Cette thèse a pour objectif d’analyser les mécanismes qui organisent les flux des élèves et des étudiants dans le système scolaire français. La différenciation des carrières des élèves se fait essentiellement au lycée et a des conséquences en termes d’inégalités des apprentissages et d’orientation ultérieure dans l’enseignement supérieur. Les différences relatives aux apprentissages sont une des raisons de l’affaiblissement du contrat didactique entre les enseignants et les élèves. Les élèves qui fréquentent les segments les moins valorisés de l’enseignement secondaire sont conscients de leur situation de relégation et ont de faibles espérances scolaires. Ceux des meilleures séries de baccalauréat ont de fortes espérances car ils acquièrent des « valeurs scolaires » reconnues dans l’enseignement supérieur ou sur le marché du travail. L'existence d'un baccalauréat à statut unique, mais de fait organisé en séries différenciées permet une mobilité scolaire à la marge tout en produisant une insidieuse fiction d’égalité. En conséquence, la capacité de formation de l’organisation scolaire et son efficacité en termes d'apprentissage sont réduites. La focalisation sur l'unique question de l'inégalité scolaire apparaît in fine comme un obstacle à la bonne compréhension de ce qui se joue dans l'institution scolaire et à l'identification des mécanismes qui pourraient, ne serait-ce qu'à la marge, améliorer son fonctionnement pour tous. L'enjeu serait d'étudier les possibilités d'optimisation d'apprentissage de l'ensemble des élèves, quelles que soient leurs origines sociales et leurs parcours scolaires, soit de chercher à maximiser la production de « valeurs scolaires » pour tous. / The object of this thesis is to analyse the mechanisms governing the fluxes of pupils and students in the French education system from ethnographical and statistical angles. Differentiation of the pupils' careers takes place essentially in high school, the second cycle of secondary education. This differentiation has consequences in terms of inequalities of learning and thereby of the subsequent paths followed in higher education. The differences as regards academic learning are one of the reasons why the educational contract between teachers and pupils is losing impetus. Pupils engaged in the least valued sectors of secondary education are aware of their second-best status and consequently do not place great expectations in their academic future. Pupils following the "best" streams of the baccalauréat can entertain high hopes as they acquire an "academic ranking" which is acknowledged in higher education or on the job market. The organisation of the baccalauréat streams allows a marginal academic mobility but an insidious fiction of equality blankets the mechanisms governing the fluxes. This fiction results in the pupils believing less not only in the educational institution but also in their cursus. Analysis of the mechanisms involved in the educational system should question their "usefulness" and their "efficiency" rather than their strictly equalitarian functioning. This analysis standpoint enables the possibilities of maximisation of the pupils' acquisition of knowledge and, more broadly speaking, of their "academic values" to be envisaged, whatever their academic class or social background.

Amostras de água de chuva foram coletadas no campus da USP Ribeirão Preto (RP) de agosto de 2002 a dezembro de 2005. Cerca de 84% (n=127) das amostras apresentaram excesso de acidez, com pH médio de 5,12. Não se observou sazonalidade no pH de acordo com o período de safra da cana. As concentrações médias ponderadas pelo volume (MPV, em mol L-1): K+ 3,9 (n=175), Na+ 2,1 (n=172), Ca2+ 5,0 (n=175) e Mg2+ 1,8 (n=168), observadas em RP, bem como seus fluxos de deposição por via úmida, foram ligeiramente mais elevadas que aquelas encontradas em chuvas de regiões com características semelhantes. As concentrações destes cátions foram sazonais, com um aumento no período de safra, sendo que a maior diferença foi observada para o íon K+, indicando a sua importante fonte na queima de biomassa. A sazonalidade do íon Ca2+ aponta para a importância das atividades agrícolas, intensificadas no período de safra, na emissão deste cátion para a atmosfera. Observaram-se boas correlações lineares entre as concentrações de Na+ e K+ (0,67626) e de Na+ e Ca2+ (0,77822), indicando a possibilidade de emissões pirogênicas e a ressuspensão do solo serem fontes de emissão de Na+. A MPV de carbono orgânico dissolvido (COD) encontrada em RP foi mais elevada que na Amazônia, onde também há intensa queima de biomassa, porém seus fluxos por