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  • 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

Avaliação da biodegradabilidade e toxicidade de fluidos dielétricos de transformadores em solo e meio aquático / Evaluation of the biodegradability and toxicity of transformer dielectric fluids in soil and aquatic environment

Sanderson, Karina 13 December 2017 (has links)
Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2018-04-26T18:38:37Z No. of bitstreams: 1 Karina_Sanderson_2017.pdf: 3684654 bytes, checksum: 61d1f7f0f704e49f62966d42bae3ceae (MD5) / Made available in DSpace on 2018-04-26T18:38:37Z (GMT). No. of bitstreams: 1 Karina_Sanderson_2017.pdf: 3684654 bytes, checksum: 61d1f7f0f704e49f62966d42bae3ceae (MD5) Previous issue date: 2017-12-13 / Power distribution companies constantly contaminate the environment with dielectric fluids due to power transformer failures and leaks. In this way, these fluids should be studied, as they may entail the vulnerability of the fauna and flora. In this sense, the objective of this work was to investigate the deleterious effects of vegetal and mineral dielectric fluids, through biodegradability, acute toxicity, chemical attributes and soil degradation (oils and greases) tests as well as soybean phytotechnical characteristics evaluation. In the tests of the immediate biodegradability, vegetal dielectric fluids of crambe, W3, W6 and W9 and one based on mineral oil (Lubrax) were studied. For the acute toxicity tests with Danio rerio and Artemia salina and the soil toxicity tests using soybean (Glycine max L.), the W3 and Lubrax dielectric fluid were used. The biodegradability analysis was evaluated by the action of microorganisms that transformed the sample into CO2, being measured by titulometry. For the acute toxicity studies, two distinct experiments were performed, where the organisms were exposed to different concentrations of the W3 and Lubrax dielectric fluids and to the FSA of the fluids. The FSA of W3 and Lubrax used in the Danio rerio assay were subjected to gas chromatography analysis. The acute toxicity tests with Danio rerio and Artemia salina were carried out in order to know the approximate range of fluid toxicity, taking into account the lower dilution that caused lethality in 50% of organisms (LC50). The soil chemical attributes analyzed were: pH, P, K, Ca, Mg, CTC and V. The content of oils and greases of the dielectric fluids was quantified by the Soxhlet type extraction method. For the phytothecnical evaluations, emergence, plant height, stem diameter, root length, root dry matter, number of pods and grains, and the mass of one thousand grains were analyzed. Vegetable dielectric fluids are biodegradable over a period of 14 days, while mineral oil is difficult to biodegrade. In the acute toxicity study, W3 had a lower LC50 than Lubrax, causing higher mortality in the organisms. The LC50 for the Danio rerio was 2.46 gL-1 (Lubrax) and 0.318 gL-1 (W3). For Artemia salina the LC50 was 4.63 gL-1 (Lubrax) and 0.641 gL-1 (W3). In relation to the FSA tests, the Lubrax one caused a greater toxic effect on the organisms, while the W3 had no toxic effect on 50% of organisms. The LC50 values for Lubrax were 4.89% for the Danio rerio and 7.67% for Artemia salina. Chromatographic analysis of FSA of the fluids was not conclusive, it only suggests that the toxicity may be related to the solubility of all the substances present in Lubrax and not only to the solubility of n-alkanes. The chemical attributes of the soil did not change significantly, only the carbon presented increasing variation in relation to the concentrations of the fluids. There was a reduction of the TOG during the agricultural years and the soils in the presence of W3 presented greater degradation than those with Lubrax. The increase in the concentration of the dielectric fluids caused a reduction in the phytotechnical characteristics of the soybean. Plants from soil contaminated with W3 showed better development compared to plants that were in soil contaminated with Lubrax. / As concessionárias de energia, constantemente, contaminam o meio ambiente com fluidos dielétricos, devido a falhas e vazamentos de transformadores de potência. Desta forma, estes fluidos devem ser estudados, pois podem pode implicar na vulnerabilidade da fauna e da flora. Neste sentido, este trabalho teve como objetivo investigar os efeitos deletérios do fluido dielétrico vegetal e mineral, através de ensaios de biodegradabilidade, toxicidade aguda, ensaios dos atributos químicos e degradação (óleos e graxas) do solo e das avalições das características fitotécnicas da soja. Nos ensaios da biodegradabilidade imediata foram estudados os fluidos dielétricos vegetais de crambe, W3, W6 e W9 e um à base de óleo mineral (Lubrax). Para os ensaios de toxicidade aguda com Danio rerio e Artemia salina e para os ensaios de toxicidade em solo utilizando a soja (Glycine max L.), foram usados o fluido dielétrico W3 e o Lubrax. A análise da biodegradabilidade foi avaliada pela ação de microrganismos que transformaram a amostra em CO2, sendo medido por titulometria. Para os estudos da toxicidade aguda foram realizados dois experimentos distintos, onde os organismos foram expostos às diferentes concentrações de fluido dielétrico W3 e Lubrax e onde foram expostos à FSA dos fluidos. A FSA do W3 e Lubrax utilizado no ensaio com o Danio rerio foram submetida a análise de cromatografia gasosa. Os ensaios de toxicidade aguda com o Danio rerio e a Artemia salina foram realizados com o intuito de se conhecer a faixa aproximada de toxicidade dos fluidos, levando em consideração a menor diluição que causou letalidade em 50% dos organismos (CL50). As análises dos atributos químicos do solo foram: pH, P, K, Ca, Mg, CTC e V. O teor de óleos e graxas dos fluidos dielétricos foi quantificado pelo método de extração em aparelho tipo Soxhlet. Para as avaliações fitotécnicas da soja analisou-se a emergência, altura de planta, diâmetro do caule, comprimento radicular, matéria seca radicular, número de vagens e de grãos e a massa de mil grãos. Os fluidos dielétricos vegetais são biodegradáveis num período de 14 dias, enquanto o óleo mineral é difícil de ser biodegradado. No estudo da toxicidade aguda o W3 apresentou uma CL50 menor do que o Lubrax, causando maior mortalidade nos organismos. A CL50 para o Danio rerio foi de 2,46 gL-1 (Lubrax) e de 0,318 gL-1 (W3). Para a Artemia salina a CL50 foi de 4,63 gL-1 (Lubrax) e 0,641 gL-1 (W3). Em relação aos ensaios com a FSA, o Lubrax causou maior efeito tóxico aos organismos. O W3 não apresentou efeito tóxico a 50% dos organismos. Os valores da CL50 para o Lubrax foi de 4,89% para o Danio rerio e 7,67% Artemia salina. A análise cromatográfica da FSA dos fluidos não foi conclusiva, apenas sugere que a toxicidade pode estar relacionada com a solubilidade de todas as substâncias presentes no Lubrax e não apenas com a solubilidade dos n-alcanos. Os atributos químicos do solo não sofreram alterações significativas, apenas o carbono apresentou variação crescente em relação às concentrações dos fluidos. Houve redução do TOG durante os anos agrícolas e os solos em presença do W3 apresentaram maior degradação do que os em solos com Lubrax. O aumento da concentração dos fluidos dielétricos ocasionou redução nas características fitotécnicas da soja. As plantas em solo contaminadas com W3 apresentaram melhor desenvolvimento em relação às plantas que estavam no solo contaminado com Lubrax.
42

