Techn. Universiẗat, Diss., 2001--Berlin.

En raison des de l’augmentation de la pollution à l’échelle mondial du notamment aux gaz d'échappement des automobiles, de nouvelles réglementations d'émissions ont été mises en place depuis les années 1990. Ces règlementations ont conduit à une évolution des carburants traditionnels vers les biocarburants et à des systèmes de post-traitement des gaz d'échappement, notamment pour les moteurs diesel, de plus en plus sophistiqués. Ils comprennent à ce jour une série d'unités catalytiques, contenant un filtre à particules, un catalyseur d’oxydation pour traiter le monoxyde de carbone et les hydrocarbures et enfin un catalyseur pour réduire les oxydes d’azote. Dans ce travail de thèse, deux de ces systèmes catalytiques industriels ont été étudiés, les catalyseurs à l'oxydation diesel (DOC) et les catalyseurs de réduction catalytique sélective (SCR). Une attention particulière est accordée à leur performance en présence de composés métaux alcalins. En effet, les alcalins sont présent dans les biocarburants et lorsque le biodiesel est utilisé comme carburant de remplacement, ils vont donc être présents dans les gaz d’échappement et à priori dans les systèmes de post-traitement. / Due to global lean exhaust gas and new emission regulations, exhaust after-treatment systems of diesel engines are getting more and more sophisticated and comprise a series of catalytic units. In the present work, two of these catalytic systems were studied, Diesel Oxidation Catalysts (DOC) and Selective Catalytic Reduction (SCR) catalysts. Particular attention is paid to their performance in the presence of alkali compounds when bio-diesel is utilized as the alternative fuel.Firstly, this thesis focuses on the catalytic behavior of the Diesel Oxidation Catalyst using different aging characteristics of road mileage in order to improve the efficiency of an ammonia SCR system on an after-treatment line composed by a DOC + DPF + SCR. The studied catalyst is a commercial diesel oxidation catalyst (Pt/Pd/Al2O3) provided by Continental. Hydrothermal aging under different conditions on carrots of monolith were performed. Also studied in the monolith form over the commercial DOC, the influence of the addition of different alkali metal species (K and Na) on the commercial DOC through catalytic tests performed on this structured catalyst under multicomponent (C3H6 / CO / NO / NO2) co-feeding conditions was explored. Aiming at investigating the effects of the presence of different alkali metal species on the DOC at the level of active phase, homemade bimetallic DOC is prepared and then different alkali metal species incorporated. Finally, encouraged by the evident influence of alkali compounds on DOCs, their impacts on the downstream SCR catalysts are also studied in this thesis. The studied SCR catalyst is a commercial V2O5-based catalyst provided by UMICORE company.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-03-13T14:08:07Z No. of bitstreams: 1 RobertoJoseDeOliveiraJunior_DISSERT.pdf: 4558013 bytes, checksum: ae1fd02e52749f7856f3376116d58668 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-03-20T11:11:30Z (GMT) No. of bitstreams: 1 RobertoJoseDeOliveiraJunior_DISSERT.pdf: 4558013 bytes, checksum: ae1fd02e52749f7856f3376116d58668 (MD5) / Made available in DSpace on 2018-03-20T11:11:30Z (GMT). No. of bitstreams: 1 RobertoJoseDeOliveiraJunior_DISSERT.pdf: 4558013 bytes, checksum: ae1fd02e52749f7856f3376116d58668 (MD5) Previous issue date: 2017-11-24 / Pensar em avalia??o no ensino de Geografia tamb?m ? pensar a doc?ncia e seus contextos socioeducativos, o que inclui o espa?o e a cultura escolar, o tempo e os sujeitos envolvidos nessa tessitura. Ao considerar os estudos a respeito da pr?tica docente e avalia??o da aprendizagem, o presente trabalho tem como objetivo analisar a influ?ncia do Exame Nacional do Ensino M?dio (ENEM) nos procedimentos de avalia??o utilizados por professores de Geografia, em turmas concluintes do Ensino M?dio de escolas p?blicas de Natal-RN. Para isso, o trabalho se fundamenta teoricamente em autores que est?o na interface entre a Geografia, o ensino, e a educa??o, a exemplo de estudiosos como Santos (2006), Morin (2014), Cavalcanti (1998), Vesentini (2009/2013), Tardif (2002), Zabala (1998), Luckesi (2011) e Lib?neo (2013). O estudo foi desenvolvido a partir de pesquisa explorat?ria realizada em cinco escolas p?blicas de Natal-RN, com participa??o de 5 professores de Geografia e 218 estudantes concluintes do Ensino M?dio. Metodologicamente foi realizado levantamento de dados nos microdados do Instituto Nacional de Estudos e Pesquisas Educacionais An?sio Teixeira (INEP) e, com a finalidade de definir o recorte emp?rico, foi utilizada a t?cnica da amostragem probabil?stica para escolha das escolas pesquisadas. Utilizamos a abordagem qualitativa para a coleta e tratamento dos dados, obtidos por meio de observa??o participante; uso de di?rio de campo; question?rios aplicados com estudantes; entrevistas semiestruturadas com professores de Geografia; coleta e an?lise documental. O contato com o espa?o escolar e os resultados obtidos mostraram que, com embasamento nos direcionamentos propostos pelo Novo ENEM, ? poss?vel se pensar em procedimentos e estrat?gias de avalia??o mais contextualizadas com a realidade vivida nas escolas p?blicas. Todavia, constatou-se a exist?ncia de desafios consider?veis quando relacionamos a proposta de avalia??o preconizada no Novo ENEM e os registros verificados nas escolas p?blicas participantes da pesquisa, assim como nos relatos expostos pelos estudantes e docentes dessas institui??es: condi??es infraestruturais que n?o potencializam o ensino e a aprendizagem, aus?ncia de atividades de forma??o continuada para os docentes (principalmente relacionadas ? avalia??o da aprendizagem e sobre o ENEM), entre outros desafios. Portanto, a??es pedag?gicas e de pesquisas, as quais busquem investigar os processos de avalia??o no ensino e na aprendizagem de Geografia, s?o fundamentais, pois contribuem para reflex?o cr?tica e direcionam/sensibilizam um processo formativo mais significativo de constru??o do conhecimento geogr?fico nas escolas de Educa??o B?sica. / Thinking about evaluation in Geography teaching is also thinking about teaching and its socio-educational contexts, which includes school culture and space, the time and those who are involved in this process. Considering the studies regarding to teaching practice and learning evaluation, this work aims to analyze the influence of the High School National Exam (ENEM) in the procedures of evaluation used by Geography teachers in senior high school classes in public schools of Natal, RN. Therefore, this work is theoretically based on authors who are at the interface between Geography, Teaching and Education, such as Santos (2006), Morin (2014), Cavalcanti (1998), Vesentini (2009/2013), Tardif (2002), Zabala (1998), Luckesi (2011) and Lib?neo (2013). The study was developed from an exploratory survey conducted in five public schools of Natal, with the participation of 5 Geography teachers and 218 senior high school students. Methodologically, data collection was carried out in microdata of Instituto Nacional de Estudos e Pesquisas Educacionais An?sio Teixeira (INEP) and, for the purpose of defining empirical cut-off, it was used the probabilistic sampling technique for choosing the schools. Qualitative approach was used for the collection and processing of data, obtained through participant observation, field diary, questionnaires for the students, semi-structured interviews with the Geography teachers involved, collection and document analysis. The contact with school and the results obtained showed that, based on the guidelines proposed by the New ENEM, it is possible to think about evaluation procedures and strategies more contextualized with the reality lived in public schools. However, there were considerable challenges when we relate the proposal of the evaluation recommended by the New ENEM to the existent records in the participant public schools, as well as in the reports presented by the students and teachers of these institutions: infrastructure conditions that do not potentialize the teaching and learning process, absence of activities of continuing education courses for teachers (specially those related to learning evaluation and to ENEM), among other challenges. Thus, pedagogical and research actions, which seek to investigate the processes of evaluation in the teaching and learning of Geography, are fundamental, for they contribute to critical thinking and lead / sensitize to a more meaningful formative process of Geographical knowledge construction in Basic Education schools.

