Bibliographies thématiques / Nutrient dynamic

Littérature scientifique sur le sujet « Nutrient dynamic »

Auteur : Grafiati
Publié le 14 mars 2023

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Articles de revues sur le sujet "Nutrient dynamic"

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Niu, Lixia, Pieter van Gelder, Xiangxin Luo, Huayang Cai, Tao Zhang et Qingshu Yang. « Implications of Nutrient Enrichment and Related Environmental Impacts in the Pearl River Estuary, China : Characterizing the Seasonal Influence of Riverine Input ». Water 12, no 11 (19 novembre 2020) : 3245. http://dx.doi.org/10.3390/w12113245.

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The Pearl River estuary is an ecologically dynamic region located in southern China that experiences strong gradients in its biogeochemical properties. This study examined the seasonality of nutrient dynamics, identified related environmental responses, and evaluated how river discharge regulated nutrient sink and source. The field investigation showed significant differences of dissolved nutrients with seasons and three zones of the estuary regarding the estuarine characteristics. Spatially, nutrients exhibited a clear decreasing trend along the salinity gradient; temporally, their levels were obviously higher in summer than other seasons. The aquatic environment was overall eutrophic, as a result of increased fluxes of nitrogen and silicate. This estuary was thus highly sensitive to nutrient enrichment and related pollution of eutrophication. River discharge, oceanic current, and atmospheric deposition distinctly influenced the nutrient status. These factors accordingly may influence phytoplankton that are of importance in coastal ecosystems. Phytoplankton (in terms of chlorophyll) was potentially phosphate limited, which then more frequently resulted in nutrient pollution and blooms. Additionally, the nutrient sources were implied according to the cause–effect chains between nutrients, hydrology, and chlorophyll, identified by the PCA-generated quantification. Nitrogen was constrained by marine-riverine waters and their mutual increase-decline trend, and a new source was supplemented along the transport from river to sea, while a different source of terrestrial emission from coastal cities contributed to phosphate greatly.
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Kalra, Tarandeep S., Neil K. Ganju et Jeremy M. Testa. « Development of a submerged aquatic vegetation growth model in the Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST v3.4) model ». Geoscientific Model Development 13, no 11 (2 novembre 2020) : 5211–28. http://dx.doi.org/10.5194/gmd-13-5211-2020.

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Abstract. The coupled biophysical interactions between submerged aquatic vegetation (SAV), hydrodynamics (currents and waves), sediment dynamics, and nutrient cycling have long been of interest in estuarine environments. Recent observational studies have addressed feedbacks between SAV meadows and their role in modifying current velocity, sedimentation, and nutrient cycling. To represent these dynamic processes in a numerical model, the presence of SAV and its effect on hydrodynamics (currents and waves) and sediment dynamics was incorporated into the open-source Coupled Ocean–Atmosphere–Wave–Sediment Transport (COAWST) model. In this study, we extend the COAWST modeling framework to account for dynamic changes of SAV and associated epiphyte biomass. Modeled SAV biomass is represented as a function of temperature, light, and nutrient availability. The modeled SAV community exchanges nutrients, detritus, dissolved inorganic carbon, and dissolved oxygen with the water-column biogeochemistry model. The dynamic simulation of SAV biomass allows the plants to both respond to and cause changes in the water column and sediment bed properties, hydrodynamics, and sediment transport (i.e., a two-way feedback). We demonstrate the behavior of these modeled processes through application to an idealized domain and then apply the model to a eutrophic harbor where SAV dieback is a result of anthropogenic nitrate loading and eutrophication. These cases demonstrate an advance in the deterministic modeling of coupled biophysical processes and will further our understanding of future ecosystem change.
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Bonachela, J. A., S. D. Allison, A. C. Martiny et S. A. Levin. « A model for variable phytoplankton stoichiometry based on cell protein regulation ». Biogeosciences 10, no 6 (27 juin 2013) : 4341–56. http://dx.doi.org/10.5194/bg-10-4341-2013.

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Abstract. The elemental ratios of marine phytoplankton emerge from complex interactions between the biotic and abiotic components of the ocean, and reflect the plastic response of individuals to changes in their environment. The stoichiometry of phytoplankton is, thus, dynamic and dependent on the physiological state of the cell. We present a theoretical model for the dynamics of the carbon, nitrogen and phosphorus contents of a phytoplankton population. By representing the regulatory processes controlling nutrient uptake, and focusing on the relation between nutrient content and protein synthesis, our model qualitatively replicates existing experimental observations for nutrient content and ratios. The population described by our model takes up nutrients in proportions that match the input ratios for a broad range of growth conditions. In addition, there are two zones of single-nutrient limitation separated by a wide zone of co-limitation. Within the co-limitation zone, a single point can be identified where nutrients are supplied in an optimal ratio. When different species compete, the existence of a wide co-limitation zone implies a more complex pattern of coexistence and exclusion compared to previous model predictions. However, additional comprehensive laboratory experiments are needed to test our predictions. Our model contributes to the understanding of the global cycles of oceanic nitrogen and phosphorus, as well as the elemental ratios of these nutrients in phytoplankton populations.
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Bonachela, J. A., S. D. Allison, A. C. Martiny et S. A. Levin. « A model for variable phytoplankton stoichiometry based on cell protein regulation ». Biogeosciences Discussions 10, no 2 (21 février 2013) : 3241–79. http://dx.doi.org/10.5194/bgd-10-3241-2013.

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Abstract. The elemental ratios of marine phytoplankton emerge from complex interactions between the biotic and abiotic components of the ocean, and reflect the plastic response of individuals to changes in their environment. The stoichiometry of phytoplankton is, thus, dynamic and dependent on the physiological state of the cell. We present a theoretical model for the dynamics of the carbon, nitrogen and phosphorus contents of a phytoplankton population. By representing the regulatory processes controlling nutrient uptake, and focusing on the relation between nutrient content and protein synthesis, our model qualitatively replicates existing experimental observations for nutrient content and ratios. The population described by our model takes up nutrients in proportions that match the input ratios for a broad range of growth conditions. In addition, there are two zones of single-nutrient limitation separated by a wide zone of co-limitation. Within the co-limitation zone, a single point can be identified where nutrients are supplied in an optimal ratio. The existence of a wide co-limitation zone affects the standard picture for species competing for nitrogen and phosphorus, which shows here a much richer pattern. However, additional comprehensive laboratory experiments are needed to test our predictions. Our model contributes to the understanding of the global cycles of oceanic nitrogen and phosphorus, as well as the elemental ratios of these nutrients in phytoplankton populations.
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Torres-Duque, Fabiola, Armando Gómez-Guerrero, Libia I. Trejo-Téllez, Valentín J. Reyes-Hernández et Arian Correa-Díaz. « Stoichiometry of needle litterfall of Pinus hartwegii Lindl. in two alpine forests of central Mexico ». Revista Chapingo Serie Ciencias Forestales y del Ambiente 28, no 1 (décembre 2021) : 57–74. http://dx.doi.org/10.5154/r.rchscfa.2020.12.077.

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Introduction: It is essential to have baselines on nutrient dynamics in forests, due to disturbances that climate change may cause.Objective: To quantify the annual production of needles of Pinus hartwegii Lindl. and the proportion of nutrients in the alpine forests of Jocotitlán (JO) and Tláloc (TL) mountains, Estado de México.Materials and methods: A total of 12 circular needle litter traps (30 cm diameter) were placed at ground level, in each forest, distributed in four topographically contrasting sites. For one year, 228 leaf mass measurements and 1 140 chemical determinations were made to determine needle stoichiometry. Measurements were subjected to a longitudinal analysis of variance, by testing trends over time (P < 0.05).Results and discussion: Needle production in JO were 67 % higher (11.2 Mg∙ha-1∙year-1) than in TL (6.7 Mg∙ha-1∙year-1); needle litterfall was higher during summer (June and July, months with higher precipitation). For JO, nutrient flux was 98.0, 5.2, 8.7, 24.6, and 5.6 kg∙ha-1∙year-1 for N, P, K, Ca, and Mg, respectively; for TL it was 55.3, 3.4, 7.8, 14.4, and 4.7 kg∙ha-1∙year-1 in the same order of nutrients. Nutrient concentrations were lower from March to May. Except for K, nutrient concentrations and needle production showed quadratic and cubic seasonal trends. Mg dynamics and N:Mg and N:K ratios in TL were more positive for tree growth.Conclusions: Jocotitlán and Tláloc forests produce significant needle mass (compared to other ecosystems) with high dynamic in nutrient transfers.
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Liu, Xingyue, Ziyuan Wang, Xi Liu, Zhiyun Lu, Dawen Li et Hede Gong. « Dynamic Change Characteristics of Litter and Nutrient Return in Subtropical Evergreen Broad-Leaved Forest in Different Extreme Weather Disturbance Years in Ailao Mountain, Yunnan Province ». Forests 13, no 10 (10 octobre 2022) : 1660. http://dx.doi.org/10.3390/f13101660.