Uso de resíduo da extração de celulose e o impacto em solo de cerrado cultivado com eucalipto e espécie arbórea nativa /

Arruda, Otton Garcia de. January 2012 (has links)
Orientador: Marlene Cristina Alves / Banca: Francisco Maximino Fernandes / Banca: Rafael Montanari / Resumo: Com a produção de papel e celulose as indústrias do setor têm gerado diariamente grandes quantidades de resíduos sólidos e efluentes, constituindo-se em uma grande preocupação ambiental e econômica. No intuito de retornar com estes subprodutos de forma sustentável à natureza, esse trabalho teve como objetivo testar a eficácia de um resíduo orgânico advindo da indústria de papel e celulose quanto a sua influência sobre os atributos químicos e físicos do solo e desenvolvimento de plantas arbóreas. O experimento foi implantado em um Latossolo Vermelho distrófico no município de Selvíria, MS. O delineamento experimental foi em blocos ao acaso, onde se avaliou o clone Eucalyptus spp. e a espécie nativa Mabea fistulifera com cinco tratamentos: sem adubação (controle), adubação mineral, 10 t ha -1, 15 t ha-1 e 20 t ha-1 do resíduo celulósico. Nas camadas de solo de 0-0,05; 0,05-0,10; 0,10-0,20 e 0,20-0,40 m avaliaram-se os atributos químicos: MO, pH, P, K, Ca, Mg, H + Al, Al e calculou-se a SB, CTC e V%; e os atributos físicos: macroporosidade, microporosidade, porosidade total, densidade do solo, estabilidade de agregados em água, resistência do solo à penetração e infiltração de água. Para as características dendrométricas das plantas foram avaliados: altura média de plantas, diâmetro do caule na superfície do solo (DSS) e diâmetro médio das copas (DMC) trimensalmente, até os 21 meses. Para a cultura do eucalipto, também foram determinados o diâmetro a altura do peito (DAP), o volume de madeira e o incremento médio anual do volume de madeira aos 21 meses. Os resultados foram analisados aplicando-se a comparação entre médias, contrastes e análise de regressão. Concluiu-se que o uso de resíduo celulósico influenciou os atributos do solo estudado, principalmente nas camadas superficiais do solo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: A large amount of solid waste and effluents have been daily generated by industries due to the cellulose and paper production, becoming a major environmental and economic concern. In order to return with these by-products in a sustainable way to nature, the aim of this study was to test the effectiveness of an organic waste from cellulose and paper industry as its influence on soil chemical attributes and development of eucalyptus plants. The experiment was implanted in an Oxisol in the city of Selvíria, MS, Brazil. A randomized block design was used, which evaluated Eucalyptus spp. and and the native species Mabea fistulifera with five treatments: no fertilization (control), mineral fertilizers, 10 t ha -1, 15 t ha-1 and 20 t ha-1 of cellulosic residue. In the soil layers of 0-0,05; 0,05-0,10; 0,10 - 0,20 and 0,20 - 0,40 m, were evaluated: organic matter, pH, P, K, Ca, Mg, H+AL, Al and calculated the sum of bases, CEC and base saturation, and physical attributes: macroporosity, microporosity, total porosity, bulk density, aggregate stability in water, soil resistance to penetration and water infiltration. For the plants dendrometric characteristics were evaluated: plant height, stem diameter at the soil surface and diameter of the crown quarterly, up to 21 months. For the cultivation of eucalyptus the diameter at breast height, the volume of wood and the average of the annual increment of timber volume were also determined. The results were analyzed by comparison of means, contrasts and regression analysis. In conclusion, the use of cellulosic waste influence the soil characteristics studied mainly in the surface layers of soil (0-0,10 m), negatively macroporosity and infiltration of water to the cultivation of eucalyptus and stabilit y of aggregates M. fistulifera. For the chemical increased the contents of Ca, Mg, SB and CEC of the soil for eucalyptus... (Complete abstract click electronic acces / Mestre
43

Soil health as influenced by the integration of cover crops and poultry litter in north-central Mississippi

Kovvuri, Nikitha Reddy 08 August 2023 (has links) (PDF)
Soil health-based agricultural management practices are widely promoted to improve soil structure, infiltration and reduce erosion. This study was conducted at two locations in North-Central Mississippi to evaluate the influence of different cover crop species and poultry litter on soil health that can impact crop production, climate change, and resilience. The results indicated that the cover crops showed a little effect on some soil health indicators compared to control treatment. However, in one location, rye, and a mixture of cover crops decreased bulk density and increased available water content and organic matter. The poultry litter had a positive effect on most soil physical and chemical health indicators. The cover crop species at Pontotoc decreased bulk density, increased field capacity, CEC, and total carbon. However, there was no significant effect of cover crops on most soil chemical health indicators, and soil responses may take more than five years for the changes to appear.
44

Sulfuric Acid: Its Potential for Improving Irrigation Water Quality

Bohn, H. L., Westerman, R. L. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / The 2 major environmental problems of Arizona and the southwest are the alkalinization of soil and water by irrigation and air pollution from copper smelting. It is proposed that the amelioration of both problems may be solved through a common process. This is the production of sulfuric acid from sulfur dioxide, which is the main pollutant of smelter effluent gases. The conversion process is cheap and easy, and the sulfuric acid could then be added to irrigation waters to increase the solubility of CA carbonate in the soil, thereby decreasing alkalinity. Lower alkalinity results in increased soil permeability and increased water use efficiency by plants. The potential market for sulfuric acid in irrigation was calculated, on the basis of neutralizing 90% of the bicarbonate ion concentration in Colorado River water and Arizona well water, to be about 1.6 million tons annually, representing about 1/3 of the sulfur now dissipated by smelters as air pollution. This market includes both the Imperial Valley of California and the Mexicali Valley of Mexico, both of which are currently experiencing mounting salinity problems. Salinity itself is not amenable to this treatment, but the cumulative increase in NA and bicarbonate may be slowed and reversed, leading to gradual soil stabilization.
45

