Quarry fines are by-products of the aggregate extraction and productionprocesses. Because such fine material cannot be marketed, it becomes aburden for the aggregate industry, resulting in stockpiles of financiallyunexploited material. Even though previous research has been focused onminimizing the generation of quarry fines, far too little attention has beenpaid to maximizing their utilization instead. The aim of this thesis is toinvestigate whether 0/2 mm and 0/4 mm quarry fines can be utilized asalternative materials in the construction industry, specifically in theunbound layer of a road or as filling against a bridge. The methodologyconsisted of four laboratory tests that investigated the water content,particle size distribution and percentage of filler content, optimummoisture content (OMC) and maximum dry density (MDD) relationshipas well as bearing capacity of the materials. The results show that theamount of filler content (<0.063 mm) can significantly impact thematerial’s water-holding capacity as well as its compaction capabilities.After comparing the bearing capacity measurements to the technicalrequirements of the Swedish Transport Administration, it was found thatthe 0/2 mm fits the necessary requirements for use in the unbound layerof either a flexible or rigid pavement but not as filling against a bridge.Further research is needed to determine the material’s relationship towater absorption and resistance to freezing and thawing cycles, as it isdifficult to assess its suitability for road construction solely on theseresults; however, despite its limitations, the study provides some valuableinsights into the potential applications of quarry fines.

Intercrafts Peru Inc. has been working side by side with Peruvian handcrafts producers for over ten years and it is currently going through a financial and organizational downturn. The company has experienced net losses for the past three years and there is a need to implement changes that can revert this situation by putting the company back on track to achieve sustainable long term grow. The organization is subjected to trade practices established by the World Fair Trade Organization (WFTO) and it is through this practices that the company has established long term relationships with customers in North America, Europe and Oceania. However changes in the industry and internal inefficiencies limit the capacity of Intercrafts to increase the number of sales reaching new customers. The company was born as an initiative of the (Interregional Central of Peruvian Artisans) CIAP and explains the low bargaining power towards the suppliers because of the relationship. Furthermore this bond reinforces the social commitment of the organization from its conception, to support the sustainable development of the artisans and their environment. It is in this commitment that the company can exploit most of the potential strengths and opportunities. In this context this strategic plan proposes the use of three strategies to take the company from its current situation to the desired situation to be the best crafts exporting company in Peru in 2020: (a) Product development through strategic alliances, creating new designs capacitating the artisans to improve the products; (b) Retrenchment, restructuring some of the company’s processes to reduce costs and have an efficient operational system; and (c) Market penetration attacking the high end niche market with improved marketing. / Intercrafts Perú Inc. ha trabajado de la mano con productores de artesanía peruanos por más de 10 años y actualmente se encuentra en una mala situación financiera y organizacional. La compañía ha operado los tres últimos años incurriendo en pérdidas. Existe una necesidad por realizar cambios que puedan revertir esta tendencia y poner a la compañía en un camino de crecimiento sostenido en el largo plazo. La organización está sujeta a las prácticas de comercio establecidas por la Organización Mundial de Comercio Justo y es a través de estas prácticas que ha conseguido relaciones de largo plazo con clientes en Norte América, Europa y Oceanía. Sin embargo cambios en la industria e ineficiencias internas limitan la capacidad de Intercrafts para ampliar la base de clientes actual. La compañía nace como una iniciativa de la Central Interregional de Artesanos del Perú (CIAP). Y en esta relación se explica el bajo poder de negociación que existe hacia los proveedores. Sin embargo esta relación también refuerza el compromiso social de la compañía que, desde su concepción, está dedicada a apoyar al desarrollo sostenible de los artesanos y su entorno. Es aquí en donde se encuentras potenciales oportunidades y fortalezas que Intercrafts necesita explotar. Es en este contexto que este plan estratégico plantea el uso de estrategias para llevar a la compañía del estado actual a ser la exportadora número uno de artesanías peruanas en el 2020: (a) Desarrollo de producto alianzas estratégicas, fortaleciendo la relación con CIAP con capacitaciones y creación de diseños innovadores; (b) Atrincheramiento, reestructurando algunos de los procesos de la compañía con el fin de disminuir costos y ser más eficientes; y (c) Penetración de mercado, atacando nichos en el sector más elevado del mercado con una nueva técnica de mercadeo.

