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1
Brunner, Benjamin. "The sulfur cycle: from bacterial microenvironment to global biogeochemical cycles /." Zürich : [s.n.], 2003. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=15197.
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Formolo, Michael J. "The biogeochemical cycling of sulfur in two distinct redox regimes /." free to MU campus, to others for purchase, 2004. http://wwwlib.umi.com/cr/mo/fullcit?p3164506.
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Meixner, Thomas. "Alpine biogeochemical modeling case studies, improvements, and parameter estimation /." Diss., The University of Arizona, 1999. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_e9791_1999_256_sip1_w.pdf&type=application/pdf.
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Bagnara, Maurizio. "Modelling biogeochemical cycles in forest ecosystems: a Bayesian approach." Doctoral thesis, country:IT, 2015. http://hdl.handle.net/10449/25094.
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Forest models are tools for explaining and predicting the dynamics of forest ecosystems. They simulate forest behavior by integrating information on the underlying processes in trees, soil and atmosphere.
Bayesian calibration is the application of probability theory to parameter estimation. It is a method, applicable to all models, that quantifies output uncertainty and identifies key parameters and variables. This study aims at testing the Bayesian procedure for calibration to different types of forest models, to evaluate their performances and the uncertainties associated with them. In particular,we aimed at 1) applying a Bayesian framework to calibrate forest models and test their performances in different biomes and different environmental conditions, 2) identifying and solve structure-related issues in simple models, and 3) identifying the advantages of additional information made available when calibrating forest models with a Bayesian approach.
We applied the Bayesian framework to calibrate the Prelued model on eight Italian eddy-covariance sites in Chapter 2. The ability of Prelued to reproduce the estimated Gross Primary Productivity (GPP) was tested over contrasting natural vegetation types that represented a wide range of climatic and environmental conditions.
The issues related to Prelued's multiplicative structure were the main topic of Chapter 3: several different MCMC-based procedures were applied within a Bayesian framework to calibrate the model, and their performances were compared. A more complex model was applied in Chapter 4, focusing on the application of the physiology-based model HYDRALL to the forest ecosystem of Lavarone (IT) to evaluate the importance of additional information in the calibration procedure and their impact on model performances, model uncertainties, and parameter estimation. Overall, the Bayesian technique proved to be an excellent and versatile tool to successfully calibrate forest models of different structure and complexity, on different kind and number of variables and with a different number of parameters involved
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Bagnara, Maurizio <1985>. "Modelling biogeochemical cycles in forest ecosystems: a Bayesian approach." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7188/1/Bagnara_Maurizio_tesi.pdf.
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Forest models are tools for explaining and predicting the dynamics of forest ecosystems. They simulate forest behavior by integrating information on the underlying processes in trees, soil and atmosphere.
Bayesian calibration is the application of probability theory to parameter estimation. It is a method, applicable to all models, that quantifies output uncertainty and identifies key parameters and variables. This study aims at testing the Bayesian procedure for calibration to different types of forest models, to evaluate their performances and the uncertainties associated with them. In particular,we aimed at 1) applying a Bayesian framework to calibrate forest models and test their performances in different biomes and different environmental conditions, 2) identifying and solve structure-related issues in simple models, and 3) identifying the advantages of additional information made available when calibrating forest models with a Bayesian approach.
We applied the Bayesian framework to calibrate the Prelued model on eight Italian eddy-covariance sites in Chapter 2. The ability of Prelued to reproduce the estimated Gross Primary Productivity (GPP) was tested over contrasting natural vegetation types that represented a wide range of climatic and environmental conditions.
The issues related to Prelued's multiplicative structure were the main topic of Chapter 3: several different MCMC-based procedures were applied within a Bayesian framework to calibrate the model, and their performances were compared.
A more complex model was applied in Chapter 4, focusing on the application of the physiology-based model HYDRALL to the forest ecosystem of Lavarone (IT) to evaluate the importance of additional information in the calibration procedure and their impact on model performances, model uncertainties, and parameter estimation.
Overall, the Bayesian technique proved to be an excellent and versatile tool to successfully calibrate forest models of different structure and complexity, on different kind and number of variables and with a different number of parameters involved.
6
Bagnara, Maurizio <1985>. "Modelling biogeochemical cycles in forest ecosystems: a Bayesian approach." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amsdottorato.unibo.it/7188/.
Full textAbstract:
Forest models are tools for explaining and predicting the dynamics of forest ecosystems. They simulate forest behavior by integrating information on the underlying processes in trees, soil and atmosphere.
Bayesian calibration is the application of probability theory to parameter estimation. It is a method, applicable to all models, that quantifies output uncertainty and identifies key parameters and variables. This study aims at testing the Bayesian procedure for calibration to different types of forest models, to evaluate their performances and the uncertainties associated with them. In particular,we aimed at 1) applying a Bayesian framework to calibrate forest models and test their performances in different biomes and different environmental conditions, 2) identifying and solve structure-related issues in simple models, and 3) identifying the advantages of additional information made available when calibrating forest models with a Bayesian approach.
We applied the Bayesian framework to calibrate the Prelued model on eight Italian eddy-covariance sites in Chapter 2. The ability of Prelued to reproduce the estimated Gross Primary Productivity (GPP) was tested over contrasting natural vegetation types that represented a wide range of climatic and environmental conditions.
The issues related to Prelued's multiplicative structure were the main topic of Chapter 3: several different MCMC-based procedures were applied within a Bayesian framework to calibrate the model, and their performances were compared.
A more complex model was applied in Chapter 4, focusing on the application of the physiology-based model HYDRALL to the forest ecosystem of Lavarone (IT) to evaluate the importance of additional information in the calibration procedure and their impact on model performances, model uncertainties, and parameter estimation.
Overall, the Bayesian technique proved to be an excellent and versatile tool to successfully calibrate forest models of different structure and complexity, on different kind and number of variables and with a different number of parameters involved.
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Stamenkovic, Jelena. "The role of vegetation and soil in the biogeochemical cycling of mercury." abstract and full text PDF (free order & download UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3339148.
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McKee, Conor Michael. "Biogeochemical cycles of ammonia and dimethylsulphide in the marine environment." Thesis, University of East Anglia, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368388.
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Zhang, Rong 1971. "Self sustained thermohaline oscillations and their implications for biogeochemical cycles." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8232.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2001.Includes bibliographical references (p. 150-156).
An ocean general circulation model (OGCM) configured with a paleo ocean bathymetry such as late Permian shows that different modes of ocean circulation might exist in warm climate: a strong 'thermal mode' induced by cooling at high latitudes and a weak 'haline mode' induced by evaporation at subtropics. The 'haline mode', obtained with enhanced freshwater flux and reduced vertical diffusivity, is inherently unstable, flushed by thermally-driven polar convection every few thousand years. A 3-box model of the thermohaline circulation is developed to study the basic physical mechanism of thermohaline oscillations. By including convective adjustment and a parameterization of the localized nature of convection, the box model shows that haline mode is unstable over a certain freshwater forcing/vertical diffusivity range.
(cont.) Self-sustained oscillatory thermohaline circulations, with periods ranging from centuries to several millennia, are supported. When the amplitude of surface freshwater flux exceeds a certain threshold the haline mode stabilizes. The relationship between oscillation periods and the freshwater flux/vertical diffusivity is also studied. Biogeochemical modeling of the late Permian ocean shows that the strong 'thermal mode' leads to well oxygenated deep ocean, the weak 'haline mode' leads to depletion of deep ocean oxygen. Biogeochemical cycles driven by the thermohaline oscillation found in the 3-box model shows that: the quasi-steady 'haline mode' is correlated with lower biological productivity, depleted deep ocean oxygen, heavier surface 613C due to weak vertical mixing, the transient 'thermal mode' is correlated with higher biological productivity, oxygenated deep ocean and lighter surface 613C due to strong vertical mixing. Those correlations are consistent with rhythmic paleo records. The 613C shift during mode switch is proportional to mean ocean nutrient level.
by Rong Zhang.
Ph.D.
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Singh, Shweta. "Incorporating Biogeochemical Cycles and Utilizing Complexity Theory for Sustainability Analysis." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1345519020.
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Banaitis, Michael R. "Biogeochemical Response of a Northeastern Forest Ecosystem to Biosolids Amendments." Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/BanaitisMR2007.pdf.
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Sakaguchi, Koichi. "Spatiotemporal Scale Limits and Roles of Biogeochemical Cycles in Climate Predictions." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/268598.