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By studying the dynamic change characteristics of litter production, composition, nutrient content, and return amount of different components in different extreme weather interference years of Ailao Mountain evergreen broad-leaved forest, the paper provides theoretical support for the post-disaster nutrient cycle, ecological recovery, and sustainable development of the subtropical mid-mountain humid evergreen broad-leaved forest. Square litter collectors were randomly set up to collect litter. After drying to a constant mass, we calculated the seasonal and annual litter volume and the contents of organic carbon (C), total nitrogen (N), total phosphorus (P), total potassium (k), total sulfur (S), total calcium (Ca), and total magnesium (Mg). Finally, the nutrient return amount is comprehensively calculated according to the litter amount and element content. We tracked dynamic changes in litter quantity, nutrient composition, and nutrient components across different years. The results showed that the amount of litter from 2005 to 2015 was 7704–8818 kg·hm−2, and the order of magnitude was: 2005 (normal year) > 2015 (extreme snow and ice weather interference) > 2010 (extreme drought weather interference); the composition mainly included branches, leaves, fruit (flowers), and other components (bark, moss, lichen, etc.), of which the proportion of leaves was the largest, accounting for 41.70%–61.52%; The monthly changes and total amounts in different years exhibited single or double peak changes, and the monthly litter components in different years showed significant seasonality. In this study, the nutrient content of litter was higher than that of litter branches each year. The total amount of litter and the nutrient concentration of each component are C, Ca, N, K, Mg, S, and P, from large to small. The order of nutrient return in different years was the same as that of litter, and the returns of nutrients in litter leaves were greater than that of litter branches. The ratio of nutrient returns of litter and litter branches from 2005 to 2010 was 2.03, 1.23, and 3.69, respectively. The research shows that the litter decreased correspondingly under the extreme weather disturbance, and the impact of the extreme dry weather disturbance was greater than that of the extreme ice and snow weather disturbance. However, the evergreen broad-leaved forest in the study area recovers well after being disturbed. The annual litter amount and nutrient return amount is similar to that of evergreen broad-leaved forests in the same latitude and normal years in other subtropical regions. The decomposition rate and seasonal dynamics of litter nutrients are not greatly affected by extreme weather.
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Raghavan, Varsha, et Eduardo A. Groisman. « Species-Specific Dynamic Responses of Gut Bacteria to a Mammalian Glycan ». Journal of Bacteriology 197, no 9 (17 février 2015) : 1538–48. http://dx.doi.org/10.1128/jb.00010-15.

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ABSTRACTThe mammalian intestine provides nutrients to hundreds of bacterial species. Closely related species often harbor homologous nutrient utilization genes and cocolonize the gut, raising questions regarding the strategies mediating their stable coexistence. Here we reveal that relatedBacteroidesspecies that can utilize the mammalian glycan chondroitin sulfate (CS) have diverged in the manner in which they temporally regulate orthologous CS utilization genes. Whereas certainBacteroidesspecies display a transient surge in CS utilization transcripts upon exposure to CS, other species exhibit sustained activation of these genes. Remarkably, species-specific expression dynamics are retained even when the key players governing a particular response are replaced by those from a species with a dissimilar response.Bacteroidesspecies exhibiting distinct expression behaviors in the presence of CS can be cocultured on CS. However, they vary in their responses to CS availability and to the composition of the bacterial community when CS is the sole carbon source. Our results indicate that diversity resulting from regulation of polysaccharide utilization genes may enable the coexistence of gut bacterial species using a given nutrient.IMPORTANCEGenes mediating a specific task are typically conserved in related microbes. For instance, gutBacteroidesspecies harbor orthologous nutrient breakdown genes and may face competition from one another for these nutrients. How, then, does the gut microbial composition maintain such remarkable stability over long durations? We establish that in the case of genes conferring the ability to utilize the nutrient chondroitin sulfate (CS), microbial species vary in how they temporally regulate these genes and exhibit subtle growth differences on the basis of CS availability and community composition. Similarly to how differential regulation of orthologous genes enables related species to access new environments, gut bacteria may regulate the same genes in distinct fashions to reduce the overlap with coexisting species for utilization of available nutrients.
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Coggan, Nicole, Fiona J. Clissold et Stephen J. Simpson. « Locusts use dynamic thermoregulatory behaviour to optimize nutritional outcomes ». Proceedings of the Royal Society B : Biological Sciences 278, no 1719 (2 février 2011) : 2745–52. http://dx.doi.org/10.1098/rspb.2010.2675.

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Because key nutritional processes differ in their thermal optima, ectotherms may use temperature selection to optimize performance in changing nutritional environments. Such behaviour would be especially advantageous to small terrestrial animals, which have low thermal inertia and often have access to a wide range of environmental temperatures over small distances. Using the locust, Locusta migratoria , we have demonstrated a direct link between nutritional state and thermoregulatory behaviour. When faced with chronic restrictions to the supply of nutrients, locusts selected increasingly lower temperatures within a gradient, thereby maximizing nutrient use efficiency at the cost of slower growth. Over the shorter term, when locusts were unable to find a meal in the normal course of ad libitum feeding, they immediately adjusted their thermoregulatory behaviour, selecting a lower temperature at which assimilation efficiency was maximal. Thus, locusts use fine scale patterns of movement and temperature selection to adjust for reduced nutrient supply and thereby ameliorate associated life-history consequences.
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Ge, Xiaogai, Benzhi Zhou et Yilin Tang. « Litter Production and Nutrient Dynamic on a Moso Bamboo Plantation following an Extreme Disturbance of 2008 Ice Storm ». Advances in Meteorology 2014 (2014) : 1–10. http://dx.doi.org/10.1155/2014/750865.

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Ice storm is known to play a role in determining forest succession and litter dynamics constitute an important aspect of nutrient cycling in forest ecosystems. However, ice storm effects on amount and pattern of litterfall are not clearly understood. We investigated litter production and litter leaf nutrient dynamic in a moso bamboo plantation in China following an extreme disturbance of ice storm in 2008. The litterfall in on-years was significantly lower than in off-years. Ice storm caused total litterfall increasing from 16.68% to 35.60% and greatly disturbed the litterfall peak rhythm especially in the on-year. The litter leaf nutrient concentrations at two latitudes significantly fluctuated after ice-snow disaster in 2008, litter leaf stoichiometric traits indicated that litter leaf chemistry showed more easily decomposition with higher C/P ratio, N/P ratio, and lower C/N ratio. It is clear from this study that litterfall restoration dynamic would result in long-term changes in litter nutrient cycling and may help predicting below ground carbon dynamic in future research as well as subtropical forest inventories following extreme disturbance.
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Brønd, Søren, et Jan Scherfig. « DYNAMIC TEMPERATURE CHANGES IN NUTRIENT REMOVAL PLANTS ». Water Science and Technology 30, no 2 (1 juillet 1994) : 205–8. http://dx.doi.org/10.2166/wst.1994.0044.

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Nitrification and denitrification processes are very sensitive to temperature changes below 10 °C. Because of severe eutrophication problems in e.g. Northern Europe Nitrogen removal must be kept throughout the winter. To aid in the design and optimization of treatment plants a dynamic temperature model has been developed. The major findings is that the temperature variation is very dependent on local wind conditions. The model can be used in the design process to minimize factors causing temperature drops during cold weather periods.
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Thèses sur le sujet "Nutrient dynamic"

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Pang, Tingfan. « Dynamic analysis of water and nutrient uptake for New Guinea Impatiens ». Connect to resource, 1992. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1200588079.

