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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.
271

Produção, perda e ganho de calor em caprinos no ambiente tropical: um estudo do equilibrio térmico associado à emissão de CH4 / Heat production, gain and heat loss in goats in a tropical enviroment: study of thermal balance

Fonsêca Filho, Valdir Martins da 26 February 2015 (has links)
Made available in DSpace on 2016-08-15T20:27:57Z (GMT). No. of bitstreams: 1 ValdirMFF_TESE.pdf: 1925544 bytes, checksum: 2c6adf20cb05d72a5da15ba8f9a6a638 (MD5) Previous issue date: 2015-02-26 / To study the thermal balance associated to methane emission in goats in a tropical environment, it was used nine Anglo Nubian females weighing in average 53.89 kg. The animals were observed during nine consecutive days from 08:00 to 17:00. An indirect open calorimetry system was used with a facial mask adjusted on the animal s muzzle and the volume of O2, CO2, CH4 and water vapor in the inspired and expired air were determined as well as the respiratory rate, respiratory volume and the temperature of expired air. Several parameters were also collected such as rectal temperature, body surface and hair coat temperature, air temperature and humidity and black globe temperature. The results showed that when the air temperature was below 26 °C the heat exchange for long-wave radiation and convection were effective to maintain the thermal equilibrium of the animals, since respiratory rate, respiratory volume, rectal temperature and metabolic heat production parameters did not change. When the air temperature increased to 28 °C, there was a slight change in physiological responses. When air temperature was higher then 30°C the variation in the physiological parameters was significant. These results demonstrated that the thermal balance in Anglo Nubian goats protected from direct solar radiation for an air temperature between 20 and 25 °C is maintained primarily by the sensible heat loss and when these temperature reaches values higher then 30 °C can only be maintained by latent heat loss for a cost of significant changes in respiratory rate and volume, hence thermal comfort zone was varying from 20 to 27 °C. In this environment, methane emission from enteric fermentation was in average 8.41 kg year-1 animal-1. There was no significant correlation between the methane emission and with physiological and environmental parameters but with individual characteristics of each animal, such as body weight / Com objetivo estudar o equilíbrio térmico associado à emissão de CH4 em caprinos em ambiente tropical, o presente trabalho utilizou nove fêmeas da raça Anglo Nubiano com peso corporal médio de 53,89 kg, que foram observadas durante nove dias consecutivos entre às 08:00 até 17:00 horas. Um sistema de calorimetria indireta aberta com auxílio de máscara facial ajustada ao focinho dos animais foi utilizado para determinar o volume de O2, CO2, CH4 e H2O (vapor) no ar inspirado e expirado. Simultaneamente a esses volumes também foram determinados nos animais à frequência e volume respiratório, além das temperaturas do ar expirado, retal, superfície da pele e pelame, enquanto no ambiente foram determinados a temperatura do ar e umidade, além da temperatura do globo negro. Os resultados mostraram para uma temperatura do ar inferior a 26°C as trocas de calor por radiação de ondas longas e convecção foram eficazes para manter o equilíbrio térmico dos animais, pois frequencia respiratória e volume respiratório, além da temperatura retal e produção de calor metabólico não se alteraram, mas quando a temperatura do ar passou de 28 °C, ocorreu uma leve alteração nas respostas fisiológicas e acima 30 °C essa alteração foi bem significativa. Esses resultados demonstraram que o equilíbrio térmico dos caprinos da raça Anglo Nubiano protegidos da radiação solar direta para uma faixa de temperatura do ar entre 20 a 25 °C é mantido basicamente pela perda de calor sensível e, após 30 °C, somente pode ser conseguido via perda de calor latente à custa de alterações significativas na frequência e volume respiratório, consequentemente sua faixa de zona de conforto térmico estaria variando entre 20 a 27 °C aproximadamente quando manejados protegidos da radiação solar. Nestas condições sua emissão de CH4 é da ordem de cerca de 8,41 kg ano-1 animal-1, sendo essa emissão não correlacionada de forma significativa com as variáveis fisiológicas e ambientais avaliadas e sim com características individuais de cada animal, como seu peso corporal
272