Extensive drainage of UK peatlands has been associated with dehydration of the peat, an increase in water colour and a loss of carbon storage. Water colour has been found to be proportional to the concentration of fluvial dissolved organic carbon (DOC) (McKnight et al. 1985). It has been considered that the blocking of drainage channels represents a means of peat restoration and a way of reducing DOC losses to surface waters. This study aimed to assess the effectiveness of drain blocking at both an individual drain scale and at a larger catchment scale (up to 1km2). The effect of external parameters become more pronounced as the DOC record is examined at larger scales. The catchment is an open system and water chemistry will be influenced by mixing with water from other sources. Also it is likely that at some point the drains will cut across slope leading to the flow of any highly coloured water down slope, bypassing the blockages, and entering the surface waters downstream. Degradation of DOC will occur naturally downstream due to the effects of light and microbial activity. There is, consequently, a need to examine the wider effects of drain blocking at a catchment scale to ensure that what is observed for one drain transfers to the whole catchment. A series of blocked and unblocked catchments were studied in Upper Teesdale, Northern England. A detailed sampling programme of stream water, soil water and run off was undertaken in which a series of drains were studied in the 12 months prior to and post blocking. Water table depth, flow and weather parameters were also monitored. This study could not find a significant decline in DOC concentration at zero or first order scale post blocking; however a small yet significant decline of 2.5% in DOC concentration relative to the control catchment was recorded at the first order scale. A decrease in DOC concentration is recorded as water flows from the zero to the first order in the same catchment. The study found that the effects of DOC degradation in the catchments were very small and that DOC degradation could not solely explain the decrease in DOC concentration seen from zero to first order drains indicating the importance of dilution effects in the catchments. The blocking of peat drains does significantly decrease the export of DOC which is largely achieved by decreasing water yield. The size of the DOC export reduction caused by drain blocking is seen to decrease as scale increases providing evidence for the existence of bypass flow around the zero order drain blockages. Blocking was found to have little impact on the level of the catchment water table. This can be explained by the peat bog being naturally very wet before intervention such that when blocking did occur the soil had little capacity to take in additional water. Water yield, however, is seen to decrease post blocking indicating that water and potentially DOC is being lost from the system. Principle component analysis and event analysis were performed on the hydrological and chemical data in order to trace and define this missing component of the water balance yet the analysis found that the water chemistry in the study catchment can be defined by a relatively simple mixing trend. As such this missing water remains undefined. The presence of bypass flow and water mixing will reduce the efficiency of any drain blocking and have wider implications for upland management and its practitioners.

