Estudaram-se neste trabalho os efeitos da deposição atmosférica sobre o balanço de elementos químicos, analisando-se as entradas e saídas dos elementos através do ciclo hidrológico durante quatro anos (setembro de 1991 a agosto de 1995) na Floresta Atlântica, situada nas vizinhanças do pólo industrial de Cubatão, São Paulo. Por meio de amostragens quinzenais e de determinação da concentração iônica, avaliaram-se, em três florestas diferentemente atingidas pela impacto da poluição aérea – Pilões-menos poluída, área de referência; Moji-fortemente poluída e Paranapiacabamoderadamente poluída – os seguintes aspectos: entrada de elementos pela água de chuva; transferência pela água que atravessa a cobertura vegetal e pela solução do solo a 10cm, 60cm e 100cm de profundidade; saída e neutralização pela água de nascentes e de pequenos córregos, bem como as alterações químicas no solo induzidas pela deposição atmosférica. Na área mais poluída (Moji), as concentrações iônicas médias encontradas na precipitação que atinge a floresta e na precipitação que atinge o solo foram, respectivamente: 5 e 10 mg.L-1 para o sulfato-S, 0,5 e 0,7 mg.L-1 para o nitrato, 0,63 e 1,14 mg.L-1 para o fluoreto, 2,2 e 2,8 mg.L-1 para o amônio-N, 0,69 e 2,15 mg.L-1 para o magnésio, 3,1 e 7,7 mg.L-1 para o cálcio. Na floresta de referência, menos poluída (Pilões), as concentrações iônicas foram em média, 1/3 a 1/9 inferior a esses valores, refletindo claramente as diferenças nas cargas poluidoras que atingem cada floresta. Verificou-se que a composição química da solução do solo muda completamente com a infiltração da água. As concentrações de nitrato aumentaram de 3 a 22 vezes com a infiltração da água nos primeiros 10cm de solo do Pilões e Moji, respectivamente, valores estes bastante expressivos. Em menor proporção, isso também foi observado para o sulfato e cloreto. As mudanças nas concentrações dos elementos durante a passagem da água pelo ecossistema são explicadas pelas reações químicas que ocorrem nos diferentes compartimentos. Assim, nas florestas mais poluídas (Moji e Paranapiacaba) elas são caracterizadas pela retenção praticamente total do amônio, e parcial do sulfato, nas camadas superficiais do solo, pela liberação do alumínio dos minerais do solo e pela lixiviação extremamente alta de nitrato em conseqüência do processo de nitrificação da matéria orgânica. A deposição atmosférica nas florestas investigadas é bastante elevada e variável. Entram anualmente no solo, pela precipitação: de 122 a 255 kg.ha-1 de enxofre na forma de sulfato; de 7 a 70 kg.ha-1 de nitrogênio, principalmente na forma de amônio; e de 4 a 28 kg.ha-1 de fluoreto. Com a entrada de amônio e de nitrogênio orgânico no sistema, reações de nitrificação ocorrem na camada superficial do solo, principalmente das áreas mais atingidas pela poluição. Na floresta mais poluída (Moji), a saída de nitrato pela água do solo a 100cm de profundidade chega anualmente a 271 kg de N por hectare, enquanto a saída de enxofre alcança o valor de 386 kg de S por hectare, anualmente. A acidificação do solo em decorrência da entrada e transferência de nitrogênio e enxofre provoca a liberação de alumínio dos minerais do solo e a lixiviação de formas iônicas (mais de 240 kg de Al por ha anualmente). A transferência de íons alumínio para o lençol freático e para águas de nascentes e córregos acarreta um problema ecológico sério, pois esses íons consomem a alcalinidade e a água fica sujeita a acidificação. / The effects of atmospheric deposition upon element balance (input and output) and turnover through the hydrological cycle have been investigated from September 1991 to August 1995 (four years), in the vicinity of the industrial complex of Cubatão, State of São Paulo, Brazil. The aim was to assess atmospheric deposition and fluxes through precipitation, soil water at 10cm, 60cm and 100cm depths, and surface water as well as to investigate possible soil changes induced by atmospheric deposition. Three sites were chosen which differed significantly with respect to pollution impact: Pilões (reference site, less polluted), Moji (most polluted) and Paranapiacaba (mildly polluted). Annual averages of ionic concentrations in