L’Agence nationale pour la gestion des déchets radioactifs (Andra) a pour mission d’évaluer la possibilité d’un stockage sûr et réversible des déchets de haute activité et à vie longue (HAVL) en milieu géologique profond. Depuis 1994, l’Andra étudie dans cette optique les propriétés d’une couche argileuse, le Callovo-Oxfordien (COx) située dans l’Est du Bassin Parisien, à la limite des départements de la Meuse et de la Haute-Marne. A l’échelle du secteur d’étude, le COx constitue une couche homogène d’environ 130 mètres d’épaisseur, profonde de 500 mètres en moyenne, encadrée par deux formations calcaires, l’Oxfordien au sommet et le Dogger à la base. Le COx présente des perméabilités très faibles et des propriétés de confinement favorables pour un stockage.Les gaz rares (He, Ne, Ar, Kr et Xe) sont chimiquement inertes, leur couche de valence étant saturée, aucune liaison covalente intramoléculaire n’est généralement possible. De plus, ils possèdent de nombreux isotopes, d’origine différente, ce qui fait d’eux d’excellents traceurs en hydrogéologie. Les concentrations en gaz rares dans les environnements sédimentaires sont contrôlées par la loi de Henry : ils se dissolvent dans l’eau avec laquelle ils sont en contact, et ce en fonction de paramètres tels que la température, la salinité et la pression.Afin de compléter et préciser les propriétés du COx dans une zone de 250 km² autour du Laboratoire souterrain de Meuse/Haute-Marne, appelée « zone de transposition » (ZT), l’Andra a entrepris une campagne de forages entre Novembre 2007 et Juin 2008. Dans le cadre de cette campagne, le COx a été carotté dans quatre forages et échantillonné. L’un des forages a également recoupé l’ensemble de la pile sédimentaire Mésozoïque, depuis l’Oxfordien calcaire jusqu’à la base du Trias (-1600 mètres).Sur les quatre forages de la zone de transposition (A, B, C et D), des échantillons de roches ont été prélevés et conditionnés pour l’analyse en laboratoire des concentrations en gaz rares dissous dans les eaux porales. Les concentrations absolues en gaz rares ont été déterminées par spectrométrie de masse.Les profils en He obtenus pour chaque plateforme de forage présentent la même tendance. Les concentrations en He mesurées dans les eaux porales de la plateforme C sont en moyenne entre 2 et 3 fois plus faibles que pour les autres plateformes, et ainsi comparables aux valeurs mesurées dans le laboratoire souterrain, ce qui suggèrerait une circulation des eaux dans le Dogger comparativement moins lente que dans les autres plateformes de forage. Une modélisation 1-D des profils de concentration en He a permis de valider les mesures analytiques et de confirmer que la forme des profils est contrôlée par les concentrations en He imposées dans le Dogger. Le profil de concentrations en He mesurées dans le forage profond suggère d’une part une influence très faible voire nulle d’un flux d’origine mantellique et d’autre part une isolation des formations triasiques et du Lias adjacent. L’ensemble des résultats obtenus a ainsi permis d’avoir une meilleure connaissance des processus de transferts diffusifs dans la formation du COx et dans les aquifères encaissants. / The French Radioactive Waste Management National Agency (Andra) is studying the possibility of a high level and long lived radioactive waste repository in geological formation. Since 1994, Andra is studying the properties of the Callovo-Oxfordian (COx) argillaceous rock, located in the eastern part of the Paris Basin. In the designated zone, COx is a 130 meters thick clay rich sequence, found at a depth of about 500 meters and encompassed between two aquifers, the Oxfordian limestone above and the Dogger limestone below. Callovo-Oxfordian permeabilities are very low, which is suitable with radioactive waste disposal. Noble gases (He, Ne, Ar, Kr and Xe) are considered as natural tracers, useful in hydrogeology, for several reasons. First, noble gases are nearly chemically inert, and then no reaction occurs between them and other species. Secondly, noble gases have several isotopes and many of them have different origins, so it is possible to distinguish sources terms. Noble gases concentrations in geological formations are controlled by physical properties such as temperature, pressure and salinity. To have more information on the COx properties, Andra has selected four drilling sites in a 250 km2 area around the