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Southwell, Mark, et n/a. « Floodplains as dynamic mosaics : sediment and nutrient patches in a large lowland riverine landscape ». University of Canberra. n/a, 2008. http://erl.canberra.edu.au./public/adt-AUC20081217.144116.

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Rivers around the world are under increasing pressure from a variety of human activities. Effective management of riverine landscapes requires an ecosystem approach and one that recognises the complex interactions between their physical, chemical and biological components. Perceptions of pattern and process are central to our understanding of riverine landscapes. Pattern and process operate over multiple scales to produce heterogeneous mosaics of landscape patches that change over time. Hierarchical patch dynamics provides a useful approach to unravel pattern and process at multiple scales in riverine landscapes. This thesis adopts a hierarchical patch dynamics approach to investigate floodplain sediment and nutrient dynamics within the Barwon-Darling River in South Eastern Australia. The flow regime of the Barwon-Darling River is highly variable. As a result, it has a complex channel cross section featuring inset-floodplain surfaces that occur at multiple elevations within the channel trough. These surfaces formed the focus of this study. The texture of inset- floodplain surface sediments displays a patchy spatial distribution and one that did not reflect lateral or longitudinal gradients within this floodplain landscape. Rather a sediment textural patch mosaic was identified. Nutrient concentrations associated with the surface sediments of the inset-floodplains were also shown to vary significantly resulting in a nutrient patch mosaic. This spatial nutrient mosaic was enhanced by factors including the surface elevation of the floodplain surface. Sediment and nutrient exchange between the river channel and inset-floodplain surfaces was measured during several flows in 2001, 2002 and 2005. Pin and sediment trap data showed that significant quantities of sediment were exchanged between the river channel and floodplain surfaces during inundation with both cut and fill processes occurring. Patterns in sediment exchange appear to be related to local sediment supply and seasonal sediment exhaustion, rather than the top down geomorphic constraints considered. These material exchanges resulted in a change to the spatial configuration of the sediment textural patch mosaic. Distinct new sediment textural patches were created following inundation, while other patches were lost post inundation and other patches changed sediment textural character to move into pre-existing patches. Thus a truly dynamic sediment textural mosaic exists within this floodplain landscape. Nutrient concentrations associated with floodplain sediments also changed over time. While nutrient concentrations increased after the December 2001 flow event, they generally decreased after the March 2002 event, highlighting their dynamic nature over time. The spatial distribution of nutrient concentrations also varied over time, with a 40 percent change to the nutrient mosaic as a result of the March 2002 flow event. In addition to the influence of the changing physical template (sediment texture mosaic), nutrient concentrations were shown to be influenced by rainfall processes on non flooded surfaces, and also a number of top-down constraints and bottom-up influences operating over multiple spatial scales. Overall, the inset-floodplains studied in this thesis acted primarily as sediment and nutrient sinks, and were a source for dissolved nutrients. Nutrient exchange was associated with the exchange of sediments in this riverine landscape, over both inter-flow and decadal timescales. It was demonstrated that water resource development within the catchment reduced the number, magnitude and duration of flow events down the Barwon-Darling River and as a result reductions in the exchange of sediment, associated and dissolved nutrients between inset-floodplains and the main river channel were calculated. The greatest reductions were with the release of dissolved nutrients (42-25 percent) and the exchange of sediment and associated nutrients from high level surfaces (43 percent). Effective conservation and management of riverine ecosystems must occur at the correct scale. This study identified potential nutrient hotspots at several scales in the Barwon-Darling floodplain landscape that could be targeted by management. The low predictability of the location of nutrient hotspots at the inset-floodplain scale over time means that environmental flows should be targeted at high level surfaces (<25 000 MLD-1) that provide long term sources of carbon to the river channel. Conserving flows of this magnitude will also reinstate flow variability, an important facet of the Barwon-Darling River?s hydrology that has been changed by water resource development. The research presented in this thesis highlights the importance of not only considering pattern and process at multiple scales, but also the way in which these processes influence landscape patterns over time, leading to the identification of the appropriate scales that can best be targeted for the conservation of these systems.
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Vaillant, Grace C. « Nutrient cycling at cattle feedlots field & ; laboratory study ». Thesis, Manhattan, Kan. : Kansas State University, 2007. http://hdl.handle.net/2097/318.

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Dearden, Laura Ann. « Nutrient-mediated transcriptomes in the Paraventricular Nucleus of the Hypothalamus : dynamic regulation and downstream physiology ». Thesis, University of Bristol, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.633156.

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The obesity epidemic has fuelled research into the etiology of this complex disorder, including lifestyle, genetic vulnerability and more recently the in utero environment. Exposure to maternal obesity in utero programs metabolic dysfunction in offspring, however the mechanisms are unknown. Little is known about how the CNS senses, integrates and translates nutrient information into adjustment of neuronal and ultimately physiological function. The PVH is critical for maintaining energy- and glucosehomeostasis, but the molecular mechanisms underpinning this action remain unknown. We hypothesised that a PVH nutrient-sensitive transcriptome is critical in mediating adjustment of metabolic state, and that disruption of the PVH nutrient-mediated transcriptome may underpin physiological phenotypes in offspring exposed to an adverse in utero environment.
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Bril, Jeremy. « Measuring mussel behavior and analyzing high frequency nitrate data to explore new phenomena in dynamic nutrient cycling ». Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/466.

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Labeled by the National Academy of Engineering (NAE) as one of fourteen Grand Challenges for Engineering, the management of the nitrogen cycle has become an increasingly difficult obstacle for sustainable development. In an effort to help overcome this challenge, the goal of our study is to expand on the limited scientific understanding of how the nitrogen cycle within aquatic environments may be affected by increasing human- and climate-induced changes. To this end, we are using freshwater mussels as a sentinel species to better understand the impacts of ecosystem perturbation on nitrogen processing in large river systems. This was completed by examining the physical, biological, and chemical characteristics of a mussel habitat in the Mississippi River, evaluating the impact of the 2008 floods on the habitat and the ecosystem's nutrient processing, establishing a well-equipped mussel laboratory habitat to investigate mussel behavioral responses, and analyzing highly time resolved data to examine the mussels' contribution to daily nitrate fluxes.
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Kim, Sei Jin. « Three Essays on the Implications of Environmental Policy on Nutrient Outputs in Agricultural Watersheds and the Heterogeneous Global Timber Model with Uncertainty Analysis ». The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1439601683.

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Zabel, Paul [Verfasser], Martin [Gutachter] Tajmar et Markus [Gutachter] Czupalla. « An investigation of the dynamic behavior of a hybrid life support system and an experiment on plant cultivation with a urine-derived nutrient solution / Paul Zabel ; Gutachter : Martin Tajmar, Markus Czupalla ». Dresden : Technische Universität Dresden, 2019. http://d-nb.info/1226899730/34.

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Rodrigues, Lúcia Helena Ribeiro. « Reguladores da dinâmica das comunidades planctônicas e íctica em ecossistemas límnicos subtropicais ». reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/19125.

