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1
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, and 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.
3
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.
5
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.
6
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, and 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.Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-05-24T19:35:17Z No. of bitstreams: 1 2012_dis_rloliveirafilho.pdf: 2179639 bytes, checksum: d23643a12aa12247a31b61d72a27f60b (MD5)
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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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Griffiths, Paul. "Nutrient dynamics in manure amended grasslands." Thesis, University of Sheffield, 1993. http://etheses.whiterose.ac.uk/10198/.
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Following the surface application of different fertiliser treatments (cattle slurry, cattle manure, and inorganic fertiliser) to grassed hillslopes, the transport of nitrogen (N) and phosphorus (P) was monitored on controlled plots. The plots measured 30 m by 5 m, the lower 10 m acting as an untreated buffer zone, in order to examine the effect of following current codes of practice when applying fertilisers (MAFF and WOAD, 1991). Surface and sub-surface nutrient flow pathways were monitored, by sampling water from the saturated and unsaturated zones of the soil profile, and from surface runoff. Sub-surface flow was dominated by N03--N. However, concentrations of this N species were relatively low (3-6 mg 1-1), and differences between treatments and the control were not significant. Generally, this indicated immobilisation of N species and P fractions, outputs in plant uptake and possibly to atmosphere (denitrification). For surface runoff, concentrations of N and P from treated plots were significantly higher than those from the control. N was largely present as organic-N and NH4+-N for the slurry and manure (15 mg 1-1 and 5 mg 1-1 respectively), and as NH4+-N and N03--N for the inorganic fertiliser (20 mg 1-1 in both cases). P was largely present as P04--P (0.5 mg 1-1 for manure and slurry, 10 mg 1-1 for inorganic fertiliser), except for the manure treatment, where some 75 % of the total was organic-P. The 10 m buffer was effective in reducing the delivery of N and P in surface runoff, differences between the treatments and the control being rendered insignificant. This result was qualified in terms of the ratio of the buffer area to the treated area and the relatively low surface loads of N and P observed. N and P transport was then examined under less controlled conditions at the field to headwater catchment scale (4-18 ha). Sub-surface throughflow was associated with similar concentrations of N03--N (3-8 mg 1-1) and very low concentrations of P04--P (0.03-0.1 mg 1-1). These concentrations appeared to vary more in relation to seasonal changes in the level of discharge from the catchment than to changes in land-use, which implied that N and P in sub-surface throughflow was transport rather than supply limited. This was in broad agreement with observations made at the plot scale. At this larger scale, fluctuations in the concentrations of NH4+-N and P04--P occurred during rainfall events in response to what was probably the short-term occurrence of surface runoff from partial source areas of reduced infiltration capacity or variable source areas of saturation. These short-term fluctuations implied variations in topography and the distribution of surface derived N and P at the catchment scale. There was evidence of the occurrence of preferential flow during field experiments at both scales, which had important implications for the timing and magnitude of N and P transport. Finally, a functional and semi-distributed mathematical model was constructed to operate at the headwater catchment scale, and the effect of spatial variability in the interaction between land-use and topography on the transport of N and P was considered further.
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Wuta, Menas. "Nutrient dynamics in miombo woodlands in Zimbabwe." Thesis, University of Edinburgh, 2003. http://hdl.handle.net/1842/27719.
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Miombo woodlands are tropical savanna formations dominated by genera Brachystegia, Julbernardia and Isoberlinia and are widespread in central and southern Africa. These woodlands are an important resource providing among other things, grazing and browse for livestock and wildlife, medicines for local people, food like mushroom and honey and timber for building and fuel. Understanding the structural and functional characteristics of miombo ecosystems and the factors affecting and controlling production is therefore important, both for their significance in understanding the environment and also for their value to local communities. In addition to soil moisture, herbivory and fire, soil nutrients are known to be an important determinant of savanna ecosystems. Nutrient dynamics have been studied at two Zimbabwean sites providing a range of representative miombo environments - the Henderson Research Station near Mazowe and the Mukuvisi Woodlands in Harare. The aim of the research has been to assess the major inputs and outputs of macronutrient nutrients (principally N, P, K, Ca and Mg) in miombo woodlands and to determine the effects of fire on nutrient cycling. The quantities of nutrients added in rainfall and throughfall were measured during the 1999/2000 and 2000/2001 rainy seasons. Additions of mineral N in rainfall were 14.7 and 7.4 kg/ha/yr at the Mukuvisi Woodlands experimental sites for the 1999/2000 and 2000/2001 rainy seasons respectively. Mineral N added at the Henderson Research Station experimental sites was 12.3 and 5.7 kg/ha/yr for the 1999/2000 and 2000/2001 rainy seasons respectively. Cation input in rainfall was very low at Henderson compared to Mukuvisi, a result which can be explained by the high level of pollution in and around Harare. The amount of cations added during the 2000/2001 ranged from 0.8 to 7.8 kg/ha/yr and 0.2 to 1.2 kg/ha/yr for Mukuvisi Woodlands and Henderson Research Station experimental sites respectively, with K being the highest added in rainfall at both study areas. Nutrients were altered significantly by the canopy. Most of the N was absorbed and/or adsorbed whereas cations were significantly increased. Stem flow was measured only at Henderson Research Station sites and nutrient additions were very low (< 0.3 kg/ha/yr) compared to throughfall. Dominant miombo tree species were found to conserve nutrients by re-absorbing them from senescing leaves. Phosphorus had the largest percentage withdrawn for all the dominant tree species and this ranged from 48 to 75 % of the total P in mature leaves (in November 1999). Total N, K and Mg withdrawn ranged from 22 to 33, 22 to 31 and 12 to 21 % respectively. Litterfall at the study sites ranged from 2.20 to 4.44 t/ha/yr. Litterfall (< 2 cm) is the largest nutrient cycling pathway in miombo woodlands, transferring between 36.6 to 65.2 kg N/ha/yr; 5.5 to 10.2 kg P/ha/yr; 15.3 to 26.7 kg K/ha/yr; 28.7 to 53.8 kg Ca/ha/yr; 4.9 to 8.6 kg Mg/ha/yr and 1.2 to 2.1 kg Na/ha/yr to the woodland floor. Litter decomposition was