Pěstování ječmene jarního v konvenčním a ekologickém systému hospodaření - ochrana rostlin a emise skleníkových plynů / Barley growing in conventional and organic farming system - plant protection methods and greenhouse gases emissions

BÍNA, Martin January 2017 (has links)
The aim of this diploma thesis was an evaluation of the environmental aspects of growing of the chosen feeding varieties of a spring barley in various systems of farming. Further purpose of this diploma thesis was a quantification of an emission load bond with the unit of area, and the unit of yield of spring barley, in the scope of conventional and ecological system of farming. The part of this study was a formation of the literature survey about problems of the conventional and ecological growing of the spring barley, with the focus on the agrotechnical requirements and environmental aspects. The practical part was performed in the area of the Faculty of Agriculture in Czech Budejovice.
273

Carbon and water footprint for a soft drink manufacturer in South Africa

Wessels, Maria Magdalena 11 1900 (has links)
The aim of this study was to determine a carbon and water footprint for a beverage manufacturing company. The carbon footprint etermination was conducted on Scope 1 and Scope 2. The water footprint was determined on the blue water and grey water. The beverage production volumes of the beverage manufacturing company were used to determine both the carbon and the water footprint. The theoretical background to this study was based on both local and international beverage companies and the outcome for the carbon and water footprint was benchmarked against the local and international companies. The objectives of this study were achieved by calculating a carbon and water footprint for the beverage company. The carbon footprint unit of measure is g CO2e / litre produced and the water footprint is litre water/litre produced. The unit of measure for pollutant grey water footprint is measured in milligram. Based on the results achieved in this study, commendations for carbon and water footprint reductions were made to the beverage company. Reduction targets for production year 2020 were also recommended based on the implementation of the reduction plans. / Environmental Sciences / M. Sc. (Environmental Management)
274

Emissões de metano e consumo de forragem por ovinos em sistema de integração lavoura-pecuária : efeito do método de pastoreio e da intensidade de pastejo / Methane emissions and forage intake by sheep on integrated croplivestock system: effect of stocking method and grazing intensity