precipitation found in open field and below the tree canopy amounted to 5 and 10 mg.L-1, respectively, for sulfate-S, 0.5 and 0.7 mg.L-1 for nitrate, 0.63 and 1.14 mg.L-1 for fluoride, 2.2 and 2.8 mg.L-1 for ammonium-N, 0.69 and 2.15 mg.L-1for Mg, and 3.1 and 7.7 mg.L-1 for Ca at the most polluted site (Moji). The relatively ”clean” reference site (Pilões) attained 1/3 to 1/9 of these averages, thus clearly reflecting the difference in air pollution load. Chemical composition in the liquid phase is completely changed when precipitation infiltrates the soil profile. Nitrate concentration increases by the factor 3 to 22. A clear increase is also found for sulfate and chloride. Concentration changes during ecosystem passage of seepage are interpreted in relation to chemical reactions taking place in different compartments. They are characterized by an almost complete retention of ammonium and some retention of sulfate in the upper soil layers, and at the most polluted site by mobilization of Al from soil minerals and very high leaching of nitrate as a consequence of nitrification of organic matter. The forests under investigation are characterized by a very high input from the atmosphere. Between 122 and 255 kg S per hectare are annually carried into soil by precipitation in the form of sulfate, 7 to 70 kg of nitrogen mainly in the form of ammonium, 4 to 28 kg of fluoride. Input of ammonium and organic bound nitrogen is followed by nitrification in the topsoil. At the most polluted site (Moji), nitrate output with seepage amounts to 271 kg N per ha and year, sulfate output to more than 386 kg S. Soil acidification associated with turnover of sulfur and nitrogen is followed by the release of aluminum from soil minerals, and leaching of ionic forms of Al (up to 240 kg Al per hectare annually). Transfer of aluminum ions to groundwater and surface water can have serious ecological effects. Alkalinity is consumed, and the water is subject to acidification.

Metazoans have evolved conserved mechanisms to promote cell survival under low oxygen tensions by initiating a transcriptional cascade centered on the action of Hypoxia Inducible transcription Factors (HIFs). In aerobic conditions, HIFs are inactivated by ubiquitin-proteasome-mediated degradation of their a subunit, which is dependent on prolyl hydroxylation by 2-oxoglutarate (2-OG) and Fe(II)-dependent prolyl hydroxylases (PHDs). In hypoxia, HIF-$\alpha$ is no longer hydroxylated and is therefore stabilised, activating a global transcriptional response to ensure cell survival. Interestingly, HIFs can also be activated in aerobic conditions, however the mechanisms of this oxygen-independent regulation are poorly understood. Here, I have explored the role of the vacuolar H+-ATPase (V-ATPase), the major proton pump for acidifying intracellular vesicles and facilitating lysosomal degradation, in regulating HIF-$\alpha$ turnover. Unbiased forward genetic screens in near-haploid human cells identified that disruption of the V-ATPase leads to activation of HIFs in aerobic conditions. Rather than preventing the lysosomal degradation of HIF-$\alpha$, I found that V-ATPase inhibition indirectly affects the canonical proteasome-mediated degradation of HIF-$\alpha$ isoforms by altering the intracellular iron pool and preventing HIF-$\alpha$ prolyl hydroxylation. In parallel, I characterised two putative mammalian V-ATPase assembly proteins, TMEM199 and CCDC115, identified by the forward genetic screen and subsequent mass spectrometry analysis. I confirmed that both TMEM199 and CCDC115 are required for V-ATPase function, and established assays to determine how TMEM199 and CCDC115 associate with components of the core V-ATPase complex. Lastly, to measure how V-ATPase activity leads to changes in the labile iron pool, I developed an endogenous iron reporter using CRISPR-Cas9 knock-in technology. This approach confirmed that iron homeostasis is impaired during V-ATPase inhibition, and demonstrated that exogenous ferric iron can restore the labile iron pool in a transferrin-independent manner. Together my studies highlight a crucial link between V-ATPase activity, iron homeostasis, and the hypoxic response pathway.