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As comunidades mudam no tempo e espaço em função de pressões decorrentes da estrutura do habitat e disponibilidade de recursos. O entendimento das relações ecológicas e interações das comunidades são essenciais para o manejo com objetivo de melhorar a qualidade da água através de interferências na cadeia trófica aquática e na dinâmica do ecossistema através de modelagem ecológica. O presente estudo foi desenvolvido em dois sistemas límicos subtropicais no extremo sul do Brasil: banhados temporários (‘campos de cultivo de arroz’) e um grande lago raso, lagoa Mangueira. O objetivo do trabalho nos banhados temporários constituiu-se em avaliar a dinâmica das comunidades planctônicas e íctica durante o desenvolvimento desses ecossitemas (um ciclo produtivo de cultivo de arroz). Nossos resultados evidenciaram um claro gradiente temporal direcionado pela disponibilidade de nutrientes no banhado temporário. Entretanto, as variáveis limnológicas não apresentaram nenhuma tendência espacial entre as estações amostrais. Através de regressão linear verificou-se correlação positiva entre clorofila a, nutrientes, biomassa zooplanctônica e, em especial, biomassa de copépodos. Por outro lado, biomassa de peixes e, particularmente, peixes planctívoros foram inversamente relacionados à concentração de clorofila a. Relações significativas entre o DOC com nutrientes, biomassa de plâncton e peixes foram igualmente identificadas ao longo do ciclo produtivo do arroz. Na lagoa Mangueira, sistema raso (zmed 3m), de 90 km de comprimento, o objetivo foi avaliar a distribuição espacial e temporal de plâncton e peixes em função da presença da macrófita emergente Zizaniopsis bonariensis. Além disso, foi verificada a existência de um gradiente longitudinal na lagoa e a estrutura da teia trófica do sistema. Análise de componentes principais e análise de redundância evidenciaram a presença de gradientes espacial (Norte/Sul) e temporal (sazonal) durante o estudo. Análise de similaridade (ANOSIM) aplicada às variáveis ambientais evidenciou diferenças significativas entre os extremos da lagoa (Norte e Sul). Transparência Secchi, DOC e clorofila a foram significativamente diferentes entre os pontos amostrais do Norte e Sul. Através de ANOVA verificou-se que os efeitos temporais sazonais são mais intensos no Norte da lagoa Mangueira. Com relação à estrutura da comunidade na lagoa Mangueira, a biomassa do bacterioplâncton, clorofila a, biomassa zooplanctônica e captura de peixes foram diferentes sazonalmente após a extração do efeito da estrutura de habitat, enquanto que no Sul apenas a clorofila a apresentou variação sazonal significativa. A estrutura de habitat (junto à Z. bonariensis e em água aberta) induziu diferenças significativas na concentração de clorofila a tanto no Norte como no Sul da lagoa Mangueira, após a extração dos efeitos decorrentes da sazonalidade. A captura de peixes também foi influenciada pela estrutura de habitat no Norte, após a extração do efeito sazonal. Análise de similaridade (ANOSIM) aplicada à comunidade de peixes também demonstrou diferenças significativas entre o Norte e o Sul da lagoa Mangueira, embora diferenças entre as áreas vegetadas e águas abertas não tenham sido verificadas. Biomassa dos peixes, número de capturas e riqueza específica foram diferentes entre os pontos amostrais. Baseado nas razões de δ13C and δ15N identificou-se a estrutura trófica da lagoa, bem como a posição trófica de espécies de peixes e as fontes de carbono do sitema. Análise de isótopos estáveis de nitrogênio permitiu a identificação de dois níveis tróficos de peixes na lagoa Mangueira. Macrófitas emergentes e perifíton foram identificadas como importantes fontes de carbono que sustentam a estrutura trófica do sistema. Análise de grupamento a partir de dados de δ13C e δ15N e de conteúdo estomacal identificou um arranjo perfeitamente filogenético entre as espécies de peixes analisadas, refletindo que, em sentido amplo, nichos alimentares são compartilhados por espécies taxonomicamente relacionadas. A dinâmica trófica da espécie de peixe dominante na lagoa, Oligosarcus jenynsii foi também analisada. Foram identificadas mudanças sazonais e ontogenéticas na dinâmica alimentar da espécie, evidenciando a grande plasticidade trófica associada com uma estratégia oportunista, característica de espécies carnívoras generalistas. As informações obtidas neste estudo permitiram identificar grande heterogeneidade espacial e claro gradiente longitudinal na lagoa Mangueira, tanto de fatores bióticos quanto abióticos, com reflexos na distribuição e abundância de plâncton e peixes. De posse destas informações foi possível alcançar um entedimento sobre a estrutura atual do sistema, bem como os direcionadores da sua dinâmica. A abordagem direcionada neste trabalho sobre o entendimento da estrutura atual de um lago raso subtropical possibilita futuros estudos na área da modelagem ecológica. A dinâmica das comunidades abordadas neste estudo vem subsidiar a parametrização de um modelo ecológico, com capacidade de estabelecer prognósticos, tendo como contorno, estressores naturais e antrópicos.
Biological communities change in time and space following driving pressures from differences in habitat structure and resource availability. Understanding the ecological role and interactions within aquatic community is essential for any management action trying to improve water quality by interferences in lake food web, ecosystem dynamics and modeling. The present study was carried out in two freshwater systems in Southern Brazil: an irrigated rice field and in a large shallow system, Mangueira Lake. The goal of this study in temporary wetlands was to evaluate the plankton and fish dynamics during a productive cycle. Our results evidenced a temporal gradient by nutrients availability in the temporary wetland studied. However, the limnological variables did not display any horizontal pattern among sampling stations. Linear regression showed a positive relationship between chlorophyll a and nutrients, zooplankton biomass and copepod biomass. In contrast, fish biomass and planktivorous fish biomass were inversely related to chlorophyll a. Statistically significant relationships between DOC with nutrients, plankton and fish biomass were also identified during the rice production cycle. In Mangueira Lake, a shallow system (zmed 3m) and 90 km long, the goal was to evaluate the spatial and temporal distribution of plankton and fish biomass as a function of the presence of the emergent macrophytes Zizaniopsis bonariensis. We also analyzed the existence of longitudinal gradient in lake and the food web structure in system. The PCA and RDA analyses showed the temporal (seasonal) and spatial (North/South) gradient during the study. Analysis of similarity (ANOSIM) applied to environmental variables showed significant differences between sampling sites (North and South). Secchi transparency, DOC and chlorophyll a were significantly different in North and South sampling sites. ANOVA results showed that season effects are stronger in the Northern sampling site. Concerning the community structure in the Mangueira Lake, bacterioplankton biomass, chlorophyll a, zooplankton biomass and fish captures were different seasonally after extracting the habitat structure effect, while in the Southern sampling site only chlorophyll a presented a seasonal significant variation. Habitat structure (by Z. bonariensis stands and open water samples) induced significant differences in chlorophyll a both in North and South samples after extracting seasonal effect. Fish captures do also responded to habitat structure in the North, after extracting the season effect. Analysis of similarity (ANOSIM) applied to fish community also showed significant differences between North and South, although no significant differences between vegetated and open water zones was observed. Fish biomass, number of captures, and richness were different between sampling sites. Based on the δ13C and δ15N ratios and analysis of stomach content of fish species, we provide also a description of food web structure, trophic positions of fish species and primary producers of system. Analysis of nitrogen isotope ratios yielded two fish trophic levels in Mangueira Lake. Emergent macrophytes and periphyton were important carbon source that sustain the food web structure of the system. Cluster analysis of δ13C and δ15N values and stomach content yielded a perfect phylogenetic arrangement of species. This result reflects that major feeding niches are shared by taxonomically related species. The feeding dynamics of the dominant fish species, Oligosarcus jenynsii was analysed by using analyses of stomach contents and stable isotopes signature. Seasonal and ontogenetic change in the feeding biology of O. jenynsii was identified, showing the high feeding plasticity, in addition to an opportunistic strategy of this generalist carnivore species. This study allows identifying a large spatial heterogeneity and clear longitudinal gradient both in biotic and abiotic factors, reflecting fish and plankton distribution and abundance. The evaluated parameters are intended to feed a mathematical model for the Mangueira Lake, looking for predictable scenarios from natural and anthropogenic stressors.
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Felix, Leonardo Gama. « Nutrient Dynamics and Foods Webs ». Laboratório Nacional de Computação Científica, 2010. http://www.lncc.br/tdmc/tde_busca/arquivo.php?codArquivo=202.