Savian, Jean Victor January 2013 (has links)
Objetivou-se avaliar como diferentes estratégias de manejo do pasto de azevém anual interferem na produção animal, no consumo de forragem e na emissão de metano por ovinos em sistema de integração lavoura-pecuária (SILP) (Capítulo II). Já no Capítulo III objetivou-se avaliar as técnicas dos nalcanos e do nitrogênio fecal na estimativa do consumo de forragem por ovinos em pastos de azevém anual. Os experimentos foram conduzidos nos anos de 2011 e 2012 na Estação Experimental da UFRGS. Foram utilizados ovinos em um SILP de soja e milho no verão, em rotação com azevém anual no inverno. Para ambos os Capítulos (II e III) foram estudados dois métodos de pastoreio (contínuo e rotativo) e duas intensidades de pastejo (moderada e baixa; 2,5 e 5 vezes o potencial de consumo de matéria seca, respectivamente) em um delineamento de blocos casualizados com 3 repetições. Para o Capítulo II, no primeiro experimento os animais experimentais eram cordeiros, enquanto no segundo foram ovelhas em lactação. Os resultados indicaram que o ganho médio diário (GMD) dos cordeiros foi maior (P<0,05) no método de pastoreio continuo que no método de pastoreio rotativo, independente da intensidade de pastejo. O ganho de peso vivo por área (GPV) apresentou a mesma resposta em ambos os experimentos, com maior GPV na intensidade de pastejo moderada (P<0,05). No experimento 1, o consumo de matéria seca (CMS) foi maior para o método de pastoreio continuo, enquanto no experimento 2 não houve diferenças entre métodos e intensidades. As emissões de CH4 diárias por animal não diferiram entre tratamentos em ambos os experimentos (P>0,05), porém, quando expressas em g CH4 kg GPV-1 as emissões foram em média 15,33% maiores (P<0.05) para o método de pastoreio rotativo, independente da intensidade de pastejo. Os resultados afirmam que as emissões de metano por animal não são afetadas pelos tratamentos impostos. Porém, do ponto de vista de sistema o método de pastoreio contínuo o mais eficiente, por apresentar menor emissão de metano por kg de ganho de peso vivo, independente da intensidade de pastejo. Para o Capítulo III, foram utilizados apenas cordeiros. Utilizou-se a metodologia dos n-alcanos e do nitrogênio fecal, por meio de coleta total de fezes com o auxílio de bolsas coletoras. Na avaliação entre os n-alcanos, verificou-se melhores resultados quando utilizando o par C31:C32. Para a metodologia do nitrogênio fecal, as equações propostas por Wang et al. (2009) e por Azevedo (2011) foram as melhores (P<0,05). A técnica do nitrogênio fecal mostrou-se mais acurado do que o uso dos n-alcanos, que superestimou os valores de consumo. / The aim of this study was to evaluate how different management strategies of Italian ryegrass affects animal production, forage intake and methane emissions by sheep in integrated crop-livestock system (ICLS) (Chapter II). In Chapter III, we aimed to evaluate the techniques of n-alkanes and fecal nitrogen in estimating forage intake by sheep grazing on ryegrass. The experiments were conducted in 2011 and 2012 at the UFRGS Experimental Station. The ICLS soybeans and corn crops in summer, in rotation with grazed Italian ryegrass in winter. For both chapters (II and III) two stocking methods (continuous or rotational) and two grazing intensities (moderate and low, 2.5 and 5 times the potential dry matter intake, respectively) were studied in a randomized block design with three replications. In Chapter II, in the first experiment, the experimental animals were lambs, while in the second were lactating ewes. The results indicated that the average daily gain (ADG) of lambs was higher (P<0.05) in the continuous method than in rotational grazing method, regardless of grazing intensity. The live weight gain per area (LWG) showed the same response in both experiments, with higher LWG values in moderate grazing intensity (P<0.05). In experiment I, higher dry matter intake (DMI) values were obtained under continuous grazing, while in experiment II, there no differences between methods and intensities. CH4 emissions per animal and per day did not differ between treatments in both experiments (P>0.05), but when expressed in g CH4 kg-1 LWG emissions were, on average, 15.33% higher (P<0.05) for rotational grazing method, regardless of grazing intensity. Methane emissions per animal were not affected by the treatments applied. However, from system point of view, the continuous grazing method is more efficient, since lower methane emissions per kg of LWG, regardless of grazing intensity, were obtained. In Chapter III, were used only lambs. The methodologies of n-alkanes and fecal nitrogen, were applied through total collection with dung bags. In relation to n-alkanes, better results were obtained when using the pair C31:C32. For the methodology of fecal nitrogen, the equations proposed by Wang et al. (2009) and Azevedo (2011) were the best (P<0.05). The technique of fecal nitrogen proved to be more accurate than the use of n-alkanes, which overestimated the intake.
275

Rotatinuous stocking : an innovation in grazing management based on animal behaviour and implications to pasture production, foraging behaviour, herbage intake and methane emission by grazing sheep

