Le radiocarbone (14C) et le tritium (3H) sont libérés dans l'environnement de manière naturelle et par les activités nucléaires. Les rejets devant perdurer pendant les prochaines décennies, il est primordial de prévoir leur devenir et leur temps de résidence dans les sols. L'objectif de cette thèse est de proposer une prévision quantitative et une modélisation simple du devenir de 14C et 3H dans les matières organiques du sol (MOS). L'originalité de ce travail est double: nous faisons l'hypothèse que l'incorporation et le devenir des atomes d'hydrogène non-échangeable (HNE) dans le sol sont couplés à la dynamique du carbone; l'approche choisie est le traçage naturel ou artificiel par les isotopes stables 13C et 2H.A travers le traçage naturel par le 13C in situ, nous avons quantifié le carbone récemment incorporé par la végétation sur quelques décennies. Nous avons alors adapté le modèle RothC à la dynamique du C profond des sols. Cela nous a permis de prévoir que 10% du C persisteront pendant plusieurs siècles dans les couches profondes. Les expériences croisées d'incubation de composés marqués en 13C et 2H nous a permis de montrer que l’activité microbienne est le moteur de l’incorporation d’hydrogène de l’eau dans les MOS et nous a permis d'établir la stœchiométrie CH des biotransformations. Ces expérimentations ont permis de proposer un modèle de la dynamique couplée de C et H des MOS à court et moyen terme (décennies). Une méta-analyse des corrélations entre les teneurs en 13C et 14C de sols mondiaux nous a permis de démontrer que l'enrichissement en 13C des MOS peut être expliqué en totalité par le rapport 13C/12C de la végétation dont elles sont issues. / Radiocarbon (14C) and tritium (3H) are naturally released into the environment but also through nuclear activities. The releases are expected to persist for the next decades, it is important to predict their fate and their residence time in soils. The objective of this thesis is to propose a quantitative prediction and a simple modeling of the fate of 14C and 3H in soil organic matter (SOM). The originality of this work is twofold: first, we hypothesize that the incorporation and fate of NEH atoms in the soil are coupled to the carbon dynamics. Second, we chose to trace carbon and hydrogen by natural or artificial 13C and 2H tracing.Through natural in situ 13C tracing, we quantified the carbon recently incorporated by vegetation in few decades. Deep horizons contain a large part of this carbon (typically 20 to 30%). We adapted the RothC model to the deep soil C dynamics. This allowed us to predict that 10% of C will persist for several centuries in the deeper layers. The labelling experiments showed that the microbial activity is driving the incorporation of hydrogen from water into SOM, and allowed us to establish the CH stoichiometry of biotransformations. These experiments were a mean to propose a model of the coupled C and H dynamics of the SOM in the short and medium term (decades). The results of this thesis contribute as well to the improvement of the interpretation of natural abundances in 13C and 2H stable isotopes. A meta-analysis of the correlations between the 13C and 14C concentrations of global soils has demonstrated that the 13C enrichment of deep organic matter can be fully explained by the 13C/12C ratio of the vegetation from which they are derived.

Arctic regions are expected to be highly sensitive to climate change regarding the prediction of disproportionately large increases in surface temperatures and their related influence over the hydrological cycle and permafrost thaw. These modifications have the potential to impact biogeochemical cycles in these regions and in particular the mobilization of organic carbon into rivers. The most crucial period in arctic rivers hydrological cycle is the spring freshet that can account for most of the annual organic carbon transfers to the ocean in a very short window of time. The focus of this thesis was to monitor the dynamic of DOM in terms of quantity and quality along the hydrological cycle of the Yenisei river, through DOM characterization approaches to reveal seasonal variations in its composition, sources, age and degradation state. The first step was to make a review of the full range of existing DOM characterization approaches in worldwide river systems to identify the most widely used, the most relevant and reliable ones. Through the development of a DOM quality measurements database, we have been able to evaluate the geographical coverage of DOM characterization studies, to give estimates and ranges of values of the main reported DOM characterization variables and to observe global trends of DOM quality across latitudinal gradient. Second stage was to investigate DOC dynamic in the Yenisei river with regard to quantity and links with water chemistry and hydrology. We conducted sampling campaigns during three consecutive years (2014 to 2016), covering with a high sampling frequency the spring flood period to capture its very dynamic evolution. We reported DOC concentrations that followed the hydrograph with highest concentrations observed a few days before peak discharge. DOC concentration also responded to discharge variation (increase, likely due to higher precipitation) in early autumn. We reported average DOC flux over the three sampling years of about 4.53 Tg yr-1 which is within the range of values reported in the literature. We observed interannual variability with annual export estimates ranging from 5.45 Tg yr-1 in 2014 to 3.57 Tg yr-1 in 2016, likely driven by discharge amplitude. We confirmed the important role of spring freshet in DOC export with on average more than 65% occurring during this period (roughly May/June). Third point was to determine DOM quality combining characterization techniques. Combination of approaches helped to strengthen observations and cross validate interpretations. Most of the variables reported from the different characterization techniques confirmed one each other. The use of lignin biomarkers, optical properties and radiocarbon age of DOM allowed us to trace DOM main sources has primarily deriving from recently produced organic matter leached from boreal forest litter and top soil horizon during the spring flood and older organic matter derived from deeper soil horizons during low flow period.