Underground Research Laboratory. From November 2007 to June 2008, on each site, Callovo-Oxfordian clay and both overlaying (Oxfordian) and underlying (Dogger) limestones were investigated. A 1600 meters deep borehole, reaching the Trias base, allows investigating the whole length of the Mesozoïc sedimentary pile.On each drilling sites (named A, B, C and D), pore water noble gases concentrations were performed by mass spectrometry. Each helium profiles show the same general trends. Helium concentrations measured in the borehole C COx pore water are about 2 to 3 times lower than those observed for the other boreholes, and so comparable with previous measurements in the Underground Laboratory. These lower concentrations for borehole C could suggest differences in water average velocities in Dogger limestone, in comparison with the other ones. Calculations using a 1-D model were done; the results corroborate analytical measurements and confirm that helium diffusion profiles in the COx are controlled by Dogger helium concentrations that were put in the model. The vertical profile of dissolved helium concentration throughout the deep borehole suggest on the one hand that there is no deep crustal flux, and on the other hand that Trias is well isolated from the Lias and Dogger overlaying formations.The whole results obtained in this study provide a better understanding about diffusive transfer processes occurring in the COx and in the surrounding limestone aquifers.

Intensive agriculture, coupled with an increase in nitrogen fertilizer use, has contributed significantly to the elevation of atmospheric greenhouse gases (GHGs), including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). Rising GHG emissions usually mean a decrease in soil carbon. Currently, soil C is twice that of all standing crop biomass, making it an extremely important player in the C cycle. Fortunately, agricultural management practices have the potential to reduce agricultural GHG emissions whilst increasing soil C. Management practices that impact GHG emissions and soil C include various tillage practices, different N fertilization amounts and treatments (synthetic N, cattle manure, or a combination of both), the use of cover crops, aeration, and water levels. Employing agricultural best management practices (BMPs) can assist in the mitigation and sequestration of CO2, N2O and soil C. Measuring soil carbon storage and GHG emissions and using them as metrics to evaluate BMPs are vital in understanding agriculture's role in climate change. The objective of this research was to quantify soil carbon and CO2 and N2O emissions in agroecosystems (dairy, crop, and meat producing farms) under differing management practices. Three farms were selected for intensive GHG emissions sampling: Shelburne Farm in Shelburne, VT, a dairy in North Williston, VT, and Borderview Farm in Alburgh, VT. At each site, I collected data on GHG (CO2 and N2O) emissions and soil carbon and nitrogen storage to a depth of 1 meter. Soil emissions of CO2 and N2O were taken once every two weeks (on average) from June 2015 through November, 2015 using static flux chambers and a model 1412 Infrared Photoacoustic Spectroscopy (PAS) gas analyzer (Innova Air Tech Instruments, Ballerup, Denmark). Fluxes were measured on 17 dates at Shelburne Farms, 13 dates at the Williston site, and 13 dates in the MINT trial. Gas samples were taken at fixed intervals over a 10-14 minute time frame, with samples normally taken every one or two minutes. I also measured soil carbon to a depth of 1m in six BMPs at Borderview Farm. Overall, I found that manure injection increased N2O and CO2 emissions, but decreased soil C storage at depth. Tillage had little to no impact on N2O emissions, except at Shelburne Farms, where aeration tillage decreased N2O emissions (marginally significant, P < 0.1). No-till did, however, decrease CO2 emissions relative to other conservation tillage practices (strip and vertical tillage) but we were unable to detect a significant change in soil C due to tillage practices. At Borderview farm, N2O emissions increased with soil NO3 and soil moisture, while CO2 emissions increased with soil temperature and nitrate. At Williston, CO2 emissions only increased with temperature; at Shelburne CO2 emissions increased with nitrate. N2O fluxes at Shelburne and Williston were not associated with any of the measured covariates.