faster at the Henderson sites where there is evidence of high termite activity. K and Na were released fastest from decomposing litter compared to other nutrients. Nutrients leached from miombo soils were in the order K (1.24-2.52 kg/ha/yr) > N03_-N (1.11-2.30 kg/ha/yr) > Ca (0.82-1.49 kg/ha/yr) > NH4+-N (0.39-0.83 kg/ha/yr) > Na (0.28-0.54 kg/ha/yr) ≈ Mg (0.32-0.52 kg/ha/yr). Potassium was the most easily leached nutrient from litter and it was also found to be the highest cation in leachate collected from 100 cm depth. Losses of N in the form of N2O were also measured and were found to range from 0.29 to 0.60 kg/ha/yr and 0.27 to 0.62 kg/ha/yr at Mukuvisi Woodlands and Henderson Research Station experimental areas respectively. Compared to nutrient additions, losses through this pathway are low. Early burning resulted in loss of nutrients N, P, Ca, Mg, K and Na from herbaceous vegetation and, from litter, only N was lost in significant amounts. From the study it can be concluded that rainfall is an important nutrient input. Throughfall also contributes substantially to nutrients added to soils in miombo woodlands especially bases. The results from this study seem to indicate that miombo woodlands cycle nutrients efficiently with minimum losses. The internal nutrient cycling comprising mainly litterfall is able to re-circulate the largest proportion of nutrients. Losses through gaseous N20 emissions and leaching losses relative to the sum of throughfall and stem flow were found to be low. Fire resulted in some nutrient losses confirming the hypothesis that burning miombo woodlands results in significant loss of nutrients.
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Jones, Gordon B. "Temporal Nutrient Dynamics in Cool-Season Pasture." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23143.
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Understanding the nutrient dynamics of pastures is essential to their profitable and sustainable management. Tall fescue [Schendonorus phoenix (Scop.) Holub.] is the predominant forage species in Virginia pasturelands. Although tall fescue pasture is common, little research has attempted to document how soil and herbage nutrient concentrations change through time. This thesis summarizes two studies conducted within the context of a larger grazing systems project near Steele\'s Tavern, VA. The objectives were to: (1) examine temporal changes in plant available soil nutrient concentrations in four grazing systems, (2) determine how hay feeding and use of improved forages affected soil and herbage nutrient concentrations (3) examine the relationship between and variability within soil and herbage nutrient concentrations, (4) analyze the seasonal variation in herbage mineral concentration with regard to beef cattle requirements, and (5) create a statistical model to predict variation in herbage mineral concentration across the growing season. Analysis of plant and soil nutrients through 5 years of grazing produced several important findings. Soil pH, P, and Ca, Mg, and B declined through five years of grazing. Higher concentrations of herbage N and K and soil P, K, Fe, Zn, and Cu were measured in hay feeding paddocks. Herbage nutrient concentrations showed less variability in P and K than did soil test results. Fertility testing in pastures is important to monitor changing nutrient concentrations, and this study showed that herbage analysis may provide a more stable and accurate assessment of pasture fertility than soil testing. Pasture herbage, grown without fertilization, contained sufficient concentrations of macronutrients to meet the requirements of dry beef cows through the growing season and to meet the requirements of lactating beef cows in April. A model was developed using soil moisture and relative humidity that predicted (R2 = 0.75) variation in herbage mineral concentration throughout the growing season. As described in this thesis, use of modeling to predict nutrient dynamics in pasture could allow for more efficient mineral supplementation strategies that lead to improved profitability, nutrient retention, and livestock health.Master of Science
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Canals, Merseburger Mª Goretti. "Nutrient dynamics and metabolism in Mediterranean streams affected by nutrient inputs from human activities." Doctoral thesis, Universitat de Barcelona, 2006. http://hdl.handle.net/10803/1434.
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A full understanding of nutrient cycling in lotic ecosystems is crucial given the increasing influence of human activities on the eutrophication of streams and rivers. However, existing knowledge about nutrient cycling in human-altered streams (i.e., receiving point and diffuse sources) is still limited. The general objective of this dissertation was to examine point source effects on stream functional attributes, such as nutrient retention, denitrification and metabolism rates. We also quantified how the studied biogeochemical processes contribute to remove dissolved inorganic nitrogen (DIN) from point and diffuse sources, and examined relationships between N uptake measured based on experimental nutrient additions and N demand estimated from metabolism measurements. We selected two reaches located upstream and downstream of a point source in two streams draining a forest- and an agriculturaldominated catchments. Hence, the point source represented the main human influence in the forested stream, whereas the agricultural stream also received diffuse sources. The point source increased concentrations of ammonium (NH4 +-N), nitrate (NO3--N), soluble reactive phosphorus (SRP) and dissolved organic carbon in the forested stream, while only increased SRP concentration in the agricultural stream. The point source effect on water chemistry was likely to be overwhelmed by diffuse sources in this latter stream. Accordingly, point source inputs decreased nutrient retention efficiency, and increased denitrification and metabolism rates in the forested stream, whereas these effects were less clear in the agricultural stream. Retention of NH4 +-N was similar to potential nitrification rates in the two reaches of the two study streams, suggesting the importance of this process in NH4 +-N removal from the water column. Retention of NO3--N was similar to potential denitrification rates in the forested stream, suggesting the importance of this process as a net sink of NO3 --N. In contrast, high NO3--N fluxes in the agricultural stream resulted in low efficiency of denitrifiers to remove N from the water column. Hence, in-stream processes controlled DIN export in the forested stream, despite point source inputs, whereas much of the NO3--N reaching the channel via diffuse sources was lost downstream in the agricultural stream. Finally, estimated N demand was not correlated with measured N demand in any of the study reaches. Nevertheless, decoupling between measured and estimated N demand was clearly lower for the upstream reach of the forested stream (i.e., site with lowest human influence) than for the downstream reach and the two reaches of the agricultural stream (i.e., sites receiving nutrient inputs from human activities). Hence, coupling between carbon metabolism and N uptake in stream ecosystems is likely to become weaker with increasing anthropogenic nutrient inputs.