Les comètes sont les vestiges de la "nébuleuse solaire", c'est-à-dire du disque proto-planétaire qui a engendré notre système solaire. Elles sont composées de glaces et de poussières contenant des matériaux et molécules organiques ainsi que des minéraux. La composition des comètes reflète au premier ordre celle des glaces interstellaires. Toutefois, cette filiation n'est pas avérée. Au cours de la période pré-accrétionelle, le matériau cométaire a potentiellement subi l'action de nombreux processus physiques (chauffage, irradiation UV et particulaire) qui ont nécessairement altéré sa structure et sa composition.L'objectif ce cette thèse est de mieux comprendre, grâce à des expériences de laboratoire, l'effet des processus de chauffage et d'irradiation ionique sur des analogues de matière cométaire (glaces et matériaux carbonés). Une partie de ces expériences porte sur l’évolution de la deutération des molécules organiques lors du réchauffement des glaces. Elles ont été menées à l’IPAG (Institut de Planétologie et d’Astrophysique de Grenoble) et au PIIM (Laboratoire de Physique des Interactions Ioniques et Moléculaires) à Marseille. Elles démontrent qu'un équilibrage isotopique a lieu au cours de la cristallisation, sur des échelles de temps de l'ordre de l'heure à des températures supérieures à 120 K, pour les groupements chimiques capables de former des liaisons hydrogènes avec l'eau (groupements -OH et -NH2). Cet équilibrage efface ainsi le fractionnement initial de certaines molécules, ou certains groupements chimiques, dans la phase post-sublimation. Ce résultat permet en particulier d'expliquer la deutération sélective des isotopologues du méthanol dans les cœurs chauds des proto-étoiles.Un second volet de la thèse a porté sur l'étude de la formation de la matière organique réfractaire présente dans les astéroïdes et les comètes. Des expériences de chauffage et d’irradiation ont été menées à l'IPAG, au GANIL (Grand accélérateur national d’ions lourds) à Caen, et au CSNSM (Centre de Sciences Nucléaires et de Sciences de la Matière) à Orsay. Nous montrons qu'un chauffage au-delà de 400° C de précurseurs simples permet la formation de carbones désordonnés polyaromatiques dont la structure est proche de celle observée dans les objets primitifs du système solaire. Les effets de l’irradiation ionique sont plus difficiles à évaluer car ils dépendent du pouvoir d'arrêt des précurseurs cibles et des ions projectiles. Des contraintes sur les doses nucléaires maximales reçues par la matière primitive sont néanmoins déduites (D<14 eV/atome). In fine, ces simulations démontrent qu'un processus de chauffage apparaît comme beaucoup plus probable que les processus radiolytiques, mais une combinaison des deux ne peut pas être exclue.Enfin, cette thèse a bénéficié des premières données in situ de la mission spatiale européenne ROSETTA en orbite autour de la comète Churyumov-Gerasimenko (67P) de juillet 2014 à septembre 2016. L’analyse des données du spectro-imageur VIRTIS-M a permis de montrer qu’un matériau organique semi-volatile, contenant notamment des acides carboxyliques, est présent de manière quasi-homogène sur toute la surface de la comète 67P. / Comets are remnants of the "solar nebula", i.e. the protoplanetary disk from which our solar system formed. They are composed of ice and dust containing minerals and organic materials and molecules. The comets' composition reflects at the first order that of interstellar ices. However, this relationship has not been proven. During the pre-accretional phase, the comet material has potentially undergone the action of many physical processes (heat, UV and particule radiation) which have undoubtedly altered its structure and composition.This thesis objective is to better understand, through laboratory experiments, the effect of heating and ion irradiation processes on cometary matter analogues (ice and carbonaceous materials). Some of these experiments focuses on the evolution of the organic molecules deuteration during ice heating. They were conducted at the IPAG (Institute of Planetology and Astrophysics of Grenoble) and the PIIM (Physics Laboratory of Ionic and Molecular Interaction) in Marseille. They demonstrate that isotopic equilibration takes place during crystallization, on a timescale of an hour at temperatures above 120 K, for the chemical groups capable of forming hydrogen bonds with water (OH and NH2 chemical groups). Thus, this equilibration erases the initial fractionation of certain molecules or certain chemical groups, during the post-sublimation phase. This result explains in particular the selective deuteration of isotopologues methanol in protostars hot cores.A second part