via úmida em ambas as regiões foram similares (0,42 molCm-2ano-1). As concentrações de COD em RP apresentaram correlações lineares significativas com K+ (0,70341) e com Ca2+ (0,61638), apontando para a queima de biomassa e ressuspensão do solo como fontes importantes de emissão de carbono orgânico para a atmosfera. As concentrações de COD nas chuvas de Araraquara foram ainda maiores que em RP, indicando pronunciadas fontes locais naquela cidade. As MPV (nmol L-1) de Cd 0,54 (n=56), Pb 3,02 (n=94) e Cu, 19,9 (n=98), encontradas nas chuvas de RP foram semelhantes a regiões urbanas e industriais do hemisfério norte, enquanto a concentração de Al (448 nmol L-1, n=126) foi menor, e a de Zn (405 nmol L-1, n=120) apresentou-se dentro das faixas de concentrações relatadas nestes locais. Com exceção de Cd, os demais metais analisados (Pb, Cu, Zn e Al) também apresentaram concentrações significativamente maiores (P=0,05) nas chuvas durante o período de safra, indicando que a queima de biomassa e as atividades agrícolas podem aumentar a emissão destes metais para a atmosfera de RP. A correlação linear significativa entre Pb e Ca2+ (0,53845), indica a participação da ressuspensão do solo no aporte atmosférico de Pb em RP, enquanto a ausência de correlação linear entre Zn e K+ (0,20182) parece indicar a presença de outras fontes significativas de Zn para a atmosfera de RP, além da queima de biomassa. O cálculo do fator de enriquecimento demonstra que Cd, Zn, Pb e Cu estão enriquecidos com relação ao solo na chuva de RP, sugerindo que estes podem ter fontes antrópicas locais e / ou distantes. A análise preliminar de componentes principais não esclareceu o peso das diferentes fontes de emissão atribuídas neste trabalho. / Rain water samples were collected based on events at the University of São Paulo - campus Ribeirão Preto - from August 2002 to December 2005. About 84% (n=127) of the samples had excess of acidity, with an average pH of 5.12. There was no correlation between the pH values and the sugar cane harvest period. The Volume Weighed Means (VWM, in mol L-1) for K+ 3.9 (n=175), Na+ 2.1 (n=172), Ca2+ 5.0 (n=175) and Mg2+ 1.8 (n=168), and their wet fluxes in RP were slightly higher than those reported to regions with similar characteristics. The concentrations for these cations were seasonal, with higher values during the harvest period. The largest difference was observed for K+, indicating its important source in the biomass burning activity. The seasonality showed for Ca2+ is probably related to the higher soil resuspension during the more intense agricultural activities. A good linear correlation observed between Na+ and K+ (0.67626) and between Na+ and Ca2+ (0.77822), suggest that Na+ may have important pirogenic as well as soil dust sources. The VWM for Dissolved Organic Carbon (DOC) in RP was higher than that reported for rainwater in the Amazon region (where the biomass burning is also intense); however, the wet fluxes from both sites were very similar (0.42 mol C m-2 ano-1). DOC concentrations were well correlated with K+ (0.70341) and Ca2+ (0.61638), suggesting that the biomass burning as well as soil dust can be important sources of organic carbon to the atmosphere. DOC concentrations in rainwater from Araraquara were even higher than those for RP, showing a high local source of organic carbon. The VWM (nmol L-1) for Cd 0.54 (n=56), Pb 3.02 (n=94) and Cu 19.9 (n=98) found in the rainwater from RP were similar to urban and industrialized regions of the Northern Hemisphere, while for Al (448 nmol L-1, n=126) it was lower, and for Zn (405 nmol L-1, n=120) the VWM was within the range reported for such areas. Except for Cd, all the other metals measured (Pb, Cu, Zn and Al) also showed higher concentrations (P=0.05) in rainwater samples during the harvest period, suggesting that biomass burning and intensive agricultural activities can increase these species concentrations in the atmosphere. The significant linear correlation between Pb and Ca2+ (0.53845) indicates that soil inputs can be of relevance for Pb atmospheric inputs in RP. On the other hand, the absence of linear correlation between Zn and K+ (0.20182) seems to indicate the presence of other important sources for Zn to the atmosphere besides biomass burning. The calculated Enrichment Factor showed that Cd, Zn, Pb and Cu are anomalously enriched in RP rainwater in relation to soil, suggesting these metals may have antroprogenic local sources as well as distant ones. The preliminary statistical analysis of principal components did not clarify the weight of the different sources of emission attributed in this work.