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There is much confidence in the global temperature change and its attribution to human activities. Global climate models have attained unprecedented complexity in representing the climate system and its response to external forcings. However, climate prediction remains a serious challenge and carries large uncertainty, particularly when the scale of interest becomes small. With the increasing interest in regional impact studies for decision-making, one of the urgent tasks is to make a systematic, quantitative evaluation of the expected skill of climate models over a range of spatiotemporal scales. The first part of this dissertation was devoted to this task, with focus on the predictive skill in the linear trend of surface air temperature. By evaluating the hindcasts for the last 120 year period in the form of deterministic and probabilistic predictions, it was found that the hindcasts can reproduce broad-scale changes in the surface air temperature, showing reliable skill at spatial scales larger than or equal to a few thousand kilometers (30° x 30°) and at temporal scales of 30 years or longer. However, their skill remains limited at smaller spatiotemporal scales, where we saw no significant improvement over climatology or a random guess. Over longer temporal scales, the feedbacks from the carbon cycle to atmospheric CO₂ concentration become important. Therefore the rest of the dissertation attempts to find key processes in the climate-carbon cycle feedback using one of the leading land-climate models, the National Center for Atmospheric Research Community Land Model. Evaluation of site-level simulations using field observations from the Amazon forest revealed that the current formulation for drought-related mortality, which lacks the ecophysiological link between short- and long-term drought stress, prevent the model from simulating realistic forest response. Global simulations showed that such dynamics of vegetation strongly influences the control of the nitrogen cycle on vegetation productivity, which then alters the sensitivity of the terrestrial biosphere to surface air temperature. This implies that if the state of the terrestrial biosphere is inconsistent with the simulated climate, either biased or prescribed, then its feedback to anthropogenic forcing could be also inconsistent.
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McClain, Michael Eugene. "Terrestrial controls on the biogeochemistry of dissolved organic matter and inorganic nitrogen in streams of the central Amazon Basin, Brazil /." Thesis, Connect to this title online; UW restricted, 1996. http://hdl.handle.net/1773/11038.
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Kesavan, Jayati. "Genetic analysis and phenotypic characterization of two Shewanella putrefaciens iron reduction-deficient mutants." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/25231.
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Brown, Dorothy Louise. "Deposition, mixing and storage timescales at the benthic boundary layer." Thesis, University of Glasgow, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.368735.
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Tisserand, Romane. "The Ni biogeochemical cycle in a tropical agromining crop system." Electronic Thesis or Diss., Université de Lorraine, 2021. https://docnum.univ-lorraine.fr/ulprive/DDOC_T_2021_0115_TISSERAND.pdf.
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L'hyperaccumulation est un phénomène qui a été découvert il y a 45 ans seulement, il a fait l'objet de nombreuses recherches, en raison du comportement inhabituel des métaux dans l'écosystème et en raison du potentiel de solutions fondées sur la nature qui en découle. La description du cycle biogéochimique du Ni des plantes hyperaccumulatrices est nécessaire pour élucider leur rôle écologique dans leur environnement naturel, mais aussi pour comprendre leur comportement potentiel dans des cultures tropicales d’agromine. L'exploitation agricole et l'exportation de la biomasse riche en Ni interrompront le cycle du Ni. Il est donc important de comprendre les mécanismes qui régissent le cycle biogéochimique du Ni dans les systèmes naturels et de cultures : Quels sont les cycles du Ni et leur impact sur le fonctionnement écologique des forêts tropicales d’hyperaccumulateurs ? Quelle est la vitesse des flux de Ni à travers les compartiments sol-plante et quelle est la dynamique et le renouvellement du Ni dans un système tropical d'hyperaccumulateurs ? À quelle vitesse une culture tropicale Agromine peut-elle épuiser le Ni dans le sol ? Comment pouvons-nous gérer la fertilisation des sols pour une culture d’agromine tropicale de Ni durable ? Les objectifs de ce doctorat étaient donc les suivants (i) d'étudier le cycle biogéochimique d'une forêt naturelle de Phyllanthus rufuschaneyi afin d'évaluer les flux de Ni dans l'écosystème ; (ii) de manipuler un tel écosystème afin d'effectuer un test de sensibilité de l'écosystème pour le flux suivant : retour de la litière au sol ; de l'absence de retour (exportation) à un doublement du retour ; (iii) d'optimiser le système de culture de P. rufuschaneyi pour l'agromine du Ni. Deux peuplements parallèles de P. rufuschaneyi ont été instrumentés, surveillés et comparés pendant deux ans (2018 et 2019), (i) une forêt secondaire naturelle de 100 m2 et (ii) un champ densément planté dans lequel les retours de litière au sol ont été calibrés ; de l'absence de retour (exportation) à un doublement du retour. Cette étude n'a pas révélé l'allopathie des plantes hyperaccumulatrices tropicales. Les plantes hyperaccumulatrices de Ni influent sur la constitution des stocks de Ni disponibles dans les couches arables. Le cycle du Ni est principalement régi par des flux internes, notamment la dégradation et le recyclage de la litière. Ce pourcentage de renouvellement du Ni ne semble pas être influencé par le taillis à court terme mais par la présence initiale de litière sur le sol. La fertilisation NPK n'a aucun effet sur le rendement en Ni à court terme (75 kg Ni ha-1 an-1), même si la fertilisation en azote a tendance à réduire le rendement en Ni de P. rufuschaneyi. Il convient de tenir compte du renouvellement du nickel lors de la conception des cultures d’agromine tropicales. Une étude plus approfondie de l’altération permettrait de préciser son rôle dans la reconstitution des stocks de Ni disponible et de nutrimentsHyperaccumulation is a phenomenon that was only discovered 45 years ago, it has been the focused of very intensive research because of the unusual behaviour of metals in the ecosystem and also because it offers a vast potential for nature-based solutions. Describing the Ni biogeochemical cycle within the soil-hyperaccumulator plants ecosystem is necessary to elucidate the ecological role of hyperaccumulator plants in their natural environment, but also to understand their potential behaviour under tropical agromining systems. Agromining and exporting Ni rich-biomass will interrupt the cycle. It is therefore important to understand the mechanisms which govern the Ni biogeochemical cycle in both natural and agromining systems: What are the Ni cycles (internal and external) and their impact on the ecological functioning of tropical hyperaccumulator forest? How rapid are the Ni fluxes across the soil-plant compartments, and what is the turnover of Ni in a hyperaccumulator tropical system? How fast can a tropical Agromining crop deplete Ni in soil? How can we manage soil fertilisation for a sustainable tropical Ni agromining crop? Therefore, the objectives were: (i) to study the biogeochemical cycling of a natural forest of Phyllanthus rufuschaneyi in order to assess and evaluate the natural fluxes of Ni in the ecosystem; (ii) to manipulate such an ecosystem in order to perform a sensitivity test of the ecosystem for the following flux: litter return to the soil; (iii) to optimize the cropping system of P. rufuschaneyi for Ni agromining. Two parallel stands of P. rufuschaneyi were instrumented, monitored and compared over two years (2018 and 2019), (i) a natural secondary 100-m2 forest and (ii) a densely planted field in which litter returns to the soil were calibrated; from no return (export) to a doubling of the return.This study did not prove allelopathy of tropical hyperaccumulator plants, despite the extreme influence of Ni hyperaccumulators in building up available Ni stocks in topsoils. Nickel cycle was mainly driven by internal fluxes, i.e. degradation and recycling of the hyperaccumulator biomass. The percentage of Ni recycled by litterfall tended to decrease with increasing litter addition to the soil and was not influenced by coppicing, at least in the short term. Major nutrient (NPK) fertilisation did not affect Ni yield (i.e. 75kg Ni ha-1 yr-1) in the short term either, even if N fertilisation reduced Ni concentrations in leaves and plant biomass production. Nickel turnover should be taken into account when designing tropical agromining crops and natural secondary forests are a good surrogate to evaluate the long term impacts of agromining. Further study of the weathering processes would help to precise the contribution of bedrock and soil mineral horizons in the Ni and nutrient budgets of the system
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Rahn, Thomas A. "Enrichment of ¹⁵N and ¹⁸O in stratospheric nitrous oxide : observations, experimental results, and implications /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1998. http://wwwlib.umi.com/cr/ucsd/fullcit?p9907828.