No description available.

Zooplankton is crucial for lake ecosystems as it is an important component in most of the food webs of these ecosystems. However, environmental changes have caused reductions in ecosystems nutrients and stoichiometry, which directly affects phytoplankton’s development and quality. Studies were carried out in 33 different lakes throughout Sweden, divided into 4 regions (Abisko, Jämtland, Västerbotten and Värmland) to assess whether differences in environmental characteristics induced differences in phytoplankton abundance and zooplankton communities. Using data from 3 different seasons of the year, I found that zooplankton composition differed between northern and southern regions, and greater differences were found between the mountain regions than between the boreal regions. Dissolved inorganic N (DIN) and dissolved inorganic N to total P ratio (DIN:TP) concentrations were lower in northern regions than in southern regions. Phytoplankton biomass increased with dissolved organic carbon (DOC), likely through the positive effects of DOC on overall nutrient availability. DOC concentrations were higher in boreal regions than in mountain regions, as also happens with chlorophyll-a. Positive correlations between DOC and 3 different zooplankton genera were proven, whereas 3 different zooplankton taxa were correlated with DIN:TP (two negatively and one positively). Lakes with lower DIN:TP ratios had higher abundances of calanoids, which were the major contributor of the dissimilarity in zooplankton composition among the regions. Therefore, the DIN:TP ratio possibly has stronger effects than DOC on zooplankton composition in Swedish oligotrophic lakes. But further increases in DOC concentrations will likely reduce the differences in zooplankton composition caused by the declines in lake DIN:TP observed in this study.

Lake browning in the northern hemisphere is endangering crucial ecosystem services. Darker water decreases fish and primary production as well as touristic and recreational values. It furthermore requires intensive treatment to receive safe drinking water. Brownification is connected to iron and coloured dissolved organic carbon (DOC). In Sweden, spruce plantations leak DOC, possibly depending in their DOC rate on tree age. Whereas wetlands are known to purify water and might contribute to the degradation of DOC. This thesis aims to investigate how different land use types and other parameters affect water colour. Ditches flowing through old spruce forests, young spruce forests, and peat wetlands in the Lake Bolmen catchment, southwestern Sweden, were sampled at in- and outlet. Highly significantly positive relationships between DOC, iron and absorbance were found. The relationship was strongest between DOC and absorbance (R² = 0.88; p < 0.001) and weakest between DOC and iron (R² = 0.54; p < 0.001). High variability led to no significant differences in the release of DOC and iron between the three land use types. However, older forests tended to increase DOC and iron loading compared to younger forests. This study suggests that not only spruce forests in general are affecting the brownification, but that several different factors like age and underlying soil type might play a critical role.