Na maior bacia hidrográfica do Planeta, o rio Amazonas transporta para os oceanos grande quantidade de carbono particulado e dissolvido. Esta visão tradicional dos rios, como carreadores de carbono para os oceanos, tem sido revista nas últimas décadas, em função de novos resultados que mostram emissões de CO2 destes sistemas para atmosfera superiores ao transporte na descarga em até uma ordem de grandeza. Diversos trabalhos já foram realizados com o objetivo de avaliar os processos que controlam essas emissões. No entanto, os mesmos ainda permanecem como uma grande fonte de incertezas. O objetivo principal deste trabalho foi quantificar os fluxos de CO2 em rios e igarapés do sudoeste da Amazônia (bacia do rio Purus, estado do Acre), levando em consideração as características químicas e físicas de cada sistema, bem como a sazonalidade da região e, assim, contribuir para melhorar as estimativas das emissões de carbono em toda a bacia Amazônica. Os resultados mostraram que durante o período de estiagem os rios apresentam águas com concentrações relativamente elevadas de bicarbonato, indicando a importância do intemperismo de carbonatos como fonte de carbono. Análises da composição isotópica do carbono inorgânico dissolvido corroboraram estes resultados. Nos igarapés, no entanto, a principal fonte de carbono é a matéria orgânica do solo. A sazonalidade exerce forte influência na pCO2 e, consequentemente, nos fluxos de CO2, com os maiores valores ocorrendo no período chuvoso. No entanto, não foi encontrada variabilidade sazonal nas taxas respiratórias o que mostra que, além da respiração, outros fatores também estão influenciando os fluxos de CO2. No período seco, o aumento significativo das concentrações de clorofila a pode indicar que processos fotossintéticos também desempenham um papel importante no balanço de C destes sistemas / In the largest basin of the planet, the Amazon river carries large amounts of particulate and dissolved carbon to the oceans. This traditional view of rivers as carriers of carbon to the oceans has been reviewed in the last decades due to new results showing that CO2 emissions to the atmosphere from these systems can surpass C transport in discharge in one order of magnitude. Several studies have been conducted to evaluate the processes controlling these emissions. However they still remain a major source of uncertainty. The main objective of this study was to quantify CO2 evasive fluxes in rivers and streams of Southwestern Amazon (Purus river basin, Acre state), taking into account chemical and physical characteristics of each system, as well as seasonality in this region and, thus, contribute to improve estimates of carbon emissions throughout the Amazon basin. The results showed that during low water the rivers have relatively high bicarbonate concentrations, indicating that carbonate weathering is an important carbon source. Dissolved inorganic carbon isotopic composition corroborated these results. However, in streams the main carbon source is soil organic matter. Seasonality has a strong influence on pCO2 and consequently on CO2 fluxes, with the highest values occurring in the rainy season. However there was no seasonal variability in respiration rates, which shows that other factors than respiration are also influencing CO2 fluxes. During the dry period, increases in chlorophyll a indicate that photosynthetic processes also play an important role in the C balance of these systems.