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Silva, Juan Carlos. "Major variations in global biogeochemical cycles in the aftermath of two Neoproterozoic global glaciations /." [S.l.] : [s.n.], 2009. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Schoemann, Véronique. "On the role of phaeocystis sp. in the biogeochemical cycles of manganese and iron." Doctoral thesis, Universite Libre de Bruxelles, 2000. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211794.
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Carey, Amy Dawn. "Calcium isotope dynamics in the Hubbard Brook sandbox experiments." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Thesis/summer2006/a%5Fcarey%5F072806.pdf.
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Malmstrom, Rex R. "Contributions of abundant bacterial groups to the flux of dissolved organic matter in the ocean." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 1.42 Mb.,170 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3200540.
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Stoklas, Ulrica F. "Variation in nutrient dynamics among full-sib families of Picea mariana (Mill.) B.S.P. at two sites differing in water availability." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0004/MQ37169.pdf.
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Neuhuber, Stephanie Maria Ulrike. "In situ measurements of redox chemical species with amperometric techniques to investigate the dynamics of biogeochemical processes in aquatic systems." Thesis, Georgia Institute of Technology, 2003. http://hdl.handle.net/1853/25737.
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Shaughnessy, Gwendolyn A. "Surface and small-scale processes of biogeochemical cycling of organic matter in tidal sediments /." Electronic version (PDF), 2007. http://dl.uncw.edu/etd/2007-3/shaughnessyg/gwendolynshaughnessy.pdf.
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Llirós, Dupré Marc. "Diversity, dynamics and activity of mesophilic Archaea in stratified feshwater lakes. Implications in biogeochemical cycles." Doctoral thesis, Universitat de Girona, 2010. http://hdl.handle.net/10803/7641.
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Aquesta tesi doctoral va estudiar la diversitat (riquesa i abundància), la distribució i la dinàmica de les comunitats planctòniques d'Archaea presents a diferents llacs estratificats temperats d'aigua dolça per aportar evidencies sobre la seva distribució i la seva possible activitat en aquests ecosistemes en relació als cicles biogeoquímics presents en els mateixos. Es varen estudiar dos estanyols d'origen càrstic (l'Estanyol del Vilar durant cinc anys consecutius (2001-2005) i l'Estanyol de Can Coromina) i un llac d'origen volcànic (Llac Kivu) analitzant, per una banda, la seva comunitat planctònica d'Archaea mitjançant una aproximació molecular i, per una altra, la seva possible activitat en aquests ambients (p.e., la nitrificació i la fixació de carboni). Per contextualitzar els resultats, es va realitzar un anàlisi in silico dels patrons de distribució global dels Archaea mesòfils mitjançant un anàlisi a nivell de llinatge combinant seqüències del gen 16S rRNA amb diferents eines estadístiques i d'ecologia general.The present PhD thesis analysed the diversity (richness and evenness), distribution and dynamics of planktonic Archaea in several temperate stratified freshwater lakes to shed some light on their distribution and potential activity in these ecosystems in relation to prevalent biogeochemical cycles. In this sense, two karstic lagoons (Lake Vilar during five consecutive years (2001-2005) and Coromina lagoon) and a volcanic lake (Lake Kivu) were studied analysing, in the one hand, their archaeal planktonic community throughout a molecular approach and, in the other hand, their potential acitivity in these environments (e.g., nitrification and carbon fixation). In order to contextualize the obtained results, an in silico phylogenetic lineage-based analysis on the global distribution of lacustrine Archaea was conducted using 16S rRNA gene sequences in combination with statistical and general ecology tools.
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Hindle, Kristi Marie. "The influence of wetting and drying cycles on the biogeochemical dynamics of mercury in sediments." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/26924.
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Decommissioning hydro-dams increases sediment exposure to air, altering biogeochemical cycling of metals. Hg and MeHg mobility was studied in reservoir sediments from two Eastern Ontario lakes (Stump (SL) and Black Donald (BDL)) submitted to wet/dry cycles with artificial rainwater (pH∼4.5) every two weeks. Leachate pH, sulphate, sulphide and MeHg, and sulphate-reducing bacteria (SRB) populations were monitored over 6 months. The sediments did buffer the rainwater at the start of the experiment, but leachate pH decreased over time for both lakes. MeHg release occurred during the first draining event (2-4 ppt), and decreased thereafter, with no relationship with pH, sulphide and sulphate. SRB populations remained constant over time. Over 70% of Hg was in the non-labile refractory organic and residual phases, where Hg moved to semi-mobile phases in SL, but shifted to more immobile phases in BDL over time. Decommissioning hydro-dam reservoirs may increase acid production and alter Hg partitioning in sediments, while MeHg release will be low.
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Johnson, Michelle. "Development of a process-based soil evolution model and its application for understanding biogeochemical cycles." Thesis, University of Leeds, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.590476.
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The position of soils at the interface between other geochemical reservoirs such as the atmosphere and lithosphere mean that they play a central role in several global biogeochemical cycles. A model which is able to simulate processes occurring within soils over the course of their development will enable further understanding and quantification of such cycles. This thesis describes the development of a process-based soil evolution model and presents first comparisons with observations from soil chronosequences. The mechanistic, soil evolution model developed incorporates the major processes of pedogenesis, including i) mineral weathering, ii) perco- . lation of rainfall, iii) leaching of solutes, iv) surface erosion, v} bioturbation and vi) vegetation-soil interactions. The specific properties the model simulates over timescales of tens to hundreds of thousand years are, soil depth, vertical profiles of elemental composition, soil solution pH, organic carbon distribution and C02 production and concentration. The model is compared with soil properties from a soil chronosequence .in Hawaii. A good agreement is observed between measured and modelled Na (which is not a plant nutrient) and Mg and Ca which are less strongly cycled. The agreement is observed across both an age and rainfall gradient, suggesting a coherent representation of modelled soil processes. Differences between measured and modelled K and P profiles are however, substantial. This suggests that for the current, simple nutrient cycling framework, the model is not capturing the active role of vegetation in obtaining nutrients. This model result therefore, indirectly indicates the important role that vegetation and mycorrhiza may play in accelerating the release of specific nutrients from minerals. Geochemical tracers from soils developed on basalts in Queensland are exploited to constrain the processes of bioturbation and erosion in the model. This study demonstrated how these tracers can be successfully used for such a model framework. With improved parameterisation of processes the model predicts an exponential soil production function for the Queensland soils and quantifies maximum erosion rates acceptable for sustaining a cover of soil. The model is applied to the long-term carbon cycle specifically to understand the relationships between erosion, vegetation and silicate mineral weathering. Results indicate the complex relationship between these factors and atmospheric C02 consumption. A particularly important result to arise from this study is that before vascular plant colonisation onto land (~360-400Ma) the sensitivity of silicate mineral weathering to C02 concentrations may have been sufficient to regulate atmospheric C02 concentrations
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Pagès, Anais. "Biogeochemical cycles (C, N, S, P and Fe) of modern and ancient microbialites (Western Australia)." Thesis, Curtin University, 2014. http://hdl.handle.net/20.500.11937/53047.
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This PhD study focused on organic, inorganic and isotopic geochemical studies of modern stromatolites from Shark Bay, Western Australia (WA) and ancient stromatolites from the Pilbara, WA. In this project, the characterisation of microbial communities, biogeochemical cycles and influence of environmental conditions on microbial mat functioning were investigated. In addition, the preservation pathways of biosignatures in microbialites through time were explored, providing a better insight into the evolution of early-life.
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Lowe, Kristine L. "Biogeochemical cycling of metals in redox-stratified marine environments : role of anaerobic microorganisms." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/25187.
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Lail, Erin M. "Biogeochemical cycling of domoic acid and its isomers in the ocean /." Electronic version (PDF), 2006. http://dl.uncw.edu/etd/2006/laile/erinlail.pdf.
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Pupin, Breno [UNESP]. "Atributos microbiológicos em ecossistemas costeiros da Ilha do Cardoso, SP." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/103875.