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Burdette, Sarah Beth. "Effects of excessive nitrogen deposition on foliar nutrient dynamics, nutrient concentrations, and nutrient ratios in a Central Appalachian hardwood forest." Huntington, WV : [Marshall University Libraries], 2002. http://www.marshall.edu/etd/descript.asp?ref=78.
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Thesis (M.S.)--Marshall University, 2002.Title from document title page. Document formatted into pages; contains x, 52 p. with maps and illustrations. Includes bibliographical references (p. 48-52).
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Obermann, Matthias. "Nutrient dynamics in temporary waters of Mediterranean catchments /." Hannover : Inst. für Siedlungswasserwirtschaft und Abfalltechnik, 2007. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=015645543&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Rolon, dos Santos Mérette Muriel. "Primary Production and Nutrient Dynamics of Urban Ponds." Thèse, Université d'Ottawa / University of Ottawa, 2012. http://hdl.handle.net/10393/20658.
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In urban areas, stormwater management ponds (SWPs) are built to mitigate polluted runoff. Although these ponds are increasing in numbers, their ecology is not well understood. Physical and chemical characteristics of 17 SWPs in the City of Ottawa were measured to determine the drivers of phytoplankton biomass (Chl. a) and primary production (PP). While total phosphorus was the best predictor of algal biomass in the ponds (as in lakes), the imperviousness of the catchment could also predict Chl. a. Planktonic PP in two ponds measured seasonally was more closely related to water residence time than to nutrient concentrations with rates approaching at times the theoretical maximum for aquatic systems. In one pond, whole ecosystem metabolism, estimated using diel changes in dissolved oxygen and δ18O-O2, suggested that these hypereutrophic systems were net sinks for carbon in the summer but likely sources to the atmosphere at other times of the year.
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Meyers, Lindsey Michele. "Wetland Assessment and Nutrient Dynamics in North Dakota." Diss., North Dakota State University, 2013. https://hdl.handle.net/10365/27215.
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Wetlands provide a variety of services and functions. Studies have highlighted the importance of wetlands in water purification, groundwater replenishment, flood control, sediment and nutrient retention and export, biodiversity, and climate change mitigation and adaptation. Additionally, wetlands are assets to food, fiber, cultural values, recreation, and tourism. These ecosystem services are provided to society free of charge and when eliminated can have negative implications. Therefore, wetland management is important, as wetlands can be lost to agriculture and urbanization. Monitoring wetland condition is a tool to analyze human impact on wetlands. Various types of wetland assessments have been created to measure biological condition. These include vegetative, rapid, functional, and intensive assessments. Data collected from assessments can be utilized for further study and analysis in addition to measuring condition. Physical characteristics can be identified that correlate with wetland condition, which provide clues to how well a wetland is functioning. Wetlands are important to nutrient cycling and storage. The levels of nutrients in vegetation, soil, and water may vary based on parent material, surrounding land use, hydrology, the type of wetland, and types of species present. Wetlands can filter excess nutrients from agricultural and urban runoff to a certain extent. High nutrient loads can cause eutrophication and anoxia and affect the biological community and wetland function. High levels of nutrients and disturbance have been correlated with exotic species invasion and decreased diversity. Stable isotopes of nitrogen and carbon have been applied to measure anthropogenic impact, nutrient sources, and denitrification levels. Four studies were completed during the summers of 2011 and 2012 on wetland assessment and nutrient dynamics across the state of North Dakota. The results indicated the importance of land use regarding wetland condition and nutrient levels. Wetlands in cropland tended to have lower floristic quality and biological condition and higher stable isotope ?15N values. Additionally, levels of phosphorus, nitrogen, and carbon differed by plant type with some indication that cattail invasion alters nutrient cycling. Furthermore, classification and regression tree modeling links wetland buffer, soil, and water data to wetland condition.North Dakota Department of Health
North Dakota Water Resources Research Institute
U.S. Environmental Protection Agency (EPA)
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Laufer, Susan Marie. "Nutrient dynamics in the Lake Manassas (Virginia) watershed." Thesis, Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/91040.
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Lake Manassas is a 706-acre public water supply reservoir for the City of Manassas, formed by the impoundment of Broad Run. It is located in western Prince William County at the periphery of the metropolitan Washington, D. c. area. Its watershed drains approximately 46,500 acres of rural land that is expected to undergo rapid development in the next 25 years.
The objective of this study was to provide a comprehensive report of the quality of water in Lake Manassas and its tributary streams, analyzing data that had been collected from October, 1984 through April, 1986, as part of a monitoring program funded by the City of Manassas.
The capacity of Lake Manassas at full pool was determined to be 4.2 billion gallons (15.8 million cubic meters) and its mean depth 25 feet (7.7 meters). The calculated volume was considerably less than had been previously thought. Trophic state indices indicated that Lake Manassas is eutrophic, and water column chemistry suggested phosphorus to be the limiting nutrient. The Vollenweider model was applied to illucidate the relative impacts of South Run and Broad Run on the lake.
While Broad Run contributed the vast majority of flow to the reservoir, higher concentrations of algal nutrients, nitrogen and phosphorus, were transported to the lake by South Run, which receives effluent from the treatment plant at Vint Hill Station, a U.S. Army reservation. Phosphorus loadings from South Run were higher than from Broad Run under baseflow conditions. On an annual basis, stormflow runoff contributed as much as twelve times the tributary baseflow loading of phosphorus.M.S.
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Kessler, Alan Christopher Kessler. "tRNA subcellular dynamics dictates modification and nutrient sensing." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1513786086369393.