Savian, Jean Victor January 2017 (has links)
The aim of this thesis was to investigate contrasting pasture management strategies on the foraging behaviour, pasture production, carcass characteristics, herbage intake, faecal gas emissions and methane emission by sheep grazing Italian ryegrass (Lolium multiflorum) pastures. The experiment was carried out in 2014 and 2015. The experimental design was a randomized complete block with four replicates and two grazing strategy treatments (traditional rotational stocking method – RT meaning pre- and post-grazing target heights of 25 and 5 cm, respectively and, “rotatinuous stocking” – RN with pre- and post-grazing target heights of 18 and 11 cm, respectively). The grazing management was based on a 1-day strip-grazing regime. Male castrated sheep were used. The actual average sward heights for the RN treatment were 17.9 and 11.1 cm (pre- and post-grazing, respectively) and 27.1 and 7.8 cm for the RT (pre- and post-grazing, respectively). The stocking period in 2014 was 146 and 140 days (RN and RT, respectively) and in 2015 it was 155 and 146 days (RN and RT, respectively). The diurnal animal activities (grazing, ruminating and resting time) did not differ between treatments, with average of 439.6, 166.9 and 85.0 minutes, respectively. The bite rate, feeding station per min and steps per min were greater at the RN than the RT treatment. Grazing time and bite rate were greater in the afternoon than morning in both treatments. Therefore, the daily herbage intake by sheep grazing Italian ryegrass was greater for the RN than the RT treatment (CHAPTER II). The herbage production in the RN was 28% higher than the RT treatment. Individual average daily gain and live weight gain per hectare were greater in the RN than the RT treatment (CHAPTER III). RN treatment presented greater final live weight, carcass and commercial cut weights from grazing sheep than RT treatment (CHAPTER IV). RN treatment had a faecal chemical quality greater than RT treatment, resulting in a greater daily nitrogen excretion per animal and greater faecal CH4 and N2O emissions (CHAPTER VI). The “rotatinuous stocking” (RN) was the better grazing management strategy for mitigation of CH4 emissions by sheep grazing Italian ryegrass, emitting 64% less CH4 per unit area and 170% less CH4 per unit of animal product than the traditional rotational stocking method (RT) (CHAPTER V).
276

Separação de CO2 em gases de combustão : aplicação de membranas e criogenia

Lopez, Diego Ruben Schmeda January 2010 (has links)
Este trabalho tem por objetivo avaliar a viabilidade técnica de processos de separação de gás carbônico em correntes de gases de combustão. Neste sentido, a separação por meio de membranas e por criogenia são avaliadas por meio de simulação de sistemas. As propostas envolvendo membranas avaliam arranjos de membranas em série, os quais são otimizados para condições de maior fluxo permeado e maior beneficio econômico. A corrente de alimentação é de 5 kmol/s e as respectivas frações molares de CO2 e N2 que compõem esta corrente são 0,15 e 0,85. Os resultados obtidos da otimização, para um arranjo de três membranas em série de polyimida de 9000 m² de área superficial, foram uma corrente de permeado de 443,1 mol/s de CO2 a 41,6%, correspondendo a aproximadamente 59% do CO2 da corrente de alimentação. Já com um arranjo de 6 membranas de 9000 m², onde a função objetivo é o maior lucro, foi selecionado o material kapton e a quantidade de CO2 separada é 161,12 mol/s, cuja concentração na mistura é de 79%, e a função objetivo tem um valor de 24.405,30 €/ano. Na outra parte do trabalho, propõe-se e avalia-se um ciclo para o aproveitamento da disponibilidade térmica na regasificação do gás natural líquido, para liquefação de CO2. Obtém-se como resultando em CO2 líquido com fração molar igual a 94%. Este processo consta de uma corrente proveniente da combustão completa de 1 mol/s de metano, contendo 1 mol/s de CO2 e 7,52 mol/s de N2. Esta corrente é comprimida e resfriada até atingir a pressão de 4000 kPa e 25 °C, posteriormente uma membrana enriquece a corrente de gases de combustão, que novamente é comprimida e resfriada até se obter a condensação e separação do CO2. Realiza-se o cálculo de equilíbrio líquido-vapor da mistura utilizando as equações de Peng-Robinson e a regra de mistura de Van der Waals no software VRTherm. A vazão molar do CO2 líquido obtida é de 0,3207 mol/s na concentração declarada. A intensidade energética do processo é de 1,135 kWh/kg de CO2 liquefeito. / The objective of this work is to evaluate the technical feasibility of carbon dioxide separation processes of flue gases streams. In this way, separation processes due membrane and cryogenics are evaluated by system simulation. The systems using membranes evaluates setup of those membranes in series, these setups are optimized for the largest permeate molar flow and the largest economic profit. The feed stream is a 5 kmol/s CO2 – N2 mixture, with molar fraction of 0.15 and 0.85 respectively. The result obtained from the optimization for a setup of three polyimide membranes of 9000 m² is a permeate stream of 443.1 mol/s with CO2 at 41.6%, corresponding to aproximadely 59% of the CO2 contained in the feed stream. When a setup of six 9000 m² membranes is analyzed using an objective function that results in the largest profit, kapton was selected as the material for the membranes. The quantity of CO2 captured is 161.12 mol/s, at 79% of concentration in the mixture, and the objective function has a value of 24,405.30 €/year. The second part of this work, proposes and evaluates a cycle that takes the thermal availability of the regasification of liquid natural gas in advantage for CO2 liquefaction. The product of the cycle is liquid CO2, with a molar fraction of 0.94. The process is fed with a stream that comes from the stoichiometric combustion of 1 mol/s of methane, that stream is composed by 1 mol/s of CO2 and 7.52 mol/s of N2. The stream is then compressed up to the pressure of 4000 kPa and cooled down to 25 °C. After that a membrane concentrates the CO2 in one stream, which is again compressed and cooled down until the condensation of CO2 is achieved. Calculations of liquid – vapor are performed with the Peng- Robinson’s equations and the Van der Waals mixture rule using the software VRTherm. The molar flow rate of liquid CO2 obtained is of 0.3207 mol/s in the concentration mentioned before. The energy intensity of the process is of 1.135 kWh/kg of liquid CO2.
277