This thesis presents a study of the electrical properties and gas sensitivity of thin films of four different organic materials. These are: (i) Langmuir-Blodgett (LB) films of tetrabutylammonium Ni(dmit)(_2) complex (Bu(_4)-Ni(dmit)(_2) complex) mixed with tricosanoic acid (TA); (ii) thin films of polypyrrole (PPy) mixed with palmitic acid (PA) obtained using the LB technique followed by two solid state reactions; (iii) cast films of polycyanopropylmethylsiloxane (PCMS); and (iv) LB films of a co-ordination polymer?5,5' methylenebis (N-hexadecylsalicydeneamine) (MBSH) (poly(CuMBSH)). LB films of (Bu(_4)-Ni(dmit)(_2) complex)/TA were characterised by electrical measurements?(AC in the frequency range 10(^2)-10(^6) Hz) at room temperature. For the other three types of films, characterisation of the structure and electrical behaviour (DC and AC in the frequency range 10(^2)-10(^6) Hz) on varying the temperature (in the range 90 - 298 K) and during the exposure to benzene, ethanol, acetonitrile and water (concentrations in the range 10(^2) -10(^5) ppm) was undertaken. During exposure to vapours, reversible changes in the electrical properties of the films were observed. The electrical behaviour and the changes during exposure to vapours were interpreted in terms of models in the literature, assuming a bulk dissolution of the vapours in the organic films. In all cases an 'anomalous' response to water was observed. For poly(CuMBSH), this effect was interpreted in terras of a Low Frequency Dispersion. The device characteristics for gas sensing applications are also discussed. Estimated minimum detectable concentrations were between 1-100 ppm for the three organic solvent vapours. Moreover, it is shown that the fi-equency behaviour for the admittance changes of the PCMS and poly(CuMBSH) devices could be exploited for the improvement of the sensitivity of a single device. The unique response of all the films to water vapour could be useful for its discrimination.

Memoria para optar al Título Profesional de Médico Veterinario / El objetivo del presente estudio fue evaluar el impacto de la adición en la dieta de perros, del extracto de Quillaja saponaria (QS), sola y/o asociada con Yucca schidigera (YS), sobre la consistencia fecal, evaluada cualitativamente mediante el “Score” fecal y la emisión de gases, generadores del mal olor fecal, como: amoníaco (NH3), ácido sulfhídrico (H2S) y tetrahidrotiofeno (THT). Se utilizaron 22 perros, ubicados en caniles individuales y alimentados por 7 días con una dieta Control, (sin extractos), que luego se distribuyeron en 3 grupos. Los cuales fueron alimentados por 25 días con una dieta Control, dieta QS (que poseía extracto de QS) y dieta QS + YS (que poseía extracto de QS con YS), respectivamente. Durante el ensayo, los animales alimentados con las dietas experimentales, se recolectaron las heces producidas, en 5 días diferentes y se evaluó la consistencia fecal, mediante el uso del “Score” fecal, que clasifica las heces de duras a blandas con puntajes de 0 a 5. Posteriormente se determinó las concentraciones de H2S, THT y NH3, durante un período de 8 hrs., con mediciones cada una hora; las lecturas de los compuestos se determinaron cada 10 segundos por 3 minutos en cada hora. La dieta QS + YS generó una disminución (P ≤ 0,05) del “Score” fecal pero este se mantuvo cercano a 4, que es considerado como aceptable, y el factor individual del perro resultó ser una variable más significativa (P ≤ 0,001), que la dieta (P = 0,027). Todas las variables consideradas en el modelo estadístico, en la determinación de gases, fueron altamente significativas (P ≤ 0,001), es decir el efecto del perro, la dieta y el tiempo de medición. Las dietas con agentes desodorizantes generaron una disminución (P ≤ 0,05) de la producción de H2S, THT y NH3, con respecto a la dieta Control, pero la dieta QS + YS generó una mayor disminución (P ≤ 0,05) en la producción de THT con respecto a la dieta QS, sin haber diferencias en los otros gases. / Desert King Chile