O trânsito das metrópoles do novo milênio é um dos problemas que mais leva ao desperdício de recursos, com a consequente redução da qualidade de vida nas metrópoles. Os gastos ligados a vários fatores fazem com que o uso do veículo na hora do pico de trânsito seja duas vezes maior que o normal. O trânsito também gera poluição e consequentemente contribui para doenças pulmonares. O problema de planejamento operacional das infraestruturas viárias em uma grande metrópole constitui algo muito complexo. Problemas deste tamanho ainda não podem ser enfrentados, pelos sistemas computacionais modernos, na sua totalidade. Este problema se resolve dividindo as metrópoles em áreas nas quais é possível conduzir estudos que resolvam as situações locais. A circulação entre zonas distantes das metrópoles é suportada pelas vias expressas, as quais podem ser otimizadas globalmente. Com o crescimento das metrópoles e de seu número de veículos, muitas vezes, as infraestruturas ficam inadequadas, fazendo com que parte dos fluxos das vias expressas invadam os bairros. Neste trabalho se propõe fortalecer a capacidade dos bairros de enfrentar as situações de fluxos intensos. O processo proposto é hierárquico tendo uma primeira fase composta de estudos locais efetuados com simulação micro/mesoscópica, e uma sucessiva otimização global baseada nos resultados das locais. O sistema de otimização necessita de um teste que avalia as soluções escolhidas ao longo do processo. Na literatura da engenharia de tráfego se encontram diferentes níveis de análise do trânsito que geram as três categorias de modelos de simulação. Estas categorias ganham os nomes de modelos microscópicos, mesoscópicos e macroscópicos, mas nenhuma se mostra apta a ser utilizada como teste do sistema proposto. Neste trabalho se propõe um simulador que abstrai o conceito de rede viária reduzindo os custos computacionais até conseguir simular uma inteira metrópole. A técnica de estudo proposta, nos testes, se revela útil em determinadas situações, mas ainda deve ser confrontada com as novas tecnologias capazes de refinar os planos operacionais em tempo real na base dos dados de sensores e câmeras espalhados nas infraestruturas. / The traffic of new-millennium metropolises is one of the problems that most cause resources waste, consequently reducing the quality of life in these metropolises. The costs related to a series of causes make the use of vehicles at rush times be twice as frequent as during other times. The traffic also generates pollution, hence contributing to pulmonary diseases. The infrastructures operational planning problems in big cities is a complex issue. Such big problems still cannot be fully faced by modern computer systems. This can be solved dividing the cities into areas where it is possible to run studies to solve local situations. The circulation between distant areas in metropolises can be done via express motorways, which can be globally improved. With the expansion of big cities and their vehicles, the infrastructures frequently become inadequate and the stream invades neighborhoods. The aim of the present work is to improve the capacity of neighborhoods streams, offering besides technical norms, a global optimization based on local results. The optimization system needs a test that evaluates the chosen solutions along the process. In traffic engineering literature, there are different levels of traffic analysis that generate the three simulation model categories. These categories are named microscopic, mesoscopic, and macroscopic models, but none of them is able to be used as test to the proposed system. In this work, it is proposed a simulator that abstracts the concept of road network, reducing the computer expenses up to the simulation of a whole city. The study technic pruioposed in the tests shows itself as useful in certain situations, but still must be confronted with new technologies able to refine the operational plans in real time based on the sensors and cameras data.