A tecnologia de fabricação de bebidas lácteas envolve a mistura de leite e soro, podendo ser fermentada por bactérias do iogurte ou probióticas e adicionada de polpa de fruta e outros aditivos permitidos. O produto final deve conter bactérias lácticas viáveis em número adequado. Os objetivos deste trabalho foram desenvolver bebidas lácteas probióticas a partir das misturas leite-soro e estudar sua vida-de-prateleira. O efeito da composição da cultura probiótica (Lactobacillus delbrueckii subsp. bulgaricus, L. acidophilus, L. rhamnosus e Bifidobacterium animalis subsp. lactis em co-cultura com Streptococcus salivarius subsp. thermophilus) e o efeito do pH final da fermentação na cinética de acidificação, pós-acidificação e contagem de bactérias probióticas foram estudados em soro de queijo Minas frescal e em diferentes misturas leite-soro. Bebidas lácteas probióticas foram desenvolvidas a partir das diferentes misturas leite-soro e a vida-de-prateleira foi determinada ao longo de 28 dias de armazenamento do produto a 4°C. As características dos produtos foram seguidas pelas determinações físico-químicas, microbiológicas e sensoriais. O soro apresentou efeito positivo sobre a velocidade máxima das co-culturas estudadas, bem como as diferentes composições das co-culturas influenciaram o parâmetro estudado. Todas as culturas apresentaram contagens maiores em pH final de fermentação 4,5, quando comparadas às obtidas em pH 5,5. A co-cultura StLb foi a mais rápida a fermentar os diferentes meios estudados e, a StLr, a mais lenta. Com a adição de açúcar e de estabilizante, os parâmetros cinéticos mostraram comportamento diferenciado daqueles obtidos em misturas leite-soro. Nas bebidas lácteas, as contagens de B. lactis mantiveram-se acima do limite exigido pela legislação até 28 dias de armazenamento do produto refrigerado. A pós-acidificação, cor e reologia variaram durante o período de armazenamento, influenciando a análise sensorial, cujos atributos obtiveram maior aceitação em bebidas elaboradas com 10% de sólidos lácteos. Os resultados indicaram que a bebida láctea elaborada com a co-cultura StBl foi a melhor alternativa para desenvolvimento de uma bebida funcional com boas características sensoriais. / The technology of production of lactic beverages involves the mixture of milk fermented by yoghurt or probiotic bacteria and whey in appropriate proportions, and the addition of fruit pulp and other allowed additives. The final product should contain viable lactic bacteria in appropriate counts. The objective of this work was to develop a probiotic lactic beverage from milk-whey mixtures and to study its shelf-life. The effect of the composition of the probiotic culture (Lactobacillus delbrueckii ssp. bulgaricus, L. acidophilus, L. rhamnosus and Bifidobacterium animalis ssp. lactis in co-culture with Streptococcus salivarius subsp. thermophilus) and the effect of the pH of the end of fermentation in the acidification kinetics, post-acidification and counts of probiotic bacteria were studied in Minas frescal cheese whey and in different mixtures milk-whey. Probiotic lactic beverages were developed from different milk-whey mixtures and the shelf-life was determined along 28 days of storage of the product at 4°C. The characteristics of the products were followed by determination of post-acidification, total acidity, color, rheology, probiotic viability and sensorial analysis. Whey presented positive effect on maximum acidification rates of the studied co-cultures, as well as the different compositions of the co-cultures influenced the studied parameter. All cultures presented higher counts when fermentation was stopped at pH 4.5, when compared to pH 5.5. The co-culture StLb presented the fast acidification performance while StLr, the slowest. The addition of sucrose and stabilizer affected the acidification kinetic parameters. In probiotic lactic beverages, counts of B. lactis were higher than the limit required by the legislation until 28 days of cool storage of the product. The post-acidification, color and rheological parameters varied during shelf-life, influencing the sensorial analysis, whose attributes obtained higher acceptance in the elaborated beverage with 10% of total solids. The results indicated that the lactic beverage elaborated with the co-culture StBl was the best alternative for development of a functional lactic beverage with good sensorial characteristics.