Produção de gases de efeito estufa e potencial de geração de créditos de carbono em processos de tratamento de esgoto sanitário

Lima, Aline Pereira 30 May 2012 (has links)
Made available in DSpace on 2016-06-02T20:00:44Z (GMT). No. of bitstreams: 1 4419.pdf: 1291851 bytes, checksum: 50bc34a5591803fda36769de553dd96e (MD5) Previous issue date: 2012-05-30 / Financiadora de Estudos e Projetos / The concept of carbon credits came from the awareness of need to reduce greenhouse gas (GHG) emissions in order to combat the worsening of global warming, discussed and formalized in the Kyoto Protocol. Emission of greenhouse gases as methane, nitrous oxide and carbon dioxide is due to several activities, among them the wastewater treatment, both domestic and industrial. This paper presents an estimation of CH4 and N2O production and energy consumption in wastewater treatment systems most used in Brazil, on which mitigation scenarios were applied to show its representation in terms of carbon credits and monetary value. This work was based on the methodologies and procedures of the Intergovernmental Panel on Climate Change - IPCC. The results show that the largest volumes of GHGs are associated with anaerobic treatments, whose emissions may exceed 200 tCO2e/year. Both suggested mitigation proposals (replacement of anaerobic systems by open aerobic processes or introduction of mechanisms for capturing and burning methane in closed reactors) show a similar emission reduction, mostly between 100 and 150 tCO2e/year for attended population of 1000 persons. However, it was found that the credit potential is in the biogas combustion because aeration demands high energy consumption. This ability to generate carbon credits, from Clean Development Mechanism (CDM), can help soften some of the implementation costs of wastewater treatment plants, as well as stimulate its modernization. / O conceito dos créditos de carbono surgiu a partir da sensibilização para a necessidade de reduzir as emissões de gases de efeito estufa (GEE) a fim de combater o agravamento do aquecimento global, discutido e formalizado no Protocolo de Quioto. A emissão de GEE na forma de metano, óxido nitroso e dióxido de carbono acontece devido a diversas atividades, dentre elas o tratamento de águas residuárias, tanto domésticas quanto industriais. Este trabalho apresenta uma estimativa da produção de CH4 e N2O e do consumo de energia dos sistemas de tratamento de esgoto mais utilizados no Brasil, sobre a qual foram aplicados cenários de mitigação para verificar sua representatividade em termos de créditos de carbono. Isto foi feito a partir de metodologias e procedimentos do Intergovernmental Panel on Climate Change - IPCC. Os resultados revelam que os maiores volumes de GEE estão associados à tratamentos anaeróbios, cujas emissões podem ser superiores a 200 tCO2e/ano. Ambas as propostas de mitigação sugeridas (substituição de sistemas anaeróbios abertos por processos aeróbios ou introdução de mecanismos de captura e combustão de metano em reatores anaeróbios) mostram redução de emissões semelhante, a maioria entre 100 e 150 tCO2e/ano para população de 1000 habitantes atendida. Entretanto, constatou-se que o potencial de obtenção de créditos está na queima do biogás pois a aeração exige alto consumo de energia. Essa possibilidade de gerar créditos de carbono, provenientes do Mecanismo de Desenvolvimento Limpo (MDL), pode contribuir para amenizar parte dos custos de implementação das estações de tratamento de esgotos, bem como estimular a sua modernização.
278