Orientador: Lucia Galvão de Albuquerque / Coorientador: Renata Helena Branco / Coorientador: Ana Claudia Ruggieri / Banca: Juliana Duarte Messana / Banca: Maria Eugênia Zerlotti Mercadante / Banca: Alexandre Berndt / Banca: Roberta Canesin / Resumo: Este trabalho foi conduzido com o objetivo de desenvolver equações de predição da emissão metano entérico além de avaliar equações descritas na literatura quanto a sua acurácia, estimar a herdabilidade da emissão de metano e estabelecer relações entre esta emissão e eficiência alimentar de bovinos Nelore em crescimento sob condições de clima tropical. Quarenta e oito bovinos Nelore foram avaliados quanto ao consumo de matéria seca, consumo de nutrientes e emissão de metano e equações foram geradas com base nos dados de consumo e avaliadas pela raiz quadrada do quadrado médio do erro de predição (RQME) e por regressão residual. A partir dos dados de emissão de metano obtidos in vivo, foram validadas equações descritas na literatura, avaliadas de acordo com os mesmos critérios utilizados para as novas equações geradas. Para a estimativa da herdabilidade foram utilizados dados de consumo individual e peso corporal de 896 bovinos Nelore (541 machos e 355 fêmeas) com peso corporal inicial médio de 276 ± 53 kg, nascidos entre 2004 e 2012 (286 ± 39 dias de idade inicial) e avaliados quanto ao consumo alimentar residual (CAR). Uma equação gerada a partir do consumo de matéria seca dos 48 animais avaliados foi utilizada para estimar a emissão de metano dos demais 896 animais, sendo outras duas equações descritas por Ellis e colaboradores também utilizadas com a mesma finalidade. A herdabilidade da emissão de metano foi estimada para cada equação. Equações incluindo as variáveis consumo de matéria seca e consumo de hemicelulose, consumo de matéria seca e consumo de carboidratos totais, consumo de energia metabolizável e consumo de celulose e consumo de carboidratos não fibrosos apresentaram os menores valores de RQME, sendo consideradas as mais ajustadas para o conjunto de dados estudado. Cinco das 17 equações descritas na literatura puderam predizer a emissão de metano adequadamente apresentando ... / Abstract: This work was conducted with the objective of developing enteric methane (CH4) emission prediction equations and to evaluate equations described in the literature as to accuracy, estimate the heritability of methane emission and linking this issue and feed efficiency of Nellore in growth under tropical conditions. Forty-eight Nellore were evaluated for dry matter intake, nutrient intake and methane emission and equations were generated based on consumption data and evaluated by the square root of the mean square prediction error (RMSE) and residual regression. From the methane emission in vivo data, equations described in the literature were validated, assessed according to the same criteria used for the new generated equations. To estimate the heritability of individual consumption, data were used and body weight of 896 Nellore (541 males and 355 females) with an average initial body weight of 276±53 kg, born between 2004 and 2012 (286±39 days old) and assessed for residual feed intake (RFI). An equation generated from dry matter intake of 48 animals evaluated was used to estimate methane emissions from the other 896 animals, and two other equations described by Ellis et al also used for the same purpose. The heritability of methane emission was estimated for each equation. Equations including the variables dry matter intake and consumption of hemicellulose, dry matter intake and intake of total carbohydrates, metabolizable energy intake and consumption of pulp and consumption of non-fiber carbohydrates had the lowest RMSE values, are considered the most adjusted to the data set studied. Five of the 17 equations described in the literature could predict methane emissions properly to the lowest RMSE values among the evaluated equations. However, the equations developed in this study were more accurate in predicting the methane emission evaluating under the same parameter. The heritability estimate (h2) of CH4 showed high magnitude ... / Doutor