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Bezold, Marie Grace. "Sediment nutrient dynamics in Fondriest agricultural settling pond." Wright State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=wright1622555814026793.
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Filho, Romildo Lopes de Oliveira. "Dynamics of phosphorus in mangroves impacted by the state of CearÃ." Universidade Federal do CearÃ, 2012. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=8737.
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Estudos recentes demonstram a eficÃcia do manguezal em reter nutrientes e, em
especial, a capacidade dos componentes minerais do seu solo em tamponar elevados teores
de fÃsforo. Em geral, os solos dos manguezais tÃm sido considerados como importantes
sumidouros de nutrientes devido a sua grande capacidade de depuraÃÃo de efluentes.
Entretanto, dependendo das condiÃÃes geoquÃmicas existentes, esses solos podem funcionar
como fonte de fÃsforo para outros ambientes e/ou para as Ãguas costeiras. Tendo em vista
que o comportamento geoquÃmico do fÃsforo, bem como seu papel na eutrofizaÃÃo dos
corpos d'Ãgua, Ã melhor avaliado atravÃs do comportamento de suas diferentes fraÃÃes, o
presente trabalho visa realizar um fracionamento das diferentes formas de fÃsforo em
manguezais impactados por distintos efluentes. O objetivo da presente dissertaÃÃo à estudar
trÃs Ãreas a fim de se avaliar como as atividades impactantes interferem no processo de
ciclagem de nutrientes (com especial Ãnfase na dinÃmica das formas de fÃsforo) e, como o
manguezal suporta o estresse ocasionado por estas atividades. AlÃm disso, se avaliarà o
potencial de eutrofizaÃÃo de cada uma das atividades antrÃpicas. Levando-se em
consideraÃÃo os impactos que esses ambientes sofrem em consequÃncia de distintas
atividades, foram estabelecidas as seguintes Ãreas de estudo: um manguezal impactado por
efluentes de carcinicultura; um manguezal impactado por efluentes urbanos; e uma Ãrea
controle localizada em uma Ãrea preservada que ainda encontra-se pouco afetada por
impactos antrÃpicos. Nas amostras foram determinados pH, Eh, salinidade, granulometria e
teores totais de C e P. AlÃm disso, foi realizada a extraÃÃo seqÃencial de fÃsforo que
permite a diferenciaÃÃo de 7 fraÃÃes: P trocÃvel (NaCl-P); P associado a Ãxidos de Fe (FeP);
P orgÃnico (AH-P); fÃsforo ligado a hidrÃxidos de Al (Al-P); P associado a compostos
de cÃlcio (Ca-P); fÃsforo associado à matÃria orgÃnica refratÃria (P-RES) e fÃsforo nÃo
reativo (P-NR). Os resultados obtidos indicam que o descarte de efluentes nos manguezais
aumenta a quantidade de fÃsforo nesses ambientes, principalmente nas formas orgÃnicas; o
fÃsforo ligado aos compostos de cÃlcio à a principal fraÃÃo inorgÃnica nesses ambientes.
Palavras-chave: ciclagem de nutrientes; extraÃÃo sequencial; carcinicultura; efluente
domiciliarRecent 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.
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Nielsen, Eric J. "Algal suscession and nutrient dynamics in Elephant Butte Reservoir /." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd741.pdf.
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Segal, Richard Daniel. "Primary production and nutrient dynamics in solar salt ponds." University of Western Australia. School of Water Research, 2006. http://theses.library.uwa.edu.au/adt-WU2006.0053.
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[Truncated abstract. Formulae and special characters in this field can only be approximated. See PDF version for accurate reproduction.] Solar salt producers use solar energy to evaporate seawater as it flows through a series of ponds. The Shark Bay Salt solar ponds, at Useless Inlet in Western Australia, vary in salinity from that of seawater to four times seawater, over the pond sequence. Water column photosynthesis and biomass decreased markedly with increasing salinity along the pond sequence, while benthic productivity increased as cyanobacterial mats developed. Correspondingly, net productivity shifted from autotrophy to heterotrophy in the water column and from heterotrophy to autotrophy in the benthos. Both shifts occurred at intermediate salinity in the pond sequence, where there was low production in both the water column and benthos. Within individual ponds, productivity, algal biomass and physico-chemical conditions were relatively constant over the year of study. Transitions between benthic and planktonic production along the pond sequence were driven mostly by direct responses to salinity stress, as well as the formation of a gypsum crust on the pond floors at higher salinity (>120 g kg-1). This transition is similar to that which occurs in saline lakes undergoing anthropogenic salinisation and identifies critical salinities for the restoration of these lakes.
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Segal, Richard Daniel. "Primary production and nutrient dynamics in solar salt ponds /." Connect to this title, 2005. http://theses.library.uwa.edu.au/adt-WU2006.0053.
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Sagoo, Elizabeth. "Nutrient dynamics and growth at a coppice biofuel site." Thesis, University of Leeds, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417739.
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Mitchell, Mark E. "Nutrient Cycling Dynamics and Succession in Green Roof Ecosystems." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin150487303109878.
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Schofield, Hannah Kate. "A biogeochemical study of nutrient dynamics in artificial soil." Thesis, University of Plymouth, 2015. http://hdl.handle.net/10026.1/3766.