This thesis examines sulfide oxidation in 4 physically and mineralogically diverse acid sulfate soil (ASS) materials collected from coastal floodplain sites in north-eastern New South Wales. The aim of this study is to gain further understanding of the process of sulfide oxidation in ASS materials, which will allow improved and more effective management strategies to be applied to these materials. The process of sulfide oxidation was examined using laboratory incubation experiments. The oxidation of pyrite was the primary cause of initial acidification of the ASS materials studied. Although the acid volatile sulfur fraction increased in concentration by an order of magnitude over the initial 8 days of incubation, the subsequent oxidation of this fraction did not result in substantial acidification. Sulfate (SO42-) was the dominant sulfur species produced from sulfide oxidation, however, water-soluble SO42- was a poor indicator of the extent of sulfide oxidation. The sulfoxyanion intermediates thiosulfate (S2O32-) and tetrathionate(S4O62-) were only detected in the early stages of incubation, and their relative abundance appeared to be pH dependent. The diminishing presence of these 2 sulfur species as oxidation progressed was indicative that ferric iron (Fe3+) and bacterial catalysis were driving the oxidation processes. The rate of sulfide oxidation, and consequent rate of acidification, was highly dependent on the soil pH and oxygen availability. Accelerated sulfide oxidation was only observed at low pH (i.e. pH < 4.0) when oxygen availability was not limited. The application of sub-optimal amounts of neutralising agents prevented severe soil acidification in the short-term (i.e. up to 2 months), but had little effect on decreasing the rate of sulfide oxidation and acidification in the long-term. Sub-optimal amounts of CaCO3 accelerated sulfide oxidation and acidification of the peaty marcasitic ASS material resulting in elevated soluble Fe and Al concentrations. For some of the ASS materials, sub-optimal applications of seawater-neutralised bauxite refinery residue (SNBRR) also resulted in elevated soluble Al concentrations. The response of partially-oxidised ASS materials to the exclusion of oxygen was variable. The rate of sulfide oxidation, acidification and the production of soluble oxidation products generally decreased markedly when subjected to anoxia. However, especially in highly acidic ASS materials (i.e. pH < 3.5), sulfide oxidation and acidification generally occurred (albeit at much slower rates), most probably due to oxidation by Fe3+. Rapid sulfide re-formation occurred in the peat ASS material that had been oxidised for 63 days, with 0.47% reduced inorganic sulfur (SCR) formed over 60 days of anoxia. Biogeochemical sulfide formation consumes acidity, however, sulfide re-formation was ineffective in reversing acidification under the conditions of this experiment. The peroxide oxidation methods examined were method dependent and substantially underestimated peroxide oxidisable sulfur, sulfidic acidity and net acidity. The precipitation of jarosite during peroxide oxidation was a major factor contributing to the underestimation in these ASS materials. Clay mineral dissolution may contribute towards the underestimation of both sulfidic and net acidity using peroxide oxidation methods. The atmospheric loss of sulfur and acidity was also identified as a possible additional interference. This study has shown that the initial pH of an ASS material is a useful indicator (additional to those already used) of the potential environmental hazard of an ASS material when oxygen is expected to be non-limiting, such as when ASS materials are excavated and stockpiled. The recommended action criteria need to be reassessed as the data indicate that the current criteria are conservative for alkaline and neutral ASS materials, but should be lowered for all acidic ASS materials (i.e. pH < 5.5) to 0.03% sulfide regardless of texture. Alternative strategies are necessary for the management of ASS materials that are subject to oxidation when the addition of optimal rates of neutralising materials cannot be ensured. The treatment of sites containing actual ASS materials by management strategies that rely on oxygen exclusion need to be accompanied by strategies that include either acid neutralisation or containment in order to reduce acid export from the site. The peroxide oxidation methods examined were subject to substantial interferences, and consequently are unable to reliably provide accurate measurements of the reduced inorganic sulfur fraction, sulfidic acidity, and net acidity in ASS materials.