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, 2016. / Global methane (CH4) emissions are divided mostly into three sources; biogenic, thermogenic and pyrogenic. The sources can be anthropogenic or natural in origin. Anthropogenic sources include emissions associated with agriculture (rice paddies and ruminants), waste (landfill and waste water), biomass burning and fossil fuels. Landfills have been implicated as one of the largest anthropogenic sources of atmospheric CH4 globally and as a significant contributor to global warming. According to the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report anthropogenic sources account for 304 – 368 TgCH4/year and methanogenesis in landfills and waste contributes between 67 and 90 TgCH4/year to this amount (between 22 and 24% of emissions). / GR2016

Orientador: Arnaldo Alves Cardoso / Coorientador: Maria Angélica Martins Costa / Banca: Andrew George Allen / Banca: Maria Lúcia Arruda de Moura Campos / Resumo: Este estudo foi desenvolvido com o objetivo de avaliar possíveis impactos de fontes antropogênicas na composição da atmosfera no litoral norte do estado de São Paulo, município de Caraguatatuba. Desde a primeira década do século XXI, este local sofre forte impacto de mudanças nas atividades econômicas impulsionadas pelo projeto de extração de óleo e gás contidos em reservas do pré-sal, pois a região é um dos polos de recebimento e distribuição de petróleo e derivados. Espera-se que o continuo aumento das instalações industriais, trânsito de veículos e embarcações e expansão da área urbana tenham continuidade ainda por muitos anos. Apesar dos possíveis efeitos que essas mudanças podem causar no ambiente não existe nenhum dado sobre composição da atmosfera local e este trabalho apresenta as primeiras medidas de gases ácidos e aerossol atmosférico. As amostragens foram feitas próximo aos limites da área urbana e, de forma concomitante, no alto da Serra do Mar e com isso buscou-se reconhecer possíveis alterações na composição química de gases e aerossol durante os processos de circulação de ar que usualmente ocorrem entre o continente e o oceano e que são influenciados também pelas emissões locais e reações fotoquímicas. Para avaliá-los foi feita caracterização química da atmosfera em relação aos componentes iônicos solúveis do aerossol, aos gases ácidos na fase gasosa e à amônia. Os aerossóis foram coletados por amostrador Hi-Vol, para distribuição do material particulado em sei... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study was developed with the objective of evaluating the possible impacts of anthropic sources on the composition of the atmosphere of a littoral region (Caraguatatuba) located in the state of São Paulo (Brazil). This coastal region is under heavy impact from emissions of various compounds into the atmosphere. The site was chosen as a receiving center for oil and gas extraction products from deepwater reserves known as "pre-sal". The continued growth of industrial facilities, increased traffic of vehicles and ships, along with expansion of the urban area is expected to increase in the coming years. Despite the possible effects on the environment, there is no data on the composition of the local atmosphere. This work presents the first measurements made in the atmosphere of acid gases and aerosol. The samplings were made close to the urban limits of the city and concomitantly at a sampling point located high in the mountains. Possible changes in the chemical composition of gases and aerosols during air circulation processes, which usually occur between the continent and the ocean, have been studied. These processes are mainly influenced by local emissions, photochemical reactions and air circulation. Samples of formic acid, acetic acid, sulfur dioxide, hydrogen chloride and nitric acid were collected using sequential filtration with cellulose filters treated with sodium carbonate. Ammonia was collected with cellulose filter impregnated with oxalic acid. Samples of particu... (Complete abstract click electronic access below) / Mestre

