No presente estudo perseguimos os seguintes objetivos: a) caracterizar o grau de degradação física e química de solos usados em cultivo agrícola por várias décadas, originalmente cobertos por Mata Atlântica (Floresta Estacional Semidecidual) em Botucatu, SP; b) avaliar as alterações biológicas destes solos ao longo de 16 meses pós-reflorestamento com diferentes modelos de associação de espécies da Mata Atlântica. As áreas experimentais estavam localizadas em duas propriedades (Fazenda Lageado e Edgardia) da Faculdade de Ciências Agronômicas (FCA/UNESP) em Botucatu-SP. O clima da região é do tipo tropical com inverno seco (Cwa, classif. de Köppen). Os solos das áreas experimentais são os seguintes: um Nitossolo Vermelho (NV) de textura argilosa; um Argissolo Vermelho-Amarelo (AVA) álico, de textura areia-franca; e um Latossolo Vermelho-Amarelo (LVA) álico, de textura arenosa. Seis tratamentos (delineamento em blocos casualizados, com três repetições) foram usados: Testemunha; Semeadura Direta; Taungya; Consorciação; Restauração e, por fim, Fragmentos Florestais. Os atributos físicos (textura, densidade e porosidade) foram avaliados nas camadas de 0-10, 10-20 e 20-40cm, os atributos químicos (pH, MO, P, S, K, Ca, Mg, H, Al, CTC, B, Cu, Fe, Mn e Zn) nas camadas de 0-5, 5-10, 10-20 e 20-40cm e os atributos biológicos (C da biomassa microbiana, liberação de CO2 e mineralização de N) nas camadas de 0-5 e 5-20cm. No NV, o teor de argila no solo degradado foi 57% maior do que o obtido no solo sob o Fragmento Florestal (camada 0-10cm), no AVA, 33% maior e, no LVA, 77% menor. Este efeito, no NV e AVA, foi atribuído à remoção de camadas superiores do solo, mais arenosas, pela erosão e exposição das camadas inferiores mais argilosas. No LVA, o menor teor de argila e silte no solo degradado foiatribuído à perda destas frações por eluviação ou em suspensão na enxurrada. O pH, teor de MO, de P e de Ca nos solos NV e LVA foram bem superiores nos Fragmentos Florestais relativamente aos obtidos nas áreas com solos degradados. Diferenças menos acentuadas foram observadas no AVA, como também detectadas para a composição textural, indicando que este solo está menos degradado que os demais. A CTC dos solos mostrou-se altamente correlacionada com os teores de argila e de MO. Isto destaca a importância da preservação da composição granulométrica e elevação dos teores de MO com o intuito de restaurar importantes propriedades físico-químicas do solo, como a CTC. Em áreas com cobertura florestal (Fragmentos Florestais do NV, AVA e LVA), o C da biomassa microbiana apresenta maiores valores na camada superficial e no verão. Fato atribuído a condições mais favoráveis (MO, pH, umidade, temperatura, etc) à manutenção da vida microbiana no solo. O C da biomassa microbiana e, em menor escala, a liberação de CO2 apresentaram-se como bons indicadores das alterações ocorridas após o reflorestamento com as diferentes associações de espécies. No LVA, como o solo desta área se apresenta mais degradado, em relação ao NV e ao AVA, a alta correlação e relação C microbiano/C orgânico indica que a biomassa microbiana é um importante compartimento de reserva do C orgânico do solo. Quanto aos atributos biológicos, as diferenças entre os Fragmentos Florestais e os demais tratamentos continuam a existir nas três áreas e camadas, devendo ser gradativo o retorno desses atributos à condição pré-existente; ademais, o tempo de retorno sofrerá influência das condições edafoclimáticas da área e da associação de espécies presentes. / This study seeks to: a) characterize the degree of physical and chemical degradation of the soils used in agricultural cultivation for several decades, originally covered by the Atlantic Forest (Seasonal Semideciduous Forest) in Botucatu, SP; b) evaluate the biological changes of these soils along a 16-month post-reforestation with different models of species association of the Atlantic Forest. The experimental areas were located in two properties (Fazenda Lageado and Edgardia) of the Agronomic Sciences College (FCA/UNESP) in Botucatu-SP. The climate in that region is the tropical type with dry winter (Cwa, Köppen class.). The soils of the experimental areas are: clayey Red Nitosol (NV), loamy alic Red-Yellow Argisol (AVA), and sandy alic Red-Yellow Latosol (LVA). Six treatments (randomized block design with three replications) were used: Test; Direct Seeding; Taungya; Consortium; Restoration and finally Forestal Fragments. The physical attributes (texture, density and porosity) were evaluated in layers of 0-10, 10-20 and 20-40cm; the chemical attributes (pH, MO, P, S, K, Ca, Mg, H, Al, CTC, B, Cu, Fe, Mn and Zn) in layers of 0-5, 5-10, 10-20 and 20-40cm and the biological attributes (Microbial biomass C, CO2 release and N mineralization) in layers of 0-5 and 5-20cm. The clay content in the degraded soil in NV was 57% higher than that obtained in soil under Forest Fragment (0-10cm layer), 33% higher in AVA, and 77% lower in LVA. This effect in NV and AVA was accredited to the removal of the soil top layers, which are sandier due to the erosion and exposition of the lower layers that are more clayey. In LVA the lowest clay and silt content in the degraded soil was accredited to the loss of these fractions by eluviation or flood suspension. The pH, MO, P and Ca contents in NV and LVA soils were much higher in Forestal iv Fragments regarding those reached in degraded soil areas. The less marking differences were observed in AVA and also detected for the textural composition, thus indicating that this soil is less degraded than the other ones. The CTC of the soils was highly correlated with the clay and MO contents. That highlights the importance of preserving the granulometric composition and elevation of the MO contents in order to restore important physical-chemical soil properties, such as the CTC. In primary forest areas (NV, AVA and LVA Forestal Fragments), the microbial biomass C presents higher values at the top layer and in the summer, a fact accredited to more favorable conditions (MO, pH, moisture, temperature, etc) for the maintenance of the microbial life in the soil. The microbial biomass C and, in a lesser scale, the CO2 release were good indicators of the changes occurred after the reforestation with the different species associations. In the LVA, since the soil of this area is more degraded in relationship to NV and AVA, the high correlation and microbial C/organic C relationship indicate that the microbial biomass is an important reserve compartment of the soil organic C. As to the biological attributes, the differences between the Forestal Fragments and the remaining treatments still exist in the three areas and layers, and the return to the pre-existing attributes is likely to be gradual; moreover, the time of return should undergo influences of the pedoclimatic conditions of the area and of the association of the present species.

