• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 25
  • 6
  • 6
  • 6
  • 6
  • 6
  • 6
  • 3
  • 3
  • 2
  • 1
  • Tagged with
  • 47
  • 47
  • 47
  • 14
  • 12
  • 10
  • 5
  • 5
  • 4
  • 4
  • 4
  • 4
  • 4
  • 3
  • 3
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Medição do aporte atmosférico dos elementos-traço nos municípios de Campinas e Paulínia com auxílio da espécie vegetal Tillanásia usneoides (L.) / Measurement of atmospheric supply of trace elements in Campinas and Paulínia with support of vegetal specie Tillandsia usneoides (L.)

Ferreira, Guilherme Gonçalves Pereira da Silva, 1981- 18 August 2018 (has links)
Orientador: Jacinta Enzweiler / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-18T23:22:14Z (GMT). No. of bitstreams: 1 Ferreira_GuilhermeGoncalvesPereiradaSilva_M.pdf: 2045815 bytes, checksum: e8ef791fcd875da45872a42710b54a97 (MD5) Previous issue date: 2011 / Resumo: A bromélia epífita Tillandsia usneoides (L.) foi utilizada para realizar um biomonitoramento atmosférico em sete locais ao longo de uma transecta que passa pelos municípios de Campinas e Paulínia. Os pontos escolhidos situam-se próximos a rodovias, indústrias e avenidas, assim como em locais mais afastados de atividades antrópicas. Amostras da planta foram introduzidas por aproximadamente dois meses em cada um locais durante cinco intervalos sequenciais, entre abril de 2009 e março de 2010. Os objetivos foram conhecer a distribuição sazonal e espacial das concentrações de elementos-traço (Al, Ba, Bi, Cd, Co, Cu, Cr, Fe, Ga, Hf, Ni, Nb, Pb, Rb, Sb, Sn, Sr, Ti, Sr, Ce, Pr, V, Y e W), estabelecer relações com dados climáticos e parâmetros de qualidade do ar e estimar as fontes a partir dos aportes medidos. Após o período de exposição, as amostras da planta foram removidas, liofilizadas e moídas. Uma alíquota foi dissolvida em meio ácido (HNO3 e HF destilados) e analisada em espectrômetro de massas com plasma indutivamente acoplado (ICP-MS). O material de referência certificado de folhas de macieira NIST 1515 foi analisado para o controle da qualidade. Os resultados das concentrações obtidas de cada elemento nas amostras expostas foram normalizados em relação a amostras-controle, não expostas, para obter um Coeficiente de Enriquecimento (CE). Os maiores aportes de elementos-traço foram identificados nos meses de abril-junho/09, setembro/09-novembro/09 e janeiro/10-março/10, atribuídos à presença de maiores concentrações de material particulado e de poluentes na atmosfera, além de fatores climáticos não favoráveis a sua dispersão nesses períodos. Os menores coeficientes de enriquecimento obtidos para o período de maior pluviosidade - novembro/09-dezembro/10 - foram atribuídos à remoção parcial dos poluentes por deposição úmida. O maior aporte total foi medido no ponto CSC (Careca Sport Center), e os elementos que apresentaram maiores CE foram Al, Cr, Co, Ni, Y, W, Ce e Pr. A principal fonte para esses resultados provavelmente é a poeira do solo, e secundariamente o tráfego de veículos e emissões de indústrias próximas. No ponto FEAGRI (no campus da Unicamp) um conjunto de elementos, entre eles Ni e Co, apresentou CE relativamente elevados, e que foram atribuídos principalmente à poeira do solo local. O ponto CENTRO (centro de Campinas) apresentou os maiores CE de Ba, Sn, Cu e Sb, com aportes Pb, Cd, Bi, Al, Fe, Ga, Nb, Ti também elevados, associados principalmente ao tráfego de veículos. Nos pontos de Paulínia aportes relativamente elevados foram medidos para Ba, Sb, Bi e V e que foram associados ao tráfego e indústrias na região, incluindo as petroquímicas. Os pontos CABRAS e MSG, mais distantes de influências antrópicas, apresentaram as menores concentrações de metais poluentes em razão da distância relativa às fontes e ao posicionamento favorável quanto à direção dos ventos principais, respectivamente. Os dados obtidos sugerem que os aportes estão associados a fontes locais e ao transporte de curta distância por ventos NO, enquanto o transporte de longa distância por ventos sudeste, não foi confirmado / Abstract: The epiphytic bromeliad Tillandsia usneoides (L.) was used as biomonitor of the atmosphere at seven sites along a transect of the municipalities of Campinas and Paulinia. The selected sites are located near highways, industries and avenues, as well as in places farther away from human activities. The samples of were introduced by about two months during five sequential intervals, from April 2009 to March 2010. The goals were to know the seasonal and spatial concentrations of trace metals (Al, Ba, Bi, Cd, Co, Cu, Cr, Fe, Ga, Hf, Ni, Nb, Pb, Rb, Sb, Sn, Sr, Ti, Sr, Ce, Pr, V, Y e W), establish relationships with climatic data and parameters of air quality and estimate the sources of the deposition. After the exposure period, the plants samples were taken to the laboratory, freeze dried and ground. An aliquot was dissolved (HNO3 plus HF, purified by sub-boiling), and analyzed by inductively coupled plasma mass spectrometry (ICPMS). The certified reference material Apple Leaves NIST SRM 1515 was analyzed for quality control. The measured concentrations of exposed plants were normalized against control samples of non exposed plants to obtain the coefficient of enrichment (CE). The largest inputs of traceelements were identified in April-June/09, September-November/09 and January-March/10, which are also the periods with higher concentrations of particulate matter and pollutants in atmosphere together with less favorable climatic factors to their dispersion. The lowest CE values in November/09-January/10 were attributed to the partial removal of atmospheric pollutants by wet deposition. The highest depositions was measured at CSC (Careca Sport Center) and Al, Cr, Co, Ni, Y, W, Ce e Pr showed high CE. The main sources for such results probably are soil dust, nearby traffic and industrial emissions. At FEAGRI (at Unicamp campus) a set of elements, including Co and Ni, presented relatively high CE, which were attributed mainly to dust from local soil. The site at Campinas downtown presented the highest CE of Ba, Sn, Cu and Sb, and also significant input of Pb, Cd, Bi, Al, Fe, Ga, Nb, Ti mainly due to the traffic of vehicles. At the sites in Paulínia, relatively high CE were obtained for Ba, Sb, Bi e V, which were associated to traffic and industrial sources. The sites CABRAS and MSG presented the lowest concentrations of metallic pollutants, because they are favored by the distance from anthropogenic sources and the position regarding the direction of main winds, respectively. The data suggest that the deposition of metallic elements is related to local sources and to short distance transport by NW wind, while long distance transport by SE winds was not confirmed / Mestrado / Geologia e Recursos Naturais / Mestre em Geociências
42