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Artificial soils have been employed within the Biomes of the Eden Project since its construction in 2000. Produced from sand, bark, composted green waste and lignite clay, these soils were designed to have their nutrient concentrations controlled through careful fertiliser applications. However, following variable environmental conditions, management practices and planting, the soils across the site are performing variably with regard to nutrient retention and storage. Experiments were conducted to assess the performances of an artificial soil in terms of nutrient cycling. This was carried out in three phases: Firstly, soils from the Humid Tropics and Outdoor biomes were sampled and examined, using a range of analytical techniques, to determine the nutrient characteristics of the established artificial soils from across the Eden Project site. This demonstrated that many of the nutrient concentrations of the artificial soils were consistent with those reported for naturally formed soils within comparable environments. All soil samples were of sandy loam texture (ISO 14688-1), with the sand-sized fraction representing > 50 % of the particle size composition. Statistical analyses suggested that management practices had a greater impact on the nutrient characteristics of artificial soils than environmental conditions. Secondly, an artificial soil was produced, following the Eden Project protocol, to examine its performance under controlled environmental conditions. This was packed into 4 columns (1 m height by 110 mm diameter), maintained at 15 ˚C and subjected to an irrigation regime for 52 weeks. Following 26 weeks of irrigation, 2 of the 4 columns were fertilised. Leachate was analysed for dissolved constituents as were solid samples of the fresh soil and of soil samples collected from the columns following 52 weeks irrigation. Leachate concentrations for all nutrients, excepting phosphate, were observed to decline over the irrigation period. Leached phosphate concentrations increased from weeks 0 to 2, and then remained relatively constant. Low nitrogen concentrations within the leachate from weeks 2 to 38 were caused by nitrogen immobilisation within the soil, whilst subsequent mineralisation resulted in increased concentrations from Week 38. Analyses of solid phase constituents determined little variation with depth. Fertiliser application demonstrated a significant (p < 0.05) increase in leachate concentrations for some dissolved organic nitrogen and nitrate, phosphate, magnesium and calcium and a decrease in pH. Fertiliser application observations showed less prominent differences for the extracted and solid phase constituents. Thirdly, biochar was applied to the artificial soil at three concentrations (10 %, 5 % and 2 %) plus a control (0 %), to determine whether biochar application may improve nutrient characteristics of artificial soils. The biochar amended soils were packed into mesocosms and maintained at 15 ˚C for 6 weeks. In general, leachate analyses demonstrated a decrease in nutrient losses to leaching with increasing biochar concentration, highlighting the potential for improved nutrient retention within the soils.
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Licamele, Jason David. "Biomass Production and Nutrient Dynamics in an Aquaponics System." Diss., The University of Arizona, 2009. http://hdl.handle.net/10150/193835.
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The goal of this study was to prove that aquaponic systems can produce lettuce of equal growth and quality compared to hydroponic lettuce production and to determine the stocking density of fish required for plant growth. Aquaponics is the integration of recirculating aquaculture and hydroponic plant production. The project had four objectives. The first objective was to determine the biomass of fish required for plant growth to develop a fish to plant density ratio. The second objective was to compare lettuce grown with aquaponic water and a hydroponic solution under the same environmental conditions. The third objective was to compare the quality of lettuce grown with aquaponics water plus nutrient supplementation with a hydroponic solution. The fourth objective was to determine the nitrogen dynamics in the aquaponic system and to compare the nutrient composition of lettuce grown with aquaponics water with nutrient supplementation and hydroponic solution. It was determined that under the specified environmental conditions 5 kg m⁻³ of Nile tilapia (O. niloticus) fed 2% of their body weight daily yields on average 4.7 kg m⁻² of lettuce (L. sativa cv. Rex) in 35 days. There was no significant difference (p ≤ 0.05) in biomass or chlorophyll concentration index in lettuce (L. sativa cv. Rex) grown with aquaponics water and nutrient supplements versus a hydroponic solution. The aquaponics solution generated equal biomass and chlorophyll concentration indexes compared to the hydroponic solution. Aquaponics water plus supplementation can yield L. sativa cv. Rex with equal biomass accumulation and chlorophyll concentration indexes compared to hydroponics lettuce. Nutrients added to the aquaponics system consisted of iron, manganese, and zinc. These nutrient concentrations became depleted in the aquaponics water over time and were not replenished via the fish feed. Dolomite was added to the aquaponics system every two weeks to increase the buffering capacity of the water and maintain optimal pH levels. Aquaponics lettuce had similar nutrient composition to hydroponic lettuce. One head of L. sativa cv. Rex (176.75 ± 31.03) will assimilate approximately 5.96 grams of nitrogen (3.38% per dry gram lettuce). One kilogram of fish will yield 6.4 lettuce heads (1,128 grams) and fixate 38.13 grams of nitrogen.
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Nielsen, Eric J. "Algal Succession and Nutrient Dynamics in Elephant Butte Reservoir." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/280.
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A water quality model was created for Elephant Butte Reservoir, New Mexico to understand nutrient dynamics and algal response during a three year period. The model chosen for this study was CE-QUAL-W2 because of its proven ability to represent hydrodynamics and the ability to represent multiple algal groups. Elephant Butte has been subject to large algal blooms. This study examined the phosphorus loading into the reservoir to see if it could sustain the observed algal growth. Data showed that the amount of bioavailable phosphorus was more than enough to support large blooms. This study also was an initial attempt to model multiple groups of algae that will later be used in other water quality models built and maintained by the US Bureau of Reclamation. Four algal species were modeled; diatoms, dinoflagellates, cyanobacteria and greens. Research into literary values of kinetic parameters for multiple algal species was conducted and the results were compiled in this paper to assist future modeling efforts. Because Elephant Butte was often nitrogen-limited the calibration of algal growth was difficult. Algal growth was very sensitive to the adjustment of kinetic parameters for nitrogen half-saturation, light requirements, growth rates and temperature rate multipliers.
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Lins, Sílvia Rafaela Machado. "Nutrients dynamics in tropical forest fragments located in an area of Atlantic Forest of the state of Alagoas." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/91/91131/tde-17102017-103106/.