As coberturas de hidroxiapatita (HAp) são utilizadas para aumentar a osteointegração em implantes de titânio (Ti), devido à sua capacidade de promover a biomineralização para corrigir defeitos esqueléticos e craniofaciais. O objetivo desta pesquisa foi avaliar a influência dos revestimentos sobre culturas primárias de osteoblastos. Na primeira fase de estudos, desenvolvemos uma nova abordagem de revestimento baseada em filmes Langmuir-Blodgett (LB) de dihexadecilfosfato (DHP) e ácido octadecilfosfônico (OPA) depositados em discos Ti, e crescimento subsequente de cristais de HAp. Analisamos a viabilidade dos osteoblastos, a atividade da fosfatase alcalina (ALP) e a formação da matriz mineralizada por métodos colorimétricos e a morfologia das culturas por microscopia eletrônica de varredura e microscopia confocal. Os resultados revelaram que o revestimento DHP/HAp aumentou a viabilidade dos osteoblastos até 150% em comparação com o controle em todos os dias testados. O revestimento OPA/HAp promoveu a maior viabilidade ao 14 dias (190%). A atividade de ALP foi aumentada apenas pelo revestimento de DHP/HAp ao 14º dia em comparação com o controle e Ti limpo. A microscopia eletrônica de varredura e as microfotografias confocais revelaram diferenças morfológicas entre os osteoblastos cultivados em ambos os revestimentos, aumentando o seu número e o espalhamento. O revestimento de DHP/HAp aumentou a produção de nódulos biomineralizados. O ensaio de biomineralização pela técnica do Vermelho de Alizarina mostrou que o revestimento de OPA/HAp possuía uma concentração de cálcio (Ca2+) 1,88 vezes superior à cobertura de DHP/HAp. Uma vez que a literatura relata que o Ca2+ pode estimular ou inibir a atividade da ALP e, consequentemente, o processo de biomineralização, as diferenças no comportamento desses dois revestimentos podem estar relacionadas às diferenças de concentração de superfície de Ca2+. O bom desempenho do revestimento de DHP/HAp pode estar relacionado às características da composição química, adicionada à técnica de deposição LB. Na segunda fase da pesquisa, as monocamadas de Langmuir de DHP e dipalmitoil fosfatidilcolina (DPPC) foram testadas e utilizadas para incorporar o paratormônio 1-34 (PTH 1-34) (DHP/Ca+PTH e DPPC/Ca+PTH, respectivamente). Também foram testadas as ações dos revestimentos DHP/HAp com PTH em solução (DHP/HAp+PTH S) e gotejado (DHP/HAp+PTH G) em culturas de osteoblastos. Um potencial zeta negativo em pH 7,4 foi encontrado (-14,9 mV) para o PTH 1-34. A isoterma de DPPC mostrou um aumento da área mínima ocupada por molécula lipídica após a injeção de PTH na subfase de água (50 ?L de solução 0,5 mg/mL) em 10,97 Å2, o que pode ser devido à inserção de PTH neste filme. A área mínima de DHP foi alterada em 2,3 Å2, o que não é estatisticamente significativo. A análise de QCM mostrou um depósito de 72,5 ng de PTH em filme de DPPC e 29,3 ng de PTH em filme de DHP para cada 25 ?g de PTH injetado na cuba de Langmuir. A viabilidade celular e a formação da matriz mineralizada de culturas de osteoblastos crescidas em DHP/Ca+PTH e revestimentos DPPC/Ca+PTH diminuíram quando comparadas com Ti limpo. Os revestimentos DHP/HAp+PTH S e DHP/HAp+PTH G mostraram ser tão eficientes quanto o Ti DHP/HAp para estimular o processo de biomineralização. Mas a cobertura de DHP/HAp+PTH G aumentou a viabilidade dos osteoblastos e a formação de matriz mineralizada quando comparada com Ti DHP/HAp. Esta é uma cobertura inovadora que abre precedentes para o uso da técnica de gotejamento em HAp para outros hormônios e drogas que agem sobre o tecido ósseo. / Due to their ability to promote biomineralization, Hydroxyapatite (HAp) coatings are used to increase the osteointegration in titanium (Ti) implants, in order to correct skeletal and craniofacial defects. The objective of the research was to evaluate the influence of the coatings on osteoblasts primary cultures. In the first phase of the research we developed a new coating approach based on Langmuir-Blodgett (LB) films of dihexadecyl phosphate (DHP) and octadecylphosphonic acid (OPA) deposited on Ti discs and subsequent growth of HAp crystals. We analyzed the osteoblast viability, alkaline phosphatase (ALP) activity and mineralized matrix formation by colorimetric methods, and the morphology of the cultures by scanning electron microscopy and confocal micrographies. The results revealed that the DHP/HAp coating increased osteoblast viability up to 150% compared to the control at all days tested. The OPA/HAp coating promoted the highest viability on the 14th day (190%). The ALP activity was enhanced only by the DHP/HAp coating on the 14th day compared to control, and clean Ti. To explore the morphology of the cells, the scanning electron microscopy and confocal micrographies were obtained, and revealed morphological differences between osteoblasts grown on both coated Ti compared to clean Ti. Both coatings increased the number and spreading of osteoblasts, while the DHP/HAp coating enhanced the production of biomineralized nodules. The Alizarin Red assay showed that OPA/HAp coating has 1.88 times higher calcium (Ca2+) concentration than DHP/HAp. The same test confirmed the increase of mineralization only by DHP/HAp coating compared to clean Ti. Since literature reports that Ca2+ can stimulate or inhibit the ALP activity and consequently, the biomineralization process, the differences on the behavior of these two coatings could be related to the Ca2+ surface concentration differences. The good performance of the DHP/HAp coating can be explained due to the characteristics of the chemical composition, added to the LB deposition technique. In the second phase of the research, Langmuir monolayers of DHP and dipalmitoyl phosphatidylcholine (DPPC) was tested and used to incorporate 1-34 parathyroid hormone (PTH 1-34) (DHP/Ca+PTH, and DPPC/Ca+PTH, respectively). DHP/HAp coatings with PTH in solution (DHP/HAp+PTH S), and dropped (DHP/HAp+PTH G) also were tested on osteoblasts cultures. A negative zeta-potential at pH 7.4 was found (-14.9 mV) to PTH 1-34. The Langmuir isotherm of DPPC showed an increase of the minimum area occupied per lipid molecule after the PTH injection into the water subphase (50 ?L of 0.5 mg/mL solution) by 10.97 Å2, which could be due to the insertion of PTH in this film. The DHP minimum area changed by 2.3 Å2, which is not statistically significant. The QCM analysis showed the deposit of 72.5 ng of PTH on DPPC film, and 29.3 ng of PTH on DHP film for each 25 ?g of PTH injected into the Langmuir trough. The cell viability and matrix mineralization of osteoblasts cultures grown on DHP/Ca+PTH, and DPPC/Ca+PTH coatings decreased when compared to clean Ti. DHP/HAp+PTH S and DHP/HAp+PTH G coatings proved to be as efficient as Ti DHP/HAp to stimulate the biomineralization process. But DHP/HAp+PTH G increased the osteoblast viabilitiy and formation of mineralized matrix when compared to Ti DHP/HAp. This is an innovative coating that sets the precedent for the use of the drip technique on HAp for other hormones and drugs that act on bone tissue.