Effects of Fire on Water Infiltration Rates in a Ponderosa Pine Stand

Zwolinski, Malcolm J. 23 April 1971 (has links)
From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / The importance of pine forest as a timber and water producing area has led to intensive management, including protection from wildfire. This has resulted in dense stand growth with increased destructive fire potential and transpirational water loss. In Arizona, as in many areas, prescribed forest burning has been used to effectively reduce these fuel hazards. Some question has arisen about the possible side effects of such treatments, particularly air pollution and reduction of infiltration and water yield. In an effort to determine the effects on infiltration, plots receiving various treatments (control, light burn, heavy burn) were fitted with fusion pyrometers before burning, to measure soil surface temperatures during burning. After burning, infiltrometers were installed. Surface temperatures did not exceed 200 degrees f. For the light burns, and ranged over 350-500 degrees f. During heavy burns. Both heavy and light burns produced highly significant decreases in infiltration capacities after burning and the surface 2 inches showed increases in soil pH, carbon and total nitrogen percentages. Infiltration capacities returned to normal after overwintering and were attributed to frost action on soil texture and porosity. The soil chemical changes decreased slowly over 2 years. Soil water repellency also increased and the significance of this is discussed.
46

Role of Composition, Structure and Physico-Chemical Environment on Stabilisation of Kuttanad Soil