L'acidification des océans (AO) est un phénomène induit par l'augmentation de la pression partielle en CO2 (pCO2) atmosphérique d'origine anthropique caractérisé par une diminution du pH de l'eau de mer et une modification des paramètres de la chimie des carbonates. L'AO est susceptible d'impacter toutes les espèces marines mais les organismes calcifiants y seraient les plus sensibles. Dans le cadre de cette thèse, les réponses physiologiques des algues Corallinacées (algues rouges calcaires) et de la crépidule (mollusque gastéropode) ont été étudiées sous des conditions de pCO2 actuelles et prévues pour la fin du siècle. Les réponses des Corallinacées à l'AO en termes de production primaire et de calcification ont varié suivant les espèces, d'une absence de réponse chez Corallina elongata à une diminution de 80% de la calcification nette journalière chez le maërl Lithothamnion corallioides. La crépidule est en revanche une espèce très tolérante à l'augmentation de la pCO2. Aucune dépression métabolique n'a été observée chez les adultes malgré une diminution de la calcification nette induite par l'augmentation de la dissolution de la coquille externe. La taille des jeunes stades de son cycle de vie (embryons et larves) a été réduite sous conditions de pCO2 élevées mais aucune diminution de la respiration ou mortalité importante n'a été observée. Ces espèces calcifiantes ont une importance écologique majeure au sein des écosystèmes côtiers de Manche et Atlantique nord-est. Les changements physiologiques induits par l'AO sur ces espèces clé sont susceptibles de modifier les flux de matière et d'énergies au sein des écosystèmes dans lesquels elles sont des espèces ingénieures.

Radiative forcing by increased atmospheric levels of greenhouse gases (GHGs) produced by human activities could lead to strongly undesirable effects on oceans and their dependent human systems in the coming centuries. Such dangerous anthropogenic interference with the climate system is a possibility the UN Framework Convention on Climate Change (UNFCCC) calls on nations to avoid. Unacceptable consequences of such interference could include inundation of coastal areas and low-lying islands by rising sea level, the rate of which could exceed natural and human ability to adapt, and ocean acidification contributing to widespread disruption of marine and human food systems. Such consequences pose daunting socioeconomic costs, for developing nations in particular. Drawing on existing literature, we define example levels of acceptable global marine change in terms of global mean temperature rise, sea level rise and ocean acidification. A global-mean climate model (ACC2), is implemented in an optimizing environment, GAMS, and coupled to an economic model (DICE). Using cost-effectiveness analysis and the tolerable windows approach (TWA) allows for the computation of both economically optimal carbon dioxide emissions pathways as well as a range in carbon dioxide emissions (the so-called ``emissions corridor'') which respect the predetermined ceilings and take into account the socio-economically acceptable pace of emissions reductions. The German Advisory Council on Global Change (WBGU) has issued several guardrails focused on marine changes, of which we find the rate and absolute rise in global mean temperature to be the most restrictive (0.2 degrees Celsius per decade, 2 degrees Celsius total). Respecting these guardrails will require large reductions in both carbon and non-carbon GHGs over the next century, regardless of equilibrium climate sensitivity. WBGU sea level rise and rate of rise guardrails (1 meter absolute, 5 cm per decade) are substantially less restrictive, and respecting them does not require deviation from a business-as-usual path in the next couple hundred of years, provided common assumptions of Antarctic ice mass balance sensitivity are correct. The ocean acidification guardrail (0.2 unit decline relative to the pre-industrial value) is less restrictive than those for temperature, but does require emissions reductions into the coming century.