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A food web comprises exchanges of matter and energy that occur among species and between biotic and abiotic environment. Given that abiotic components form the basal resources, the approach of this work consists of evaluating the effects of nutrients input in strategic models that describe food web and chain dynamics. Its focus lies on the determination of the nature of equilibrium populations as well as on their dynamics for different functional responses. Strategic models that describe the behavior of interactive populations under nutrient inputs are an important basis for outlining general phenomena that occur in community dynamics.
Uma rede trófica reúne as trocas de matéria e energia que ocorrem entre as espécies e entre o meio biótico e abiótico. Visto que os componentes abióticos formam a fonte de recursos basais, a abordagem deste trabalho consiste na avaliação dos efeitos da entrada de nutrientes alóctones em modelos estratégicos que descrevem a dinâmica de redes e cadeias tróficas, concentrando-se na determinação das características das populações de equilíbrio e das dinâmicas das espécies com diferentes respostas funcionais. Modelos estratégicos que contêm informações acerca do comportamento de populações interativas frente à entrada de nutrientes são uma base importante no delineamento de fenômenos gerais que podem ocorrer dentro da dinâmica de comunidades.
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Oliveira, Filho Romildo Lopes de. « Dynamics of phosphorus in mangroves impacted by the state of Ceará ». reponame:Repositório Institucional da UFC, 2012. http://www.repositorio.ufc.br/handle/riufc/17165.

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OLIVEIRA FILHO, Romildo Lopes de. Dinâmica de fósforo em manguezais impactados por águas residuárias no Estado do Ceará. 2012. 62 f. Dissertação (Mestrado em ecologia e recursos naturais)- Universidade Federal do Ceará, Fortaleza-CE, 2012.
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Recent studies demonstrated the efficacy of mangrove retaining nutrients and, in particular, the ability of the mineral component of the buffer in its high soil phosphorus levels. In general, the mangroves have been considered as important sinks of nutrients due to its high capacity purification of effluents. However, depending on the geochemical conditions exist, these soils can act as a source of phosphorus to other environments and / or coastal waters. Given that the geochemical behavior of phosphorus and its role in eutrophication of water bodies, is best measured by the behavior of its different fractions, this paper aims at a fractionation of the different forms of phosphorus in wetlands impacted by different effluent. The objective of this project is to study three areas in order to assess how activities impacting interfere in the process of nutrient cycling (with special emphasis on the dynamics of phosphorus forms) and, as the marsh supports the stress caused by these activities. Also, if you evaluate the potential for eutrophication of each human activities. Taking into consideration the impact that these environments suffer as a result of separate activities, were established the following areas of study: a marsh impacted by effluents from shrimp, a marsh impacted by effluents, and a control area located in a preserved area that still finds is little affected by human impacts. The samples were determined pH, Eh, salinity, grain size and the total content of C and P. In addition, extraction was performed sequentially phosphorus which allows differentiation of fractions 7: P exchangeable (NaClP), P associated with iron oxides (Fe-P); organic P (AH-P), the bound phosphorus hydroxides Al (Al-P), P associated with compounds of calcium (Ca-P); phosphorus associated refracting matter (P-RES) and unreacted phosphorus (P-NR). The results indicate that the discharge of effluents in mangrove increases the amount of phosphorus in these environments, especially in organic form, the phosphorus bound to carbonate is the major inorganic fraction in these environments.
Estudos recentes demonstram a eficácia do manguezal em reter nutrientes e, em especial, a capacidade dos componentes minerais do seu solo em tamponar elevados teores de fósforo. Em geral, os solos dos manguezais têm sido considerados como importantes sumidouros de nutrientes devido a sua grande capacidade de depuração de efluentes. Entretanto, dependendo das condições geoquímicas existentes, esses solos podem funcionar como fonte de fósforo para outros ambientes e/ou para as águas costeiras. Tendo em vista que o comportamento geoquímico do fósforo, bem como seu papel na eutrofização dos corpos d'água, é melhor avaliado através do comportamento de suas diferentes frações, o presente trabalho visa realizar um fracionamento das diferentes formas de fósforo em manguezais impactados por distintos efluentes. O objetivo da presente dissertação é estudar três áreas a fim de se avaliar como as atividades impactantes interferem no processo de ciclagem de nutrientes (com especial ênfase na dinâmica das formas de fósforo) e, como o manguezal suporta o estresse ocasionado por estas atividades. Além disso, se avaliará o potencial de eutrofização de cada uma das atividades antrópicas. Levando-se em consideração os impactos que esses ambientes sofrem em consequência de distintas atividades, foram estabelecidas as seguintes áreas de estudo: um manguezal impactado por efluentes de carcinicultura; um manguezal impactado por efluentes urbanos; e uma área controle localizada em uma área preservada que ainda encontra-se pouco afetada por impactos antrópicos. Nas amostras foram determinados pH, Eh, salinidade, granulometria e teores totais de C e P. Além disso, foi realizada a extração seqüencial de fósforo que permite a diferenciação de 7 frações: P trocável (NaCl-P); P associado a óxidos de Fe (FeP); P orgânico (AH-P); fósforo ligado a hidróxidos de Al (Al-P); P associado a compostos de cálcio (Ca-P); fósforo associado à matéria orgânica refratária (P-RES) e fósforo não reativo (P-NR). Os resultados obtidos indicam que o descarte de efluentes nos manguezais aumenta a quantidade de fósforo nesses ambientes, principalmente nas formas orgânicas; o fósforo ligado aos compostos de cálcio é a principal fração inorgânica nesses ambientes. Palavras-chave: ciclagem de nutrientes; extração sequencial; carcinicultura; efluente domiciliar.
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Livres sur le sujet "Nutrient dynamic"

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Danfaer, Allan. A dynamic model of nutrient digestion and metabolism in lactating dairy cows = : En dynamisk model af næringsstoffernes fordøjelse og omsætning hos malkekøer. Frederiksberg [Denmark] : i kommission hos Landhusholdningsselskabets forlag, 1990.

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Dominique, Bachelet, dir. MC1, a dynamic vegetation model for estimating the distribution of vegetation and associated ecosystem fluxes of carbon, nutrients, and water : Technical documentation : version 1.0. Portland, OR : U.S. Dept. of Agriculture, Forest Service, Pacific Northwest Research Station, 2001.

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Meena, Ram Swaroop, dir. Nutrient Dynamics for Sustainable Crop Production. Singapore : Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-13-8660-2.

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DeAngelis, D. L. Dynamics of Nutrient Cycling and Food Webs. Dordrecht : Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2342-6.

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Dynamics of nutrient cycling and food webs. London : Chapman & Hall, 1992.

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Agroecosystems : Soils, climate, crops, nutrient dynamics, and productivity. Toronto : Apple Academic Press, 2014.

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Kersebaum, Kurt Christian, Jens-Martin Hecker, Wilfried Mirschel et Martin Wegehenkel, dir. Modelling water and nutrient dynamics in soil–crop systems. Dordrecht : Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-4479-3.

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Krishna, K. R. Agroecosystems of South India : Nutrient dynamics, ecology and productivity. Boca Raton, Fla : BrownWalker Press, 2010.

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Manasbal lake Kashmir : Phytoplankton photosynthesis, nutrient dynamics, and trophic status. Delhi : Utpal Publications, 2010.

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Knight, Paula. Nutrient dynamics within vegetation belts in an agricultural catchment area. Manchester : UMIST, 1996.

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Chapitres de livres sur le sujet "Nutrient dynamic"

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Hannon, Bruce, et Matthias Ruth. « Two-Stage Nutrient Uptake ». Dans Modeling Dynamic Biological Systems, 75–79. Cham : Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-05615-9_8.

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Ruth, Matthias, et Bruce Hannon. « Two-Stage Nutrient Uptake Model ». Dans Modeling Dynamic Biological Systems, 69–73. New York, NY : Springer New York, 1997. http://dx.doi.org/10.1007/978-1-4612-0651-4_8.

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Wlaschin, Katie F., et Wei-Shou Hu. « Fedbatch Culture and Dynamic Nutrient Feeding ». Dans Cell Culture Engineering, 43–74. Berlin, Heidelberg : Springer Berlin Heidelberg, 2006. http://dx.doi.org/10.1007/10_015.

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George, R. Y. « Metabolism of Antarctic Krill, Euphausia superba, and Its Tropho-Dynamic Implications ». Dans Antarctic Nutrient Cycles and Food Webs, 324–29. Berlin, Heidelberg : Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82275-9_46.

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Liu, Shirong. « Nitrogen cycling and dynamic analysis of man made larch forest ecosystem ». Dans Nutrient Uptake and Cycling in Forest Ecosystems, 391–97. Dordrecht : Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-0455-5_45.