Investing in the environment : essays on energy efficiency and on the substitution of resources / L'investissement dans l'environnement : essais sur l'efficacité énergétique et sur la substitution des ressources

Mosiño, Alejandro 21 September 2012 (has links)
Les gaz à effet de serre (GES) sont en partie responsables du changement climatique. L'humanité est donc confrontée à un choix : soit de réduire les émissions des gaz qui sont la cause du problème, ou bien de prendre de mesures pour permettre aux populations de surmonter les conséquences de ces changements. Dans cette thèse, nous nous concentrons sur la première solution sous la prémisse selon laquelle une grande partie de l'effet de serre provient des activités humaines. Plus précisément, nous proposons quelques essais sur la modélisation des déterminants des investissements ayant pour objet la réduction des GES, en particulier des investissements dans l'amélioration de l'efficacité énergétique, et des investissements dans la substitution de ressources (fossiles) non-renouvelables par des ressources renouvelables. Tout d'abord nous essayons et expliquons la lente diffusion de certains investissements dans l'efficacité énergétique dans un cadre d'équilibre général. Ensuite, nous étudions les déterminants de la substitution des ressources non-renouvelables par des ressources renouvelables lorsque celles-ci sont des substituts parfaits. Enfin, nous tenons compte de la nécessité permanente de ressources sales, même si des technologies plus propres sont disponibles. Toutes ces questions sont basées sur des modèles qui ne peuvent être entièrement résolus analytiquement. Par conséquent, nous proposons dans cette thèse une méthodologie basée sur les propriétés des polynômes de Chebyshev pour calculer les solutions. / Greenhouse gases (GHG) are responsible for some climate change. Humanity faces a choice: either reducing the emissions of these gases or adapt to climate change. In this dissertation we focus on the first solution under the premise that a large part of the greenhouse effect comes from human activities. More precisely, we propose some essays on modeling the determinants of investing in reducing GHG through improving energy efficiency and substituting non-renewable resources (fossil fuels) by renewable resources. We first try and explain the slow diffusion of some energy efficient investments in a general equilibrium framework. We then study the determinants of switching from non-renewable resources to renewable resources when these are perfect substitutes. Finally, we account for the need of dirty resources even if cleaner technologies are available. All these issues are based on models that cannot be fully solved analytically, therefore we also propose in this dissertation a methodology based on the properties of Chebyshev polynomials to compute the solutions.
279

GERAÇÃO DE METANO EM LAGOA ANAERÓBIA: UM ESTUDO DE CASO EM ABATEDOURO DE BOVINOS / GENERATION OF METHANE IN ANAEROBIC POND: A CASE STUDY IN CATTLE SLAUGHTERHOUSE