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000737578.pdf: 3803187 bytes, checksum: b8c4f772c3838e4786b19e09a8dc45b5 (MD5)Os manguezais apresentam características que os diferenciam dos demais ecossistemas. O objetivo deste trabalho foi estudar os grupos microbianos (bactérias totais, esporuladas, Gram-negativas, actinobactérias, nitrificantes, desnitrificantes e fungos), as atividades metabólicas de bactérias e fungos, as atividades microbianas relacionadas ao ciclo do C, N, P (atividade respiratória, da desidrogenase, amonificante, nitrificante, da urease, da protease, solubilizadora de fosfato e da fosfatase ácida), além das análises químico-físicas (umidade, matéria orgânica, carbono orgânico total, carbono solúvel, carboidratos totais, fracionamento do fósforo, pH e salinidade) do solo de manguezal e compará-las com os de floresta e restinga. As amostras de solos foram coletadas durante o verão e o inverno, nas profundidades de 0 – 2 cm, 2 – 5 cm e 5 – 10 cm. Os micro-organismos isolados foram testados quanto à habilidade de produzir amilase, fosfatase ácida e/ou solubilizar fosfato inorgânico. Os resultados foram interpretados com análise estatística univariada. Excetuando os fungos totais, as contagens dos demais grupos microbianos decresceram significativamente (p < 0,05) na seguinte ordem: floresta > manguezal > restinga. As populações de actinobactérias predominaram no solo de floresta, porém foram semelhantes (p < 0,05) nos solos de manguezal e de restinga. O número das bactérias desnitrificantes foi similar nos solos de floresta e de manguezal e maior que o do solo de restinga. As contagens dos micro-organismos decresceram significativamente 11 e 21% da camada superficial para a 2 – 5 cm e 5 – 10 cm, porém as desnitrificantes aumentaram 44 e 166%. Enquanto o número de bactérias totais, esporuladas, Gram-negativas, nitrificantes e desnitrificantes decresceu (p < 0,05) 32% em média do verão para o inverno, o das actinobactérias permaneceu invariável e dos fungos aumentou 29%...
Mangroves has characteristics that differentiate them from other ecosystems. The objective of this study was to evaluate the frequency of microbial groups (total, sporulating, Gram-negative, actinomycetes, nitrifying, denitrifying bacteria and fungi), the bacteria and fungi metabolic activities, microbial activities related to the cycle of C, N, P (respiration, dehydrogenase, ammonium-oxidizing, urease, protease, solubilizing phosphate and acid phosphatase activities), and chemical-physical analysis (moisture, organic matter, total organic carbon, soluble carbon, carbohydrates, fractionation phosphorus, pH and salinity) from mangrove soil, comparing them with the restinga and forest soils. Soil samples were collected during the summer and winter, at depths of 0 – 2 cm, 2 – 5 cm and 5 - 10 cm. The microorganisms isolated were tested for their ability to produce amylase, acid phosphatase and/or solubilize inorganic phosphate. Results were interpreted with univariate statistical analysis. Except fungi total scores of other microbial groups decreased significantly (p < 0.05) in the following order: forest > mangrove > restinga. Populations of actinomycetes predominated in the forest soil, but were similar (p < 0.05) in mangrove soils and restinga. The denitrifying bacteria number was similar in forest and mangrove soil and higher than restinga soils. The microorganism counts decreased significantly 11 and 21% the surface layer for 2 - 5 cm and 5 - 10 cm, however, denitrifying increased 44 and 166%. While total number, sporulating, Gram-negative, nitrifying and denitrifying bacteria decreased (p < 0.05), on average 32% from summer to winter, actinomycetes remained unchanged and fungi increased 29%...
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Hillmer, Kiekebusch Ingrid Andrea. "Scales of interactions between physical processes, primary producers and nutrients in aquatic ecosystems." University of Western Australia. Centre for Water Research, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0177.
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[Truncated abstract] Estimating internal biogeochemical fluxes is essential to the understanding of the dynamic of aquatic ecosystems. Different ecological approaches have been used to gain insight into the internal cycling, but success has been limited. A critical point is the identification of the characteristic scales of patterns and the underlying processes affecting the behaviour of biological and chemical species. Failing to capture these scales leads to misinterpretation of field and numerical data. In this study, key aspects in the design of ecological surveys are identified to ensure that the internal biogeochemical processes are well represented. In the first part of this thesis, a 1D reaction-diffusion-advection equation is used to investigate the formation of patterns and relevant time and spatial scales. This is used to define an approach for the determination of a critical domain size that allows differentiation of the role of local and internal cycling from advective fluxes across the open boundaries in a shallow coastal ecosystem. By using a 3D numerical model, in conjunction with an extensive field data set, it is shown that domain sizes must be larger than this critical value in order to capture the patterns generated within the system. For smaller domains, transport processes control the evolution of the system across the boundaries misleading the interpretation of the internal ecological dynamics. The study of the influence of boundary fluxes on ecological patchiness was motivated by the need to define the size of the domain necessary for the assessment of the impact of a sewage outflow on a coastal regime. The quantification of biogeochemical processes has proven to be difficult to achieve especially under conditions of high spatial and temporal hydrodynamic and biogeochemical variability. In the second part of this thesis, a Lagrangian experimental design is employed to estimate biogeochemical rate coefficients in situ. A set of four drogues and a cross-transect sampling design is used to capture the patchy distribution of phytoplankton and nutrient species, and high transport and mixing rates. ... Total chlorophyll from both models shows similar behavior when the variability in the 3D model, expressed as Chlamax/Chlamin, is low. When Chlamax/Chlamin is high, the difference between the biomass predicted by the two models reaches 30% due to the generation of localised patches. Comparison of the 1D and 3D results highlights the need of using models that are able to resolve the spatial complexity to some extent, as the use of averaged properties may produce misleading results. This is especially important in the presence of patches with differential physiological and biogeochemical characteristics, and nonlinear processes, in which case biomass average is not necessarily linearly related to the averaged environment.
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Meneghine, Aylan Kener [UNESP]. "Análise metagenômica e potencial biotecnológico de microrganismos de solo e água de uma área agrícola com adubação orgânica." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/147993.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O composto orgânico produzido a partir de carcaças, resíduos animais e vegetais é uma alternativa viável para a substituição total ou parcial dos fertilizantes minerais utilizados na atualidade. No processo de compostagem participam diferentes populações microbianas, e com isso o composto torna-se um sistema rico para utilização como fertilizante no solo, complementando assim as necessidades nutricionais e microbianas do meio ambiente. Entretanto, há poucos trabalhos envolvendo análise da diversidade bacteriana em solos sob uso de composto orgânico feito a partir de carcaças, e também pouco se conhece sobre o impacto ambiental do uso agrícola de composto orgânico na qualidade da água. Existe também a questão se há influência da água utilizada para irrigação na qualidade do solo. O objetivo central desse trabalho foi analisar a diversidade bacteriana e perfil funcional de um solo de horta e da água de um córrego utilizada para irrigação. E como objetivo secundário, através do isolamento de bactérias da água verificar o potencial biotecnológico de produção e uso de exopolissacarídeo como bioemulsificante de óleo e hidrocarbonetos. As amostras de solo e água utilizadas nesse trabalho foram coletadas na área do departamento rural da Fundação Parque Zoológico de São Paulo, em setembro de 2014. Todo material coletado foi transportado até o Laboratório de Bioquímica de Micro-organismos e de Plantas, onde realizou-se a extração de DNA total e sequenciamento através de tecnologia Ion Proton (Life Technologies), isolamento bacteriano, produção e aplicação de exopolissacarídeo como bioemulsificante. Ao analisar o DNA metagenômico observou-se que tanto na água quanto no solo há uma abundância de bactérias encontradas normalmente em áreas agrícolas sob influência de composto orgânico feito a partir de outras fontes. Verificou-se também, através da análise dos genes relacionados com os ciclos biogeoquímicos, abundância de genes do processo de desnitrificação na amostra de solo. Além de se observar que na análise da estrutura taxonômica dos ciclos biogeoquímicos, não há bactérias em comum entre as amostras de solo e água com do composto orgânico. Porém ao avaliar o perfil funcional total da água, solo e outros dez metagenomas, através de uma análise de agrupamento hierárquico, notou-se que a água causa maior influência no solo do que o próprio composto orgânico. Com relação ao isolamento bacteriano, foi possível isolar a bactéria Sphingomonas sp., sendo que o isolado identificado demonstrou produzir grande quantidade de exopolissacarídeo (EPS). O EPS formou emulsões estáveis após 24 horas e 168 horas. Além disso o EPS foi um melhor agente emulsificante para hexano e querosene dentre todos os óleos analisados. Os resultados mostraram contribuição significativa com relação ao potencial do EPS como agente bioemulsificante que aumentaria a degradação de hidrocarbonetos e efeitos de emulsificação em biotecnologia ambiental.