of the thesis focused on the study of the formation of refractory organic matter found in asteroids and comets. Heating and irradiation experiments were conducted at the IPAG, at the GANIL (Grand National Accelerator heavy ion) in Caen, and the CSNSM (Nuclear Sciences Centre and the Material Sciences) in Orsay. We show that heating simple precursors above 400° C allows the formation of disordered polyaromatic carbons whose structure is close to that observed in the primitive objetcs of the solar system. Ion irradiation effects are more difficult to assess because they depend on the stopping power of precursors target and projectile ions. Nevertheless, constraints on maximum nuclear doses received by primitive matter are deducted (D>14 eV/atom). Ultimately, these simulations demonstrate that heating processes appear to be much more likely than radiolytic processes, but a combination of the two can not be ruled out.

Nas mais diversas atividades industriais hoje existentes está presente a problemática dos resíduos gerados e seu gerenciamento. Os efluentes líquidos são uma grande fonte de poluição dos recursos hídricos, sendo necessário o controle das condições de seu descarte. Para efluentes contendo poluentes orgânicos uma das alternativas de tratamento que vem sendo muito utilizada é o uso de Processos Oxidativos Avançados - POA’s. Esses processos se baseiam na geração de radicais livres, principalmente o radical hidroxila (HO.), que possui alto poder oxidante e pode promover a degradação de vários compostos poluentes eficientemente. Esses processos têm obtido grande atenção devido ao aumento da complexidade e dificuldade no tratamento de águas residuárias, o que tem sido motivo para a busca de novas metodologias visando a remediação desses rejeitos. Diante disso, o presente trabalho tem por objetivo estudar os processos (POA’s), para a degradação da matéria orgânica em efluente oriundo da descontaminação de madeira tratada com Arseniato de Cobre Cromatado – CCA. Este efluente é gerado através de extração ácida em ciclos de madeira tratada com CCA que foram utilizados como postes tanto de eletricidade como de telefonia. O efluente gerado na extração ácida foi caracterizado através dos parâmetros de pH, Condutividade, Demanda Química de Oxigênio, Carbono Orgânico Dissolvido, Sólidos totais e metais. Após caracterização, o efluente foi submetido aos processos oxidativos avançados de Fotólise, Fotocatálise heterogênea, Eletrólise e Fotoeletrooxidação, a fim de degradar a matéria orgânica. Depois de realizados os processos, o efluente foi caracterizado novamente com os mesmos parâmetros. Pode-se concluir que todos os processos utilizados alcançaram resultados positivos, degradaram a matéria orgânica, mas o processo que obteve melhor rendimento de degradação foi o de Eletrólise que degradou 68% da matéria orgânica presente no efluente. / In the most diverse industrial activities exist today is present the problem of waste generated and its management. Liquid effluents are a major source of pollution of water resources, requiring the control of the disposal conditions. For wastewater containing organic pollutants the use of Advanced Oxidation Processes - POA's has been widely used. These processes are based on the generation of free radicals, especially the hydroxyl radical (HO.), which has high oxidizing power and can promote the degradation of several polluting compounds efficiently. These processes have achieved great attention due to the increasing complexity and difficulty in the treatment of residual waters, which has been the reason for the search of new methods for remediation of these wastes. Therefore, this paper aims to study these processes (POA's) for the degradation of organic matter in the effluent coming from the decontamination of wood treated with CCA - chromated copper arsenate. This effluent is generated by cycles of acid extraction of wood treated with CCA which were used as both telephone and electricity poles. The effluent generated by the acid extraction was characterized by the parameters pH, conductivity, chemical oxygen demand, dissolved organic carbon and metals. After characterization, the effluent was subjected to advanced oxidation processes photolysis, heterogeneous photocatalysis, Electrolysis and photoelectrooxidation (which are the three processes together) in order to degrade organic matter. After the effluent treatment, the solution was again characterized by the same parameters. It can be concluded that all the processes used have achieved positive results, degradeding organic matter, but the process that showed the best performance degradation was the electrolysis with 68% less organic matter.