A intensificação da agricultura convencional que ocorreu nas últimas décadas na região Sudeste da Província de Buenos Aires (Argentina), provocou degradação das propriedades do solo e redução da fertilidade nitrogenada, apesar dos níveis relativamente elevados de matéria orgânica nesse solo. A inclusão de pastagens (P) nas rotações agrícolas e a adoção da semeadura direta (SD), como manejos alternativos à lavoura convencional (LC), visaram deter a degradação desse solo. A adoção de diferentes sistemas de manejo influem na dinâmica do nitrogênio no solo, modificando a sua disponibilidade às plantas. Com base nesta hipótese, o objetivo geral deste trabalho foi o de quantificar os processos de mineralização, nitrificação e consumo brutos do nitrogênio em um Molisol do SE da Província de Buenos Aires, manejado durante 17 anos com LC e transformado para P ou SD. Os processos brutos do ciclo do nitrogênio foram quantificados pela técnica da diluição do isótopo 15N. Foram realizados os seguintes experimentos: (a) avaliação em laboratório de taxas de mineralização bruta (TMB), consumo bruto (TCB) e nitrificação bruta (TNB) em amostras deformadas e em condições de umidade e temperatura constantes; (b) avaliação dos efeitos do manejo na distribuição das frações granulométricas da matéria orgânica; (c) avaliação das relações entre os processos brutos do ciclo do nitrogênio e as frações granulométricas da matéria orgânica, (c) avaliação em laboratório dos efeitos da temperatura e da umidade do solo nas TMB e TCB e (d) determinações de TMB e TCB em campo durante o ciclo da cultura de milho nos manejos SD, LC e pastagem. A metodologia de diluição do isótopo 15N permitiu a determinação de taxas de mineralização e de consumo bruto em solo com diferentes sistemas de manejo, tanto em condições de laboratório, com amostras deformadas, quanto diretamente em campo, com amostras indeformadas. Na quantificação da taxa de nitrificação bruta, a marcação do solo com amônio-15N não se mostrou adequado, levando a resultados muito variáveis, com evidencias de estimulação pelo substrato. Em todos os experimentos a TCB foi maior que a TMB e as quantidades totais consumidas superaram àquelas mineralizadas. Após seis anos da implantação dos manejos alternativos á LC (SD e P), os processos brutos de transformação do nitrogênio no solo apresentaram marcante estratificação, sendo maiores nas camadas superficiais do solo. As TMB da pastagem foram maiores às da LC, indicando melhora na condição biológica do solo, enquanto que SD somente manifestou uma tendência nesse sentido. Nos três manejos, grandes quantidades de C e N estiveram presentes nas frações <50 &#956;m, nas quais, a matéria orgânica tem alta proteção física e não foi modificada pelo manejo. A pastagem acumulou maior quantidade de C e de N nas frações leves >50 &#956;m que LC. Não se encontrou um padrão simples relacionando a TMB e a TCB com as variáveis das frações granulométricas. Equações de regressão múltiplas para LC incluíram o C e N das frações mais finas, enquanto que para P apareceram as frações leves maiores que 50 µm, sugerindo recuperação da MO do solo. A temperatura e a umidade do solo modificaram as TMB e TCB, sendo que as maiores taxas ocorreram a 25°C e a 70% MCR. LC não apresentou resposta nem a temperatura nem a umidade de solo. Em determinações feitas em campo, após de 9 anos de instalados os manejos, as variações das TMB e TCB foram associadas, principalmente, às variações na umidade do solo. As TMB e TCB na pastagem foram geralmente maiores que as de LC e SD. SD apresentou maiores TMB e TCB que LC no final do ciclo do milho. As quantidades mineralizadas e consumidas acumuladas por SD foram significativamente maiores às correspondentes de LC, embora a cultura de milho não foi beneficiada por essas diferenças devido a disponibilidade de N no solo não coincidir com os estádios de máxima demanda pelas plantas. / The intensification of conventional agriculture in Southeast of Buenos Aires Province (Argentina), caused (conducted to) soil degradation and reduction of nitrogen fertility, despite the relatively high levels of organic matter on this soil. No tillage systems (SD) and inclusion of pastures (P) in agricultural rotations are alternative soil managements to reduce the effects of conventional tillage (LC). Management systems affect the soil nitrogen dynamics modifying its availability to the plants. The objective of this work was to quantify the gross nitrogen mineralization, nitrification and consumption processes in a Molisol, which was previously under LC for 17 years. In 1994 it was transformed to P, SD or continued on LC. The gross nitrogen cycle processes were quantified using the isotope 15N dilution technique. The following experiments were carried out: (a) laboratory evaluation of gross mineralization (TMB), consumption (TCB) and nitrification rates (TNB) in disturbed soil samples with constant soil moisture and temperature conditions; (b) evaluation of the effect of management systems in the size distribution of soil organic matter; (c) evaluation of the relationships between the gross nitrogen processes and in the size fractions of organic matter, (c) laboratory evaluation of the effect of temperature and soil moisture on TMB and TCB, and (d) determination of TMB and TCB on field conditions during the growing season of maize under SD and LC and in a pasture during the same period. The isotope 15N dilution technique allowed the determination of gross mineralization rates for different management practices both in laboratory conditions with disturbed samples, and on field conditions with intact soil samples. For measurements of gross nitrification rates, soil label with 15N-ammonium was not adequate, producing highly variable results and evidences of substrate stimulation. In all the experiments, the TCB was greater than TMB and the consumed total amounts were higher than the mineralized ones. After six years since management’s installation, both the TMB and TCB gross nitrogen processes in soil were strongly depending of the soil depth, being the highest in the top 0-5 cm layer. The pasture TMBs were higher than LC ones, suggesting improvement in the soil biological condition, while SD only presented a trend in this way. For the three management systems, high levels of C and N contents were determined in <50 &#956;m fractions, in which, the organic matter has a high level of physical protection and it was not modified by the management. The largest relative increase in C and N contents occurred in light > 50 &#956;m fractions of pasture. A simple pattern relating the TMB and TCB with the organic matter size fractions was not found. Linear multiple regression analysis for LC included C and N content on the <50 &#956;m fractions, however for P models, the C and N contents on light >50 &#956;m are frequently included variables, suggesting recovery of soil OM. The TMB and TCB were affected by soil moisture and temperature, appearing as optimal conditions to gross mineralization temperature of 25°C and soil moisture of 70% of field capacity. For field determinations, after 9 years of management installation, the variations of TMB and TCB were mainly associates to the soil moisture variations. Pasture TMB and TCB values were higher than LC and SD.TMB and TCB values of SD management system were higher than LC only on the February and March soil samplings. For all the management systems TCB was higher than TMB, being the total consumed amounts, higher than the mineralized ones. Total mineralized N was higher on SD than LC; however, the corn crop was not benefited since N availability did not meet the period of highest N demand.