Suganya, K January 2013 (has links) (PDF)
Soft soil deposits of coastal regions and lowland areas pose many geotechnical problems but it is indispensable to utilize these grounds to meet the growing demand for infrastructure with ever increasing urbanization and industrial development. Soft soils are generally associated with high compressibility and low strength characteristics which augment the risk of huge settlements and foundation failure. It is essential to understand the complex behaviour of the ground consisting of soft clays as construction and maintenance of infrastructure in these areas is challenging. Marine sediments mostly possess open microstructure irrespective of the differences in their mineral composition and sedimentation environment. Also this particular microstructure in marine sediments is generally accompanied by the presence of a great amount of organic residues and fragments of marine organisms. Formation of pyrite is also possible because of the presence of decomposable organic matter, dissolved sulfate and reactive iron minerals. These soils due to their inherent mineralogy and microstructure have high void ratios and consequently high water holding capacity which explains the reason for their low shear strength and high compressibility characteristics. And often the formation environment is conducive for incorporation of organic content in the soft clay deposits which further aggravates the problem. A complete characterization of the soil can enhance the understanding of soil behavior and therefore can play a crucial role in suggesting suitable and sustainable ground improvement method. Soft clay deposits of Kuttanad area in Kerala, India extending to varying depths below the ground level, present a challenge as a foundation soil due to low bearing capacity and high settlement. Geologically Kuttanad is considered as a recent sedimentary formation. In the geological past, the entire area was a part of the Arabian Sea. Presently Kuttanad area covers an area of about 1,100 km2. Many intriguing reports of distresses to structures founded on this soil are available. An over view of specific characteristics of soft clays along with the comprehensive description of soft clays from various parts of the world is presented in the introductory Chapter. Deep soil mixing and mass stabilization methods are found to be relatively advantageous in reducing differential settlements and in achieving expeditious construction. A more detailed review of literature on Kuttanad soil problems and various ground improvement methods adopted are presented. The different ground improvement techniques attempted are soil reinforcement, stone columns, preloading etc. Soil mixing can be relatively advantageous over the other conventional ground improvement methods. Laboratory studies carried out earlier with different binders such as cement, lime and lime fly ash combinations did not exhibit appreciable improvement in soil strength. It is reasoned that the lack of understanding of the soil characteristics is responsible for the limited success of these attempts. Based on the review of literature the detailed scope of the work is presented at the end of Chapter 1. The method of collection of the soil from Kuttanad region, methods adopted for characterization of soil, characteristics of various binders used and testing procedures adopted for assessing the geotechnical behavior with and without binders are described in Chapter 2. In order to characterize the soil for understanding its behaviour under different conditions as well as to gauge its response to different stabilizers, a detailed physico¬chemical, mineralogical, morphological and fabric studies are carried out and presented in Chapter 3. An attempt has been made to explain the role of components of soils such as organic substances, pyrite and sesquioxides for variations in its properties with change in water content. The high water holding capacity of the soil reflected in its Liquid limit along with relatively low plasticity characteristics of the soil has been explained as due to the presence of minerals such as metahalloysite and gibbsite, the flocculated fabric, porous organic matter and water filled diatom frustules (amorphous silica). Based on the study conducted on the plasticity characteristics of Kuttanad soil under different conditions of drying and treatment, it was brought about that the organic content plays a dominant role in particle cementation and aggregation causing a substantial reduction in plasticity upon drying. Further, the presence of minerals such as pyrite and iron oxides also account for the plasticity changes. The significant changes in soil properties upon drying have also been successfully explained in Chapter 4. Attempts made to stabilize the soil using conventional chemical stabilizers are described in Chapter 5. The effect of binders on the strength improvement of soil has been explained