La microflore joue un rôle majeur dans la mobilité des éléments métalliques et métalloïdes dans les sols. L’activité bactérienne globale d’oxydation de l’AsIII en AsV tend à diminuer la toxicité et la mobilité de l’arsenic (As) dans les sols, cependant l’effet de la matière organique (MO) sur cette activité n’a pas été déterminé jusqu’à présent. Il est important de répondre à cette question car sur des sites pollués, un apport de MO peut être préconisé dans le cadre d’opérations de phyto-stabilisation. Par ailleurs, dans un contexte de pollution diffuse, les pratiques agricoles d’amendement des sols pourraient avoir un impact sur le transfert d’As. L’objectif de ce projet de thèse était donc de quantifier l’influence de la MO sur la spéciation de l’As par la microflore de sols pollués, et les conséquences de ce processus sur la mobilité du métalloïde. L’influence de la MO sur la spéciation de l’As a été évaluée (1) au niveau physiologique et moléculaire, sur l’activité de deux souches pures et (2) au niveau global, par l’évaluation de l’activité d’oxydation de l’AsIII par les communautés microbiennes de sols pollués et des incubations de sols. L’effet de la nature même de la MO a été examiné à travers la comparaison de substrats simples et complexes. Les expériences réalisées avec les souches de Thiomonas delicata et Herminiimonas arsenicoxydans ont montré un effet négatif de la MO sur la vitesse spécifique d’oxydation de l’AsIII. L’extrait de levure (EdL) induit une diminution de l’expression du gène aioA codant pour la grande sous-unité de l’arsénite-oxydase permettant l’oxydation de l’arsenic, avec les deux souches pures. Au niveau plus global des communautés microbiennes de sols, l’activité AsIII-oxydantes a été évaluée sur 8 sols pollués par de l’As. Les mesures ont été effectuées dans des milieux de cultures contenant différentes concentrations de MO. Deux MO complexes ont été comparées : l’EdL et une mixture synthétique de molécules organiques (SMOM) dont la composition a été inspirée par les caractéristiques de la MO de sols réels (rapport C/N, contenu en groupes fonctionnels). Des corrélations ont été recherchées entre les caractéristiques des sols et la constante de vitesse d’oxydation de l’AsIII par la microflore, avec et sans ajout de MO. La vitesse d’oxydation de l’AsIII par la microflore des sols semble limitée par la MO disponible, et cette limitation est levée par un apport de 0,08 g.L-1 de C apporté sous forme d’EdL ou de SMOM. Lorsque l’apport de MO s’élève à 0,4 g.L-1 de C, des résultats divergents sont observés : l’EdL est moins inhibiteur que la SMOM. Enfin, une expérience a été réalisée dans le but d’évaluer l’influence combinée de l’activité microbienne et de l’apport de SMOM sur la mobilisation de l’As présent dans quatre sols pollués, incubés au laboratoire en suspension. Une mobilisation dans la phase aqueuse de l’As présent dans les sols pollués est observée en présence de SMOM et de microorganismes actifs. Ce travail de thèse apporte un éclairage sur le rôle important joué par le métabolisme de la MO au sein du cycle biogéochimique de l’As, phénomène devant être pris en compte lors des études visant à optimiser la remédiation des sites pollués / The soil microflora plays a major role in the mobilization of metals and metalloids in soils. The global bacterial oxidation of AsIII to AsV tends to decrease the toxicity and mobility of arsenic in soils. The effect of organic matter (OM) on bacterial AsIII oxidation in presence of oxygen and its potential impact on the behavior of arsenic in non-saturated soils has not been determined up to date. However, supply of OM on polluted sites can be proposed in the context of a phytostabilization operation. Furthermore, agricultural soils affected by diffuse As pollution may be fertilized by organic amendments that could impact arsenic transfer. The objective of the present PhD thesis was to quantify the influence of OM on the speciation of As by the polluted soil microflora and the consequences of this process on arsenic mobility. The influence of OM on the speciation of As was evaluated (1) at the physiological and molecular levels on two pure strains and (2) at global level by AsIII oxidation measurements by microbial communities from polluted soils and on soils incubations. The effect of the nature of OM was considered through the comparison of simple and complex substrates. The experiments with Thiomonas delicata and Herminiimonas arsenicoxydans showed a negative effect of OM on the specific AsIII oxidation rate. Yeast extract (YE) induced a decrease of aioA gene (encoding for the big subunit of arsenite oxidase responsible for AsIII oxidation) expression with both pure strains. At the level of soils microbial communities, AsIII oxidizing activity were measured on 8 As-polluted soils. Measurements were realized in culture media containing different concentrations of OM. Two complex OMs were compared: YE and a synthetic mixture of organic matters (SMOM) whose composition was inspired from soils OM characteristics (C/N ratio and proportion of functional