Le sol est un compartiment majeur de stockage du carbone (C) organique de l’écosystème terrestre. Il joue un rôle important dans la régulation du climat. Toute variation des flux de carbone entre l’atmosphère et l’écosystème terrestre pourrait avoir un impact important sur l’augmentation de CO2 dans l’atmosphère, mais aussi sur la diminution des teneurs en matière organique du sol et donc sur la fertilité des sols. Au Nord Cameroun, les sols sont exposés à de longues périodes sèches (5 à 6 mois par an) qui alternent avec une saison humide. La période de transition entre ces deux saisons, peut durer de mi-avril à fin juin et est caractérisée par des pluies très irrégulières. Ces cycles d’humectation-dessiccation pourraient selon la littérature accentuer la minéralisation du carbone organique du sol et le cycle des éléments nutritifs. L’objectif de cette étude est de quantifier l’impact des cycles humectation-dessiccation sur la minéralisation du carbone dans un contexte soudano-sahélien. Pour faire des mesures représentatives sur le terrain, il est nécessaire d’étudier la variation sur 24 heures de la respiration du sol après humectation suite à une période sèche. Cette mise au point méthodologique a montré que la respiration du sol présente une courbe quadratique au cours de la journée, devenant presque linéaire au cours de la nuit. La température et l’humidité du sol ont permis d’expliquer au moins 73% des variations sur 24 heures. Ces observations ont été utilisées pour proposer une méthode pour estimer la respiration moyenne diurne et nocturne après humectation des sols. La méthode proposée dans cette étude a l’avantage d’être basée sur un nombre réduit de mesures et est par conséquent plus facile à mettre en œuvre pour suivre la respiration du sol sur 24 heures après les premières pluies. Une première étude expérimentale de terrain a permis de montrer que la ré-humectation des sols et le mode de gestion des pailles ont augmenté la minéralisation du carbone de ces sols. En revanche, la fréquence des cycles humectation-dessiccation des sols sur une période de 50 jours n’a pas augmenté la minéralisation cumulée du carbone des sols. Au Nord Cameroun, la minéralisation rapide des pailles rend difficile l’augmentation des stocks de carbone du sol par conservation des pailles des cultures précédentes à la surface du sol. Dans une seconde expérimentation de laboratoire, en conditions contrôlées, les cycles humectation-dessiccation n’ont pas augmenté la minéralisation du carbone organique du sol et de l’azote (N) par rapport aux sols maintenus humides. Cependant, les émissions de CO2 ont augmenté avec l’addition de paille enrichie en carbone-13. Cette addition de la paille marquée a augmenté la minéralisation de la matière organique du sol (priming effect). La minéralisation de la paille a diminué avec les cycles humectation-dessiccation et la quantité de paille restante était de 102 µg Cg-1 sol sur les sols ré-humectés contre 48 µg Cg-1 sol sur les sols maintenus humides. L’absence de cette réponse de la minéralisation du carbone et d’azote du sol aux cycles humectation-dessiccation pourrait être liée à une baisse de l’activité microbienne durant les périodes de dessèchement et l’absence d’une augmentation soutenue des taux de minéralisation du carbone avec les cycles ultérieurs d’humectation-dessiccation. / Soil as a major storage component for terrestrial ecosystem’s organic carbon plays an important role in regulating climate and agricultural production. Any variation of carbon fluxes between the atmosphere and the terrestrial ecosystem can have a significant impact on the increase of carbon dioxide in the atmosphere but also the decrease in soil organic matter and thus accelarate soil fertility degradation. In northern Cameroon, the transition period between long dry periods with a wet season is characterized by very irregular rainfall that can last several weeks. These wetting-drying cycles can accentuate the mineralization of soil organic carbon and nutrient cycling. The objective of this study is to assess the impact of wet-dry cycles on carbon mineralization in a sudano-sahelian context. From methodological stand field measurements require to study the soil respiration variation over 24 hours after a wet period. This methodological test has shown that soil respiration has a quadratic curve during the day, becoming almost linear during the night. The temperature and soil moisture have explained together the variation over 24 hours (at least 73% ; p< 0.001). These observations have been used to propose a method for estimating the mean daytime and nighttime soil respiration after wetting the soil. Indeed the method proposed in this study has the advantage of being based on a small number of measurements and is, therefore, easier to implement to monitor 24-h soil respiration after the first rains following a long dry period. A first experiment has shown that the wetting of the soil and mulching increased soil carbon mineralization. However, wetting-drying cycles on soil did not increase the cumulative mineralization of soil carbon more than keeping the soil continuously moist. Indeed, in northern Cameroon, the rapid mineralization of crop residues makes it difficult to increase soil carbon stocks by mulching. In a second laboratory experiment, the wetting-drying cycles did not increase organic carbon and nitrogen mineralization from soils added with straw. However, carbon dioxide emissions increased on straw amended soils compared to soils without straw. This addition of the labeled straw increased mineralization of soil organic matter (priming effect). The mineralization of the straw also decreased with the wetting-drying cycles, thus the amount of straw remaining on soils was 102 µg C g-1 soil on re-wetted soils compared to 48 µg C g-1 soil for those with constant moisture. The lack of response for C and N mineralization during wetting-drying cycles may be linked to a decrease of microbial activity during dry periods and the lack of a steady increase in the carbon mineralization rate with subsequent wetting-drying cycles.

Este trabalho objetivou relacionar a produtividade agroindustrial da cana-de-açúcar com o aproveitamento do nitrogênio (N) das adubações sucessivas em cana-planta e soqueiras, em sistema de cultivo mínimo sem o revolvimento do solo ou escarificações das entrelinhas na reforma do canavial ou após os cortes, respectivamente - e quantificar a contribuição da palhada proveniente da colheita mecanizada na nutrição da cultura. O experimento foi instalado em março de 2005, em um Latossolo Vermelho Eutrófico muito argiloso da Fazenda Santa Terezinha, Jaboticabal, SP e foi conduzido durante quatro ciclos agrícolas consecutivos até julho de 2009. O delineamento experimental na cana-planta foi blocos casualizados, com quatro tratamentos (doses de N-uréia 0, 40, 80 e 120 kg ha-1 no sulco de plantio, juntamente com 120 kg ha-1 de P2O5 e K2O) e quatro repetições (parcelas de 48 sulcos x 15 m). Nos ciclos de 1ª a 3ª soqueiras, as parcelas de cana-planta foram subdivididas em outros quatro tratamentos (0, 50, 100 e 150 kg ha-1 de N) e quatro repetições (subparcelas de 12 linhas x 15 m). Na 3ª soqueira a adubação com N foi de 100 kg ha-1 em todas as parcelas, visando detectar efeitos residuais das fertilizações anteriores na produtividade da cana no 4º ciclo. Em todas as parcelas dos ciclos de soqueiras também aplicou-se 150 kg ha-1 de K2O como KCl. Na dose 80 kg ha-1 de N em cana-planta, foram instaladas microparcelas contendo uréia e/ou material vegetal marcado com 15N, simulando os resíduos anteriores à reforma (palhada, PAR ou rizomas, RAR da variedade RB855536) remanescentes no solo após o cultivo mínimo. O objetivo foi avaliar a contribuição do fertilizante-15N e dos resíduos vegetais-15N na nutrição nitrogenada da cultura em ciclos consecutivos. Após o corte da cana-planta, novas microparcelas contendo palhada pós colheita (PPC-15N, variedade SP81-3250) foram dispostas nos tratamentos 800 e 80150 kg ha-1 de N em cana-planta e soqueiras, respectivamente, para avaliar a contribuição do N-PPC na nutrição da cultura e a influência do N aplicado em soqueiras na disponibilização do N-PPC. Um estudo complementar foi desenvolvido em sacos telados contendo PAR-15N em cana-planta (dose 80 kg ha-1 de N) e PPC- 15N em soqueiras (doses 80-0 e 80-150 kg ha-1 de N), visando quantificar a decomposição