Evolution of Anthropogenic Pb and Pb isotopes in the deep North Atlantic Ocean and the Indian Ocean

Lee, Jong-Mi, Ph. D. Massachusetts Institute of Technology January 2013 (has links)
Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2013. / Cataloged from PDF version of thesis. / Includes bibliographical references. / Pb and Pb isotopes in the ocean have varied on decadal to centennial time scales due to anthropogenic Pb inputs. Thus, tracing the temporal variation of Pb and Pb isotopes in the ocean provides information on the major sources of Pb and the transport of Pb from sources to the ocean surface and into the ocean interior. In this thesis study, first, a method was developed for the analysis of dissolved Pb and other trace elements in seawater using single batch nitrilotriacetate resin extraction and isotope dilution ICP-MS, which was applied in analyzing seawater Pb concentrations in the rest of the study. A -550 year history of the Pb and Pb isotopes in the deep North Atlantic Ocean is reconstructed using a deep-sea coral, showing the infiltration of anthropogenic Pb to deep sea. Comparing the results to the surface North Atlantic Ocean Pb record using a Transit Time Distribution model, the mean transit time of Pb is estimated to be -64 years. This is longer than the transit time estimate assuming simple advection from a source, showing the importance of advective-diffusive mixing in the transport of Pb to the ocean interior. The later part of the thesis investigates Pb in the Indian Ocean, where no useful Pb data have been previously reported. First, using annually-banded surface growing corals, I reconstruct variations of Pb and isotopes in the surface waters of the central and eastern Indian Oceans during the past half-century. Results of the study show the increase of Pb concentrations from the mid-1970s, and major sources of the Pb are discussed, including leaded gasoline and coal burning, based on their emission histories and Pb isotope signatures. Second, Pb concentration and isotope profiles are presented from the northern and western Indian Oceans. Higher Pb concentrations and lower Pb isotope ratios (206Pb/ 207Pb, 208Pb/207Pb) are found in the upper water column (<I 500m) as a result of anthropogenic Pb inputs, and their distributions are largely controlled by the water circulation in the Indian Ocean. / by Jong-Mi Lee. / Ph.D.
43