Orientador: Tadeu de Siqueira Barros / Coorientador: Wagner Cotroni Valenti / Banca: Antonio Fernando Monteiro Camargo / Banca: Lúcia Helena Sipaúba Tavares / Banca: Matheus Nicolino Peixoto Henares / Banca: Irineu Bianchini Junior / Resumo: O objetivo deste estudo foi investigar o fluxo de gases do efeito estufa (GEE) em viveiros de criação de organismos aquáticos. Nós testamos se o uso de sistemas multitróficos e multiespaciais (IMTA), povoados com lambari-do-rabo-amarelo (Astyanax lacustris) e camarão-da-amazônia (Macrobrachium amazonicum) numa região tropical, altera o fluxo de gases do efeito estufa em comparação com um sistema de monocultivo de A. lacustris. Nós desenvolvemos um experimento em viveiros de fundo natural com três tratamentos e quatro réplicas: monocultivo (Tetra), IMTA livre (Free IMTA) e IMTA tanque rede (Cage IMTA). O experimento durou 68 dias, entre os meses de novembro e janeiro de 2016. Nós mensuramos os fluxos de dióxido de carbono (CO2), metano (CH4) e óxido nitroso (N2O) por meio das metodologias difusiva e dissolvida. A média dos fluxos na metodologia difusiva foi de -8.93 mg.m-2.h-1 para o CO2, -0.88 mg.m-2.h-1 para o CH4 e 1.78 mg.m-2.h-1 para o N2O. A concentração de CO2 variou de 0.0481 a 0.6668 mg.L-1, CH4 de 0.0003 a 0.0053 mg.L-1 e N2O de 0.0789 a 0.1177 mg.L-1. Nossos resultados indicam variação ao longo do tempo, com maior fluxo de GEE no início do experimento, diminuição ao longo do período de cultivo e tendência de neutralidade com relação a emissão de GEE no final do período experimental. / Abstract: The aim of this study was to investigate Greenhouse Gases (GHG) fluxes in aquaculture ponds. We tested if the use of Integrated Multi Trophic Aquaculture (IMTA) with Yellow tail tetra (Astyanax lacustris) and Amazon River prawn (Macrobrachium amazonicum) in a tropical environment changes the GHG flows in comparation with A. lacustris monoculture. We developed an experiment in earthen ponds with three treatments and four replications: monoculture (Tetra), two species free in the pond (Free IMTA) and fishes in cage and prawns free (Cage IMTA). Experiment ran 68 days between November and January 2016. We measured fluxes of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) with diffusive and dissolved methodologies. Mean of diffusive fluxes was -8.93 mg.m-2 .h-1 for CO2, -0.88 mg.m-2 .h-1 for CH4 e 1.78 mg.m-2 .h-1 for N2O. Concentration of CO2 oscillated between 0.0481 and 0.6668 mg.L-1, CH4: 0.0003 and 0.0053 mg.L-1 e N2O: 0.0789 a 0.1177 mg.L-1 . Our results indicate variations over time, with higher fluxes at the beginning of experiment, decreasing over the growing period and trend of neutrality regarding to the GHG emissions at the end of experimental period. / Doutor

Este trabalho pretende avaliar o efeito da salinomicina no consumo de feno coast cross e sal proteinado, na digestibilidade total, ruminal in situ e in vitro, taxas de produção de gases e taxas de fermentação. Para a avaliação da digestibilidade e degradabilidade in situ foram utilizados 4 novilhos Holandeses com peso médio de 350 kg ± 43 kg. O delineamento experimental utilizado foi o quadrado latino com 4x4. No ensaio in vitro foram utilizados 4 substratos *8 inóculos *2 corridas com delineamento em blocos e arranjo fatorial. Os tratamentos estudados foram: 0; 0,1; 0,2; 0,3 mg de salinomicina /kg de peso vivo. Não foram encontradas diferenças significativas (p>0,05) no consumo de MS(1,92; 1,73; 1,60; 1,63 %PV), digestibilidade aparente da MS (81,79; 80,32; 