This thesis broadly addresses the issue of materials sustainability in the production of Portland cement concrete. Two methods are presented, both aimed at achieving more sustainable concrete through the use of waste and recycled materials. The first method involves utilizing reclaimed asphalt pavement (RAP) as an aggregate in structural concrete, and the second method involves utilizing waste quarry fines as partial replacement of Portland cement in concrete mixes. Many efforts have been made in recent years to justify the use of RAP aggregates in concrete. All previous efforts appear to unanimously report a reduction in concrete performance with varying proportions of RAP usage. The poor performance of RAP aggregates in concrete is attributed mainly to a larger, more porous interfacial transition zone (ITZ) and to the cohesive failure of the asphalt. It is hypothesized that the detrimental impact on the ITZ is attributable to organic compounds leached from the asphalt in the high pH pore solution. This study proves the presence of organic compounds in the pore solution and demonstrates that there is an apparent retardation of cement hydration. This study also attempted to pretreat the RAP in a sodium hydroxide (NaOH) solution to pre-leach the organic compounds. The pretreatment demonstrated that organic compounds were leached and that NaOH modified the asphalt surface chemistry. However, only a marginal improvement in compressive strength was observed by completing the pretreatment. Replacement of Portland cement by filler products is a practice aimed at reducing the carbon footprint of concrete, such as is common with Type IL Portland limestone cement. This study investigates the impact of replacing cement with seven different quarry fines materials. The quarry fines were used to replace cement at 5% to 20% by volume in either cement paste or mortar samples that were then analyzed for various physicochemical properties. It was found that all the quarry fines had detrimental impact on the hydration kinetics of cement pastes. The inclusion of quarry fines was also found to cause varying degrees of reduction in mortar compressive strength. While further analyses of the quarry fines are required, quarry fines 2, 5 and 7 did display encouraging signs to suggest the potential for use as a filler material in blended cements. / Master of Science / This thesis broadly addresses the issue of sustainability in the cement and concrete industry. Sustainability is a significant problem for the cement and concrete industry due to the large amount of carbon emissions produced in the manufacturing process of Portland cement. One method to reduce the carbon footprint of concrete is to use recycled aggregates, and reclaimed asphalt pavement (RAP) is investigated in this thesis as a recycled aggregate option. Previous studies have shown that the use of RAP in concrete results in poor mechanical performance when compared to conventional concrete. In this thesis, the RAP was pretreated by soaking it in sodium hydroxide (NaOH) to see if any improvement is noted. It was determined that the pretreatment resulted in marginal improvements in concrete performance. Another method to reduce the carbon footprint of concrete is through the use of substitutions of Portland cement. In this thesis, quarry fines from around Virginia were investigated for potential as substitutive material. Quarry fines are a by-product from quarrying operations and are often considered a waste material because they have limited applications. This study analyzed the performance of cementitious materials prepared with various substitutive percentages of quarry fines and found that, in general, the inclusion of quarry fines resulted in a decrease of mechanical performance. In total, seven quarry fines were tested and only two showed potential for use as a substitution in Portland cement concrete. These two investigations are essential in reaching the goal of reducing the carbon footprint of the cement and concrete industry.