The organic compost produced from carcasses, animal and vegetable waste is a viable alternative to full or partial replacement of mineral fertilizers used nowadays. In the composting process there are involved different microbial populations, and the compost becomes a rich system for use as a fertilizer in the soil, thereby supplementing the nutritional and microbial requirements of the medium. However, there are few studies involving the analysis of bacterial diversity in soil under use of organic compost made from carcasses, and also little is known about the environmental impact of agricultural use of organic compost in water quality. Furthermore, there is also the question of whether there is influence of the water used for irrigation on soil quality. Because of these questions, the central objective of this study was to analyze the bacterial diversity and functional profile of a soil from vegetable garden and freshwater used for irrigation from a local stream. As a secondary objective, we aimed to verify the production and biotechnology potential of a bacterial exopolysaccharide as oil and hydrocarbons bioemulsifier. Soil and freshwater samples used in this study were collected at rural department of the Zoo Foundation Park of São Paulo, in September 2014. All material collected was transported to the Laboratório de Bioquímica de Micro-organismos e de Plantas where we proceeded with the total DNA extraction experiments, sequencing through Ion Proton technology (Life Technologies), bacterial isolation, production and application of exopolysaccharide as bioemulsifier. By analyzing the metagenomic DNA it was observed that both freshwater and soil were plenty of bacterial communities normally found in agricultural areas under influence of organic amendments. Through the analysis of genes related to biogeochemical cycles, it was found abundance of genes about denitrification process in the soil sample. Also it can be noted by the analysis of the taxonomic structure of biogeochemical cycles, there was no bacteria shared between soil and freshwater samples with the organic compost. But when evaluating the functional profile of freshwater, soil and other ten metagenomes, we observed that freshwater causes greater influence on the soil than the organic compost. Regarding the bacterial isolation, it was possible to identify the bacteria Sphingomonas sp., and it has been shown to produce large amount of exopolysaccharide (EPS). The EPS has shown stability in its emulsions after 24 hours and 168 hours. Additionally, it’s a better emulsifying agent for hexane and kerosene among other oils analysed. Furthermore, our findings promoted significant contribution by showing EPS potential as a bioemulsifier agent that would enhance hydrocarbon degradation and emulsification effects in environmental biotechnology.
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Pupin, Breno. "Atributos microbiológicos em ecossistemas costeiros da Ilha do Cardoso, SP /." Jaboticabal, 2013. http://hdl.handle.net/11449/103875.
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Orientador: Ely NahasBanca: Marli de Fátima Fiori
Banca: Diva de Souza Andrade
Banca: José Eduardo Corá
Banca: Jackson Antônio Marcondes de Souza
Resumo: Os manguezais apresentam características que os diferenciam dos demais ecossistemas. O objetivo deste trabalho foi estudar os grupos microbianos (bactérias totais, esporuladas, Gram-negativas, actinobactérias, nitrificantes, desnitrificantes e fungos), as atividades metabólicas de bactérias e fungos, as atividades microbianas relacionadas ao ciclo do C, N, P (atividade respiratória, da desidrogenase, amonificante, nitrificante, da urease, da protease, solubilizadora de fosfato e da fosfatase ácida), além das análises químico-físicas (umidade, matéria orgânica, carbono orgânico total, carbono solúvel, carboidratos totais, fracionamento do fósforo, pH e salinidade) do solo de manguezal e compará-las com os de floresta e restinga. As amostras de solos foram coletadas durante o verão e o inverno, nas profundidades de 0 - 2 cm, 2 - 5 cm e 5 - 10 cm. Os micro-organismos isolados foram testados quanto à habilidade de produzir amilase, fosfatase ácida e/ou solubilizar fosfato inorgânico. Os resultados foram interpretados com análise estatística univariada. Excetuando os fungos totais, as contagens dos demais grupos microbianos decresceram significativamente (p < 0,05) na seguinte ordem: floresta > manguezal > restinga. As populações de actinobactérias predominaram no solo de floresta, porém foram semelhantes (p < 0,05) nos solos de manguezal e de restinga. O número das bactérias desnitrificantes foi similar nos solos de floresta e de manguezal e maior que o do solo de restinga. As contagens dos micro-organismos decresceram significativamente 11 e 21% da camada superficial para a 2 - 5 cm e 5 - 10 cm, porém as desnitrificantes aumentaram 44 e 166%. Enquanto o número de bactérias totais, esporuladas, Gram-negativas, nitrificantes e desnitrificantes decresceu (p < 0,05) 32% em média do verão para o inverno, o das actinobactérias permaneceu invariável e dos fungos aumentou 29%...
Abstract: Mangroves has characteristics that differentiate them from other ecosystems. The objective of this study was to evaluate the frequency of microbial groups (total, sporulating, Gram-negative, actinomycetes, nitrifying, denitrifying bacteria and fungi), the bacteria and fungi metabolic activities, microbial activities related to the cycle of C, N, P (respiration, dehydrogenase, ammonium-oxidizing, urease, protease, solubilizing phosphate and acid phosphatase activities), and chemical-physical analysis (moisture, organic matter, total organic carbon, soluble carbon, carbohydrates, fractionation phosphorus, pH and salinity) from mangrove soil, comparing them with the restinga and forest soils. Soil samples were collected during the summer and winter, at depths of 0 - 2 cm, 2 - 5 cm and 5 - 10 cm. The microorganisms isolated were tested for their ability to produce amylase, acid phosphatase and/or solubilize inorganic phosphate. Results were interpreted with univariate statistical analysis. Except fungi total scores of other microbial groups decreased significantly (p < 0.05) in the following order: forest > mangrove > restinga. Populations of actinomycetes predominated in the forest soil, but were similar (p < 0.05) in mangrove soils and restinga. The denitrifying bacteria number was similar in forest and mangrove soil and higher than restinga soils. The microorganism counts decreased significantly 11 and 21% the surface layer for 2 - 5 cm and 5 - 10 cm, however, denitrifying increased 44 and 166%. While total number, sporulating, Gram-negative, nitrifying and denitrifying bacteria decreased (p < 0.05), on average 32% from summer to winter, actinomycetes remained unchanged and fungi increased 29%...
Doutor
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Erickson, Heather E. "Nitrogen and phosphorus availability, ecosystem processes and plant community dynamics in boreal wetland meadows /." Thesis, Connect to this title online; UW restricted, 1994. http://hdl.handle.net/1773/5590.
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Aigars, Juris. "The role of the sediments in the biogeochemical cycles of nutrients in the Gulf of Riga." Thesis, Stockholm University, Department of Geology and Geochemistry, 2001. https://dspace.lu.lv/dspace/handle/7/376.
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Porada, Philipp [Verfasser]. "Process-based modelling of lichens and bryophytes and their role in global biogeochemical cycles / Philipp Porada." Mainz : Universitätsbibliothek Mainz, 2014. http://d-nb.info/1047249944/34.
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Hurrell, Elizabeth Rose. "Climate change and biogeochemical cycles on East African mountains revealed by stable isotopes of diatom frustules." Thesis, Lancaster University, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.547985.
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Potier, Hugo. "Major and trace elements in the changing Arctic environment : interactions between C-N-Mo-V biogeochemical cycles." Electronic Thesis or Diss., Sorbonne université, 2024. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2024SORUS094.pdf.