Saline water evaporation from porous media with the associated salt precipitation patterns is frequently observed in a number of industrial and environmental applications and it is important in a variety of topics including, but not limited to, water balance and land-atmosphere interaction, terrestrial ecosystem functioning, geological carbon storage, and preservation of historical monuments. The excess accumulation of salt in soil is a global problem and is one of the most widespread soil degradation processes. Thus, it is important to understand the dominant mechanisms controlling saline water evaporation from porous media. This process is controlled by the transport properties of the porous medium, the external conditions, and the properties of the evaporating fluid. During saline water evaporation from porous media, the capillary induced liquid flow transports the solute towards the evaporation surface while diffusive transport tends to spread the salt homogeneously thorough the porous medium. Therefore, the solute distribution is influenced by the competition between the diffusive and convective transport. As water evaporates, salt concentration in the pore space increases continually until it precipitates. The formation of precipitated salt adds to the complexity of the description of saline water evaporation from porous media. In this dissertation, the effects of salt concentration, type of salt, and the presence of precipitated salt, on the evaporation dynamics have been investigated. The obtained results show that the precipitated salt has a porous structure and it evolves as the drying progresses. The presence of porous precipitated salt at the surface causes top-supplied creeping of the evaporating solution, feeding the growth of subsequent crystals. This could be visualized by thermal imaging in the form of appearance and disappearance of cold-spots on the surface of the porous medium, brought about by preferential water evaporation through the salt crust. My results show that such a phenomenon influences the dynamics of saline water evaporation from porous media. Moreover, a simple but effective tool was developed in this dissertation capable of describing the effects of ambient temperature, relative humidity, type of salt and its concentration, on the evaporative fluxes. Additionally, pore-scale data obtained by synchrotron x-ray tomography was used to study ion transport during saline water evaporation from porous media in 4D (3D space + time). Using iodine K-edge dual energy imaging, the ion concentration at pore scale with a high temporal and spatial resolution could be quantified. This enabled us to reveal the mechanisms controlling solute transport during saline water evaporation from porous media and extend the corresponding physical understanding of this process. Within this context, the effects of particle size distribution on the dispersion coefficient were investigated together with the evolution of the dispersion coefficient as the evaporation process progresses. The results reported in this dissertation shed new insight on the physics of saline water evaporation from porous media and its complex dynamics. The results of this dissertation have been published in 3 peer-reviewed journal papers together with one additional manuscript which is currently under review.

Na maior bacia hidrográfica do Planeta, o rio Amazonas transporta para os oceanos grande quantidade de carbono particulado e dissolvido. Esta visão tradicional dos rios, como carreadores de carbono para os oceanos, tem sido revista nas últimas décadas, em função de novos resultados que mostram emissões de CO2 destes sistemas para atmosfera superiores ao transporte na descarga em até uma ordem de grandeza. Diversos trabalhos já foram realizados com o objetivo de avaliar os processos que controlam essas emissões. No entanto, os mesmos ainda permanecem como uma grande fonte de incertezas. O objetivo principal deste trabalho foi quantificar os fluxos de CO2 em rios e igarapés do sudoeste da Amazônia (bacia do rio Purus, estado do Acre), levando em consideração as características químicas e físicas de cada sistema, bem como a sazonalidade da região e, assim, contribuir para melhorar as estimativas das emissões de carbono em toda a bacia Amazônica. Os resultados mostraram que durante o período de estiagem os rios apresentam águas com concentrações relativamente elevadas de bicarbonato, indicando a importância do intemperismo de carbonatos como fonte de carbono. Análises da composição isotópica do carbono inorgânico dissolvido corroboraram estes resultados. Nos igarapés, no entanto, a principal fonte de carbono é a matéria orgânica do solo. A sazonalidade exerce forte influência na pCO2 e, consequentemente, nos fluxos de CO2, com os maiores valores ocorrendo no período chuvoso. No entanto, não foi encontrada variabilidade sazonal nas taxas respiratórias o que mostra que, além da respiração, outros fatores também estão influenciando os fluxos de CO2. No período seco, o aumento significativo das concentrações de clorofila a pode indicar que processos fotossintéticos também desempenham um papel importante no balanço de C destes sistemas / In the largest basin of the planet, the Amazon river carries large amounts of particulate and dissolved carbon to the oceans. This traditional view of rivers as carriers of carbon to the oceans has been reviewed in the last decades due to new results showing that CO2 emissions to the atmosphere from these systems can surpass C transport in discharge in one order of magnitude. Several studies have been conducted to evaluate the processes controlling these emissions. However they still remain a major source of uncertainty. The main objective of this study was to quantify CO2 evasive fluxes in rivers and streams of Southwestern Amazon (Purus river basin, Acre state), taking into account chemical and physical characteristics of each system, as well as seasonality in this region and, thus, contribute to improve estimates of carbon emissions throughout the Amazon basin. The results showed that during low water the rivers have relatively high bicarbonate concentrations, indicating that carbonate weathering is an important carbon source. Dissolved inorganic carbon isotopic composition corroborated these results. However, in streams the main carbon source is soil organic matter. Seasonality has a strong influence on pCO2 and consequently on CO2 fluxes, with the highest values occurring in the rainy season. However there was no seasonal variability in respiration rates, which shows that other factors than respiration are also influencing CO2 fluxes. During the dry period, increases in chlorophyll a indicate that photosynthetic processes also play an important role in the C balance of these systems.

