la réduction des interférences potentielles pour quatre autres métaux. Deuxièmement, une puce microfluidique en polydiméthylsiloxane (PDMS) a été fabriqué et couplé à un lecteur optique portable spécialement conçu pour les sondes de GNPs. Cet appareil a été d'abord testé pour la détection de l'aluminium (AlIII) comme composé modèle, par des sondes de GNPs à fin d'examiner la compatibilité de la puce microfluidique avec les sondes de GNPs et la sensibilité aux changements de couleur correspondante du GNPs. Elle a démontré une LOD comparable (1,2 ppm) à celui de la spectrométrie UV-Vis (1,3 ppm) et les opérations étaient simples puisque seulement le pipetage était nécessaire. L'aspect remarquable du dispositif est que les puces microfluidiques de PDMS sont jetables et peuvent être reformulées pour d'autres dosages ainsi, de sorte que les sondes de GNPs non-libellées développées dans cette étude pour la détection de PbII peuvent être éventuellement intégrés dans des études futures. L'utilisation des sources de lumière à faisceau LED aux longueurs d'onde contrôlables est une autre caractéristique permettant une capacité multi-analyte, qui pourrait être examinée dans un proche avenir.