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The Northeastern Atlantic Forest of Brazil contains thousands of forest fragments at different stages of regeneration, some recovering from abandoned agricultural fields, while others recovering from chronic disturbances such as fire, logging, and poaching. Some of these fragments kept protected for several reasons: corporate responsibility, compliance with the forest code, preservation of biodiversity, among others. Although these fragments are far from having the same species richness of plant and animal, they can perform important ecosystem services, such as protection of water bodies, reservoir of important nutrients and carbon (C). This is especially important if we consider that there are global initiatives such as REDD + with the objective of assessing secondary forests and forests in recovery process as important C pools. On the other hand, the management and preservation of these fragments depends on a solid knowledge about their structure and nutrient cycle. There is a relatively rich literature on the loss of biodiversity in these Northeastern forest fragments. Much less is available, however, about the structure and function of these fragments. This work intends to contribute to fill this gap, providing solid scientific information on four forest areas and a secondary forest, where a restoration program was implemented in the State of Alagoas, Northeast of Brazil. After a brief introduction, chapter one discusses the structure of these fragments through a complete forest inventory, where individuals density, height and diameter at breast height (DBH) were measured for each tree with DBH >= 10 cm. With these allometric data, we estimated the basal area and aboveground live biomass (AGLB), comparing these attributes with other estimates available in the literature. In chapter two, we investigated the distribution of nutrients in the forest fragments, where we measured the foliar concentration of C, nitrogen (N) and phosphorus (P). At the same time, we measured the litterfall mass in each fragment and its nutrient content for a one year period of sampling. With this information we were able to establish how these areas cycled their main limiting nutrients and C. Finally, in the last chapter we approached the partition of C and nutrient stocks, above and belowground, in order to evaluate the importance of C pools and nutrients in the forest fragments and understand the role of these fragments in a world that urgently needs to store C in a sustainable reservoir.A Floresta Atlântica do Nordeste do Brasil contém milhares de fragmentos de florestas em diferentes estágios de regeneração, alguns se recuperando de campos agrícolas abandonados, enquanto outros se recuperam de distúrbios crônicos como incêndio, extração de madeira e caça furtiva. Alguns desses fragmentos ficaram protegidos por várias razões: responsabilidade corporativa, cumprimento do código florestal, preservação da biodiversidade, entre outros. Embora estes fragmentos estejam longe de ter a mesma riqueza de espécies vegetais e animais, podem desempenhar importantes serviços ecossistêmicos, como proteção de corpos d\'água, reservatório de importantes nutrientes e carbono. Isso é especialmente importante se considerarmos que há iniciativas globais como o REDD+ que visam avaliar florestas secundárias e de recuperação como importantes reservatórios de carbono (C). Por outro lado, a gestão e preservação destes fragmentos dependem de um conhecimento sólido sobre a sua estrutura e ciclo de nutrientes. Há uma literatura relativamente rica sobre a perda de biodiversidade nestes fragmentos florestais do Nordeste. No entanto, muito menos está disponível sobre a estrutura e o funcionamento destes fragmentos. Este trabalho pretende contribuir para o preenchimento desta lacuna, fornecendo informações científicas sólidas sobre quatro áreas florestais e uma floresta secundária, onde foi implantado um programa de restauração no Estado de Alagoas, Nordeste do Brasil. Após uma breve introdução, o capítulo um discute a estrutura desses fragmentos através de um inventário florestal completo, onde a densidade indivíduos, sua altura e diâmetro à altura do peito (DAP) foram medidos para cada árvore com DAP >= 10 cm. Com esses dados alométricos, estimamos a área basal e a biomassa viva acima do solo (AGLB), comparando esses atributos com outras estimativas disponíveis na literatura. No capítulo dois, investigamos a distribuição de nutrientes nos fragmentos florestais, onde medimos a concentração foliar de C, nitrogênio (N) e fósforo (P). Ao mesmo tempo, medimos durante um ano a massa da serapilheira em cada fragmento e seu teor de nutrientes. Com essas informações pudemos estabelecer como essas áreas ciclam seus principais nutrientes limitantes e C. Finalmente, no último capítulo abordamos a partição dos estoques de C e nutrientes, acima e abaixo do solo, com o objetivo de avaliar a importância dos pools de C e nutrientes nos fragmentos de floresta e entender qual o papel desses fragmentos em um mundo que necessita urgentemente estocar C em um reservatório sustentável.
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Oliveira, Silas Maciel de. "Nutrients dynamics in corn-Brachiaria intercropping systems." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/11/11136/tde-10052018-171143/.
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Corn (Zea mays L.) intercropped with Brachiaria spp. plays an important role in tropical agriculture management, providing residues or forage to areas intensively cropped. Although previous studies provide useful information about effects of intercropping on soil management and crop yield, a better understanding of how corn-Brachiaria intercropping systems impacts exogenous and endogenous nutrient dynamic is needed. Two experiments were performed in the both conventional and late planting season. In the first, corn and palisadegrass (Brachiaria brizantha cv. Marandu) monoculture were compared with two intercropping patterns, directed for production of residues or forage, with simulated animal grazing. Biomass, crop nitrogen (N) content, N derived from fertilizer and N budget were measured. Among farming systems, variable responses remained almost unchanged during period of simultaneous growth. After corn harvest, intercropping patterns achieved greater biomass (0.6-11 Mg ha-1) and N content (12-318 kg ha-1) relative to fallow preceded by corn monoculture, but it results in overall gains (pre and post-harvest) only to conventional planting season. N fertilizer recovery was not affected by intercropping patterns. When corn and Brachiaria were intercropped to establish pasture, simulated grazing after grain harvest had a tightly influence on N budget, approximately -221 kg ha-1. The second experiment investigated the influence of Brachiaria species on corn nutrients partitioning and their cycling after corn harvest. Biomass, N, phosphorus (P) and potassium (K) content were evaluated using corn intercropped with three species of Brachiaria (B. Brizantha cv Marandu, B. ruziziensis, and B. hybrid cultivar