Bohrz, Gabrieli Irrigaray 14 April 2010 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aims to evaluate the emission of methane (CH4) generated in an anaerobic stabilization pond used to treat wastewater from a cattle slaughterhouse, which is located in Santa Maria, Rio Grande do Sul (RS). In addition to the quantification of CH4 by gas chromatography, it was evaluated the emissions of other greenhouse effect gases (GHG) such as carbon dioxide (CO2) and nitrous oxide (N2O). It was verified the occurrence of two types of fluxes for a release of produced methane: the diffusive, with a daily average equal to 196.0 ± 51 mgCH4m-2h-1; and the ebullient, resulting of the random and sudden release of gases in the form of bubbles with variations between 67.0 and 1295.0 mgCH4m-2h-1. The flow rates values calculated from theoretical models presented significantly higher than the experimental ones, ranging from 387.0 to 410.0 mgCH4m-2h-1, since it was not taken into account the different variables of interference in anaerobic treatment, such as the needs and interactions between bacteria, dilution of the wastewater, and physical-chemical factors. The data revealed a higher production of CO2 (55 vol%) than CH4 (45 vol%) indicating reduction in the production of CH4 and its partial oxidation caused by oscillation in the layer of foam found during the research period. The presence of N2O in the samples indicated the presence of O2 dissolved in the wastewater. The results of this study evidenced that the anaerobic ponds constitute important sources of GHG, emphasizing the importance to control the use of this technology, as a way of mitigating the emission of gaseous compounds into the atmosphere and contribute to reducing the possible negative effects in the environment. / Este trabalho objetiva avaliar a emissão de metano (CH4) gerado em uma lagoa de estabilização anaeróbia utilizada no tratamento de águas residuárias de um abatedouro de bovinos, o qual está localizado no município de Santa Maria, Rio Grande do Sul (RS). Adicionalmente à quantificação do CH4 por cromatografia gasosa, foi avaliada a emissão de outros gases de efeito estufa (GEE), tais como o dióxido de carbono (CO2) e o óxido nitroso (N2O). Foi verificada a ocorrência de dois tipos de fluxos para a liberação de metano produzido: o difusivo, com média diária igual a 196,0 ± 51 mgCH4m-2h-1; e o ebulitivo, resultante da liberação aleatória e súbita de gases na forma de borbulhas, com variações entre 67,0 e 1.295,0 mgCH4m-2h-1. Os valores de fluxos calculados a partir de modelos teóricos apresentaram-se sensivelmente maiores do que os experimentais, variando de 387,0 a 410,0 mgCH4m-2h-1, uma vez que não levaram em conta as diferentes variáveis de interferência no tratamento anaeróbio, como as necessidades e interações entre bactérias, diluição do efluente líquido, e fatores físico-químicos. Os dados revelaram uma maior produção de CO2 (55 vol%) do que de CH4 (45 vol%) indicando redução na produção de CH4 ou sua oxidação parcial causada por oscilação na camada de escuma verificada durante o período da pesquisa. A presença de N2O nas amostras indicou a presença de O2 dissolvido no efluente. Os resultados obtidos nesse estudo evidenciam que as lagoas anaeróbias constituem importantes fontes de GEE, ressaltando a importância no controle na utilização dessa tecnologia, como uma forma de mitigar a emissão de compostos gasosos para a atmosfera e contribuir para a redução nos possíveis efeitos negativos sobre o meio ambiente.
280

Injeção de dejetos líquidos de suínos no solo e inibidor de nitrificação como estratégias para reduzir as emissões de amônia e óxido nitroso / Injection of pig slurry in soil and nitrification inhibitor as strategies to reduce ammonia and nitrous oxide emissions