groups). Correlations were searched between soils characteristics and AsIII bio-oxidation rate constants with and without added OM. Results indicate that AsIII oxidation rate by the soil microflora was limited by available OM and this limitation was removed by the addition of 0.08 g L-1 of organic C as YE or SMOM. When the addition of OM reached 0.4 g L-1 of C, divergent results were observed: YE was less inhibiting than SMOM. Finally, an experiment was carried out to evaluate the combined influence of microbial activity and SMOM addition on As mobilization from polluted soils incubated as slurries at laboratory scale. A mobilization of As present in the polluted soils was observed in presence of both SMOM and active microorganisms. This PhD thesis enlightens the important role played by OM metabolism within the biogeochemical cycle of As, which should be given consideration in the context of polluted site remediation

Les chondrites carbonées de type 1 et 2 comprennent les météorites les plus primitives d’un point de vue chimique et pétrologique. Ce caractère primitif est associé à l’abondance de matière organique qui est une phase privilégiée pour l’étude des phénomènes concernant l’héritage du matériel présolaire et sa transformation dans la nébuleuse puis sur les premiers corps. L’objet de cette thèse est l’étude de l’influence des processus post-accrétionnels sur les caractéristiques moléculaires de la matière organique et en particulier la mesure des effets d’oxydation dus à l’altération aqueuse. Nous avons mené une étude comparative basée sur la structure carbonée et l’analyse des fonctions oxygénées et soufrées d’une dizaine de météorites dont les histoires géologiques ont été déterminées par ailleurs. Le degré d’oxydation du soufre, hétéroatome mineur dans la fraction insoluble, a été mesuré par micro-spectrométrie SK-Xanes. La spectroscopie FT-IR a permis la description des structures fines des chaines carbonées et des fonctions riches en oxygène, hétéroatome majeur. La spectrométrie de masse à très haute résolution Orbitrap a été utilisée pour décrire la diversité hétéroatomique des molécules solubles de la chondrite Renazzo (CR2). Les chaines carbonées des chondrites de classe CI et Murchison se différencient de celle des autres météorites par une abondance en groupements terminaux méthyles à la fois supérieure et invariable. Les chondrites de type 1 sont les seules porteuses de fonctions soufrées oxydées acides alors que la spéciation du soufre dans les chondrites de type 2 est invariable. De la même façon, et cette fois pour l’ensemble des chondrites étudiées, les groupements carbonyles sont majoritairement dans les fonctions cétones, en proportion indépendante du degré d’altération aqueuse. Tous les paramètres mesurés dans cette étude nous poussent à conclure que la variabilité moléculaire au sein des chondrites carbonées de type 1 et 2 trouve moins son origine dans l’empreinte de l’hydrothermalisme que dans une hétérogénéité du précurseur organique accrété par chaque corps parent. En particulier, nos mesures invalident l’hypothèse selon laquelle l’altération serait à l’origine d’une conversion oxydative des chaines carbonées en fonctions acides carboxyliques. / Type 1 and 2 carbonaceous chondrites include the most chemically and petrologically pristine meteorites. This intactness goes along with the abundance of organic matter which is a phase of choice to investigate the presolar material processing in the nebula and then on the first bodies. The purpose of this thesis is to study the influence of post-accretional processes on the molecular characteristics of organic matter and in particular the extent of oxidation effects due to aqueous alteration. We have carried out a comparative study based on the carbon structure and functional analysis of more than ten meteorites whose geologic histories were independently determined. The redox degree of sulfur in the insoluble fraction was measured by SK-Xanes spectroscopy. FT-IR spectroscopy gave access to the fine structures of aliphatic chains and oxygen-rich functions. Orbitrap very high resolution mass spectrometry was used to describe the heteroatomic diversity of soluble molecules in the Renazzo (CR2) chondrite. The aliphatic chains of CI chondrites and Murchison differ from others by a higher and unchanging abundance of methyl groups. Type 1 chondrites are the only carriers of oxidized sulfur functions whereas the sulfur speciation in type 2 chondrites is invariable. For all studied chondrites, the carbonyl groups are mainly under the form of ketones and their abundance can’t be related to the degree of aqueous alteration. Any parameters we have measured in this study lead us to conclude that the molecular variability among type 1 and 2 carbonaceous chondrites are less due to the footprint left by the hydrothermal activity than due to the heterogeneity of an organic precursor accreted by each parent body. In particular, our measurements invalidate the hypothesis that the alteration would cause an oxidative conversion of aliphatic chains to carboxylic acid functions.