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Schreurs, N. M., F. Garcia-Launay, T. Hoch, C. Jurie, J. Agabriel, D. Micol et B. Picard. « Dynamic modelling of contractile and metabolic properties of bovine muscle ». Dans Modelling nutrient digestion and utilisation in farm animals, 209–17. Wageningen : Wageningen Academic Publishers, 2011. http://dx.doi.org/10.3920/978-90-8686-712-7_23.

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Moline, Mark A., Oscar Schofield et Joe Grzymski. « Impact of Dynamic Light and Nutrient Environments on Phytoplankton Communities in the Coastal Ocean ». Dans Dynamic Modeling for Marine Conservation, 144–63. New York, NY : Springer New York, 2002. http://dx.doi.org/10.1007/978-1-4613-0057-1_8.

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Johnson, Billy E., Zhonglong Zhang et Charles W. Downer. « Watershed Scale Physically Based Water Flow, Sediment and Nutrient Dynamic Modeling System ». Dans Landscape Ecology for Sustainable Environment and Culture, 145–71. Dordrecht : Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-6530-6_8.

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Aarthi, R., et D. Sivakumar. « Dynamic Tuning of Fuzzy Membership Function for an Application of Soil Nutrient Recommendation ». Dans Advances in Intelligent Systems and Computing, 107–17. Singapore : Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-0475-2_10.

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DeAngelis, D. L. « Nutrients and autotrophs : variable internal nutrient levels ». Dans Dynamics of Nutrient Cycling and Food Webs, 63–80. Dordrecht : Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-011-2342-6_4.

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Actes de conférences sur le sujet "Nutrient dynamic"

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Zhu, Qiaoqiao, et Weiyong Gu. « Effects of Dynamic Loading on Cell Viability in Intervertebral Disc ». Dans ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80452.

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Sufficient nutrient supply has long been regarded as a crucial factor for maintaining intervertebral disc (IVD) cell viability and preventing IVD degeneration1,2. Due to avascular nature of the tissue, nutrients for IVD cells are transported, mainly by diffusion, through the dense extracellular matrix of the tissue from the peripheral and endplate vasculatures. Experimental studies on the effects of nutrient deprivation on IVD cell viability showed that glucose is the most critical nutrient affecting the cell density in IVD3–5. Because of the difficulties in studying mechano-biology of human IVD in vivo, numerical simulations are necessary to investigate how the disturbances of biological, physical, and chemical signals can affect the cellular metabolism and viability in IVD. However, to date, there is no adequate theoretical model that is able to describe the change of cell density in IVD under dynamic conditions. Therefore, the objective of this study was to develop a new constitutive model for cell growth/death in human IVD and to analyze the cell metabolism and cell viability in IVD under dynamic, mechanical loading conditions using numerical methods based on the mechano-electrochemical mixture theory6,7.
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Huang, Chun-Yuh, et Wei Yong Gu. « Effects of Compression on Distributions of Oxygen and Lactate in Intervertebral Disc ». Dans ASME 2007 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2007. http://dx.doi.org/10.1115/sbc2007-176025.

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Since the intervertebral disc (IVD) is the largest avascular cartilaginous structure in the human body, poor nutrient supply has been suggested as a potential mechanism for disc degeneration. The previous theoretical studies have shown that the distributions of nutrients and metabolites (e.g., oxygen, glucose, and lactate) within the IVD depended on tissue diffusivities, nutrient supply, cellular metabolic rates, and coupling effects between nutrient and metabolite [1,2]. Our recent theoretical study suggested that dynamic compression can promote transport of neutral solute in the anisotropic cartilaginous tissue by enhancing both diffusive and convective solute fluxes [3]. However, the effect of compression on distributions of nutrients and metabolites in the IVD has not been studied. The objective of this study was to examine the effects of compression on distributions of oxygen and lactate in the IVD under static and dynamic unconfined compression using a new formulation of the triphasic theory.
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Zhang, Ning, et Weihao Wang. « Investigation of Water pH in Calcasieu Lake Area Using Regional Scale Hydrodynamic Models ». Dans ASME 2017 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fedsm2017-69208.

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In Southwest Louisiana, the Calcasieu Lake and surrounding water systems are the major fresh water sources to the nearby coastal wetlands and agricultural areas. There are two national wide life refuges located in both east and west sides of Calcasieu Lake. Both refuges are covered by coastal wetlands. The health of the wetland vegetation is essential to the wetland losses in the area. One of the major problems related to the health of marshes is the nutrient deficiency. In addition, the surface water system is a possible source for agriculture use that requires sufficient nutrient components in water. Understanding the transport and distribution of various nutrients in the coastal water system is very important to the above-mentioned issues. In this study, a regional scale hydrodynamic model was utilized to simulate the hydrodynamics, salinity transport and sediment transport in this major water system in Southwest Louisiana. The pH distribution in water is a good indication of many nutrient components, such as phosphorous, and is essential to understand the nutrient distributions in the target area. A pH calculation procedure was implemented in the model to determine pH values based on the salinity and other water properties. The model results can be used to indicate the dynamic change of nutrient distributions and the areas of nutrient deficiency.
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Sauer, Thomas J., et Ehsan Samei. « Modeling dynamic, nutrient-access-based lesion progression using stochastic processes ». Dans Physics of Medical Imaging, sous la direction de Hilde Bosmans, Guang-Hong Chen et Taly Gilat Schmidt. SPIE, 2019. http://dx.doi.org/10.1117/12.2513201.

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Bilaletdin, Ä., H. Kaipainen et T. Frisk. « Dynamic nutrient modelling of a large river basin in Finland ». Dans WATER POLLUTION 2008. Southampton, UK : WIT Press, 2008. http://dx.doi.org/10.2495/wp080061.

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Huang, Chun-Yuh, et Wei Yong Gu. « Effects of Compression on Glucose Consumption in Intervertebral Disc ». Dans ASME 2008 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2008. http://dx.doi.org/10.1115/sbc2008-192812.

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Nutrition supply is a concern for the health of avascular cartilaginous tissues such as intervertebral disc (IVD). Maintaining tissue integrity relies on cellular biosynthesis of extracellular matrix, which is an energy demanding process [1]. In the IVD, energy is mainly generated through glycolysis (i.e., glucose consumption). Metabolism of nutrients (e.g., oxygen and glucose) within the IVD depends on local concentrations of nutrients, and coupling effects between nutrient level and metabolic rate [2,3]. Our previous theoretical study had developed a new theoretical formulation by incorporating the metabolic rates of solutes into the mechano-electrochemical mixture theory [4,5]. By using this new theoretical model, the distribution of oxygen and lactate can be predicted within the IVD under static and dynamics compressions [4]. However, the effect of compression on glucose consumption in the IVD has not been studied. The objective of this study was to examine the effects of compression on glucose consumption in the IVD under static and dynamic unconfined compression numerically.
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Ono, Eiichi, Kenneth A. Jordan et Joel L. Cuello. « Dynamic Monitoring of Nutrient Species In Hydroponic Solutions For Advanced Life Support ». Dans 31st International Conference On Environmental Systems. 400 Commonwealth Drive, Warrendale, PA, United States : SAE International, 2001. http://dx.doi.org/10.4271/2001-01-2276.

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Farrell, Megan J., Eric S. Comeau et Robert L. Mauck. « Dynamic Culture Improves Mechanical Functionality of MSC-Laden Tissue Engineered Constructs in a Depth-Dependent Manner ». Dans ASME 2011 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2011. http://dx.doi.org/10.1115/sbc2011-53442.