Yunta es una organización no lucrativa que se desarrolla en el ámbito de educación, específicamente en el desempeño socio-emocional de niños y adolescentes en situaciones vulnerables. Yunta surge como iniciativa de sus fundadores en Arequipa, quienes se percataron que la educación no es solo adquisición de conocimiento, sino requiere una sólida base psicológica para el correcto desarrollo de los menores. El principal objetivo del programa que Yunta desarrolla es el desarrollo de auto-estima y el desarrollo del sentido de la posibilidad. El presente trabajo propone el desarrollo del Plan Estratégico de Yunta, el cual se sostiene en los lineamientos definidos por el profesor Fernando D’Alessio Ipinza, director general de CENTRUM Católica. Como resultado de un seguimiento estricto de esta metodología, se determinó que el compromiso y trabajo de todos los que forman parte de Yunta, resulta en un requisito indispensable para la mejora de la organización. El plan sugiere la implementación de siete estrategias que permitirán que al 2020 Yunta sea reconocida como una organización sostenible que crea agentes de cambio en la sociedad peruana. Estas estrategias incluyen: (a) desarrollo de mercado para incrementar el número de patrocinadores, (b) desarrollo de productos a través de alianzas estratégicas con universidades que permita atraer alumnos extranjeros y profesionales que deseen aportar a la organización, (c) rightsizing a fin de incrementar el número de personas trabajando en el área administrativa de Yunta, (d) interna – calidad total a fin de promover una cultura de transparencia y análisis cuantitativo, (e) diversificación concéntrica a fin de crear nuevos programas innovadores para diferentes mercados, (f) penetración de mercado a través de alianzas estratégicas con agencias de publicidad que incrementen la exposición de la marca Yunta ,y (g) interna – cultura a fin de promover una cultura interna de innovación y desarrollo de R&D a través de alianzas estratégicas con organizaciones internacionales. / Yunta is a non-profit organization in the education sector, specifically concerning in the socio-emotional achievements of children and teenagers in vulnerable situations. Yunta is the result of the initiative of its founders in Arequipa, who realized that not only getting knowledge is important, but having solid psychological support for the well-being of the minors. The principle objective of Yunta is the socio-emotional development and the increase in the sense of possibility. This project propose the elaboration of a Strategic Plan for Yunta, based on the guidelines defined by professor Fernando D’Alessio Ipinza, general director of CENTRUM Católica. As a result of the application of this methodology, it was determined that the commitment and work of all the members of Yunta, is an indispensable requirement to the improvement of the organization. The plan suggests seven strategies to enable Yunta to be recognized by 2020 as a sustainable organization that empowers children that become agents of change in Peruvian society. These strategies include : (a) market development to amplify the scope of sponsors, (b) product development to develop a strategic alliance with universities in Perú to attract college students and professionals that are interested in volunteering, (c) rightsizing to increase the number of staff member supporting the administrative areas in Yunta, (d) internal - total quality to promote an internal culture of transparency and quantitative analysis, (e) concentric diversification to develop a strategic alliance with international organizations in order to create new innovative programs, (f) market penetration to develop a strategic alliance with a publicity agency to create brand awareness, and (g) internal - culture to promote an internal culture of innovation and R&D by developing strategic alliances with Yunta’s international associates.

The purpose of this research is to develop a 2015-2020 Strategic plan for Creamás, a Peruvian NGO that fosters the dreams and ambition of children through education and diverse workshops. The company began operating in the country in 2009 and throughout the years has managed to become a referent in the NGO national industry. In order to do that the model proposed by Fernando D’Alessio was followed throughout the nine chapters of the document. After thorough research, meetings with the directorates and volunteers, and on-site visitation, data was analyzed in an attempt to decipher the current holistic situation of the organization; its strengths, weaknesses and which opportunities and threats the external situation posed the organization. By complementing such information with a newly proposed vision and mission, and the identified organization’s interests; six long term objectives were defined with their correspondent short-term objectives. Besides that, five strategies were chosen in order for the Creamás to achieve its objectives and as a consequence, its desired vision. Furthermore, in order for Creamás to assess the implementation of this Plan, the document includes the proposed Balanced Scorecard; with the short-term objectives and their correspondent indicators. The fallouts of this work indicate that currently Creamás lacks operational efficiency due to the poor training of its volunteers, is still unable to measure its actual impact on the students, and does not possess a solid funding structure; all of them a must if the firm is to remain relevant in the industry / El objetivo de este trabajo es desarrollar un Plan Estratégico de Creamás para el periodo 2015-2020. Creamás es una ONG peruana que promueve que más niños tengan sueños y ambiciones por medio de clases de matemática y talleres complementarios. La empresa empezó a operar en el país en 2009 y a través de los años ha logrado convertirse en una reconocida organización. Para el desarrollo del trabajo se siguieron los nueve pasos del planeamiento estratégico definidos por Fernando D’Alessio (D’Alessio, 2013). Luego de una detallada investigación, reuniones con Directores y voluntarios, y visitas en campo, se analizó la data recogida a fin de descifrar la situación actual de la organización; sus fortalezas, debilidades y las oportunidades y amenazas que el entorno le presenta. Al complementar esta información con una nueva propuesta de visión y misión, además de los intereses de la empresa; se definieron seis objetivos a largo plazo. Asimismo, se eligieron cinco estrategias para alcanzarlos y que Creamás consiga lograr su situación futura deseada. Para la implementación del presente Plan, el documento incluye un Tablero de Control Balanceado con objetivos a corto plazo y sus indicadores de medición correspondientes. Los resultados de la investigación indican que Creamás presenta problemas en cuanto a eficiencia operacional debido al pobre entrenamiento que reciben sus voluntarios, no es capáz de medir el impacto que causa en los estudiantes y no cuenta aún con una sólida estructura de donaciones; situaciones que deben ser resueltas para mantenerse relevante en la industria.