80,32 e 80,49), na degradação in situ da MS (52; 51,25; 49,20 e 51,38) e na degradação in vitro da MS (45,31; 45,64; 45,77; 45,03) entre os vários tratamentos. Os únicos parâmetros onde foram identificadas alterações significativas entre os tratamentos foram no volume final de gases in vitro e nas curvas de taxas de fermentação. Os valores encontrados de para o volume final de gases foi de 231,8; 204; 168 e 157,78 ml /g de MS para a dose de 0; 0,1; 0,2 e 0,3 mg de salinomicina/ kg de PV, respectivamente. O tratamento 3 foi o que teve menores perdas de energia. / This experiment was conducted to evaluate the effect of graded levels of salinomycin on feed intake, apparent di estibility, gas production and fermentation rate, degradability in situ and in vitro of cynodon hay supplemented with proteic salt with 0, 0.1, 0.2 and 0,3mg of salynomicin per kg LW. Intake , digestibility and degradabilty studies were analysed as a latine square design 4x4 and in vitro trials followed the block randomized design with a two factors (inocula and substrate). No differences (p>)0,05) were found between the treatments for DM intake (1.92, 1.73, 1.60, 1.63 per % LW), DM digestibility (81.79, 80.32, 80.32 and 80.49), DM in situ degradability (52, 51.25, 49.20 and 51.38) and in vitro DM degradability (45.31, 45.64, 45.77 and 51.38). Differences between treatments were found only for potencial gas production in vitro (231.8, 204, 168 and 157.78 ml/g DM) for 0, 0.1, 0.2 and 0,3 mg of salinomycin/kg LW. Therefore, wasting energy was minimized at treatment 3.

A emissão de gases de efeito estufa (GEE) é uma das principais causas do aquecimento global, sendo uma problemática mundial das últimas décadas. O dióxido de carbono (CO2), o metano (CH4) e oxido nitroso (N2O) são os principais GEE e os ruminantes são uns dos maiores contribuintes com a produção desses gases no mundo, devido ao processo digestivo de fermentação entérica. Na busca de estratégias para diminuir as emissões de metano e melhorar a produtividade animal, aditivos alimentares têm sido utilizados nas dietas dos animais. Assim, o objetivo deste trabalho foi avaliar a inclusão de aditivos alimentares sobre a produção de metano determinada pela técnica do gás traçador SF6, assim como, o consumo de matéria seca, a dinâmica ruminal e a contagem total e diferencial de protozoários do rúmen. Seis vacas não-gestantes e não-lactantes, com peso vivo médio de 784 &plusmn; 87 kg e canuladas no rúmen, foram distribuídas a uma das três dietas experimentais, seguindo-se delineamento experimental em quadrado latino 3x3 replicado (n= 18 unidades experimentais), sendo os tratamentos: 1) Controle (CON): Dieta basal sem inclusão de aditivo; 2) Monensina (MON): Dieta com adição de 300 mg de monensina sódica por animal por dia; 3) Tanino (TAN): Dieta com adição de 68 g de extrato de tanino condensado de Acácia-negra (Acacia mearnsii) por animal por dia. Os alimentos foram fornecidos duas vezes ao dia, na forma de ração completa. Cada período experimental foi constituído por 21 dias, sendo 10 dias de adaptação às respectivas dietas. A partir do dia 16 até o dia 21 foram coletados os dados de consumo de matéria seca e de produção de metano, sendo este último determinado a cada 24 horas, pela técnica do gás traçador de SF6. No dia 21, coletou-se conteúdo ruminal para determinação de protozoários. Quanto à dinâmica ruminal, foi realizado o esvaziamento ruminal nos dias 10 (3 horas após alimentação matinal) e 11 (imediatamente antes da alimentação matinal) de cada período experimental. Os resultados foram analisados através do procedimento MIXED onde o modelo incluiu o efeito de tratamento como fator fixo e os efeitos de animal dentro de quadrado, quadrado e período como fatores aleatórios. Não houve diferenças significativas (P&gt;0,05) entre os tratamentos para as variáveis do consumo de matéria seca, como também, para os parâmetros de dinâmica ruminal (P&gt;0,05) (matéria