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Limitations associated with the use of autologous chondrocytes (CH) for cartilage tissue engineering beget the need for alternative cell sources. Mesenchymal stem cells (MSC) are clinically attractive due to their ability to undergo chondrogenesis in three-dimensional culture [1,2]; however, when compared to CH, MSC fail to develop functional equivalence [2,3]. We have previously shown a marked depth-dependence in local equilibrium modulus of MSC-laden gels, with the superficial zones (where maximal media exchange occurs) considerably stiffer than regions removed from nutrient supply (center and bottom of construct); less dramatic depth-dependence was observed in CH-laden gels [4]. Similarly, other studies have shown depth-dependent properties in CH-laden gels with the construct edge generally stiffer than the center [5]. Given this apparent influence of nutrient supply, the objective of the current study was to assess the impact of dynamic culture (via orbital shaking) on the development of depth-dependent mechanical properties in both MSC and CH-laden hydrogels. Furthermore, we assessed cell viability and matrix content throughout the construct depth to determine the mechanism by which this depth-dependency arises. We hypothesized that improved nutrient transport would reduce construct inhomogeneity (particularly for MSC-laden constructs) and improve bulk mechanical properties.
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Asahi, Toshimasa, Toshimasa Asahi, Kazuhiko Ichimi, Kazuhiko Ichimi, Kuninao Tada et Kuninao Tada. « NUTRIENT DYNAMICS IN EELGRASS (ZOSTERA MARINA) MEADOW AND THE VARIATION OF NUTRIENT CONTENTS OF EELGRASS ». Dans Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.31519/conferencearticle_5b1b938251aa95.85691438.

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Nutrient dynamics in seagrass beds and nutrient demands of seagrass biomass are not clear, although nutrient uptake of seagrass has been experimentally studied in the laboratory. We conducted the field observations and the bottom sediment core incubations to estimate nutrient fluxes in the seagrass, Zostera marina meadow. DIN (nitrate, nitrite and ammonium) concentrations were always low particularly during the Z. marina growing season (from spring to summer), and water exchanges caused by tidal currents hardly supplied nutrient demand for Z. marina. Sediment pore water also supplied insufficient nutrients to Z. marina, because pore water had less volume than the water column, although DIN concentrations of pore water were 10-100 fold higher than those of the water column. Nutrient flux from sediment to water column estimated by the sediment core incubation experiments showed a similar rate with tidal water exchange. Thus, our results suggested that Z. marina adapted for low nutrient concentrations and each nutrient source in the Z. marina meadow slightly contributed but could not support Z. marina growth. We found that another nutrient source, for example, precipitation, supplied high DIN to the Z. marina meadow. After rainfall, the DIN concentration of seawater in the Z. marina meadow increased 2-5 times higher. Moreover, nitrogen content of eelgrass also increased 2-3 times higher during several days. Those results suggested that Z. marina was usually exposed to a low nutrient concentration but could uptake abundant nutrients from temporary nutrient supplies such as precipitation.
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Asahi, Toshimasa, Toshimasa Asahi, Kazuhiko Ichimi, Kazuhiko Ichimi, Kuninao Tada et Kuninao Tada. « NUTRIENT DYNAMICS IN EELGRASS (ZOSTERA MARINA) MEADOW AND THE VARIATION OF NUTRIENT CONTENTS OF EELGRASS ». Dans Managing risks to coastal regions and communities in a changing world. Academus Publishing, 2017. http://dx.doi.org/10.21610/conferencearticle_58b4316623b72.

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Nutrient dynamics in seagrass beds and nutrient demands of seagrass biomass are not clear, although nutrient uptake of seagrass has been experimentally studied in the laboratory. We conducted the field observations and the bottom sediment core incubations to estimate nutrient fluxes in the seagrass, Zostera marina meadow. DIN (nitrate, nitrite and ammonium) concentrations were always low particularly during the Z. marina growing season (from spring to summer), and water exchanges caused by tidal currents hardly supplied nutrient demand for Z. marina. Sediment pore water also supplied insufficient nutrients to Z. marina, because pore water had less volume than the water column, although DIN concentrations of pore water were 10-100 fold higher than those of the water column. Nutrient flux from sediment to water column estimated by the sediment core incubation experiments showed a similar rate with tidal water exchange. Thus, our results suggested that Z. marina adapted for low nutrient concentrations and each nutrient source in the Z. marina meadow slightly contributed but could not support Z. marina growth. We found that another nutrient source, for example, precipitation, supplied high DIN to the Z. marina meadow. After rainfall, the DIN concentration of seawater in the Z. marina meadow increased 2-5 times higher. Moreover, nitrogen content of eelgrass also increased 2-3 times higher during several days. Those results suggested that Z. marina was usually exposed to a low nutrient concentration but could uptake abundant nutrients from temporary nutrient supplies such as precipitation.
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Rapports d'organisations sur le sujet "Nutrient dynamic"

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Fisher, Joshua, Richard Phillips et Tom Evans. Nutrient Cycle Impacts on Forest Ecosystem Carbon Cycling : Improved Prediction of Climate Feedbacks from Coupled C–Nutrient Dynamics from Ecosystem to Regional Scales. Office of Scientific and Technical Information (OSTI), août 2017. http://dx.doi.org/10.2172/1377633.

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Grizzard, T. Henderson, G.S. Clebsch, E. Seasonal Nutrient Dynamics of Foliage and Litterfall on Walker Branch Watershed, a Deciduous Forest Ecosystem. Office of Scientific and Technical Information (OSTI), janvier 1999. http://dx.doi.org/10.2172/814435.

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Kelly, J. M. Dynamics of Litter Decomposition, Microbiota Populations, and Nutrient Movement Following Nitrogen and Phosphorus Additions to a Deciduous Forest Stand. Office of Scientific and Technical Information (OSTI), octobre 2002. http://dx.doi.org/10.2172/814493.

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Or, Dani, Shmulik Friedman et Jeanette Norton. Physical processes affecting microbial habitats and activity in unsaturated agricultural soils. United States Department of Agriculture, octobre 2002. http://dx.doi.org/10.32747/2002.7587239.bard.

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experimental methods for quantifying effects of water content and other dynamic environmental factors on bacterial growth in partially-saturated soils. Towards this end we reviewed critically the relevant scientific literature and performed theoretical and experimental studies of bacterial growth and activity in modeled, idealized and real unsaturated soils. The natural wetting-drying cycles common to agricultural soils affect water content and liquid organization resulting in fragmentation of aquatic habitats and limit hydraulic connections. Consequently, substrate diffusion pathways to soil microbial communities become limiting and reduce nutrient fluxes, microbial growth, and mobility. Key elements that govern the extent and manifestation of such ubiquitous interactions include characteristics of diffusion pathways and pore space, the timing, duration, and extent of environmental perturbations, the nature of microbiological adjustments (short-term and longterm), and spatial distribution and properties of EPS clusters (microcolonies). Of these key elements we have chosen to focus on a manageable subset namely on modeling microbial growth and coexistence on simple rough surfaces, and experiments on bacterial growth in variably saturated sand samples and columns. Our extensive review paper providing a definitive “snap-shot” of present scientific understanding of microbial behavior in unsaturated soils revealed a lack of modeling tools that are essential for enhanced predictability of microbial processes in soils. We therefore embarked on two pronged approach of development of simple microbial growth models based on diffusion-reaction principles to incorporate key controls for microbial activity in soils such as diffusion coefficients and temporal variations in soil water content (and related substrate diffusion rates), and development of new methodologies in support of experiments on microbial growth in simple and observable porous media under controlled water status conditions. Experimental efforts led to a series of microbial growth experiments in granular media under variable saturation and ambient conditions, and introduction of atomic force microscopy (AFM) and confocal scanning laser microscopy (CSLM) to study cell size, morphology and multi-cell arrangement at a high resolution from growth experiments in various porous media. The modeling efforts elucidated important links between unsaturated conditions and microbial coexistence which is believed to support the unparallel diversity found in soils. We examined the role of spatial and temporal variation in hydration conditions (such as exist in agricultural soils) on local growth rates and on interactions between two competing microbial species. Interestingly, the complexity of soil spaces and aquatic niches are necessary for supporting a rich microbial diversity and the wide array of microbial functions in unsaturated soils. This project supported collaboration between soil physicists and soil microbiologist that is absolutely essential for making progress in both disciplines. It provided a few basic tools (models, parameterization) for guiding future experiments and for gathering key information necessary for prediction of biological processes in agricultural soils. The project sparked a series of ongoing studies (at DTU and EPFL and in the ARO) into effects of soil hydration dynamics on microbial survival strategy under short term and prolonged desiccation (important for general scientific and agricultural applications).
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Bachelet, Dominique, James M. Lenihan, Christopher Daly, Ronald P. Neilson, Dennis S. Ojima et William J. Parton. MC1 : a dynamic vegetation model for estimating the distribution of vegetation and associated carbon, nutrients, and water—technical documentation. Version 1.0. Portland, OR : U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station, 2001. http://dx.doi.org/10.2737/pnw-gtr-508.