Trace element dispersion patterns around the North Silver Bell extension, Silver Bell porphyry copper deposit, Pima County, Arizona

Korkowski, Bradley John January 1982 (has links)
No description available.
44

Chemical pollution arising from heavy inorganic industries in Richards Bay - an assessment.

January 2004 (has links)
The industrial port of Richards Bay on the eastern seaboard of KwaZulu-Natal, South Africa has undergone rapid growth over the last 25 years. This industrial growth has inevitably led to an increase in the anthropogenic pollutant inputs in the area. However, the degree of this contamination has not previously been assessed not been accompanied by an awareness of its environmental impacts. This project serves to assess the current environmental situation of the area and provide background levels against which the environmental impacts of further growth in the area can be assessed. The main pollution point sources in the area were identified as a pulp and paper plant, a sulfuric acid/fertiliser plant and aluminium smelters. The chemical and physical processes involved within these industries were identified and discussed in detail. The common inorganic pollutants emitted by these industries were identifies as trace metals, sulfur dioxide, NOx gases and fluoride. It was these pollutants that therefore became the focus of this study. Reservoirs within Richards Bay that may become sinks for contamination were identified and water, sediment and soil samples were taken from these reservoirs. The samples were analysed for trace metal contamination, pH, alkalinity and fluoride levels. Analysis of the acidity and alkalinity of water, sediment and soils samples demonstrated that there is presently no long-term acidification of the environment in Richards Bay. The only samples that showed increased acidity were the soils taken from the roadside sites immediately outside the industries. This lack of overall acidification indicates that, at present, there are no detrimental effects of acidic emissions on the hydrosphere and geosphere. Only cursory investigations were conducted into the fluoride levels found in water samples. None of the samples analysed demonstrated detectable amounts of fluoride present. Comprehensive trace metal analyses were performed on the water, sediment and soil samples through the use of ICP-AES. Levels obtained were compared with levels from samples taken from relatively uncontaminated background sites. Trace metal analysis indicated contamination of the freshwater reservoirs when compared with the background, while the soils and saltwater reservoirs remain largely uncontaminated. However, the contaminated areas did not show levels greater than quality guideline concentrations. Further studies should be conducted with regards to the trace metal contamination of the biosphere and the bioavailability of the contaminants already present in the waters, sediments and soils. More detailed investigations should also be conducted into the levels of atmospheric pollutants and fluoride levels in all reservoirs. / Thesis (M.Sc.) - University of KwaZulu-Natal, Pietermaritzburg, 2004.
45

Elemental Composition of Vegetation as an Indicator of Technogenic Influence in Ust-Kamenogorsk City / Composition élémentaire de la végétation comme un indicateur de l'influence technogénique à Ust-Kamenogorsk / Элементный состав растительности как индикатор техногенного воздействия на территории г. Усть-Каменогорска