O trânsito das metrópoles do novo milênio é um dos problemas que mais leva ao desperdício de recursos, com a consequente redução da qualidade de vida nas metrópoles. Os gastos ligados a vários fatores fazem com que o uso do veículo na hora do pico de trânsito seja duas vezes maior que o normal. O trânsito também gera poluição e consequentemente contribui para doenças pulmonares. O problema de planejamento operacional das infraestruturas viárias em uma grande metrópole constitui algo muito complexo. Problemas deste tamanho ainda não podem ser enfrentados, pelos sistemas computacionais modernos, na sua totalidade. Este problema se resolve dividindo as metrópoles em áreas nas quais é possível conduzir estudos que resolvam as situações locais. A circulação entre zonas distantes das metrópoles é suportada pelas vias expressas, as quais podem ser otimizadas globalmente. Com o crescimento das metrópoles e de seu número de veículos, muitas vezes, as infraestruturas ficam inadequadas, fazendo com que parte dos fluxos das vias expressas invadam os bairros. Neste trabalho se propõe fortalecer a capacidade dos bairros de enfrentar as situações de fluxos intensos. O processo proposto é hierárquico tendo uma primeira fase composta de estudos locais efetuados com simulação micro/mesoscópica, e uma sucessiva otimização global baseada nos resultados das locais. O sistema de otimização necessita de um teste que avalia as soluções escolhidas ao longo do processo. Na literatura da engenharia de tráfego se encontram diferentes níveis de análise do trânsito que geram as três categorias de modelos de simulação. Estas categorias ganham os nomes de modelos microscópicos, mesoscópicos e macroscópicos, mas nenhuma se mostra apta a ser utilizada como teste do sistema proposto. Neste trabalho se propõe um simulador que abstrai o conceito de rede viária reduzindo os custos computacionais até conseguir simular uma inteira metrópole. A técnica de estudo proposta, nos testes, se revela útil em determinadas situações, mas ainda deve ser confrontada com as novas tecnologias capazes de refinar os planos operacionais em tempo real na base dos dados de sensores e câmeras espalhados nas infraestruturas. / The traffic of new-millennium metropolises is one of the problems that most cause resources waste, consequently reducing the quality of life in these metropolises. The costs related to a series of causes make the use of vehicles at rush times be twice as frequent as during other times. The traffic also generates pollution, hence contributing to pulmonary diseases. The infrastructures operational planning problems in big cities is a complex issue. Such big problems still cannot be fully faced by modern computer systems. This can be solved dividing the cities into areas where it is possible to run studies to solve local situations. The circulation between distant areas in metropolises can be done via express motorways, which can be globally improved. With the expansion of big cities and their vehicles, the infrastructures frequently become inadequate and the stream invades neighborhoods. The aim of the present work is to improve the capacity of neighborhoods streams, offering besides technical norms, a global optimization based on local results. The optimization system needs a test that evaluates the chosen solutions along the process. In traffic engineering literature, there are different levels of traffic analysis that generate the three simulation model categories. These categories are named microscopic, mesoscopic, and macroscopic models, but none of them is able to be used as test to the proposed system. In this work, it is proposed a simulator that abstracts the concept of road network, reducing the computer expenses up to the simulation of a whole city. The study technic pruioposed in the tests shows itself as useful in certain situations, but still must be confronted with new technologies able to refine the operational plans in real time based on the sensors and cameras data.