This thesis examines sulfide oxidation in 4 physically and mineralogically diverse acid sulfate soil (ASS) materials collected from coastal floodplain sites in north-eastern New South Wales. The aim of this study is to gain further understanding of the process of sulfide oxidation in ASS materials, which will allow improved and more effective management strategies to be applied to these materials. The process of sulfide oxidation was examined using laboratory incubation experiments. The oxidation of pyrite was the primary cause of initial acidification of the ASS materials studied. Although the acid volatile sulfur fraction increased in concentration by an order of magnitude over the initial 8 days of incubation, the subsequent oxidation of this fraction did not result in substantial acidification. Sulfate (SO42-) was the dominant sulfur species produced from sulfide oxidation, however, water-soluble SO42- was a poor indicator of the extent of sulfide oxidation. The sulfoxyanion intermediates thiosulfate (S2O32-) and tetrathionate(S4O62-) were only detected in the early stages of incubation, and their relative abundance appeared to be pH dependent. The diminishing presence of these 2 sulfur species as oxidation progressed was indicative that ferric iron (Fe3+) and bacterial catalysis were driving the oxidation processes. The rate of sulfide oxidation, and consequent rate of acidification, was highly dependent on the soil pH and oxygen availability. Accelerated sulfide oxidation was only observed at low pH (i.e. pH < 4.0) when oxygen availability was not limited. The application of sub-optimal amounts of neutralising agents prevented severe soil acidification in the short-term (i.e. up to 2 months), but had little effect on decreasing the rate of sulfide oxidation and acidification in the long-term. Sub-optimal amounts of CaCO3 accelerated sulfide oxidation and acidification of the peaty marcasitic ASS material resulting in elevated soluble Fe and Al concentrations. For some of the ASS materials, sub-optimal applications of seawater-neutralised bauxite refinery residue (SNBRR) also resulted in elevated soluble Al concentrations. The response of partially-oxidised ASS materials to the exclusion of oxygen was variable. The rate of sulfide oxidation, acidification and the production of soluble oxidation products generally decreased markedly when subjected to anoxia. However, especially in highly acidic ASS materials (i.e. pH < 3.5), sulfide oxidation and acidification generally occurred (albeit at much slower rates), most probably due to oxidation by Fe3+. Rapid sulfide re-formation occurred in the peat ASS material that had been oxidised for 63 days, with 0.47% reduced inorganic sulfur (SCR) formed over 60 days of anoxia. Biogeochemical sulfide formation consumes acidity, however, sulfide re-formation was ineffective in reversing acidification under the conditions of this experiment. The peroxide oxidation methods examined were method dependent and substantially underestimated peroxide oxidisable sulfur, sulfidic acidity and net acidity. The precipitation of jarosite during peroxide oxidation was a major factor contributing to the underestimation in these ASS materials. Clay mineral dissolution may contribute towards the underestimation of both sulfidic and net acidity using peroxide oxidation methods. The atmospheric loss of sulfur and acidity was also identified as a possible additional interference. This study has shown that the initial pH of an ASS material is a useful indicator (additional to those already used) of the potential environmental hazard of an ASS material when oxygen is expected to be non-limiting, such as when ASS materials are excavated and stockpiled. The recommended action criteria need to be reassessed as the data indicate that the current criteria are conservative for alkaline and neutral ASS materials, but should be lowered for all acidic ASS materials (i.e. pH < 5.5) to 0.03% sulfide regardless of texture. Alternative strategies are necessary for the management of ASS materials that are subject to oxidation when the addition of optimal rates of neutralising materials cannot be ensured. The treatment of sites containing actual ASS materials by management strategies that rely on oxygen exclusion need to be accompanied by strategies that include either acid neutralisation or containment in order to reduce acid export from the site. The peroxide oxidation methods examined were subject to substantial interferences, and consequently are unable to reliably provide accurate measurements of the reduced inorganic sulfur fraction, sulfidic acidity, and net acidity in ASS materials.

Nitrogen availability and transformation in acidified and N saturated soils of Czech (The Bohemian Forest, Ore Mountains) and Ukraine (Pop Ivan massif) mountain forest ecosystems were investigated. The study was primarily focused on the role of microbial immobilization in soil N retention. The study was based on field measurements (ion exchange resins), analyses of selected soil biochemical and microbial characteristics, and on laboratory experiments (15N labelling).