based on the changes occurring in the composition, fabric and physico-chemical characteristics of soil upon addition of the binders. Lack of strength development in soil with lime has been attributed to the inherent composition of the soil hindering the formation of pozzolanic compounds and unfavourable modification of the fabric. On the other hand the soil responded well to cement stabilisation. The influence of various parameters such as Water/Cement (W/C) ratio, Initial water content, curing period and additive dosage on the strength development of cement treated soil has been examined. Cement improved the strength of the soil by binding the soil particles without depending on the interaction with the soil. It was observed that the role of initial water content is insignificant and the strength improved with reducing W/C ratio. The dependence of strength development with cement addition on the fabric at different W/C ratios has been assessed. Also the role of other additives such as Lime, Sand, Fly Ash, Ground granulated blast furnace slag, Silica fume and Sodium silicate to enhance the strength of cement treated soil has been analysed in Chapter 5. It was shown that only Sodium Silicate (NS) along with cement meets with good success. The studies on the undrained shear strength and compressibility characteristics of cemented soil carried out to understand the strength and deformation behaviour of the cemented soil are presented in Chapter 6. It is clear from the compressibility characteristics of the cemented soil that there is a well defined yield stress demarcating the least compressible pre-yield zone and more compressible post yield zone. Generally the yield stress increases with reducing water cement ratio. It is interesting to note that the post yield compressibility of the cemented soil is controlled more by the fabric of soil than by cementation effect. The study on the undrained shear behavior of cemented soil revealed that the cohesion intercept and angle of internal friction increases with addition of cement. However the impact of cementation is reflected more as increase in cohesion intercept with increasing cement content. The uniqueness of failure envelope observed for the cemented soil irrespective of whether the confining stress is above or below the yield stress has been explained in detail. A case study on the performance of embankment founded on Kuttand soil improved with Deep mixed cement columns (DMCC) has been evaluated through numerical simulations using FLAC 2D and this forms the subject matter of Chapter 7. For this work the soil properties of the Kuttanad soil determined by experimental investigations have been used. The simulation results showed that the introduction of DMCC columns improved the factor of safety against failure and reduced settlements. This study clearly endorses the analysis and the results of the test carried out on Kuttanad soil. The final chapter summarizes the details of the work carried out which brings out the importance of characterization of the soil in terms of soil components, physico-chemical environment as well as the micro structure of the soil in predicting the behaviour of the soil in changing environment and to understand the stabilization response of the soil with different binders which intern helps to select appropriate binder and or binder combinations.
47

Impact of topsoil depth and amendment application on soil health and agronomic productivity in central Ohio

Moonilall, Nall Inshan January 2022 (has links)
No description available.
48

Moisture effects on visible near-infrared and mid-infrared soil spectra and strategies to mitigate the impact for predictive modeling

Silva, Francis Hettige Chamika Anuradha 08 December 2023 (has links) (PDF)
Instrumental disparities and soil moisture are two of the key limitations in implementing spectroscopic techniques in the field. This study sought to address these challenges through two objectives. The first objective was to assess Visible-near infrared (VisNIR) and mid-infrared (MIR) spectroscopic approaches and explore the feasibility of transferring calibration models between laboratory and portable spectrometers. The second objective addressed the challenge of soil moisture and its impact on spectra. The portable spectrometers demonstrated comparable performance to their laboratory-based counterparts in both regions. Spiking with extra-weight, was the most effective calibration transfer method eliminating disparities between instruments. The samples were rewetted under nine controlled conditions for the moisture study. Results showed that spiking with extra weights significantly outperformed other techniques and model enhancement was insensitive to the moisture contents. Findings of this study will be helpful for development and deployment of in situ sensors to enable field implementation of spectroscopy.

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