The purpose if this work is to elaborate a strategic plan for the period 2015-2019 for Fútbol Más Perú, a non-profit association that started operations in Peru in February 2015. The information used for this document has been provided by the organization and by the authors’ own research. This plan has followed the model proposed by Dr. D’Alessio (2013). After reviewing the organization’s general situation and background, a new vision and mission are given; these consider both the theory and the organization’s purpose of existence. Afterwards, the external environment is analyzed to discover the players, opportunities and threats that Fútbol Más Perú will have to face. This analysis is combined with an internal evaluation of the organization, in order to find out what its main strong and weak points are, and how these cope with the environment. This analysis supports the formulation of four long-term objectives -and the respective short-term objectives- that the organization has to accomplish to see its vision fulfilled. These objectives consider the internal and external analysis and the organization’s vision and mission. Six strategies were chosen to enable the achievement of the objectives. The implementation of the strategies will be managed by controlling the achievement of the short-term objectives utilizing the Balanced Scorecard tool. Results of this work show that Fútbol Más Perú needs to increase its brand awareness to successfully attract private sponsors for its projects. Despite of having limited human resources it is possible to exploit resources not used currently, such as social media, to become more popular in the local environment. / El propósito de este trabajo es elaborar un plan estratégico para el periodo 2015-2019 para Fútbol Más Perú, una asociación sin fines de lucro que empezó operaciones en Perú en Febrero 2015. La información utilizada en este documento proviene de la organización y de la propia investigación de los autores. Este plan sigue el modelo propuesto por el Dr. D’Alessio (2013). Luego de revisar la situación general y antecedentes de la organización, se presenta una nueva visión y misión; éstas consideran tanto la teoría como la razón de existir de la organización. Posteriormente, se realiza un análisis del entorno a fin de descubrir los agentes, oportunidades y amenazas que Fútbol Más Perú tendrá que afrontar. Éste análisis es combinado con una evaluación interna de la organización, para poder encontrar sus principales puntos fuertes y puntos débiles y entender cómo éstos hacen frente al entorno. Este procedimiento apoya la formulación de cuatro objetivos de largo plazo –y los respectivos objetivos de corto plazo- que la organización debe cumplir para alcanzar su visión. Éstos objetivos consideran el análisis externo e interno y la misión y visión de la organización. Seis estrategias fueron escogidas para lograr los objetivos. La implementación de las mismas será administrada controlando la consecución de los objetivos de corto plazo, utilizando la herramienta tablero de control. Los resultados del presente trabajo demuestran que Fútbol Más Perú necesita aumentar la exposición de su marca para atraer patrocinadores para sus proyectos. A pesar de tener recursos humanos limitados, es posible explotar herramientas no usadas actualmente, como las redes sociales, para ganar popularidad en el ámbito local.