Stormwater runoff from existing impervious surfaces needs to be managed to protect downstream waterbodies from hydrologic and water quality impacts associated with development. As urban expansion continues at a rapid pace, increasing impervious cover, and climate change yields more frequent extreme precipitation events, increasing the need for improved stormwater management. Although green infrastructure such as bioretention has been implemented in urban areas for stormwater quality improvements and volume reductions, these systems are seldom monitored to validate their performance. Herein, we evaluate flow attenuation, stormwater quality performance, and nutrient cycling from eight roadside bioretention cells in their third and fourth years of implementation in Burlington, Vermont. Bioretention cells received varying treatments: (1) vegetation with high-diversity (7 species) and low-diversity plant mixes (2 species); (2) proprietary SorbtiveMediaTM (SM) containing iron and aluminum oxide granules to enhance sorption capacity for phosphorus; and (3) enhanced rainfall and runoff (RR) to certain cells (including one with SM treatment) at three levels (15%, 20%, 60% more than their control counterparts), mimicking anticipated precipitation increases from climate change. Bioretention water quality parameters monitored include total suspended solids (TSS), nitrate/nitrite-nitrogen (NOx), ortho-phosphorus (Ortho-P), total nitrogen (TN) and total phosphorus (TP), which were compared among bioretention cells’ inflows and outflows across 121 storms. Simultaneous measurements of flow rates and volumes allowed for evaluation of the cells’ hydraulic performances and estimation of pollutant load and event mean concentration (EMC) removal. We also monitored soil CO2 and N2O fluxes, as they represent a potential nutrient loss pathway from the bioretention cells. We determined C and N stocks in the soil media and vegetation, which are critical design elements of any bioretention, to determine the overall C and N balances in these systems. Significant average reductions in effluent stormwater volumes and peak flows were reported, with 31% of the storms events completely captured. Influent TSS loads and EMCs were well retained by all cells irrespective of treatments, storm characteristics, or seasonality. Nutrient removal was treatment-dependent, where the SM treatments consistently removed P loads and EMCs, and sometimes N as well. The vegetation and RR treatments mostly exported nutrients to the effluent. We attribute observed nutrient exports to the presence of excess compost in the soil filter media. Rainfall depth and peak inflow rate undermined bioretention performance, likely by increasing pollutant mobilization through the filter media. While the bioretention cells were a source of CO2, they varied between being a sink and source of N2O. CO2 fluxes were orders of magnitude higher than N2O fluxes. However, soil C and N, and plant C and N in biomass was seen to largely offset respiratory CO2-C and biochemical N2O-N losses from bioretention soil. The use of compost in bioretention soil media should be reduced or eliminated. If necessary, compost with low P content and high C: N ratio should be considered to minimize nutrients losses via leaching or gas fluxes. In order to understand trade-offs stemming from compost amendments, we conducted a laboratory pot study utilizing switchgrass and various organic soil amendments (e.g., different compost types and coir fiber) to a sandy loam soil contaminated with heavy metals and studied potential nutrient leaching and pollutant uptake. Addition of organic amendments significantly reduced metal bioavailability, and improved switchgrass growth and metal uptake potential. While no differences in soil or plant metal uptake were observed among the amendments, significant differences in nutrient leaching were observed.

Ocean-atmosphere fluxes on the West Florida Shelf (WFS) coastal ocean region are investigated using observations and derived surface fluxes from an array of buoys deployed between 1998 and 2003. The observed annual cycle shows that water column temperatures increase and are stratified when heat flux is positive, and they decrease and are well mixed when it is negative. Water temperature is minimum (maximum) when heat flux switches sign from negative (positive) to positive (negative) in early spring (autumn). Tropical and extra-tropical events help define the seasonal characteristics of the water temperature. Despite considerable daily and synoptic variability in relative humidity, observations on the WFS show that the monthly mean values are nearly constant at about 75%. Winter relative humidity varies from less than 50% to over 100% (supersaturation values of up to 3% are recorded and coincide with fog on shore) as extra-tropical fronts move over the WFS. Sensor distribution shows small spatial variations in relative humidity in the coastal ocean environment that depends on high frequency variability in meteorological conditions and low-frequency variability in oceanic conditions. Comparisons with observations show that standard climatologies are unable to reproduce spatial variability on the WFS, especially in relative humidity and surface heat flux components that are dependent on sea surface temperature. Model experiments show that careful attention must be paid in calculating and applying surface heat fluxes. Observations and models are employed to assess the relative importance of surface fluxes and convergence of heat flux by the ocean circulation in controlling ocean temperature. In spring and autumn, seasonal change in water temperature is mainly controlled by surface heat flux with smaller contributions by ocean convergence, but synoptic scale variability is controlled by both surface heat flux and ocean circulation. Surface fluxes are of primary importance in determining water temperature during the passage of tropical storms or extra-tropical fronts. The coastal ocean temperature balance is fully three-dimensional. Models must be supported by adequate surface heat flux boundary conditions. These require sufficient numbers of in situ measurement points for constraining atmospheric models. The number of observations will depend on the spatial scales of SST variability.