seca do conteúdo ruminal, massa líquida, massa sólida, massa total, assim como taxa de desaparecimento). A emissão de metano (expressa em g/d, g/kg PV, g/kg PV0,75 ou Mcal/Ani/d) com o tratamento com monensina foi menor em relação ao tratamento controle. Para a contagem total e diferencial de protozoários foi verificado efeito de aditivo para a subfamília Diplodiniinae, sendo que, o tratamento com monensina diminuiu em 27,5% a contagem desta subfamília em relação ao tratamento com tanino. Referente ao gênero Isotricha, foi observado que os tratamentos com monensina ou com tanino diminuíram em 31 e 30% respectivamente, este gênero em relação ao tratamento controle. A adição de monensina (17 mg/kg de MSI) revela-se uma alternativa para reduzir as perdas energéticas geradas na produção de metano, assim como também na redução de protozoários, que albergam microrganismos metanogênicos. Em relação ao tanino (0,4% na dieta) acredita-se que com doses mais elevadas na dieta possa resultar numa redução da emissão de metano / The emission of greenhouse gases (GHG) is a major cause of global warming, being a worldwide concern in recent decades. Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are the main greenhouse gases and ruminants are one of the major contributors to the production of these gases around the world, due to the enteric fermentation process. In the search for strategies to reduce methane emissions and to improve animal productivity, food additives have been used in animal diets lately. Thus, the aim of this trial was to assess the inclusion of food additives on methane emissions in cattle, using the sulfur hexafluoride (SF6) tracer technique, as well as on dry matter intake, rumen dynamics and total and differential counts of ruminal protozoa. Six non-pregnant and non-lactating rumen-cannulated cows (784 &plusmn; 87 kg) were assigned to a replicated 3x3 Latin square (18 experimental units). Treatments were: 1) Control (CON) basal diet with no additive inclusion; 2) Monensin (MON) addition of 300 mg of sodium monensin per animal per day, 3) Tannin (TAN) addition of 68 g of concentrated extract of condensed tannin (Acacia mearnsii) per animal per day. The animals were fed total mixed ration twice daily. Each experimental period consisted of 21 days the first 10 days were used for diet adaptation. From day 16 up to 21, data about dry matter intake and methane production were collected, the latter done every 24 hours using the sulfur hexafluoride (SF6) tracer technique. On the day 21, ruminal content was sampled for protozoa determination. Regarding the rumen dynamics, the rumen was emptied on days 10 (3 hours post-morning feeding) and 11 (right before morning feeding) of each experimental period. The results were analyzed by MIXED procedure; the model included the effect of treatment as fixed factor and the effects of period, square and animal within square as random factors. There were no significant differences (P&gt;0.05) among treatments for dry mater intake variables, nor for ruminal dynamics parameters (ruminal content dry matter, liquid mass, solid mass, total mass or disappearance rate). Methane emission (expressed in g/day, g/kg LW, g/kg LW0.75 or Mcal/Ani/day) was lower for the group receiving monensin compared to the control group. For total and differential counts of protozoa, the additives affected the Diplodiniinae subfamily, i.e. monensin decreased the count of this subfamily by 27.5%, compared to tannin. Regarding the Isotricha genus, treatments with monensin or tannin decreased it by 31 and 30% respectively, compared to the control treatment. The addition of monensin (17 mg/kg DMI) revealed to be an alternative to reduce the energy lost by methane production, as well as to decrease the protozoa, which host methanogen microorganisms. Regarding tannin (0.4% in the diet), it is believed that higher doses in the diet can lead to a reduction in methane emission