Yalaltdinova, Albina 12 November 2015 (has links)
L’accroissement de l’urbanisation et le développement industriel modifient la composition des géosphères de la Terre, en augmentant le nombre de problèmes géoécologiques et en affectant négativement la santé humaine. Actuellement, plus d'attention est accordée à la surveillance de l'état des composants de l’environnement naturel urbain. En Russie, les méthodes biogéochimiques (par ex., l'application de feuilles des arbres comme un récepteur naturel de la pollution) sont largement utilisées pour caractériser les problèmes géoécologiques des territoires dans des conditions d’intensité d’activités industrielles. Dans les pays occidentaux, les méthodes permettant d'estimer l'impact des facteurs ambiants sur la géosphère et la santé humaine sont répandues, parmi lesquelles l'évaluation des impacts du cycle de vie (ÉICV). Cependant, ces méthodes ne sont toujours pas appliquées en combinaison. L’utilisation d’indicateurs efficaces reflétant l'intensité de l'impact anthropique sur les écosystèmes; d’une cartographie de la distribution des polluants, ainsi que l'utilisation a posteriori de ces résultats dans l'évaluation des impacts sur l'environnement et la prédiction de leurs effets négatifs des entreprises industrielles (toxicité humaine et l'écotoxicité) sont pertinents pour l'évaluation complète des écosystèmes urbains. Cette méthode intégrée a été proposée et mise en œuvre sur le territoire d’Ust-Kamenogorsk, l'une des villes ayant subie des transformations technogéniques significatives au Kazakhstan avec un ensemble spécifique d’entreprises / With widespread urbanization and industrial development, the composition of the Earth's geosphere shells has changed, increasing the number of geoecological problems of territories and negatively affecting human health. Currently, more attention is being paid to monitoring the state of the components of urban natural environments. In Russia, biogeochemical methods (e.g. applying tree leaves as a kind of natural receptor of pollution) are widely used to characterize the geoecological problems of the territories under the pressure of intensive industrial activities. In Western countries, methods allowing us to estimate the impact of ambient factors on ecosystems and human health have become widespread; life cycle impact assessment is among them. However, these methods still have not been applied in combination. Therefore, the implementation of a comprehensive assessment of urban ecosystems using indicators reflecting the intensity of anthropogenic impact on ecosystems, following mapping of pollutant distributions, as well as the subsequent use of the results in the evaluation of the industrial enterprises' impact on the environment and in the prediction of the negative effects of pollution (human toxicity and ecotoxicity) are relevant. Such integrated method combining two methodologies was suggested and implemented in the territory of Ust-Kamenogorsk city, one of the significantly technogenic transformed cities in Kazakhstan with a specific set of enterprises
46

Trace Elemental Analysis of Ashes in the Combustion of the Binder Enhanced d-RDF by Inductively Coupled Plasma Atomic Emission Spectroscopy

Tai, Chia-Hui 11 1900 (has links)
Incineration is an attractive solution to the problems of disposing of municipal solid wastes and supplying energy. Because up to 25 percent of the waste in refuse-derived-fuel systems is ash, the physical and chemical characteristics of ash become more and more important for its potential impacts and methods suitable for their disposal. Trace elements concentration in ash is of great interest because of its relationship to regulatory criteria under the Resource Conservation and Recovery Act (RCRA) regarding toxicity and hazards. The applications of a microwave oven sample dissolution method has been tested on a variety of standard reference materials, with reproducible and accurate results. Fourteen trace elements, As, Ba, Be, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, Tl, V, and Zn, from the dissolved ash samples were determined by inductively coupled plasma atomic emission spectrometry.
47

Análise de elementos traço presentes em tecidos mamários canino através da técnica de fluorescência de raios X / Analysis of trace elements present in canine breast tissue by fluorescence X-ray technique