Zooplankton is crucial for lake ecosystems as it is an important component in most of the food webs of these ecosystems. However, environmental changes have caused reductions in ecosystems nutrients and stoichiometry, which directly affects phytoplankton’s development and quality. Studies were carried out in 33 different lakes throughout Sweden, divided into 4 regions (Abisko, Jämtland, Västerbotten and Värmland) to assess whether differences in environmental characteristics induced differences in phytoplankton abundance and zooplankton communities. Using data from 3 different seasons of the year, I found that zooplankton composition differed between northern and southern regions, and greater differences were found between the mountain regions than between the boreal regions. Dissolved inorganic N (DIN) and dissolved inorganic N to total P ratio (DIN:TP) concentrations were lower in northern regions than in southern regions. Phytoplankton biomass increased with dissolved organic carbon (DOC), likely through the positive effects of DOC on overall nutrient availability. DOC concentrations were higher in boreal regions than in mountain regions, as also happens with chlorophyll-a. Positive correlations between DOC and 3 different zooplankton genera were proven, whereas 3 different zooplankton taxa were correlated with DIN:TP (two negatively and one positively). Lakes with lower DIN:TP ratios had higher abundances of calanoids, which were the major contributor of the dissimilarity in zooplankton composition among the regions. Therefore, the DIN:TP ratio possibly has stronger effects than DOC on zooplankton composition in Swedish oligotrophic lakes. But further increases in DOC concentrations will likely reduce the differences in zooplankton composition caused by the declines in lake DIN:TP observed in this study.

Allochthonous organic carbon is increasing and leading to browning of freshwaters in the northern hemisphere. It is already known that an increase in allochthonous dissolved organic carbon (DOC) affects benthic primary production and respiration negatively via light limitation, however, little is known about the impact on benthic bacteria. This report aims at examining how DOC and other environmental variables affect the production and growth of benthic bacteria. This was done by analyzing data from 18 lakes in northern Sweden with different DOC concentrations. This analysis was divided into two datasets: one including data at the whole lake scale and the other including data over depth within the lakes. The result showed that DOC, average depth, and the light extinction coefficient all had a negative impact on bacterial production on a whole lake scale. The light extinction coefficient was also affecting the whole lake bacterial growth efficiency (BGE) negatively. Over depth within the lakes a higher light input increased the bacterial production. In the same dataset, light was also affecting the BGE positively, while temperature had a negative effect. The results can thus be linked to the increase in allochthonous carbon and brownification. Because allochthonous DOC have a negative effect on benthic primary production, there will be less autochthonous DOC available for benthic bacteria. Allochthonous DOC is considered less degradable than autochthonous DOC. The increase in allochthonous DOC therefore has a negative impact on benthic bacterial production, likely connected to a decrease in production of autochthonous DOC by benthic algae.

abstract: Humans are exposed up to thousands of per- and polyfluoroalkyl substances (PFAS) in the environment, but most of the research and action has been directed towards only two PFAS compounds. These two compounds are part of a subcategory of PFAS called perfluoroalkyl acids (PFAAs). It has been a challenge for the environmental community to mitigate risks caused by PFAAs due to their high persistence and lack of effective measures to remove them from the environment, especially in heavily impacted areas like fire-training sites. The goal of this work was to further answer some questions regarding the removal of PFAAs in the environment by looking at anion exchange resin characteristics and presence of a competing compound, natural organic matter (NOM), in the adsorption of environmentally relevant PFAS compounds including the two often monitored 8-carbon chain PFAAs. Two different resins were tested with two forms of counterions, in both groundwater and NOM impacted groundwater. Resin polymer matrix was the most important property in the adsorption of PFAAs, the two resins used A520E and A860 had similar properties except for their matrices polystyrene (PS) and polyacrylic (PA), respectively. The PS base is most effective at PFAAs adsorption, while the PA is most effective at NOM adsorption. The change in the counterion did not negatively affect the adsorption of PFAAs and is, therefore, a viable alternative for future studies that include regeneration and destruction of PFAAs. The presence of NOM also did not significantly affect the adsorption of PFAAs in the PS resin A520E, although for some PFAAs compounds it did affect adsorption for the PA resin. Ultimately, PS macroporous resins with a strong Type I or Type II base work best in PFAAs removal. / Dissertation/Thesis / Masters Thesis Engineering 2019