Damasceno, Fabiano 30 June 2010 (has links)
Injection of pig slurry (PS) into the soil and the addition of nitrification inhibitors have been used in some countries as a strategy for manure nitrogen (N) preservation and mitigation of its pollution potential. The effect of these practices has been assessed mainly on N losses by ammonia (NH3) volatilization and the emission of greenhouse gases (GHGs). Research in this area is still incipient in Brazil. This study was carried out to evaluate the effect of the injection of pig slurry into the soil and the use of the nitrification inhibitor dicyandiamide (DCD) in the commercial product Agrotain plus (DCD 81%) on N losses by NH3 volatilization and the emission of nitrous oxide (N2O). Two field experiments were carried out over a Paleudalf under no tillage and oat straw mulching from May 2008 to May 2010. On the experiment 1, three treatments were compared over 61 days: PS (60 m3 ha-1) on soil surface, PS injected into the soil, and a control without PS. The accumulated N-NH3 loss, over 196 hours, with PS on soil surface was 4,8 kg N-NH3 ha-1, which was decreased to only 0,03 kg N-NH3 ha-1 with PS injected into the soil. On the experiment 2, five treatments were compared: two with PS (60 m3 ha-1) on soil surface or injected into the soil, two with the addition of Agrotain plus (7 kg ha-1) to the PS prior its application on soil surface or injection into the soil, and also a control without PS or Agrotain plus. The accumulated N-NH3 volatilization over 501 hours was reduced from 8,1 kg N-NH3 ha-1 on the PS on soil surface treatment to only 0,12 kg N-NH3 ha-1 when PS was injected into the soil. The addition of Agrotain plus in surface-applied PS increased the accumulated NH3 volatilization on 6,2 kg N-NH3 ha-1 (77%). On the other hand, the nitrification inhibitor decreased the N-N2O emissions by 74% at the average of both PS application methods. Our results showed that the injection of pig slurry into the soil with the DCD addition as a nitrification inhibitor preserved the ammonia nitrogen in the slurry and reduced the N2O emissions contributing to the mitigation of the pig farming pollution potential. / A injeção de dejetos líquidos de suínos (DLS) no solo e a adição de inibidores de nitrificação vêm sendo utilizadas em alguns países como estratégias para preservar o nitrogênio (N) dos dejetos e mitigar o potencial poluidor dos mesmos. O efeito dessas práticas tem sido avaliado principalmente sobre as perdas de N por volatilização de amônia (NH3) e a emissão de gases de efeito estufa (GEE). No Brasil, a pesquisa nessa área é ainda incipiente. Este trabalho foi realizado com o objetivo de avaliar o efeito da injeção dos dejetos líquidos de suínos no solo e do uso do inibidor de nitrificação dicianodiamida (DCD), contido no produto Agrotain Plus (81% de DCD), sobre as perdas de N por volatilização de NH3 e sobre a emissão de óxido nitroso (N2O). Para isso, foram conduzidos dois experimentos a campo, de maio de 2008 a março de 2010, ambos em Argissolo Vermelho Distrófico arênico e em plantio direto, sobre palha de aveia preta. No experimento 1, foram comparados durante 61 dias três tratamentos: aplicação superficial de DLS (60m3 ha-1), injeção de DLS no solo e testemunha sem DLS. A perda acumulada de N-NH3, em 196 horas, com aplicação superficial de DLS foi de 4,8 kg de N-NH3 ha-1, a qual foi reduzida para apenas 0,03 kg de NNH3 ha-1 com a injeção dos DLS no solo. No experimento 2 foram comparados cinco tratamentos, sendo dois com aplicação de DLS (60 m3 ha-1), em superfície e com injeção no solo, dois com aplicação de Agrotain Plus (7 kg ha-1) aos DLS, antes de adicioná-los em superfície ou injetá-los no solo, além de um tratamento testemunha, sem DLS e sem Agrotain Plus. A volatilização acumulada de NH3, em 501 horas, foi reduzida de 8,1 kg de NNH3 ha-1, no tratamento com aplicação superficial dos DLS, para apenas 0,12 kg de N-NH3 ha-1, com a injeção dos mesmos no solo. Com a adição de Agrotain Plus nos DLS aplicados em superfície, a volatilização acumulada de NH3 aumentou em 6,2 kg de N-NH3 ha-1 (77%). Por outro lado, o inibidor de nitrificação reduziu a emissão de N2O em 74%, na média das duas formas de aplicação dos dejetos. Os resultados desse trabalho evidenciaram que a injeção dos dejetos no solo, aliada à adição de DCD como inibidor de nitrificação, reduz as perdas de N por volatilização de NH3 e a emissão de N2O, contribuindo para mitigar o potencial poluidor da suinocultura.

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