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Made available in DSpace on 2015-03-26T13:53:19Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1028872 bytes, checksum: d3180d9e4412d72a10b7c398f9549399 (MD5) Previous issue date: 2011-03-25 / Fundação de Amparo a Pesquisa do Estado de Minas Gerais / The content of soil organic matter (SOM) is one of the most important indicators of the quality and sustainability of soils. In forestry sector, the management practices are planned so that soil carbon (C) stocks are sustained along rotations. It seems that nitrogen (N) additions in Eucalyptus sp. plantations can accelerate the litter and labile organic matter decomposition at initial stages, but it may contribute to residue C stabilization in more recalcitrant fractions of SOM. This study aimed at quantifying under field conditions: 1) the effect of the N rate on the decomposition of eucalypt harvest residues; 2) the C dynamic into particulate organic matter (POM) and mineral associated organic matter (MAM); and 3) to determine the transfer of fertilizer nitrogen-15 to POM and MAM. The experiment was conducted on short-rotation eucalypt areas in two regions (South and West) with distintic precipitation and clay content, near Eunápolis, in Southern Bahia. The treatments consisted of four levels of N (0, 25, 50 e 100 kg ha-1), five sampling periods (0, 3, 6, 12 and 36 months) all without harvest residue removal and an additional treatment without N addition and harvest residue. Ammonium nitrate was the source of N, except at the 50 kg ha-1 at which 5 % of dose was applied as 15(NH4)2SO4 (98 atom % excess 15N). The experiment was in a randomized block design, with five replicates. Soil samples were collected at depths of 0-10, 10-20, 20-40, 40-60 cm. The application of 50 kg ha-1 of N in the South region reduced the decomposition rate of branches, bark and the combined residues (leaves + branch + bark). Branches and bark showed the higher N half-life time (t0,5). When aboveground plant residues were removed and the roots were the sole C input there was a 33 and 14 % decrease on the more stable MAM-C stocks, respectively, at the South and West regions. In South region N addition preserved more C derived from C4 plants that used to be planted in the area before the eucalypt. After three years of N additions, more fertilizer 15N was in the MAM fraction and less 15N was detected below the 10 cm depth. / Um dos principais indicadores da qualidade e da sustentabilidade dos solos é seu conteúdo de matéria orgânica (MOS). No setor florestal, as práticas silviculturais buscam a manutenção e o aumento do estoque de carbono (C) no solo. Acredita-se que a adição de nitrogênio (N) em plantios de eucalipto pode acelerar a decomposição da serapilheira e da matéria orgânica lábil nos estádios iniciais de decomposição, mas por outro lado, contribui para a estabilização do C do resíduo em frações mais estáveis da MOS. Este trabalho teve como objetivo quantificar, em condições de campo: 1) o efeito de doses de N nas taxas de decomposição do resíduo da colheita de eucalipto; 2) a transferência do seu C para a matéria orgânica particulada (MOP) e associada aos minerais (MAM); e 3) determinar a transferência do N do fertilizante para a MOP e MAM. O experimento foi conduzido em plantios comerciais de eucalipto em duas regiões com precipitações e teores de argila distintos, no município de Eunápolis, Extremo Sul da Bahia. Os tratamentos consistiram de quatro doses de N (0, 25, 50 e 100 kg ha-1), cinco épocas de coleta (0, 3, 6, 12, 36 meses), todos sem a remoção do resíduo, além de um tratamento adicional sem a adição de N e com remoção do resíduo. A fonte de N utilizada foi o nitrato de amônio (NH4NO3), com exceção da dose de 50 kg ha-1, em que 5 % da dose de N foram aplicados como 15(NH4)2SO4, com 98% átomos em excesso. O delineamento utilizado foi em blocos casualizados, com cinco repetições. As amostras de solo foram coletadas nas camadas de 0-10, 10-20, 20-40, 40-60 cm. A dose de 50 kg ha-1, na região sul, reduziu a taxa de decomposição do galho, casca, e do combinado (folha+galho+casca). Os galhos e cascas foram os componentes que apresentam os maiores tempos de meia vida (t0,5) de N. A remoção dos resíduos, com aporte de C apenas via sistema radicular, acarretou em decréscimos de 33 e 14 % no C da frações mais estáveis da MOS, da região Sul e Oeste, respectivamente. Na região Sul, a adição de N preservou o estoque de C originário de plantas C4 cultivadas previamente ao eucalipto na MAM. Após três anos da aplicação de N no solo, a maior porcentagem de 15N encontrava-se na MAM, com pouco 15N sendo perdido para camadas abaixo de 10 cm de profundidade.