This thesis examines a method for estimating the daytime fluxes of heat, water vapour and carbon dioxide at regional scales by using simple models to combine spatially resolved surface properties with bulk meteorological quantities measured at a central location. The central themes of this thesis are that the spatial and temporal variability of regional scale fluxes are contained in the surface properties and meteorology respectively and that the surface properties can be interpolated across a heterogeneous landscape using remotely sensed data. The regional scale fluxes estimated using this technique are compared to the values from three other methods and this allows some conclusions to be made regarding the relative strengths and weaknesses of each method. The surface property approach yields robust estimates of the fluxes that will be useful in researching exchange processes at regional scales, providing input parameters for, and validation of, the biosphere components of General Circulation Models and testing inventory estimates of CO2 budgets. The surface properties are derived using data from 33 aircraft flights and eight ground-based sites along a 96 km transect established during the 1995 Observations At Several Interacting Scales experiment held near Wagga Wagga, New South Wales, Australia. Surface properties examined are the evaporative fraction (ratio of evapotranspiration to available energy), the Bowen ratio (ratio of sensible heat flux to evapotranspiration), the maximum stomatal conductance (maximum stomatal opening under optimal conditions) and the water-use efficiency (ratio of CO2 flux to evapotranspiration). Maximum stomatal conductance is calculated using a simple model of the stomatal response to light and water vapour deficit assuming soil evaporation occurs at the equilibrium rate. The diurnal trend and day-to-day variability in the surface properties is found to be significantly less than the spatial variability. All of the surface properties examined show some sensitivity to the synoptic conditions. The relationships between the surface properties and the Normalised Difference Vegetation Index (NDVI) are examined using a 130 km by 50 km sub-scene from a Landsat 5 Thematic Mapper (TM) image obtained five days before the start of the experiment period. The ground-based and aircraft observations are used to calculate the source-area influencing each measurement and this is combined with the Landsat 5 TM data to produce an average, source-area weighted NDVI for each ground-based site and each aircraft location. The source-area model is important because it provides the link between the observations and the remotely sensed data by identifying the surface patch that influences the measurements. Linear relationships are found between the source-area weighted NDVI and the surface properties. The observed relationships are used to interpolate the surface properties over the region covered by the satellite image and spatial variations in water loss and CO2 uptake by the surface vegetation are identified that are not resolved by the ground-based network. Analysis of the ground-based data showed that the spatial variability of the bulk meteorological quantities used in the surface property approach was much less than the diurnal trend in these data. With the small temporal variation in the surface properties noted before, this confirms the utility of assigning the spatial and temporal variability of the fluxes to the surface properties and the meteorology respectively. The combination of surface properties derived from the aircraft data and meteorology measured at a single location at the centre of the transect shows good skill in predicting the observed fluxes. Furthermore, the discrepancies between the predictions and the observations are explained by the different source-areas of the aircraft and ground-based data and much of the bias is removed when the surface properties are scaled from the NDVI of the aircraft source-area to the NDVI of the ground-based sites. Regional scale fluxes of heat and water vapour calculated using the surface property approach agree with averages of the ground-based data and this indicates that the ground-based network was representative of the OASIS region. Estimates of regional scale CO2 fluxes are not available from the ground-based network due to the lack of measurements at the driest ground-based site but the surface property approach yields plausible values. The results demonstrate the utility of extrapolating surface properties across heterogeneous landscapes using remotely sensed data.