Mulato II, Convert HD 36) and corn monoculture. Biomass and nutrient content was not affect when corn was intercropped with Brachiaria species. After corn harvest, Brachiaria nutrient content and biomass yield were ranking from greater to lower following the order: B. brizantha > B. ruziziensis > B. convert. Relative with the corn monoculture, intercropping treatments enhanced the total biomass (corn + Brachiaria) and the nutrient accumulation only when planted at conventional season. Over 6 site-yr, benefits of intercropping appear after corn harvest, particularly at conventional planting season. Corn intercropped with Brachiaria species either had no effect N fertilizer recovery or affect N-fertilizer distribution within components of soil-plant system. Nonetheless, intercropping provide greater biomass accumulation after harvest compared with corn monoculture, resulting in larger nutrient content stored in plant component. Our results suggest a larger N requirements when crop-livestock activities was integrated. Corn intercropped with B. brizantha during conventional season was the best approach to enhanced crop yield and nutrient cycle for corn production systems.O consórcio entre milho (Zea mays L) e espécies de Brachiaria spp. (syn. Urochloa spp.) desempenha importante função no manejo da agricultura tropical, produzir resíduos ou forragem em áreas intensivamente cultivadas. Apesar de estudos anteriores fornecerem valiosas informações sobre efeitos do consórcio sobre o manejo do solo e produção de biomassa, um melhor entendimento de como este sistema de cultivo afeta a dinâmica de nutrientes (exógenos ou endógeno) é necessário. Dois experimentos foram conduzidos durante a safra e segunda safra. No primeiro, os monocultivos de milho e braquiária (Brachiaria brizantha cv. Marandu) foram comparados com dois padrões de consórcio, direcionado a produção de resíduos ou forragem, com simulação do pastejo animal. Biomassa, acúmulo de nitrogênio (N), N- fertilizante e balanço de N foram avaliados. As variáveis respostas praticamente não foram afetadas pelos sistemas de cultivos durante o período de coexistência. Após a colheita do milho, os sistemas consórciados acumularam mais biomassa (0,6 -11 Mg ha-1) e N (12-318 kg ha-1) comparado ao pousio precedido pelo monocultivo de milho, apesar destes incrementos afetarem apenas o acúmulos totais (pré+pós-colheita) do cultivo de safra. A recuperação do N-fertilizante foi semelhante entre os sitemas de cultivo. Quando o consórcio objetivou a implantação de pasto, o pastejo simulado após a colheita do milho influênciou o balanço de N, com deficit de aproximadamente -221 kg ha-1.O segundo experimento foi conduzido para investigar a influência das espécies de Brachiaria sobre o particionamento de nutrientes no milho e a ciclagem pós-colheita de grãos. Produção de biomassa, quantidades de N, fósforo (P) e postássio (K) acumuladas foram avaliadas no monocultivo de milho e em três espécies de Brachiaria spp. (B. Brizantha cv Marandu, B. ruziziensis, and B. hibrido cultivar Mulato II, Convert HD 36) em consórcio com milho. Biomassa e acúmulo de nutrientes não foram afetados no consórcio do milho com as espécies de Brachiaria. Após a colheita do milho, o acúmulo de biomassa e nutrientes das espéceis de braquiária classificadas em ordem decrescente foram: B. brizantha > B. ruziziensis > B. convert. Comparado ao monocultivo de milho, o consórcio aumentou a biomassa total (milho+braquiária) e o acúmulo de nutrientes apenas quando cultivado na safra. Entre os 6 locais/anos, os benefícios do consórcio ocorreu após acolheita do milho, especialmente para o cultivo de safra. O milho consorciado com espécies de Brachiaria não afetou a recuperação do N-fertilizante nem sua distribuição nos componentes do sistema solo-planta. Entretanto, o consórcio proporcionou maior acúmulo de biomassa após a colheita do milho se comparado ao pousio precedido pelo monocultivo de milho, aumentando a porção de nutrientes alocados no compartimento planta do sistema. Nossos resultados sugerem que a integração entre atividades de lavoura e pastejo aumenta a demanda por N do sistema de produção. O consórcio entre milho e Brachiaria brizantha cv Marandu no cultivo de safra foi a melhor estratégia para aumentar a produção de biomassa e a ciclagem de nutrientes no sistema de produção do milho.
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Klein, Lawrence S. "An Ecosystem Dynamics Model of Monterey Bay, California." Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/KleinLS2002.pdf.
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Prior, Hannah. "Total nitrogen and total phosphorus cycling in riparian ecosystems." Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285963.
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Scott, J. Thad Doyle Robert D. "Periphyton-nutrient dynamics in a gradient-dominated freshwater marsh ecosystem." Waco, Tex. : Baylor University, 2006. http://hdl.handle.net/2104/5036.
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Obermann, Matthias [Verfasser]. "Nutrient dynamics in temporary waters of Mediterranean catchments / Matthias Obermann." Hannover : Technische Informationsbibliothek (TIB), 2007. http://d-nb.info/122946073X/34.
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Weatherall, Andrew. "Use of stable isotopes to study nutrient dynamics in forests." Thesis, University of Aberdeen, 2005. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU203229.
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This study examined the contribution that nutrients released from decomposing brash (branches and needles) left on restock sites make to the growth of new trees. Stable isotope techniques were developed to trace the movement of nitrogen, potassium, magnesium and calcium within trees and from brash to new trees. Sitka spruce (Picea sitchensis (Bong.) Carr.) seedlings were labelled with 15N, 41K, 26Mg and 44Ca in either a generous or poor supply for one growing season. One group of these seedlings was provided with an unlabelled generous or poor nutrient supply for the following season. By varying the amount of nutrient supplied, the internal cycling of K and Mg, like N, was shown to be independent of current uptake. A second group of seedlings was harvested after labelling and used to stimulate brash in a model system. Nutrients released from the brash were traced into newly planted seedling trees during the next growing season. The contribution from decomposing roots was also estimated using this system. This approach is not financially viable in the forest because of the cation isotope cost. An attempt was made to predict K and Ca uptake using rubidium and strontium as surrogates. However, direct comparison of isotypically measured uptakes, indicated only a weak relationship. Instead, fieldwork concentrated on N dynamics. Brash generated from 5-year-old Sitka spruce after stem injection of 15N was used to replace brash from 50-year-old Sitka spruce on a clearfell site. Implications for management decisions during the restocking of Sitka spruce plantations in Britain are discussed.