dos resíduos durante os ciclos agrícolas e possíveis diferenças na intensidade da decomposição devido às aplicações de N em cana-planta e em soqueiras respectivamente. Nos quatro ciclos consecutivos avaliou-se a: i) produtividade agroindustrial (TCH, Mg de cana ha-1 de colmos e TPH, Mg ha-1 de pol) e características tecnológicas da matéria-prima (pol % cana e fibra %) em função dos tratamentos de N em cana-planta e soqueiras; ii) recuperação do 15Nuréia, 15N-PAR, 15N-RAR e 15N-PPC pela parte aérea da cultura (colmos, folhas secas e ponteiro) e o balanço de carbono (C) e N no sistema solo-planta e iii) decomposição da PAR e PPC pela redução da matéria seca (MS), do C, 10 macronutrientes (N, P, K, Ca, Mg e S) e carboidratos estruturais (lignina, celulose e hemicelulose). A TCH e TPH foram influenciadas pelas doses de N no plantio e nas soqueiras subseqüentes. Houve resposta linear na produtividade agroindustrial da cana-planta às doses de N do plantio e na média dos quatro ciclos agrícolas. Porém, não houve interação entre as doses de N em cana-planta e soqueiras. O tratamento 120100 kg ha-1 de N em cana-planta e soqueiras proporcionou a maior TCH acumulada nos quatro ciclos consecutivos, porém o tratamento 12050 kg ha-1 de N foi o mais viável economicamente. A recuperação do N-uréia de plantio foi mais alta no primeiro ciclo (24, 7 kg ha-1 ou 31% da dose aplicada) decrescendo ao longo ciclos agrícolas subsequentes (5%; 4% e 3%, respectivamente). O balanço de N após os quatro ciclos (2006 a 2009) indicou 43% (34,4 kg ha-1) de recuperação do Nuréia pela parte aérea da cultura, 0,2% permaneceu nos rizomas, 20% no solo e 37% foram contabilizados como perdas. Para os resíduos vegetais PAR e RAR as recuperações na parte aérea foram de 28% e 23% da quantidade inicial (14,2 e 7,4 kg ha-1, respectivamente). Em média, 0,2% do N-resíduos vegetais permaneceu nos rizomas, 52% no solo e 22% foram perdas. A soma da recuperação do N-PAR e NRAR de foi de 24,4 kg, ou seja, 39% da contribuição total de N destes resíduos, indicando serem fontes de N a longo prazo para a cana-de-açúcar. Houve correlação entre a recuperação acumulada do N-uréia e N-resíduos vegetais com a evapotranspiração acumulada dos quatro ciclos agrícolas. A recuperação do N-PPC pela parte aérea da cultura praticamente dobrou após três ciclos, devido à aplicação de N em soqueiras, 17% vs. 31% (6,9 e 12,6 kg ha-1 de N, respectivamente). O restante do N-PPC permaneceu nos rizomas (0,3% e 0,4%), no solo (69% e 61%) ou resultaram em perdas (13,4% e 7,6%). Não houve alterações nos estoques de C e N do solo com a adição de N-uréia ou N-resíduos vegetais. A decomposição da PAR e PPC foi influenciada pelas aplicações de N em cana-planta e soqueiras e pela ação biológica ao longo dos ciclos agrícolas avaliados. Essa degradação ocorreu devido à redução da relação C:N, do crescimento de raízes sob a palhada, perdas de MS, C, N, macronutrientes e carboidratos estruturais da palhada ao longo dos ciclos agrícolas. Para a PAR e PPC, a degradação da MS foi de 96% e 73% após quatro e três anos, respectivamente. Os macronutrientes que apresentaram maiores liberações foram o K 98% e 92%; Mg 97% e 70% e o Ca 95% e 55%, da quantidade inicial dos nutrientes (kg ha-1) aplicadas via PAR e PPC, respectivamente. Após quatro ciclos agrícolas os teores (g kg-1) de lignina, celulose e hemicelulose da PAR decresceram 60%, 29% e 70%. Para a PPC a redução foi de 47%, 35% e 70% em três ciclos. A degradação dos carboidratos estruturais foi influenciada pelas condições climáticas ocorridas durante os ciclos agrícolas e pela composição bioquímica inicial dos resíduos (carboidratos e nutrientes totais). Não houve diferença na degradação da MS da PPC devido à aplicação de N em soqueiras, porém houve diferença na degradação do C, na liberação de Ca, na concentração de raízes e na decomposição da lignina quando se realizou a adubação com N sobre a palhada em soqueiras / This work aimed to relate the agroindustrial yield of sugarcane with nitrogen (N) fertilization in successive cropping cycles in plant-cane and ratoons under minimum tillage system - without soil plowing or interows scarification in crop renewal and after the harvesting seasons, respectively - and to quantify the contribution of straw from mechanical harvesting on crop N nutrition. The field trial was planted in March 2005 in a very clayey Rhodic Eutrustox at Santa Terezinha Farm, Jaboticabal, Sao Paulo State and was conducted during four consecutive cropping cycles until July 2009. The plant-cane trial was designed as randomized blocks with four treatments (N-urea in increasing rates 0, 40, 80 and 120 kg ha-1 at planting added to 120 kg ha-1 P2O5 and K2O) and four replicates (48 furrows of 15 m length). For the ratoon-cane trial, (1st to 3rd ratoons) the plant-cane plots were subdivided into other four treatments (0, 50, 100 and 150 kg ha-1 N) and four replicates (12 rows x 15 m). The N fertilization of the 3rd ratoon was leveled to 100 kg ha-1 in all plots in order to detect residual effects of previous N fertilizations on sugarcane yield in this cycle. All ratoon cycles also received 150 kg ha-1 K2O as KCl. It has been installed microplots containing 15N-urea and/or 15N-labeled plant material at the 80 kg ha-1 N dose in plant-cane, simulating the crop residues prior to renewal (trash PAR or rhizomes, RAR of RB855536 variety) and which remained in soil after minimum tillage. The objective was to assess the contribution of N-fertilizer and N-residues in sugarcane N nutrition in consecutive cycles. After the plant-cane harvesting, new microplots containing post harvest trash (PPC-15N, variety SP81-3250) were placed in treatments 80-0 and 80- 150 kg N ha-1 in plant-cane and ratoons, respectively, aiming to assess the contribution of N-PPC in crop nutrition and the influence of N applied to ratoons in the N-PPC availability for sugarcane uptake. An additional study was conducted in litter bags containing PAR-15N in plant-cane (dose 80 kg ha-1 N) and PPC-15N in ratoons (doses 80-0 and 80-150 kg N ha-1) in order quantify the decomposition of trash during the crop cycles and possible differences in the decomposition rates due to N applications in plant-cane (PAR) and ratoons (PPC), respectively. In the four consecutive cycles were evaluated: i) Agroindustrial yields (TCH, Mg cane ha-1 stalks and TPH, Mg ha-1 of sugar) and raw material quality (pol% cane and fiber%) in plantcane and ratoon treatments; ii) Recovery of urea-15N, PAR-15N, 15N- RAR and 15NPPC by crop above ground parts (stalks, dry leaves and tips) and carbon (C) and N balances in the soil-plant system and iii) decomposition of PAR and PPC as reduction of dry matter (DM), C, nutrients (N, P, K, Ca, Mg and S) and structural carbohydrates (lignin cellulose and hemicellulose). The agroindustrial yields (TCH and TPH) were influenced by N rates at planting and subsequent ratoons. It hás been found linear response in crop yield due to N rates at planting and in the average of four crop cycles. However, no responses were detected in the interaction between 12 N doses in plant or ratoon cane. The highest accumulated yield (TCH) in four consecutive cycles was obtained in treatment 120-100 kg ha-1 N in plant-cane and ratoons, but treatment 120-50 kg ha-1 N has been found as the more economically viable. The recovery of N-urea applied in plant-cane was higher in the first cycle (24, 7 kg ha-1 or 31% of the applied dose) and decreased over subsequent crop cycles (5%, 4% and 3% respectively). The N balance after four cycles (2006-2009) showed 43% (34.4 kg ha-1) of total N-urea recovery by the crop above ground parts, 0.2% was found in the rhizomes, 20% in soil and 37% were counted as losses. Cane trash N-PAR and N-RAR recoveries in the above ground parts were 28% and 23% of the initial amount of N applied as crop residues (14.2 and 7.4 kg ha-1, respectively). On average, 0.2% of N-plant residues remained in the rhizomes, 52% in the soil and 22% were accounted as losses. The total recovery of N-PAR N-and RAR was 