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L'augmentation des températures et des précipitations résultant du changement climatique impacte profondément le fonctionnement des écosystèmes Arctiques. En particulier, l'augmentation de la productivité primaire liée à la levée des contraintes thermiques et hydriques pour la croissance végétale, couplée aux changements de nature du couvert végétal et au dégel du pergélisol, sont susceptibles d'engendrer de profondes modifications des cycles biogéochimiques des éléments qui constituent la matière organique, et notamment le carbone (C) et l'azote (N). Un levier majeur à la limitation par l'azote de la croissance végétale pourrait résider dans l'augmentation des flux de fixation biologique de l'azote (BNF), un processus microbien qui nécessite, entre autres, du molybdène (Mo) ou du vanadium (V). L'abondance de ces deux éléments traces pourraient ainsi elle-même limiter la disponibilité de l'azote et donc la croissance végétale dans ces écosystèmes. Ces travaux de recherche visent à améliorer notre compréhension des interactions entre les cycles biogéochimiques des éléments majeurs (C, N) et traces (Mo, V) dans ces environnements au travers des processus mentionnés précédemment. Ce travail s'est principalement focalisé sur l'apport des données stœchiométriques de différents compartiments d'habitats subarctiques situés dans la région d'Abisko, au nord de la Suède, et présentant des caractéristiques végétales et pédologiques contrastées. La caractérisation des stocks élémentaires dans la biomasse aérienne et les sols de ces habitats a permis de mettre en évidence l'importance majeure des variations de composition végétale sur la répartition de ces stocks entre des compartiments de biomasse présentant des dynamiques différentes, ainsi que les liens assez faibles entre stocks élémentaires dans la biomasse aérienne et dans les sols. La contribution de plusieurs processus pouvant expliquer les enrichissements variables du Mo et du V en surface de ces habitats a été explorée et a mis en évidence une opposition majeure entre les influences lithogénique et biologique sur l'abondance de ces deux éléments traces et l'importance de la physicochimie de la solution du sol sur leur mobilité. Enfin, une approche de modélisation de ces données a mis en évidence les liens forts entre C, N, Mo et V dans la stœchiométrie des sols et suggère que les sols organiques abritent une activité de fixation de l'azote particulièrement marquée. Les résultats de cette thèse soulignent les contraintes marquées sur l'ensemble des éléments majeurs et traces induites par des variations de couvertures végétales dans les environnements Arctiques et la potentielle limitation de la BNF par la disponibilité de Mo et V. Ces résultats appellent à une caractérisation plus fine de la biodisponibilité de ces éléments traces en lien avec des mesures centrées sur le processus de fixation pour poursuivre l'exploration de ces limitations, ainsi qu'à considérer l'interaction des cycles biogéochimiques des éléments traces et majeurs pour le devenir des écosystèmes ArctiquesClimate change is deeply affecting the functioning of Arctic ecosystems through increases in temperature and precipitation in these environments. In particular, the increase in primary productivity resulting from the lifting of thermal and hydric constraints on plant growth, coupled with changes in the nature of the plant cover and the thawing of permafrost, is likely to induce significant constraints on the biogeochemical cycles of elements composing organic matter, especially carbon (C) and nitrogen (N). An important lever to reduce nitrogen limitation of plant growth could be to increase the flux of biological nitrogen fixation (BNF), a microbial process that requires, among other elements, molybdenum (Mo) or vanadium (V). The abundance of these two trace elements may thus limit the availability of nitrogen and, therefore, the plant growth in those ecosystems. The aim of this research work is to improve our understanding of the interactions between the biogeochemical cycles of major (C, N) and trace (Mo, V) elements in these environments. It explores the potential of using stoichiometric data collected in subarctic habitats with contrasting plant and soil characteristics of the Abisko region (northern Sweden). The quantification of elemental stocks in aboveground biomass and soils highlighted the importance of variations in plant community composition for the distribution of these stocks in biomass compartments with different dynamics, as well as the relatively weak links in elemental stocks between aboveground biomass and soils. Considering several processes potentially involved in soil surface enrichment of Mo and V, both elements have distinct behaviours in light of the respective contribution of lithogenic and biological influences and the role of physicochemical conditions for their mobility. A modelling approach highlighted the strong links between N, Mo and V in soil stoichiometry and suggested that organic soils have a relatively important nitrogen-fixing activity. The results of this thesis highlight the strong interaction between major and trace elements, their expected modifications as induced by changes in vegetation in the Arctic, and the potential limitation of BNF by the availability of Mo and V. These results call for a more detailed characterisation of the bioavailability of these trace elements to microbial communities combined with measurements focusing on the BNF process in order to further explore these limitations. Finally, this work points out the need to continue exploring the interaction of biogeochemical cycles of major and trace elements for the future of Arctic ecosystems
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Yavari, Josephine R. "Temporal variability of iron speciation in rainwater and its impact on the biogeochemical cycling of iron in seawater." View electronic thesis (PDF), 2009. http://dl.uncw.edu/etd/2009-1/r1/yavarij/josephineyavari.pdf.
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Moreira, Wellington Marcelo Queixas [UNESP]. "Estudo da diversidade e atividade bacteriana em solos de floresta e sob cultivo de cana-de-açúcar." Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/103861.
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000737544.pdf: 4940477 bytes, checksum: 0101681bb21fe135e941ea5c67aaaadf (MD5)A composição e a diversidade de comunidades microbianas podem ser usadas como indicadores da qualidade do solo, pois respondem rapidamente às mudanças ambientais. A intensificação da agricultura causa significante perda de diversidade, reduzindo a habilidade do ecossistema resistir a períodos de estresse e efeitos ambientais indesejáveis. Esta redução é mais evidente quando se trata de sistemas de monocultura, impactando os microrganismos e diversos invertebrados, e também reduz a capacidade de auto-regulação do solo. Assim, este trabalho tem como objetivo analisar a diversidade bacteriana em solos de floresta e em solos cultivados com canade- açúcar (Saccharum spp.) em diferentes períodos do ano que possa estar relacionada com a dinâmica dos ciclos biogeoquímicos, bem como um estudo comparativo entre diferentes áreas de cultivo e técnicas de sequenciamento. As amostras de solo foram coletadas no município de Santa Rita do Passa Quatro, SP. Amostras de DNA metagenômico de cada solo foram extraídas e construídas quatro bibliotecas com amplicons do gene 16S rRNA e quatro bibliotecas com amplicons da região V1 e V2 (Vi) do gene 16S rRNA. Um estudo comparativo com sequencias obtidas nas mesmas condições em outra área situada no município de Mococa, SP também foi analisado. Através dos dados obtidos, foi verificado que em solos de Floresta, independente do período do ano e área analisada, os filos bacterianos e a atividade dos organismos em relação aos ciclos biogeoquímicos, permaneceram praticamente inalterados. Este fato pode ser atribuído à estabilidade desde tipo de ecossistema, no qual existe ciclagem constante de nutrientes. Nas amostras de cana-de-açúcar, observou-se variação na frequência dos organismos encontrados em relação a diferentes coletas...
Microbial communities diversity and composition can be used as soil quality indicators, because respond quickly to environmental changes. Agriculture intensification causes significant loss of diversity, reducing the ability of the ecosystem to resist to periods of stress and undesirable environmental effects. This reduction is more evident when dealing with monoculture systems, impacting the microorganisms and several invertebrates, and also reduce the capacity of the soil self regulation. So, this study aims to analyze the bacterial diversity in forest soils and in soils cultivated with sugar cane (Saccharum spp.) in different periods of the year that can be related to biogeochemical cycles dynamic, as well as a comparative study between farming areas and sequencing techniques. Metagenomic DNA samples of each soil were extracted and built four libraries with gene 16S rRNA amplicons and four libraries with amplicons from gene 16S rRNA region Vi. A comparative study with obtained sequences in same conditions in another area situated in the municipality of Mococa, SP was also analyzed. Through the obtained data, it was found that in forest soils, regardless of the period of year and the area analyzed, bacterial phyla and organisms’ activity in relation to biogeochemical cycles, remained practically unchanged. This fact can be assigned to this type of ecosystem stability, in which there is a constant nutrients cycling. In soil samples cultivated with sugar cane, was observed variation in organisms frequency found in relation to different collections...
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Ostrowski, Martin Biotechnology & Biomolecular Sciences Faculty of Science UNSW. "Physiological adaptation to nutrient limitation in a marine oligotrophic ultramicrobacterium Sphingopyxis alaskensis." Awarded by:University of New South Wales. School of Biotechnology and Biomolecular Sciences, 2006. http://handle.unsw.edu.au/1959.4/27422.