SOUSA, Robson Alexsandro de. Desenvolvimento do sorgo CV. BRS Ponta Negra irrigado com água salobra e submetido a diferentes doses de esterco bovino e biofertilizantes. 2015. 171 f. : Tese (doutorado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia Agrícola, Programa de Pós-Graduação em Engenharia Agrícola, Fortaleza-CE, 2015. / Submitted by demia Maia (demiamlm@gmail.com) on 2016-08-08T13:57:27Z No. of bitstreams: 1 2015_tese_rasousa.pdf: 2067127 bytes, checksum: 3fcff5c579666b463df7111cb934ce87 (MD5) / Approved for entry into archive by demia Maia (demiamlm@gmail.com) on 2016-08-08T13:58:47Z (GMT) No. of bitstreams: 1 2015_tese_rasousa.pdf: 2067127 bytes, checksum: 3fcff5c579666b463df7111cb934ce87 (MD5) / Made available in DSpace on 2016-08-08T13:58:47Z (GMT). No. of bitstreams: 1 2015_tese_rasousa.pdf: 2067127 bytes, checksum: 3fcff5c579666b463df7111cb934ce87 (MD5) Previous issue date: 2015 / This study aimed to evaluate the effects of salinity of irrigation water and organic compound on the development in sorghum [Sorghum bicolor (L.) Moench.] cv. BRS Ponta Negra. Therefore, three experiments were performed: the first, there was the effect of cattle manure and commercial biofertilizer Ative® and irrigation with different salinity water in the sorghum plants; in the second there was the cattle manure doses (10, 20, 30 and 40 t ha-1) and the salinity of the irrigation water; and in the third, there was the use of liquid biofertilizer Ative® doses (75, 150, 225 and 300 L ha-1 ) and salinity irrigation water. The plants were grown in pots containing 23 kg of sandy soil under greenhouse conditions. Salinity levels were 0.2; 2.0; 4.0; and 6.0 dS m-1, being used for its preparation is pond water with NaCl added in the first experiment; the second and third experiments with NaCl salts, CaCl22H2O and MgCl26H2O , the ratio of 7:2:1. The experimental design was completely randomized with five replicates in a factorial 4 x 3 in the first experiment; four replications, in a factorial 4 x 4, second and third experiments. The following variables were assessed: total dry matter; culms + sheath diameter; plant height; total leaf area; leaf succulence; bulk density leaf; sodium, potassium, chloride, calcium, magnesium and phosphorus in the leaves and culms + sheath of plants; proline and carbohydrates in the leaves of plants. In addition to the soil analysis of the experiments. The results show the three experiments that salinity affected all variables, with beneficial cattle manure and biofertilizer, however, without reducing the deleterious effects of salts when applied through irrigation water. / Este trabalho teve como objetivo avaliar os efeitos da salinidade da água de irrigação e compostos orgânicos, sobre o desenvolvimento de plantas de sorgo [Sorghum bicolor (L.) Moench.] cv. BRS Ponta Negra. Para isso foram realizados três experimentos: no primeiro, verificou-se o efeito da aplicação de esterco bovino e do biofertilizante comercial Ative® e irrigação com água de salinidades diferentes nas plantas de sorgo; no segundo, verificou-se as doses de esterco bovino (10, 20, 30 e 40 t ha-1) e a salinidade da água de irrigação; e, no terceiro, verificou-se o uso de doses de biofertilizante líquido Ative® (75, 150, 225 e 300 L ha-1) e salinidade da água de irrigação. As plantas foram cultivadas em vasos contendo 23 kg de solo arenoso, em casa de vegetação. Os níveis de salinidade foram 0,2; 2,0; 4,0; e 6,0 dS m-1, sendo que para a sua confecção utilizou-se água de açude adicionada com NaCl no primeiro experimento; no segundo e terceiro experimentos com sais de NaCl, CaCl22H2O e MgCl26H2O, na proporção de 7:2:1. O delineamento experimental foi inteiramente casualizado com cinco repetições em esquema fatorial 4 x 3, no primeiro experimento; quatro repetições, em esquema fatorial 4 x 4, no segundo e terceiro experimentos. Foram avaliadas as seguintes variáveis: matéria seca total; diâmetro do colmo; altura de plantas; área foliar total; suculência foliar; massa específica foliar; teores de sódio, potássio, cloro, cálcio, magnésio e fósforo no colmo + bainhas e limbos foliares das plantas; teores de prolina e carboidratos nas folhas de sorgo. Além das análises de solo dos experimentos. Os resultados evidenciam nos três experimentos que a salinidade influenciou todas as variáveis analisadas, apresentando efeitos benéficos do esterco bovino e biofertilizante, no entanto, sem diminuir os efeitos deletérios dos sais quando aplicados através da água de irrigação.