24.4 kg, or 39% of the total N of these residues, indicating that they are long term N sources for the sugarcane crop. There had been found a close correlation between the cumulative recovery of N-urea and N-residues with the accumulated evapotranspiration of the four crop cycles. The N-PPC recovery by sugarcane above ground parts almost doubled after three cycles due to N application in ratoons, 17% vs. 31% (6.9 and 12.6 kg ha-1 N, respectively). In other compartments, 0.3% and 0.4% of N-PPC remained in the rhizomes, 69% and 61%) in the soil and 13.4% and 7.6%) resulted in losses. There was detected no major changes in soil C and N stocks C due to the addition of N-urea and N-residues. The decomposition of PAR and PPC was influenced by N fertilizations in plant-cane and ratoons cane and by biological action over the cropping cycles. The major effects detected as trash decomposed over the agricultural cycles were the reduction in residues C:N ratio, sugarcane root growth under the trash blanket, and losses of DM, C, N, macronutrients and structural carbohydrates. The DM degradation of PAR and PPC was 96% and 73% after four and three years respectively. The nutrients that showed higher release rates were K 98% to 92%, Mg 97% to 70% Ca and 95% to 55% of the initial amount of nutrients (kg ha-1) sourced by PAR and PPC residues, respectively. After four agricultural cycles, the levels (g kg-1) of lignin, cellulose and hemicellulose from PAR decreased 60%, 29% and 70%, and for PPC the reduction was 47%, 35% and 70% in three cycles. The degradation of structural carbohydrates was influenced by climatic conditions that occurred during the agricultural cycles and the initial biochemical composition those residues (total carbohydrates and nutrients content). There was no difference in DM degradation of PPC due to N application in ratoons, however there were differences in C degradation, in the release of Ca, concentration of roots and in the decomposition of lignin when N- fertilizer has been applied over the trash blanket

L’hydrodynamique et la probabilité de minéralisation (R²AI) autour des intrusions magmatiques ont été étudiées par modélisation numérique couplant transfert de chaleur et circulation de fluide. L’objectif principal de ce travail est de tester la nature du lien génétique entre l’intrusion et le processus de minéralisation. La première série de résultats s’appuie sur une comparaison avec des exemples naturels de gisements bien connus : i) L’hydrodynamique et la localisation des zones probables de minéralisation sont fortement dépendantes de la profondeur de mise en place du pluton. Au-dessus de 4.5km de profondeur de mise en place, le seuil de perméabilité de 10-16 m² est atteint et les cellules convectives peuvent créer des zones de décharge additionnelles où des minéralisations peuvent avoir lieu ; ii) Pour toutes les profondeurs d’emplacement, la zone en dessous du pluton n'est pas favorable à la précipitation minérale ; iii) Les apophyses focalisent les fluides convectifs et les zones de minéralisation autour d’elles ; iv) La phase de refroidissement n'est pas la phase majeure de convection. La zone advective principale et celle de haute favorabilité peuvent se produire avant et pendant la phase la plus chaude d’emplacement, avant que le magma ne cristallise complètement; v) Les détachements sont capables de fortement modifier et de re-localiser les flux convectifs déclenchés par une intrusion syn-tectonique; vi) Les conditions physiques favorables à la minéraliser sont produites pendant une durée courte autour de la phase la plus chaude de l'intrusion. Même si les arguments chimiques sont absents, la circulation de fluide (induite par la mise en place de magma) joue un rôle principal dans la genèse des gisements d'or associés aux intrusions. De plus, la formation de ce type de gisement est favorisée par l'occurrence d'une auréole thermique fracturée autour de l'intrusion. La seconde série de résultats concerne l’étude du cas naturel de la minéralisation W-Au de Tighza (Jebel Aouam) au Maroc Central. Une campagne d’acquisition de données gravimétriques, l’inversion données et l’utilisation de logiciel 3D, ont permis d’obtenir la géométrie 3D complexe du pluton de Tighza. Les résultats sont les suivants : i) la zone probable de la minéralisation apparaît au début de la mise en place du magma dans la zone perméable (veine W1) et s'étend pour remplir W1 et couvrir la région autour du pluton pendant la phase la plus chaude de mise en place; ii) lors du refroidissement, la zone probable est réduite et limitée à la zone perméable (W1) pendant 0,6 Ma; iii) L’application de la température de fermeture isotopique de la muscovite et de la biotite avec la distribution du R²AI montre que les âges de refroidissement entre la minéralisation au niveau de la veine W1 et l'intrusion ne sont pas séparés de plus de 0,10 Ma. Ceci est confirmé par la datation absolue de la minéralisation de Tighza et permet de discuter la fiabilité des âges obtenus pour la minéralisation dans la veine W1. / Coupled hydro-thermal numerical modeling has been used to simulate the hydrothermal fluid flow regime and the mineralization probability (R²AI) around plutons. The main objective behind this work is to test the nature of the genetic link between mineralization and intrusions. The first series of results comes from comparison with well-constrained mineral deposits: i) Fluid circulation and mineralization patterns are strongly dependent of the emplacement depth of the pluton. Deep seated plutons emplaced below 10 km do not induce an advective heat dissipation. For emplacement depth less than 4.5 km, the permeability threshold of 10-16 m2 is reached and second order convection cells may create additional discharge zones where mineralization are expected; ii) For all emplacement depths, the pluton floor zone is not favorable for mineral deposition; iii) The apexes strongly modified the fluid flow patterns by focusing convective fluids and mineralization zones around them; iv) The cooling phase is not the main phase of convection for large pluton often associated with long-lived magma emplacement. Major advective heat dissipation and mineral deposition zone may also occur sometime before and during the hottest phase of emplacement; v) Extensional detachments faults are able to delocalize and strongly modify classical fluid flow patterns induced by coeval intrusion; vi) Favorable physical conditions for mineral deposition are encountered around middle crust pluton, during a short time span bracketing the hottest phase of intrusion. We conclude that, even if chemical arguments are absent, fluid circulation induced by granite emplacement plays a key role in the genesis of granite-related Au deposits. Moreover, formation of this type of deposit is promoted and controlled by the occurrence of a fractured thermal aureole around the intrusion. The second series of results deals with the W-Au granite related Tighza deposits (Jebel Aouam, Morocco). Based on gravimetric data, inversion, and 3D modeling software, we were able to construct the most probable complex geometry of the Tighza pluton. The 3D geometries of the pluton and major fractures (W1 vein) were injected in the hydro-thermal modeling procedure. The results are: i) the probable zone of mineralization appears at the beginning of magma emplacement within the permeable zone (W1 vein) and extends to fill up W1 and covers the area around pluton at the hottest phase; ii) During the cooling phase, the story was reversed; the probable zone was reduced and restricted in the permeable zone (W1) during 0.6 Myr of cooling; iii) Application of isotopic closure temperature of muscovite and biotite coupled with R²AI distribution shows that the cooling ages between mineralization in W1 veins and the intrusion are not separated by more than 0.10 Myr. This is confirmed by the absolute dating obtained for Tighza Au mineralization and allows discussing the significance of older ages obtained for the mineralization in W1 veins.