The current transition from Blast Furnace (BF) to Hydrogen-Direct Reduction (H-DR) is an initiative to reduce the carbon footprint in Iron and Steel production. The shift from traditional coke-based Iron and Steel making to a green H-DR requires new innovative technologies, underscoring the importance of collective efforts in this field. The production of DRI/HBI fines, which account for 1-2% wt. of DR production, poses a significant challenge for the iron and steel industries. These fines, rich in iron, are generated inside the plant during the handling, production, and transportation process. Their recycling in the DR process is difficult without proper agglomeration. Here, briquetting emerges as a promising solution to this challenge. This research work is dedicated to exploring the use of innovative binders in briquetting the DRI/HBI fines. It aims to understand the H2 -based reduction behaviour of the briquettes and the role of embedded biocarbon in enhancing resource efficiency. The study also investigates the impact of binders on the mechanical strength, moisture content, and compaction pressure of the briquettes. The optimized briquettes are then subjected to H2-based reduction using a thermogravimetric technique (TGA) followed by characterization by XRF, XRD, and LECO analysis, and mechanically evaluated to assess their potential in the next-generation H2-based Iron and Steel Making. Keywords: DRI/HBI Fines, Organic binders, Briquetting, H2 Reduction, Biocarbon, Recycling, Resource Efficiency

La flottation des particules fines est un challenge technique que l’industrie minière doit relever pour pouvoir exploiter de manière optimale certains types de gisement dont les minerais présentent des textures particulièrement fines. Cette problématique revêt une importance particulière avec la diminution des ressources minérales considérées comme conventionnelles du point de vue de la maille de libération des minéraux d’intérêt. Il existe deux manières d’optimiser les procédés de flottation pour un minerai, la recherche des paramètres de fonctionnement optimaux des équipements de flottation existants et l'élaboration de nouveaux réactifs de flottation. Les travaux des dernières décennies ont mis en évidence qu’en raison de leurs hauts régimes hydrodynamiques favorisant le contact entre les bulles et les particules, les techniques de flottation intensive étaient beaucoup plus adaptées pour le traitement des fines que les dispositifs de flottation mécanique. Cependant, en raison du temps de résidence très court au sein de ces dispositifs de flottation, il est nécessaire que la surface des minéraux d’intérêts soit rendue particulièrement hydrophobe. En ce sens, l’amélioration des performances de flottation, pour les minerais à granularité réduite, par des techniques de flottation intensive requiert l’élaboration de réactifs de flottation plus efficaces et plus sélectifs. L’objet d’étude qui a été choisi est un résidu fin produit à l’issue des différentes étapes nécessaires à l’extraction de l’or et du tellure à partir du minerai de la mine de Kankberg en Suède. Ce résidu à granularité fine possède une faible teneur en terres rares présentes sous la forme de monazite, un minéral de type phosphate. Les travaux de thèse présentés dans ce manuscrit consistaient à développer un réactif permettant d’améliorer l’adsorption d’un collecteur sur la surface de la monazite pour faciliter sa récupération lors de la flottation intensive. Il ressort de ces études que les ions lanthane peuvent améliorer significativement l’adsorption des collecteurs de type carboxylate sur la surface de la monazite et donc améliorer la flottabilité de cette dernière. Les connaissances actuelles concernant les propriétés de surface de la monazite et les mécanismes d’adsorption des collecteurs anioniques sur la surface de ce minéral sont relativement limitées. Il paraissait donc judicieux de contribuer au cours de cette thèse à l’amélioration de ces connaissances. Une étude a été menée pour évaluer l’hydroxylation de surface de la monazite qui est largement considérée dans la littérature comme influençant l’adsorption du collecteur. La manipulation de monazite peut conduire à une exposition aux radiations en raison de la radioactivité émise par la chaîne de désintégration des actinides souvent présents en quantité significative dans le réseau cristallin de la monazite. Au cours de ce projet doctoral, la synthèse de matériaux indurés analogues à la monazite a également été étudiée dans le but de faciliter le déroulement des expérimentations qui nécessitent l’utilisation de monazite. Un protocole de synthèse de poudre de monazite suffisamment indurée pour être agitée a été développé. Des mesures de mobilité électrophorétiques ont par