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Bans, Alex. A Seasonal Study of Ecoroof Metal and Nutrient Dynamics and Associated Drivers in an Ecoroof on a Commercial Building in North Portland Oregon. Portland State University Library, janvier 2000. http://dx.doi.org/10.15760/etd.7449.

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Wetzel, R. G. Dissolved organic matter and lake metabolism : Biogeochemistry and controls of nutrient flux dynamics to fresh waters. Technical progress report, January 1, 1990--December 31, 1991. Office of Scientific and Technical Information (OSTI), décembre 1992. http://dx.doi.org/10.2172/296880.

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Desiderati, Christopher. Carli Creek Regional Water Quality Project : Assessing Water Quality Improvement at an Urban Stormwater Constructed Wetland. Portland State University, 2022. http://dx.doi.org/10.15760/mem.78.

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Stormwater management is an ongoing challenge in the United States and the world at-large. As state and municipal agencies grapple with conflicting interests like encouraging land development, complying with permits to control stormwater discharges, “urban stream syndrome” effects, and charges to steward natural resources for the long-term, some agencies may turn to constructed wetlands (CWs) as aesthetically pleasing and functional natural analogs for attenuating pollution delivered by stormwater runoff to rivers and streams. Constructed wetlands retain pollutants via common physical, physicochemical, and biological principles such as settling, adsorption, or plant and algae uptake. The efficacy of constructed wetlands for pollutant attenuation varies depending on many factors such as flow rate, pollutant loading, maintenance practices, and design features. In 2018, the culmination of efforts by Clackamas Water Environment Services and others led to the opening of the Carli Creek Water Quality Project, a 15-acre constructed wetland adjacent to Carli Creek, a small, 3500-ft tributary of the Clackamas River in Clackamas County, OR. The combined creek and constructed wetland drain an industrialized, 438-acre, impervious catchment. The wetland consists of a linear series of a detention pond and three bioretention treatment cells, contributing a combined 1.8 acres of treatment area (a 1:243 ratio with the catchment) and 3.3 acre-feet of total runoff storage. In this study, raw pollutant concentrations in runoff were evaluated against International Stormwater BMP database benchmarks and Oregon Water Quality Criteria. Concentration and mass-based reductions were calculated for 10 specific pollutants and compared to daily precipitation totals from a nearby precipitation station. Mass-based reductions were generally higher for all pollutants, largely due to runoff volume reduction on the treatment terrace. Concentration-based reductions were highly variable, and suggested export of certain pollutants (e.g., ammonia), even when reporting on a mass-basis. Mass load reductions on the terrace for total dissolved solids, nitrate+nitrite, dissolved lead, and dissolved copper were 43.3 ± 10%, 41.9 ± 10%, 36.6 ± 13%, and 43.2 ± 16%, respectively. E. coli saw log-reductions ranging from -1.3 — 3.0 on the terrace, and -1.0 — 1.8 in the creek. Oregon Water Quality Criteria were consistently met at the two in-stream sites on Carli Creek for E. coli with one exception, and for dissolved cadmium, lead, zinc, and copper (with one exception for copper). However, dissolved total solids at the downstream Carli Creek site was above the Willamette River guidance value 100 mg/L roughly 71% of the time. The precipitation record during the study was useful for explaining certain pollutant reductions, as several mechanisms are driven by physical processes, however it was not definitive. The historic rain/snow/ice event in mid-February 2021 appeared to impact mass-based reductions for all metals. Qualitatively, precipitation seemed to have the largest effect on nutrient dynamics, specifically ammonia-nitrogen. Determining exact mechanisms of pollutant removals was outside the scope of this study. An improved flow record, more targeted storm sampling, or more comprehensive nutrient profiles could aid in answering important questions on dominant mechanisms of this new constructed wetland. This study is useful in establishing a framework and baseline for understanding this one-of-a-kind regional stormwater treatment project and pursuing further questions in the future.
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Hovav, Ran, Peggy Ozias-Akins et Scott A. Jackson. The genetics of pod-filling in peanut under water-limiting conditions. United States Department of Agriculture, janvier 2012. http://dx.doi.org/10.32747/2012.7597923.bard.

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Pod-filling, an important yield-determining stage is strongly influenced by water stress. This is particularly true for peanut (Arachishypogaea), wherein pods are developed underground and are directly affected by the water condition. Pod-filling in peanut has a significant genetic component as well, since genotypes are considerably varied in their pod-fill (PF) and seed-fill (SF) potential. The goals of this research were to: Examine the effects of genotype, irrigation, and genotype X irrigation on PF and SF. Detect global changes in mRNA and metabolites levels that accompany PF and SF. Explore the response of the duplicate peanut pod transcriptome to drought stress. Study how entire duplicated PF regulatory processes are networked within a polyploid organism. Discover locus-specific SNP markers and map pod quality traits under different environments. The research included genotypes and segregating populations from Israel and US that are varied in PF, SF and their tolerance to water deficit. Initially, an extensive field trial was conducted to investigate the effects of genotype, irrigation, and genotype X irrigation on PF and SF. Significant irrigation and genotypic effect was observed for the two main PF related traits, "seed ratio" and "dead-end ratio", demonstrating that reduction in irrigation directly influences the developing pods as a result of low water potential. Although the Irrigation × Genotype interaction was not statistically significant, one genotype (line 53) was found to be more sensitive to low irrigation treatments. Two RNAseq studies were simultaneously conducted in IL and the USA to characterize expression changes that accompany shell ("source") and seed ("sink") biogenesis in peanut. Both studies showed that SF and PF processes are very dynamic and undergo very rapid change in the accumulation of RNA, nutrients, and oil. Some genotypes differ in transcript accumulation rates, which can explain their difference in SF and PF potential; like cvHanoch that was found to be more enriched than line 53 in processes involving the generation of metabolites and energy at the beginning of seed development. Interestingly, an opposite situation was found in pericarp development, wherein rapid cell wall maturation processes were up-regulated in line 53. Although no significant effect was found for the irrigation level on seed transcriptome in general, and particularly on subgenomic assignment (that was found almost comparable to a 1:1 for A- and B- subgenomes), more specific homoeologous expression changes associated with particular biosynthesis pathways were found. For example, some significant A- and B- biases were observed in particular parts of the oil related gene expression network and several candidate genes with potential influence on oil content and SF were further examined. Substation achievement of the current program was the development and application of new SNP detection and mapping methods for peanut. Two major efforts on this direction were performed. In IL, a GBS approach was developed to map pod quality traits on Hanoch X 53 F2/F3 generations. Although the GBS approach was found to be less effective for our genetic system, it still succeeded to find significant mapping locations for several traits like testa color (linkage A10), number of seeds/pods (A5) and pod wart resistance (B7). In the USA, a SNP array was developed and applied for peanut, which is based on whole genome re-sequencing of 20 genotypes. This chip was used to map pod quality related traits in a Tifrunner x NC3033 RIL population. It was phenotyped for three years, including a new x-ray method to phenotype seed-fill and seed density. The total map size was 1229.7 cM with 1320 markers assigned. Based on this linkage map, 21 QTLs were identified for the traits 16/64 weight, kernel percentage, seed and pod weight, double pod and pod area. Collectively, this research serves as the first fundamental effort in peanut for understanding the PF and SF components, as a whole, and as influenced by the irrigation level. Results of the proposed study will also generate information and materials that will benefit peanut breeding by facilitating selection for reduced linkage drag during introgression of disease resistance traits into elite cultivars. BARD Report - Project4540 Page 2 of 10
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Nutrient dynamics in five off-stream reservoirs in the lower South Platte River basin, March-September 1995. US Geological Survey, 2002. http://dx.doi.org/10.3133/wri024142.

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