A estabilização de solos é uma técnica através da qual se busca a melhoria das características de comportamento do solo, especialmente em termos de resistência, deformabilidade, durabilidade e permeabilidade (Ingles & Metcalf, 1972). A ágil e rápida determinação do ganho de resistência de solos artificialmente cimentados ainda não é precisa, e necessita de grande aprimoramento. Com esse objetivo se desenvolveu um equipamento para previsão da resistência de solos moles orgânicos artificialmente cimentados que oferece rapidez nos ensaios e precisão nos resultados. O equipamento basicamente funciona com a cravação de uma haste com base circular alargada adaptada em um anel dinamométrico de nylon que penetra no solo e cujos resultados têm relação linear com a resistência à tração por compressão diametral e resistência à compressão simples independente do tipo de solo, adição de agente cimentante, tipo de agente cimentante, teor de umidade da mistura e tempo de cura. Neste estudo também são mostrados resultados do melhoramento de solo com diferentes teores de cimento e cal, bem como os efeitos dos teores de turfa e resíduo de folhas de eucalipto moídas. Além disso, são avaliados os efeitos do pH baixo através da acidificação das amostras com ácido clorídrico e sulfúrico. O teor de umidade do solo apresenta grande influência nos resultados, pois quanto maior a umidade menor a resistência ou maior o consumo de cimento. A adição de ácido húmico em teores de 0,5%, 2,1% e 4,0% apresentou redução de resistência à compressão simples. As misturas com resíduo de folha de eucalipto moídas e turfa apresentaram redução de resistência e também retardo na atuação dos agentes cimentantes. As misturas com adições de cimento atingiram de uma forma geral resultados superiores comparados com adições de cal virgem. No entanto a combinação de cimento e cal virgem apresentou ótimo desempenho até mesmo superior às misturas com adição de cimento. / Soil stabilization is a technique which seeks to improve the performance characteristics of the soil, especially in terms of strength, deformability, durability and permeability (Ingles & Metcalf, 1972). The agile and rapid determination of the resistance gain of artificially cemented soils is still not accurate and needs major improvement. The main objective of present research was the development and testing, as well as the correlation with standard equipments results, of an apparatus for predicting the resistance of artificially cemented organic soft soils in a fast and accurate testing procedure. The equipment developed in present research basically works with the penetration of a rod with a circular base (adapted in the tip of a dynamometer ring made of nylon) into cement treated soft soils whose results have linear relationship with the tensile strength and compression strength regardless of soil type, addition of cementing agent, type of cementing agent, moisture content of the mixture and curing time. In this study are also shown results of soil improvement due to insertion of different amounts of cement and/or lime, and the effects of the amounts of peat and crushed eucalyptus leaves into soil strength. Furthermore, the effects are evaluated from low pH by acidifying the sample with specific acids. The moisture content of the soil has a major influence on the results, the higher the humidity the lower resistance or higher cement consumption. The addition of humic acid at levels of 0.5%, 2.1% and 4.0% showed a reduction of the compressive strength. Mixtures with waste ground eucalyptus leaf and peat showed a delayed action on cementing agents. Some combinations of cements (cement, lime and ash) showed excellent performance. Combinations of cements generally obtained higher results compared to lime addition. However combinations of cement and lime came up with results better than mixtures with only cement.