ailleurs montré que les propriétés de surface de ces monazites de synthèse sont identiques à celles d’une monazite naturelle à composition complexe démontrant par ailleurs que la présence de nombreuses substitutions atomiques dans le réseau cristallin de la monazite n’avait pas d’influence sur sa mobilité électrophorétique. / The flotation of fine particles is a technical challenge that the mining industry must address to efficiently exploit certain types of deposit whose ores are finely textured. This issue is of particular importance with the depletion of mineral resources considered as “conventional” with regards to the liberation mesh of minerals of interest. There are two basic approaches to optimise the flotation process for a particular ore, the research for the best working parameters of existing flotation devices and the development of new flotation reagents. The research works in the past decades highlight that, owing to their high hydrodynamic regimes, intensive flotation technologies are more adapted to the treatment of fine particles than conventional mechanical flotation devices. However, due to the short residence time in intensive flotation cells, it is essential that the surface of the minerals of interest has been particularly hydrophobised. In this sense, the improvement of the flotation performance for fine grained ores implies both the use of new flotation technologies and the development of more efficient and more selective flotation reagents. The selected object of studies is a fine grained residue produced after the extraction of gold and tellurium out of the ore from the Kankberg mine which is located in Sweden. This fine material contains low amounts of rare earth elements, in the form of monazite, a phosphate mineral. The thesis works presented in this manuscript consists of developing a reagent that improves the adsorption of the collector on the surface of monazite to facilitate its recovery throughout intensive flotation. The conducted studies emphasise that lanthanum ions significantly promote the adsorption of carboxylate type collectors on the monazite surface thereby increasing the floatability of this mineral. Current knowledge regarding the surface properties of monazite and the mechanism of anionic collectors adsorption on the monazite surface are relatively limited. Therefore, it seems wise to contribute to improving this knowledge during this thesis. A study was carried out to assess the hydroxylation of the monazite surface which is largely considered in the literature as a phenomenon influencing the collector adsorption. The handling of monazite may cause radiation exposure because of the radioactive decay chains of the actinide elements naturally present in the monazite crystal lattice. During this thesis, the synthesis of indurated monazite analogue materials was also investigated to facilitate the conduct of experiments. A protocol of synthesis of monazite powder sufficiently indurated to be mechanically stirred has been developed. Electrophoretic mobility measurements highlight that the surface properties of the synthetic monazite materials were similar to those of natural monazite with complex chemistry showing, in addition, that the presence of several atom substitutions in the monazite crystal lattice has no influence on its electrophoretic mobility.

El presente proyecto profesional tuvo como objetivo desarrollar una propuesta estratégica para la organización social Vía Código al año 2022. Esta es una organización sin fines de lucro que desarrolla habilidades digitales y blandas en jóvenes peruanos en situación de vulnerabilidad. Con la finalidad de responder a dicho objetivo, se tomó como referencia al proceso estratégico para organizaciones sin fines de lucro de Allison y Kaye (2015). Para desarrollar la propuesta estratégica; en primer lugar, se elaboró una descripción detallada de la organización y se identificaron sus desafíos estratégicos; en segundo lugar, se identificaron sus grupos de interés y se realizó un diagnóstico interno que permitió identificar sus fortalezas y debilidades; en tercer lugar, se analizó el entorno de la organización identificando las oportunidades y amenazas que esta afronta. Estos tres pasos, sirvieron de insumo para el desarrollo de la propuesta estratégica, con lo cual se planteó una nueva propuesta de misión, visión, valores y teoría de cambio. Además, se plantearon cuatro estrategias de proyectos a realizar en los próximos tres años: fortalecer los servicios de desarrollo web; expandir las capacitaciones en habilidades digitales y blandas para jóvenes vulnerables no privados de su libertad con aliados; empezar a capacitar en habilidades blandas a jóvenes vulnerables privados de libertad en conjunto con el Estado; y