La digestion anaérobie en voie sèche représente une opportunité de développement de la méthanisation sur le territoire français au vu des gisements agricoles disponibles sur le territoire. Toutefois, l’importance des verrous scientifiques et technologiques de par leur nombre et leur complexité rend cette technologie non mature et peu développée sur le territoire français. Dans ces travaux de thèse, il a été étudié dans un premier axe la mise au point de la détermination de la demande chimique en oxygène (DCO) pour des substrats solides avec un kit commercial rendant celle-ci utilisable sans dilution des déchets et utilisant une faible quantité de réactifs. Cette méthode est un outil de suivi des installations. Un deuxième axe d’étude qui s’est attaché à l’étude de la phase d’acidification, verrou majeur de la méthanisation phase sèche, a démontré l’impact de la conservation et de l’origine des inocula sur leur capacité à gérer une phase d’acidification en présence de déchets facilement hydrolysables. L’inoculum est un paramètre majeur de la méthanisation voie sèche et est pourtant peu étudié. Un troisième axe de cette thèse concerne l’étude des transferts hydriques sur des substrats d’origine agricole par une méthodologie de traçage et de modélisation via le modèle à deux régions d’eau mobile et immobile. L’évolution des transferts hydriques a été étudiée au cours de la digestion anaérobie de fumier bovin en digesteur 60 L montrant une diminution de la perméabilité du massif après le deuxième pic de production de méthane. Par conséquent, tout l’inoculum recirculé passe par les côtés et non au sein du massif solide. Deux fréquences de recirculation ont été testées permettant d’obtenir une amélioration de la production de méthane d’environ 20 %. La caractérisation des transferts hydriques obtenus pour ces deux modalités sont identiques après 32 jours de dégradation anaérobie. Le gain de méthane obtenu se fait donc jusqu’au deuxième pic de production de biogaz par la recirculation. Les bilans hydriques et massiques effectués sur ces digesteurs 60 L démontrent que 36 % de la matière organique sont retrouvés dans le digestat montrant un procédé non optimisé. Le quatrième axe d’étude a été de comprendre et d’étudier la dynamique des populations méthanogènes au sein de digesteurs de méthanisation voie sèche de 60 L selon deux configurations. Des expérimentations modulant l’immersion du massif solide ont conduit à obtenir une amélioration de 13 % de production de méthane pour la condition favorisant l’immersion. Cette augmentation de production de méthane est induite par une plus forte quantité de Methanosarcinaceae. La dynamique des populations méthanogènes a été étudiée dans la phase solide et liquide au cours de la digestion anaérobie montrant un transfert microbien de la phase liquide à solide pour un ordre des bactéries hydrogénotrophes, une hiérarchie de ces « hydrogénotrophes » dans le milieu et un fort développement des « acétotrophes » dans le milieu solide servant de support. Dans un cinquième axe, la mise en oeuvre de la tomographie électrique sur un digesteur de 30 m3 a permis de valider son utilisation pour localiser la phase liquide, les zones de potentiels méthane et les zones dégradées dans un container en fonction des protocoles de remplissage et de vidange du digesteur. Cette méthode est disponible pour localiser les zones mortes et donc pour optimiser le procédé de méthanisation en voie sèche type batch. A travers ces expérimentations menées à différentes échelles et avec différentes problématiques, des méthodologies ont été adaptées pour la compréhension des mécanismes et le suivi du procédé de méthanisation par voie sèche. / The dry anaerobic digestion (AD) process is an opportunity to develop the methanization in France. Agricultural waste is abundant in France. However, many scientific and technical locks are complex and must be solved to develop the dry anaerobic digestion process in France. In this work, the chemical oxygen demand (COD) method was adapted for solid waste no implying waste dilution or a high quantity of reagent. This COD method was available to monitor and manage the dry AD process. The study of acidification phase, a major lock of the dry AD process, showed that the storage condition and the origin of inoculum influence the capacity to manage this phase. The inoculum is a major parameter of the dry AD process. But, the inoculum is few studied.On another part of experiments concerned the water transfers studied on agricultural waste with a tracing method. The modeling of the elution curves to determine the diffusion and the convective transfers was made with a model with two Mobile-Immobile regions. The evolution of water transfers was studied during the AD cycle showing a decrease about the permeability of solid phase after the second peak of methane production. Thus, the inoculum passes on the board of solid phase. Two recirculations were tested allowing to obtain an improvement the methane production about 20 % after the AD cycle. The water transfers of these two recirculations modalities were identical after the AD cycle. The improvement of methane production occurred after the second peak of the methane production. Water and mass balances made showing that 36 % of organic matter was find in the digestat. Consequently, the process was not optimized. Others experiments modulating the immerged part of solid phase showed an improvement of the methane production about 13 % with the increasing of immerged part. This methane improvement was induced by the development of Methanosarcinaceae. The methanogens dynamics were studied in the liquid and solid phases during the AD process showing (i) a population transfer between the liquid phase to the solid phase, (ii) a hierarchy of hydrogenotrophs methanogens in the media, and (iii) a strong development of acetotrophs methanogens in the solid phase. In the final part, the electrical tomography was implemented in a dry AD batch at full scale (30 m3). This method was adapted to localize the liquid phase, the zones of methane potential and the degraded zones according to filling and the emptying protocols. This method can detect the “dead” zones of process in dry AD process.Though, experiments carried out at different scales and with different problematic and several methodologies were adapted to understand the dry AD process. Moreover, the optimization of dry AD process was finding to increase the methane production.