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Sphingopyxis (formerly Sphingomonas) alaskensis, a numerically abundant species isolated from Alaskan waters and the North Sea represents one of the only pure cultures of a typical oligotrophic ultramicrobacterium isolated from the marine environment. In this study, physiological and molecular characterization of an extinction dilution isolate from the North Pacific indicate that it is a strain of Sphingopyxis alaskenis, extending the known geographical distribution of this strain and affirming its importance as a model marine oligotroph. Given the importance of open ocean systems in climatic processes, it is clearly important to understand the physiology and underlying molecular biology of abundant species, such as S. alaskensis, and to define their role in biogeochemical processes. S. alaskensis is thought to proliferate by growing slowly on limited concentrations of substrates thereby avoiding outright starvation. In order to mimic environmental conditions chemostat culture was used to study the physiology of this model oligotroph in response to slow growth and nutrient limitation. It was found that the extent of nutrient limitation and starvation has fundamentally different consequences for the physiology of oligotrophic ultramicrobacteria compared with well-studied copiotrophic bacteria (Vibrio angustum S14 and Escherichia coli). For example, growth rate played a critical role in hydrogen peroxide resistance of S. alaskensis with slowly growing cells being 10, 000 times more resistant than fast growing cells. In contrast, the responses of V. angustum and E. coli to nutrient availability differed in that starved cells were more resistant than growing cells, regardless of growth rate. In order to examine molecular basis of the response to general nutrient limitation, starvation and oxidative stress in S. alaskensis we used proteomics to define differences in protein profiles of chemostat-grown cultures at various levels of nutrient limitation. High-resolution two-dimensional electrophoresis (2DE) methods were developed and 2DE protein maps were used to define proteins regulated by the level of nutrient limitation. A number of these proteins were identified with the aid of mass spectrometry and cross-species database matching. The identified proteins are involved in fundamental cellular processes including protein synthesis, protein folding, energy generation and electron transport, providing an important step in discovering the molecular basis of oligotrophy in this model organism.
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Cabana, Gilbert. "A comparative study of food-web processes in aquatic systems using stable isotopes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape16/PQDD_0026/NQ29900.pdf.
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Von, Der Heyden Bjorn Phillip. "Distribution and characterization of marine iron-rich particles." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85822.
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Thesis (PhD)--Stellenbosch University, 2013.ENGLISH ABSTRACT: This thesis investigates questions surrounding the role that iron-rich colloids (nominally sized between 0.02 μm and 0.2 μm) and particulates (>0.2-0.45 μm) play in the context of the greater iron biogeochemical cycle. To this end, this study complements a review of reported size-fractionated iron (Fe) measurements with chemical and mineralogical data derived from synchrotron-based xray measurements. From an extensive literature review, the global surface ocean colloidal iron (cFe) pool is found to be highly dynamic, frequently exhibiting seasonal trends and nutrient-like behaviour. Spatial variability in surface ocean colloidal iron concentration is primarily a function of total iron supply, although the concentration and strength of iron-binding ligands, and inorganic thermodynamic constraints are additional influential factors. The size-fractionated study of colloidal Fe has rendered considerable evidence pointing towards direct or indirect biological utilization of this cFe pool; however, a more complete understanding of cFe-biological interaction necessarily requires better knowledge of cFe chemistry and mineralogy. To address these issues, this thesis documents the development of a novel x-ray microscopy and spectroscopy technique for determining the Fe speciation of individual Fe-rich particles under environmental conditions. Variations in the peak splitting in iron L3-edge XANES (X-ray Absorption Near-Edge Structure) spectra reflect changes in the local coordination environment surrounding the metal centre. Specifically, the energy splitting ( ΔeV) and intensity ratio of the split peaks at the L3-edge vary as a function of the Fe valence state, the number and chemistry of coordinating ligands and polyhedral distortion effects; and combinations of the two parameters are found to be characteristic of individual Fe minerals. To understand Fe speciation, the Δ eV versus intensity ratio plot was successfully applied to a variety of environmental Fe particles (greater than 20 nm diameter) collected from two ocean basins; the Southern Ocean and the south western Pacific Ocean. Speciation differences in Fe particles collected from the Southern Ocean show distinct compositional trends between the coasts of South Africa and Antarctica, with different Fe pools associated with the different oceanographic frontal zones. Despite the oxygenated nature of the seawater sampled, the presence of significant particle-hosted Fe(II) was observed in both the Southern Ocean at high latitudes, and at sampling sites proximal to the Kermadec Ridge in the Pacific Ocean. Ferrous iron particles at the latter study area were shown to be strongly associated with carbon functional groups, notably alcohol and carboxamine moieties. These findings, relating to particle chemical differences and associations with organic matter, have significant implications for our understanding of particle behaviour, their surface interactions and the role that they play in primary productivity and global elemental cycles.
AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek kwessies met betrekking tot die rol wat ysterryke kolloïede (van nominale groottes tussen 0.02 μm en 0.2 μm) en partikels (>0.2-0.45 μm) in die konteks van die groter ysterbiogeochemiese siklus speel. Vir hierdie doel bou die studie voort op ’n oorsig van aangemelde grootte-gefraksioneerde yster- (Fe-)metings met behulp van chemiese en mineralogiese data wat uit sinchrotrongebaseerde x-straalmetings verkry is. Na aanleiding van ’n uitvoerige literatuurstudie, blyk die globale poel kolloïdale yster (cFe) op die see-oppervlak hoogs dinamies te wees en toon dit dikwels seisoenale tendense en voedingstofagtige gedrag. Ruimtelike veranderlikheid in die cFekonsentrasie op die see-oppervlak is hoofsaaklik ’n funksie van totale ystervoorsiening, hoewel die konsentrasie en sterkte van ysterbindende ligande sowel as anorganiese termodinamiese beperkings ook ’n invloed kan hê. Die grootte-gefraksioneerde studie van kolloïdale Fe het beduidende bewyse opgelewer wat op die direkte of indirekte biologiese benutting van hierdie cFe-poel dui. Tog verg ’n vollediger begrip van cFe- biologiese interaksie noodwendig meer kennis van die chemie en mineralogie van cFe. Om hierdie kwessies te ondersoek, dokumenteer hierdie tesis die ontwikkeling van ’n innoverende X-straalmikroskopie- en X-straalspektroskopietegniek om die Fe-soortvorming van individuele Feryke partikels in omgewingsomstandighede te bepaal. Variasies in die pieksplitsing van yster-L3 rand-XANES- (“X-ray absorption near-edge structure”-)spektra weerspieël veranderlikheid in die lokale koördinasie-omgewing rondom die metaalkern. In die besonder wissel die energiesplitsing ( eV) en intensiteitsverhouding van die splitsingspieke by die L3-rand na gelang van die Fevalensietoestand, die getal en chemie van koördinasie-ligande, en poliëdriese distorsie-effekte, en kombinasies van die twee parameters blyk kenmerkend van individuele Fe-minerale te wees. Om Fe-soortvorming te verstaan, is die stipping van Δ eV versus intensiteitsverhouding suksesvol toegepas op ’n verskeidenheid Fe-omgewingspartikels (groter as 20 nm in deursnee) wat uit twee oseaankomme – die Suidelike Yssee en die suidwestelike Stille Oseaan – bekom is. Soortverskille in Fe-partikels wat uit die Suidelike Yssee bekom is, toon kenmerkende samestellingspatrone tussen die kus van Suid-Afrika en Antarktika, en verskillende Fe-poele word met die verskillende oseanografiese frontsones verbind. Ondanks die suurstofhoudende aard van die seewatermonsters, is beduidende Fe(II) in partikels opgemerk in die Suidelike Yssee by hoë breedteliggings sowel as op studieterreine naby die Kermadec-rif in die Stille Oseaan. Ysterhoudende partikels van laasgenoemde studieterrein het ’n sterk verband met koolstof- funksionele groepe, veral alkohol en karboksamien, getoon. Hierdie bevindinge met betrekking tot die chemiese verskille tussen partikels en die verband met organiese materie het beduidende implikasies vir ons begrip van partikelgedrag, die oppervlak-interaksies van partikels, en die rol wat dit in primêre produktiwiteit en globale elementsiklusse speel.
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Moreira, Wellington Marcelo Queixas. "Estudo da diversidade e atividade bacteriana em solos de floresta e sob cultivo de cana-de-açúcar /." Jaboticabal, 2013. http://hdl.handle.net/11449/103861.