Cozer, Thamara Cristina 30 March 2016 (has links)
CAPES / Estudos realizados com cães apontam que dos grupos tumorais analisados, os de mama representam cerca de 25% a 50% dos tipos de tumores. Deste total, metade é considerado maligno. Apesar de representar um valor considerável de malignidade, estudos nesta área são poucos representativos e escassos na literatura. É de conhecimento que os tumores são causados por mudanças químicas e bioquímicas que ocorrem na célula. Atualmente, pesquisas são realizadas para entender o comportamento dessas alterações e por este motivo é de grande valia conhecer os elementos traço presentes nestes tecidos. Para esta finalidade a técnica mais empregada é a de ED-XRF (Fluorescência de Raios X de Dispersão de Energia), uma vez que é uma técnica analítica não destrutiva que permite determinar e quantificar a composição elementar das amostras, porém não identifica elementos com baixos números atômicos (menor que Z=10). Foram analisadas 56 amostras de tecido mamário canino benignas e malignas, fixadas em formalina a 10% tamponada e mantida à temperatura ambiente. Primeiramente para a quantificação dos elementos traço Ca, Fe, Cu e Zn foram determinadas as curvas de calibração de padrões diluídos em água, com concentrações de Ca, Fe, Cu e Zn, variando de 400 mg/kg a 35 mg/kg, de 20 mg/kg a 2 mg/kg, de 10 mg/kg a 1 mg/kg e de 100 mg/kg a 9 mg/kg, respectivamente. As medições foram submetidas à técnica de ED-XRF utilizando um tubo de raios X com ânodo de prata e técnica de exposição de 30 kV e 100uA e um tempo de exposição de 1000 segundos (incerteza ≤ 3%). O código XRMC (X-Ray Monte Carlo) foi utilizado para validação do método experimental, que tem o objetivo de simular computacionalmente as respostas esperadas para os ensaios experimentais validando assim a eficácia da metodologia. As concentrações dos elementos traço obtidas foram analisadas estatisticamente onde verificou-se uma variação significativa do elemento Zn, estando este presente em maior concentração no tecido mamário maligno do que no benigno. Este resultado pode estar relacionado à presença deste elemento nas matrizes de metaloproteinases, e em neoplasias malignas estão mais concentradas porque há característica de invasão tumoral neste tipo de neoplasia. Em outra comparação estatística pode-se verificar que os elementos traços Fe, Cu e Zn tem concentração equivalente tanto na região central do tumor tanto quanto na periferia, com exceção do Ca, este concentrando-se mais na região tumoral o que pode se dever às calcificações. Estudos nessa área são de grande potencial por permitir um melhor entendimento do processo patológico em tumores mamários caninos. / Studies with dogs show that the breast cancer represent about 25% to 50% of tumor types. Of this total, half is considered malignant. Despite representing a considerable amount of malignancy, studies in this area are few representative and scarce in the literature. It is known that tumors are caused by chemical and biochemical changes that occur in the cell. Currently, surveys are conducted to understand the behavior of these changes and for this reason, it is of great value to know the trace elements present in these tissues. For this purpose, the most common technique is to ED-XRF (X-Ray Fluorescence Energy Dispersion) since it is a non-destructive analytical technique to determine and quantify the elemental composition of the samples, although it doesn’t identify elements with low atomic numbers (less than Z= 10). Were analyzed 56 samples of canine breast tissue benign and malignant, fixed in 10% buffered formalin and kept at ambient temperature. First, for the measurement of trace elements Ca, Fe, Cu and Zn were determined standards for calibration curves diluted in water to concentrations of Ca, Fe, Cu and Zn, ranging from 400 mg/kg to 35 mg/kg, from 20 mg/kg to 2 mg/kg, from 10 mg/kg to 1 mg/kg and from 100 mg/kg to 9 mg/kg, respectively. Measurements were subjected to ED-XRF technique using an X-ray tube with silver anode and exposure technique of 30 kV and 100 uA and exposure time of 1000 seconds (uncertainty ≤ 3%). The XRMC code (X-Ray Monte Carlo) was used for validation of experimental method, which is intended to simulate by computer the expected responses for experimental tests, therefore validating the methodology efficiency. The concentrations of trace elements obtained were analyzed statistically where there was a significant variation of Zn element, the latter being present in higher concentration in malignant breast tissue than benign. This result may be related to the presence of this element in the matrix metalloproteinases, and malignant neoplasms are more concentrated because there are characteristic of tumor invasion in this type of neoplasm. In another statistical comparison it can be seen that the trace elements Fe, Cu and Zn is equivalent concentration both in the central region of the tumor as well as in the periphery, with the exception of Ca, this focusing more on the tumor region may be due to calcifications. Studies in this area are of great potential for allowing a better understanding of the disease process in canine mammary tumors.

Page generated in 0.2085 seconds