Este estudo teve como objetivo avaliar os efeitos da aplicação de biossólido sobre as taxas de mineralização e de lixiviação de N, as modificações de fertilidade do solo, a nutrição e o crescimento de povoamentos de Eucalyptus grandis plantados em um Latossolo Vermelho-Amarelo Distrófico não-degradado (sob cultivo mínimo) e outro degradado. O experimento foi conduzido no município de Salto de Pirapora, SP. A área experimental foi constituída de quatro blocos e nove tratamentos; em três tratamentos, a camada superficial do solo (0-20cm) foi removida (solo degradado). Os tratamentos na área com solo não-degradado, cultivado no sistema de cultivo mínimo, foram: (1) Controle, (2) Fertilização mineral, (3) 10 t ha-1, (4) 20 e (5) 40 t ha-1 de biossólido (base seca), todos com suplementação de P e K, e (6) 10 t ha-1 de biossólido, sem suplementação de P e K; na área com solo degradado, os tratamentos foram: (7) Controle, (8) 20 e (9) 40 t ha-1 de biossólido, todos com suplementação de P e K. Nos tratamentos 1, 4 e 8 foram monitoradas as taxas de mineralização e de lixiviação de N no solo. No solo não-degradado, nos primeiros sete meses pós-aplicação do biossólido (PAB), houve aumento das taxas de mineralização de N, do pH, da concentração de P resina, e diminuição das concentrações de K, Ca e Mg trocáveis. Aos doze meses PAB, as concentrações de P-resina aumentaram, e as de matéria orgânica e N total diminuíram. As concentrações foliares de N aumentaram aos três meses, de N e P aos sete meses, e as de K diminuíram aos doze meses PAB. No solo degradado que recebeu 20 t ha-1 de biossólido, as quantidades de N mineralizadas, em sete meses, foram semelhantes às obtidas no não-degradado sem biossólido, e as taxas de lixiviação de N foram maiores do que no solo não-degradado com a mesma dose. Nesta época, no solo degradado, o biossólido aumentou concentrações de P-resina, Ca, Mg e S, o pH somente na camada 0-3 cm e, aos doze meses, aumentou as concentrações de C, N totais, de matéria orgânica, de P-resina, de Ca trocável, e diminuiu e aumentou, respectivamente, as concentrações de S nas camadas 0-3 e 3-30 cm do solo. Houve aumento das concentrações foliares de N, aos três meses, de N, P, Mg e S aos sete meses, e de Ca aos doze meses PAB. O biossólido aumentou as taxas de crescimento do E. grandis, aos sete meses PAB, nas duas condições de solo e, aos doze e aos vinte e dois meses PAB, nos tratamentos em solo degradado. No tratamento em solo degradado que recebeu 40 t ha-1 de biossólido, as árvores tiveram crescimento semelhante ao dos tratamentos em solo não-degradado. Nas duas condições de solo, as variâncias entre tratamentos relativas ao crescimento das árvores foram explicadas principalmente pela maior absorção de N pelas plantas. / The aim of this study was to evaluate the effects of biosolid application on the mineralization and leaching rates of N, the changes of soil fertility, nutrition and growth of Eucalyptus grandis cultivated in a non-degraded (under minimum tillage) and in a degraded Red-Yellow Latosol (Oxissol). It was carried out in Salto do Pirapora district, São Paulo State, Brazil. The experimental area included four blocks and nine treatments; in three of them, the topsoil (0-20cm) was removed (degraded soil). Treatments in the non-degraded soil area, cultivated under minimum-tillage system, were: (1) Control, (2) Mineral fertilization, (3) 10 t ha-1, (4) 20 and (5) 40 t ha-1 of biosolid, all supplemented with P and K and (6) 10 t ha-1 of biosolid with no P and K supplementation; in the degraded soil area, the treatments were: (7) Control, (8) 20 and (9) 40 t ha-1 of biosolid, all supplemented with P and K. Mineralization and leaching rates of N in the soil were monitored in treatments 1, 4 and 8. In non-degraded soils, on the first seven months after biosolid application (ABA), increasing of N mineralization rates, pH, concentration of the soil P-resin, and decreasing concentrations of exchangeable K, Ca and Mg were observed. Twelve months ABA, P-resin concentrations increased, and organic matter and total N decreased. N concentration in foliage increased at three months, N and P at seven months and K decreased at twelve months FBA. The amounts of mineralized N in the degraded soil with biosolid (20 t ha-1), at seven months, were similar to those achieved in the Control under non-degraded soil; N leaching was higher in degraded than those in non-degraded soil with the same amount of biosolid. In that age, in degraded soil, the biosolid increased the concentrations of P-resin, Ca, Mg and S and pH, only at 0-3 cm layer and, at twelve months, increased the total C and N, organic matter, P-resin, exchangeable Ca, and S concentrations decreased in 0-3 and increased in 3-30 cm layers. N, P, Mg and S concentrations in foliage increased at seven months and Ca at twelve months ABA. The biosolid increased the growth rates of E. grandis at seven months ABA in both soil conditions, and at twelve and twenty-two months ABA in degraded soil. In degraded soil treatment that received 40 t ha-1 of biosolid, the growth of trees was similar to those of non-degraded soil treatments. In both soil conditions, the variances between treatments regarding tree growth were explained mainly by higher plants N uptake.

Les roches mantelliques exposées sur le plancher océanique et/ou en contact avec l’atmosphère au niveau d’une ophiolite, sont en déséquilibre et s’altèrent, via les réactions de serpentinisation (i.e. d’hydratation et oxydo-réduction) et les réactions de carbonatation. Ces réactions d’altération jouent un rôle important dans les échanges chimiques entre la Terre profonde et les enveloppes externes, en particulier dans le cycle des volatils (C, H et O) via la minéralisation du CO2 atmosphérique, la production d’hydrogène et la formation d’hydrocarbures et de molécules prébiotiques. L’ophiolite d’Oman est un « laboratoire naturel » idéal pour étudier ces réactions depuis l’hydrothermalisme océanique jusqu’à l’altération continentale actuelle.Cette thèse présente les résultats d’une étude multi-technique et multi-échelle réalisée sur une série de péridotites serpentinisées et carbonatées échantillonnées sur deux sites, Wadi Dima et Batin (Massif de Wadi Tayin), considérés comme représentatifs des processus d’altération affectant l’ophiolite d’Oman. Ces travaux combinent caractérisations (micro-)structurales (EBSD, µ-tomographie), pétrographiques et minéralogiques (Raman, Cathodoluminescence, (3D-)XANES), et analyses géochimiques (EPMA, (LA)-ICPMS) et isotopiques (isotopes du O, C micro-bulk et in-situ).L’étude des harzburgites de Wadi Dima a permis d’identifier la succession des épisodes de serpentinisation et de carbonatation qui ont affecté les péridotites lors du refroidissement de la lithosphère jusqu’à la mise en place de l’Ophiolite d’Oman. La serpentinisation commence en domaine océanique (appauvrissement en REE, anomalie négative en Ce) durant le refroidissement initial de la lithosphère océanique et/ou au début du détachement intra-océanique à < 200-220°C, par la formation des veines de lizardite. Cette serpentinisation continue avec la formation de chrysotile au centre de la structure maillée, remplaçant l’olivine. Le dernier stade de serpentinisation a lieu simultanément au premier stade de carbonatation et engendre l’altération complète de la péridotite à < 100°C. Le système est contrôlé par des hétérogénéités locales (anomalies en Ce et variation de la composition isotopique en carbone). La carbonatation continue à < 50°C lors de la transition en domaine continental. Des veines de carbonates se forment par interaction avec des fluides issus des sédiments durant la convergence et avec des fluides de surface et de sub-surface durant l’altération actuelle de l’ophiolite. Ce processus marque le passage d’un régime hydrothermal océanique dont la chimie est dominée par la composition de la roche, à un régime hydrothermal continental dont la chimie est contrôlée par la composition du fluide dans des fractures. Paradoxalement, la structure initiale du manteau contrôle l’orientation et la distribution des veines de carbonate.Le site de Batin se distingue par sa structure complexe avec la présence de nombreux filons de gabbros et de pyroxénites et des évidences d’imprégnation magmatique. La serpentinisation y est marquée par la formation de textures atypiques en anneau ("fingerprint") caractérisées par des variations des teneurs en Fe-Mg et du redox à micro-échelle et par des compositions isotopiques en oxygène en déséquilibre. Ces caractéristiques sont interprétées comme résultant de déséquilibres locaux dans les processus de transport-nucléation-réaction pouvant être liés à plusieurs paramètres : forts gradients de température, redox, composition du fluide, et de perméabilité.Cette thèse apporte de nouvelles données vis-à-vis des relations temporelles et spatiales entre les réactions de serpentinisation et de carbonatation, les hétérogénéités chimiques à micro-échelle et l’impact de ces réactions d’altération sur les bilans globaux des volatils (C, H et O) en Oman. Elle met particulièrement en évidence la possibilité