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Orientadora: Lúcia Maria Carareto AlvesBanca: Antonio Carlos Monteiro
Banca: Haroldo Alves Pereira Júnior
Banca: Luciano Takeshi Kishi
Banca: Mariana Carina Frigieri Salaro
Resumo: A composição e a diversidade de comunidades microbianas podem ser usadas como indicadores da qualidade do solo, pois respondem rapidamente às mudanças ambientais. A intensificação da agricultura causa significante perda de diversidade, reduzindo a habilidade do ecossistema resistir a períodos de estresse e efeitos ambientais indesejáveis. Esta redução é mais evidente quando se trata de sistemas de monocultura, impactando os microrganismos e diversos invertebrados, e também reduz a capacidade de auto-regulação do solo. Assim, este trabalho tem como objetivo analisar a diversidade bacteriana em solos de floresta e em solos cultivados com canade- açúcar (Saccharum spp.) em diferentes períodos do ano que possa estar relacionada com a dinâmica dos ciclos biogeoquímicos, bem como um estudo comparativo entre diferentes áreas de cultivo e técnicas de sequenciamento. As amostras de solo foram coletadas no município de Santa Rita do Passa Quatro, SP. Amostras de DNA metagenômico de cada solo foram extraídas e construídas quatro bibliotecas com amplicons do gene 16S rRNA e quatro bibliotecas com amplicons da região V1 e V2 (Vi) do gene 16S rRNA. Um estudo comparativo com sequencias obtidas nas mesmas condições em outra área situada no município de Mococa, SP também foi analisado. Através dos dados obtidos, foi verificado que em solos de Floresta, independente do período do ano e área analisada, os filos bacterianos e a atividade dos organismos em relação aos ciclos biogeoquímicos, permaneceram praticamente inalterados. Este fato pode ser atribuído à estabilidade desde tipo de ecossistema, no qual existe ciclagem constante de nutrientes. Nas amostras de cana-de-açúcar, observou-se variação na frequência dos organismos encontrados em relação a diferentes coletas...
Abstract: Microbial communities diversity and composition can be used as soil quality indicators, because respond quickly to environmental changes. Agriculture intensification causes significant loss of diversity, reducing the ability of the ecosystem to resist to periods of stress and undesirable environmental effects. This reduction is more evident when dealing with monoculture systems, impacting the microorganisms and several invertebrates, and also reduce the capacity of the soil self regulation. So, this study aims to analyze the bacterial diversity in forest soils and in soils cultivated with sugar cane (Saccharum spp.) in different periods of the year that can be related to biogeochemical cycles dynamic, as well as a comparative study between farming areas and sequencing techniques. Metagenomic DNA samples of each soil were extracted and built four libraries with gene 16S rRNA amplicons and four libraries with amplicons from gene 16S rRNA region Vi. A comparative study with obtained sequences in same conditions in another area situated in the municipality of Mococa, SP was also analyzed. Through the obtained data, it was found that in forest soils, regardless of the period of year and the area analyzed, bacterial phyla and organisms' activity in relation to biogeochemical cycles, remained practically unchanged. This fact can be assigned to this type of ecosystem stability, in which there is a constant nutrients cycling. In soil samples cultivated with sugar cane, was observed variation in organisms frequency found in relation to different collections...
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Kessouri, Fayçal. "Cycles biogéochimiques de la mer Méditerranée : processus et bilans." Thesis, Toulouse 3, 2015. http://www.theses.fr/2015TOU30367/document.
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La Méditerranée est caractérisée par une grande variété de régimes trophiques qui s'explique par les apports fluviaux, les ratios azote/phosphore particulièrement élevés dans le bassin oriental, et par les processus hydrodynamiques en particulier le mélange vertical dans les régions situées au nord. Cette thèse qui s'inscrit dans le cadre du projet MerMEX, composante du chantier MISTRALS, a pour objectif l'étude des cycles biogéochimiques en Méditerranée. Elle s'appuie en particulier sur les observations acquises dans le cadre du projet DeWEx et sur la modélisation couplée physique biogéochimie 3D. À l'échelle du bassin et à l'échelle régionale du sous-bassin occidental. La première étude à l'échelle du bassin sur une période de 10 ans a permis d'effectuer une classification de régimes biogéochimiques, en fonction de leurs caractéristiques physiques et biogéochimiques. Les zones oligotrophes présentes au sud du bassin oriental et occidental sont caractérisées par une faible efflorescence et par de grandes profondeurs de nutriclines. Tandis qu'au nord du bassin, au large de Rhodes, en mer Adriatique et dans le bassin Liguro-provençal, le régime oligotrophe estival est suivi en hiver par une dynamique verticale intense, la convection profonde. Cette dernière est considérée comme le moteur de la circulation thermohaline. Elle entraine un enrichissement des eaux de surface en sels nutritifs qui permet une efflorescence rapide et intense au printemps. L'océan Atlantique représente une source de matière organique pour la Méditerranée. Cette mer représente en revanche une source de sels nutritifs pour l'Atlantique. Ensuite, un modèle à très haute résolution a été imbriqué dans le modèle de bassin pour quantifier les processus physiques et biologiques qui déterminent la variabilité temporelle de la disponibilité et de la stœchiométrie des sels nutritifs en Méditerranée nord-occidentale. La convection profonde hivernale entraîne une homogénéisation des propriétés biogéochimiques sur la colonne d'eau, et une stœchiométrie vers des valeurs estivales. Cette région bascule d'un régime d'eutrophie lors de la convection profonde vers un régime oligotrophe après le bloom de printemps. Lors du premier régime la production primaire est dominée par une production nouvelle en surface, alors que lors du deuxième régime la production phytoplanctonique de subsurface est essentiellement régénérée. Les masses d'eau adjacentes à la zone de convection et celles situées au sud sont caractérisées par une dominance de production régénérée toute l'année. Une partie de la matière organique particulaire est exportée en dessous de la couche épipélagique. Cet export de matière organique est variable et est fortement lié à la dynamique verticale des masses d'eauThe Mediterranean Sea is characterized by various trophic regimes due to river inputs, as well as heterogeneous nitrogen to phosphorus ratios and hydrodynamic processes, in particular vertical mixing. The objective of this thesis that was performed in the framework of the MISTRALS program is the study of the biogeochemical cycles of these various regimes that composed the Mediterranean. It is mainly based on the in situ observations collected during DeWEx project and on 3D physical/biogeochemical modeling at the scale of the entire basin and at the regional of the western sub-basin. The first study is a ten-year basin scale study which allows an ecological classification, giving bioregions in function of their physical and biogeochemical properties. Southern oligotrophic areas in both eastern and western sub-basins are characterized by low efflorescence and deep nutriclines. While in the north, near Rhodes Island, in the southern Adriatic Sea and in the Liguro-Provencal sub-basin, the summer oligotrophic regime is altered annually by intense vertical dynamics, the deep convection. This process is considered as a driving force of the thermohaline circulation and entrains an enrichment of nutrients in surface layer which allows rapid and intense blooms in spring. The Mediterranean receives organic matter from the Atlantic Ocean, while, it is a source of inorganic matter for the Atlantic. In a second part of this thesis, a high resolution model on the western sub-basin was embedded in the basin model to quantify the physical and biological processes that determine the temporal variability of the nutrient stocks and their stoichiometry. The north-western Mediterranean turns from an eutrophic regime during deep convection to an oligotrophic regime after the spring bloom. During the eutrophic regime new production dominates the primary production at the surface while during the oligotrophic regime primary production is essentially associated to subsurface regenerated one. Adjacent water masses of the convection zone and west-southern regions are characterized by a dominance of regenerated production all over the year
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Vinson, Joshua S. "Role of oxygen and salinity on biogeochemical processes controlling mercury and monomethylmercury flux from estuarine sediments." View electronic thesis, 2008. http://dl.uncw.edu/etd/2008-2/r1/vinsonj/joshuavinson.pdf.
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Nugent, Michelle V. "Biogeochemical dynamics of iron and sulfur in sediments from hydro-electric dams submitted to wetting and drying cycles." Thesis, University of Ottawa (Canada), 2005. http://hdl.handle.net/10393/26996.
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Water level changes due to the decommissioning of hydro-electric dams can result in sediment exposure to air. Oxidation of sediments can decrease the pH as a result of iron sulfides changing into iron oxides. The present study was designed to simulate drying and wetting cycles of shallow lake sediments from two lakes (Stump and Black Donald Lakes in Ontario), in order to assess the mineralogical changes of Fe-rich minerals. Our results indicate that the total reactive iron fraction of the sediment increased after the wetting and drying cycles. This increase was caused by the weathering of pyrite and Fe-silicates and their subsequent transformation into more Fe-reactive mineral species. The pH of the surface sediments also decreased following the addition of simulated rainwater and the oxidation of iron sulfides in the sediments. This preliminary study shows that the decommissioning of hydro-electric dams will have an effect on the biogeochemical cycles of iron and sulfur.
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Karle, Ida-Maja. "On redox reactions and transport processes of solutes in coastal marine sediments /." [Göteborg] : Analystical and Marine Chemistry, Dept. of Chemistry, Göteborg University, 2006. http://www.loc.gov/catdir/toc/fy0706/2006455268.html.
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Maldonado-Pareja, Maria Teresa. "Iron acquisition by marine phytoplankton." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0022/NQ50215.pdf.
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