In der vorliegenden Arbeit wurde die Methode der magnetischen Kernspinresonanz (NMR) eingesetzt, um beim Schadstoffabbau stattfindende Prozesse und geochemische Reaktionen zerstörungs- und beprobungsfrei zu untersuchen. Dies ist möglich, da die gelösten Elektronenakzeptoren Sauerstoff und Eisen paramagnetisch sind und somit einen Ein uss auf die NMRRelaxationszeiten ausüben. Der lineare Zusammenhang zwischen der gelösten Sauerstoff- beziehungsweise Eisen-Konzentration und den NMR-Relaxationsraten 1/T1 und 1/T2 wurde quantifiziert. Weiterhin wurde der bereits bekannte Einfluss der Matrixoberflächen von porösen Medien auf die Relaxation von Wasser nachgewiesen. Die paramagnetischen Zentren auf Sandoberflächen führen ebenfalls zu einer Verkürzung der Relaxationszeiten. Es wurde gezeigt, dass die kleinsten Korngrößen der verwendeten Sande den größten Einfluss auf die Oberflächenrelaxation haben. Wird die Oberflächenrelaxation berücksichtigt, ist auch in porösen Medien die ermittelte lineare Abhängigkeit der Relaxationszeiten von der Ionenkonzentration anwendbar, um den Gehalt an gelösten paramagnetischen Ionen aus Relaxationsmessungen zu ermitteln. Beispielhaft wurde der Anstieg der Eisen(III)-Konzentration in der Porenlösung von natürlichen Sanden infolge der Auflösung eisenhaltiger Mineralien von den Oberflächen zeitlich und räumlich detailliert betrachtet. Eine durchgeführte Modellierung zeigte, dass das Reaktionssystem zu Beginn der Reaktion von der Diffusion dominiert wird, am Ende dann die Reaktionsgeschwindigkeit der bestimmende Parameter ist. Die beim biologischen Schadstoffabbau auftretenden Redoxprozesse des Eisens wurden durch rein chemische Reaktionen unter Verwendung von Oxidations- und Reduktionsmitteln simuliert. Die zeitlich und räumlich detaillierte Beobachtung des Anstiegs beziehungsweise des Abfalls der gelösten Eisen(III)-Konzentration in der (Poren-)Lösung war mit NMR-Relaxometrie trotz der Schnelligkeit der Reaktionen möglich. Mit Hilfe der anschliessenden Modellierung wurde der wichtige Einfluss des pH-Wertes auf den genauen Ablauf der Reaktionen deutlich gemacht. Nur in sehr sauren pH-Bereichen (pH < 3) liegen die Eisen(III)-Ionen in Lösung vor. Weiterhin wurde der Einfluss der Mikroorganismen selbst auf die NMR-Relaxations- und Diffusionsmessungen untersucht. Im Rahmen dieser Arbeit wurde an Medien mit Lactobacillus und Penicillium eine Verschiebungen in den Relaxationszeitverteilungen hin zu kleineren Relaxationszeiten gemessen. Dies basiert auf der bereits bekannten Verringerung der Mobilität der Spins innerhalb der Biomasse. Für Bakterien von Geobacter metallireducens konnte erstmals der Verbrauch von Eisen(III)-Ionen durch Reduktion während des Wachstum anhand der ansteigenden T2-Relaxationszeit gezeigt werden.