de stocker du CO2 et de produire de l’H2 simultanément lors de l’altération du plancher océanique. / Mantle rocks exposed in seafloor and/or directly in contact with atmosphere in ophiolite system are thermodynamically and chemically in disequilibrium. Mantle alteration is driven by serpentinization (ie, hydration and oxidation-reduction reactions) and carbonatization reactions. These reactions play an major role in the chemical exchanges between the deep mantle and the outer envelops, especially in the global mass budget of volatiles (C, H and O) via CO2 mineralization, hydrogen production and formation of hydrocarbons and prebiotic molecules. Oman ophiolite is an ideal "natural laboratory" for studying alteration reactions in mantle rocks from ocean hydrothermalism to modern continental weathering.This thesis presents the results of a multi-technical and multi-scale study on carbonate-hosted serpentinized peridotites in two sites, Wadi Dima and Batin (Wadi Tayin massif), considered representative of the alteration processes affecting the Oman ophiolite. This work combines (micro-) structural (EBSD, µ-tomography), petrographical (EPMA), mineralogical (Raman, Cathodoluminescence, (3D-)XANES), geochemical ((LA)-ICPMS) and isotopic studies (O, C in situ and micro-bulk).Studies in Wadi Dima harzburgites have highlighted successive episodes of serpentinization and carbonatization in Oman peridotites from oceanic lithosphere cooling to Oman Ophiolite emplacement. Serpentinization occurs in oceanic setting (REE depletion, negative Ce anomalies), probably during the onset of the oceanic lithosphere cooling and / or of the intra-oceanic detachment, at < 200-220°C, driven by the formation of lizardite veins constituting the mesh structure. Serpentinization continues at lower temperature with the formation of chrysotile in the center of the mesh structure, replacing olivine. The last stage of serpentinization is concurrent with early carbonatization and generates the complete peridotite alteration at < 100°C. In this rock-dominated system, fluid flow paths are controlled by nano-porosity (etch pits), by pore scale weakness and by local heterogeneity in permeability, generating local chemical heterogeneities (Ce anomalies variability and carbon isotope heterogeneity). Carbonatization continues at < 50°C during the transition in continental setting. Carbonate veins are formed during interaction with sediment-derived fluids during intra-oceanic detachment at the onset of obduction and with surface and sub-surface fluids during modern continental Ophiolite weathering. This process records the transition from oceanic diffuse-flow rock-dominated to cooler continental fluid-focused-flow fluid-dominated hydrothermal systems. Paradoxically, initial mantle structure controls orientation and distribution of carbonate veins.Batin site is distinguished by its complex structure with the presence of abundant gabbros and pyroxenites dikes, evidence of magmatic impregnation peridotites. Serpentinization is charcheterized by the formation of an uncommon texture in rings ("fingerprint") at the expense of olivine, marked by chemically variation in Fe-Mg and redox at microscale and by disequilibrium oxygen isotopic composition. These features are interpreted as resulting from local disequilibrium in the transport-nucleation-reaction processes that may be related to several parameters: high temperature gradient, redox, fluid composition, and permeability.This thesis brings new constraints on temporal and spatial relations between serpentinization and carbonatization reactions, on local chemical heterogeneities at micro-scale and on the global chemical budget of volatiles (C, H and O) in Oman peridotites. It has highlighted the possibility to store CO2 and producing H2 simultaneously during subseafloor alteration.

Résumé indisponible / Résumé indisponible

Este estudo teve como objetivo avaliar os efeitos da aplicação de biossólido sobre as taxas de mineralização e de lixiviação de N, as modificações de fertilidade do solo, a nutrição e o crescimento de povoamentos de Eucalyptus grandis plantados em um Latossolo Vermelho-Amarelo Distrófico não-degradado (sob cultivo mínimo) e outro degradado. O experimento foi conduzido no município de Salto de Pirapora, SP. A área experimental foi constituída de quatro blocos e nove tratamentos; em três tratamentos, a camada superficial do solo (0-20cm) foi removida (solo degradado). Os tratamentos na área com solo não-degradado, cultivado no sistema de cultivo mínimo, foram: (1) Controle, (2) Fertilização mineral, (3) 10 t ha-1, (4) 20 e (5) 40 t ha-1 de biossólido (base seca), todos com suplementação de P e K, e (6) 10 t ha-1 de biossólido, sem suplementação de P e K; na área com solo degradado, os tratamentos foram: (7) Controle, (8) 20 e (9) 40 t ha-1 de biossólido, todos com suplementação de P e K. Nos tratamentos 1, 4 e 8 foram monitoradas as taxas de mineralização e de lixiviação de N no solo. No solo não-degradado, nos primeiros sete meses pós-aplicação do biossólido (PAB), houve aumento das taxas de mineralização de N, do pH, da concentração de P resina, e diminuição das concentrações de K, Ca e Mg trocáveis. Aos doze meses PAB, as concentrações de P-resina aumentaram, e as de matéria orgânica e N total diminuíram. As concentrações foliares de N aumentaram aos três meses, de N e P aos sete meses, e as de K diminuíram aos doze meses PAB. No solo degradado que recebeu 20 t ha-1 de biossólido, as quantidades de N mineralizadas, em sete meses, foram semelhantes às obtidas no não-degradado sem biossólido, e as taxas de lixiviação de N foram maiores do que no solo não-degradado com a mesma dose. Nesta época, no solo degradado, o biossólido aumentou concentrações de P-resina, Ca, Mg e S, o pH somente na camada 0-3 cm e, aos doze meses, aumentou as concentrações de C, N totais, de matéria orgânica, de P-resina, de Ca trocável, e diminuiu e aumentou, respectivamente, as concentrações de S nas camadas 0-3 e 3-30 cm do solo. Houve aumento das concentrações foliares de N, aos três meses, de N, P, Mg e S aos sete meses, e de Ca aos doze meses PAB. O biossólido aumentou as taxas de crescimento do E. grandis, aos sete meses PAB, nas duas condições de solo e, aos doze e aos vinte e dois meses PAB, nos tratamentos em solo degradado. No tratamento em solo degradado que recebeu 40 t ha-1 de biossólido, as árvores tiveram crescimento semelhante ao dos tratamentos em solo não-degradado. Nas duas condições de solo, as variâncias entre tratamentos relativas ao crescimento das árvores foram explicadas principalmente pela maior absorção de N pelas plantas. / The aim of this study was to evaluate the effects of biosolid application on the mineralization and leaching rates of N, the changes of soil fertility, nutrition and growth of Eucalyptus grandis cultivated in a non-degraded (under minimum tillage) and in a degraded Red-Yellow Latosol (Oxissol). It was carried out in Salto do Pirapora district, São Paulo State, Brazil. The experimental area included four blocks and nine treatments; in three of them, the topsoil (0-20cm) was removed (degraded soil). Treatments in the non-degraded soil area, cultivated under minimum-tillage system, were: (1) Control, (2) Mineral fertilization, (3) 10 t ha-1, (4) 20 and (5) 40 t ha-1 of biosolid, all supplemented with P and K and (6) 10 t ha-1 of biosolid with no P and K supplementation; in the degraded soil area, the treatments were: (7) Control, (8) 20 and (9) 40 t ha-1 of biosolid, all supplemented with P and K. Mineralization and leaching rates of N in the soil were monitored in treatments 1, 4 and 8. In non-degraded soils, on the first seven months after biosolid application (ABA), increasing of N mineralization rates, pH, concentration of the soil P-resin, and decreasing concentrations of exchangeable K, Ca and Mg were observed. Twelve months ABA, P-resin concentrations increased, and organic matter and total N decreased. N concentration in foliage increased at three months, N and P at seven months and K decreased at twelve months FBA. The amounts of mineralized N in the degraded soil with biosolid (20 t ha-1), at seven months, were similar to those achieved in the Control under non-degraded soil; N leaching was higher in degraded than those in non-degraded soil with the same amount of biosolid. In that age, in degraded soil, the biosolid increased the concentrations of P-resin, Ca, Mg and S and pH, only at 0-3 cm layer and, at twelve months, increased the total C and N, organic matter, P-resin, exchangeable Ca, and S concentrations decreased in 0-3 and increased in 3-30 cm layers. N, P, Mg and S concentrations in foliage increased at seven months and Ca at twelve months ABA. The biosolid increased the growth rates of E. grandis at seven months ABA in both soil conditions, and at twelve and twenty-two months ABA in degraded soil. In degraded soil treatment that received 40 t ha-1 of biosolid, the growth of trees was similar to those of non-degraded soil treatments. In both soil conditions, the variances between treatments regarding tree growth were explained mainly by higher plants N uptake.