empezar a capacitar en habilidades digitales y blandas a jóvenes privados de libertad fuera de los Centros de Diagnóstico y Rehabilitación Juvenil. En línea con ello, para que la ejecución de estos proyectos sea viable, se plantearon dos estrategias de financiamiento o modelo de negocio: fortalecer los servicios de desarrollo web y empezar a desarrollar actividades de recaudación de fondos puntuales. Así también, para asegurar que la organización pueda ejecutar las estrategias antes mencionadas es necesario que esta fortalezca sus capacidades internas, por lo que se plantearon siete estrategias en relación a ello, por ejemplo: fortalecer los procesos de gestión estratégica, fortalecer los procesos de gestión financiera del webshop, incrementar la visibilidad de la labor de la organización, fortalecer la red de aliados estratégicos, entre otras. Es importante resaltar que las estrategias propuestas fueron validadas con el equipo directivo de Vía Código. Por último, con la finalidad de garantizar la implementación y control de la propuesta estratégica, se desarrollaron herramientas que permiten tangibilizar y evaluar la misma: el balanced scorecard de Kaplan (2001) adaptado a organizaciones sociales con trece objetivos, acompañados de iniciativas estratégicas e indicadores para cada uno de ellos; el mapa estratégico que visibiliza las conexiones y relaciones de causa-efecto entre los objetivos; y un plan de acción a tres años que operativiza la propuesta estratégica.

Afin de garantir une gestion durable du massif forestier des Landes de Gascogne (maintien de la fertilité et production élevée), des études sont nécessaires sur la biodisponibilité du phosphore (P) qui est un facteur limitant. Une évaluation fiable de la biodisponibilité du P passe par la quantification des processus d’acquisition par les plantes, à savoir l’interception racinaire, le transport dans la solution et la mobilisation à l’interface solide-solution d’ions phosphates. Dans ce contexte, l’objectif général de la thèse était de faire un bilan biogéochimique de la biodisponibilité du P dans les sols forestiers des Landes de Gascogne, c'est-à-dire une analyse quantitative et comparative des processus physico- chimiques (diffusion) et biologiques (minéralisation et reminéralisation) de réapprovisionnement de la solution en ions phosphates ainsi qu’une caractérisation du système de prélèvement (racines fines) du Pin maritime. Les résultats ont montré une déficience en P pour l’ensemble des sols étudiés. Ils ont également montré une importance variable, en fonction de la profondeur et du type de lande (humide à sèche), des différents processus biologiques et physico-chimiques dans le réapprovisionnement de la solution. Le rôle des micro-organismes, via la minéralisation du P organique du sol et en tant que source (reminéralisation) et puits (immobilisation) de P, est particulièrement important dans les sols peu réactifs vis-à-vis du P comme les litières ou certains sols minéraux de surface. L’étude du système de prélèvement (racines fines, ectomycorhizes) suggère que le prélèvement de P par le Pin maritime concerne aussi bien les horizons de surface que ceux du sous-sol. / In order to guarantee a sustainable management of the forest range the “Landes de Gascogne” (maintaining fertility and elevated productivity), the bioavailability of phosphorus (P), a growth limiting factor, needs to be studied. An accurate evaluation of P bioavailability implies the quantification of plant acquisition processes such as root interception, soil solution transport and the mobilisation of phosphate ions at the soil-soil solution interface. The main objective of the PhD study was to assess a biogeochemical balance of the P bioavailability in the forest soils of the “Landes de Gascogne”, i.e. to carry out an quantitative and comparative analysis of the physical-chemical (diffusion) and biological (mineralization and remineralization) processes of replenishing the soil solution with phosphate ions, as well as the characterisation of the tree uptake system (fine roots) of maritime pine. The results have shown that all of the soils studied are very deficient in P. They have further shown a varying importance of the different biological and physical-chemical processes in supplying P to the soil solution according to the site class (humid to dry moorlands). The role of the microorganisms, via the mineralization of organic P, as a source (remineralization) or a sink (immobilization) of P, is particularly important in the litter and top mineral layers featuring a very low reactivity versus P. The study of the uptake system (fine roots and ectomycorrhizae) suggests that uptake of P by maritime pine takes place both in top soil horizons and in deeper soil horizons.