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Albertin, Andrea Ruth. "Nutrient dynamics in Florida springs and relationships to algal blooms." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0024853.
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Bartels, Kim [Verfasser]. "Conformational dynamics and substrate specificity in nutrient transporters / Kim Bartels." Hamburg : Staats- und Universitätsbibliothek Hamburg Carl von Ossietzky, 2020. http://d-nb.info/122504197X/34.
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Harre, Nick T. "Dynamics of Early-Season Weed Management and Soybean Nutrition." OpenSIUC, 2014. https://opensiuc.lib.siu.edu/theses/1422.
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The popularity of growers using only postemergence (POST) herbicides for weed management in soybean was enabled by the commercialization of glyphosate-resistant soybean. The efficacy and flexibility provided by this technology diminished the use of soil residual herbicides and arguably, increased soybean yield loss from early-season weed competition. While, the rapid evolution and biogeographical spread of herbicide-resistant weeds, especially glyphosate-resistant biotypes, has renewed interest into the use of soil residual products, herbicide-resistant soybean technologies continue to be developed that may once again entice growers into POST-only weed management systems. The commercial interest in soybean yield advancements justifies further characterizing the benefits provided by early-season weed control beyond those of herbicide-resistance management. Furthermore, as awareness heightens regarding techniques that will enhance the sustainability of agro-ecosystems, specific focus on resource utilization will help to evaluate the viability of this weed management strategy. Field experiments were conducted across four sites throughout southern Illinois in 2012 and 2013 to study the influence of early-season weed management strategies on soybean nutrient accumulation, grain yield parameters, and the acquisition of nutrients by broadleaved and grass weeds. Increasing periods of weed competition duration were established by removing weeds at heights of 10, 20, 30 or 45 cm with glyphosate. A weed-free treatment utilizing a comprehensive soil residual and POST herbicide program was included to implement a weed-free comparison. Two standard herbicide management strategies that simulate common grower practices were also evaluated for comparison: flumioxazin PRE followed by glyphosate POST and two sequential POST glyphosate applications. Averaged across all 11 mineral nutrients analyzed in this experiment, broadleaved weeds accumulated 149 and 108% more nutrients than grasses in 2012 and 2013, respectively. Competition from 20-cm weeds reduced the acquisition of N, P, Ca, Mg, S, Fe, B, Cu, and Zn by soybean in 2012; these nutrients in addition to K and Mn were reduced by the same level of competition in 2013. N and Fe were the nutrients in soybean most notably impacted by weed interference. Reductions in soybean grain yield were the result of competition with 30-cm weeds in 2012, and 10-cm weeds in 2013; while, both standard herbicide regimens yielded less than the weed-free treatment in 2013 only. Additionally in 2013, average soybean seed weight and grain oil content was reduced when weeds were not removed before a height of 10 and 20 cm, respectively. The rate of decomposition and nutrient release was measured for waterhemp and giant foxtail desiccated by glyphosate at heights of 10, 20, 30, and 45 cm in two southern Illinois soybean fields. Weed biomass was grown under greenhouse conditions to ensure homogeneity and litterbag methodology was utilized to track in situ mass and nutrient losses, expressed as a decay constant (k) regressed over time according to the single exponential decay model. The effect of specie and height both had a strong influence on the intrinsic properties of the weed biomass and the associated rate of decay. Concentrations of the recalcitrant cell wall components (cellulose, hemicellulose, and lignin) were generally greatest as weed height (plant age and development) increased and with giant foxtail compared with waterhemp. Ca, Mg, and S concentrations were greater in waterhemp, while N was greater in giant foxtail. N and K concentrations decreased with increasing weed height. After 16 weeks, 10-cm waterhemp and giant foxtail detritus had lost 10 and 12% more mass compared to the 45-cm height. Decomposition rates revealed mass loss was highest for 10-cm waterhemp (kD = 0.022) and lowest for 45-cm giant foxtail (kD = 0.011) and this process was negatively correlated to the overall amount of cell wall constituents (r = -0.73). Nutrient release rates followed a similar trend in that shorter (younger) weeds and waterhemp liberated nutrients more readily. Across all tested plant material, K was the nutrient most rapidly released, whereas, Ca was the most strongly retained nutrient. Although the pressing challenge of managing herbicide-resistant weeds justifies the implementation of early-season weed control tactics, this research suggests there are ancillary benefits that are provided by this strategy. The use of a robust, broad-spectrum soil residual herbicide program in conjunction with timely POST applications provides the foundation for early-season weed management, thereby minimizing non-crop nutrient use and enhancing the nutrient acquisition capacity in soybean. This strategy facilitates more sustainable crop production by requiring fewer supplemental nutritional inputs while also protecting grain yield.
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Lakish, Benjamin. "Nutrients and chlorophyll dynamics in Fort Cobb Reservoir." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4956.
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Thesis (M.S.)--University of Missouri-Columbia, 2007.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 31, 2008) Includes bibliographical references.
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Malik, Vikram Singh. "Growth and nutrient dynamics of nutrient-loaded black spruce seedlings in relation to neighbouring vegetation on boreal mixedwood sites." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq41467.pdf.
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Villalobos-Vega, Randol. "Water Table and Nutrient Dynamics in Neotropical Savannas and Wetland Ecosystems." Scholarly Repository, 2010. http://scholarlyrepository.miami.edu/oa_dissertations/389.
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The Tropical savannas of central Brazil (cerrado) and the Everglades wetland (Florida) ecosystems are ideal systems to study landscape spatial mosaics and their interactions. Both ecosystems show a variety of plant physiognomies distributed within small spatial scales and elevation gradients. Such variety of plant physiognomies provide an opportunity to investigate the roles of climate, topography, nutrient availability and water table dynamics as determinants of plant physiognomic distributions, and their role in shaping regional systems. South Florida Wetlands and the tropical savannas of central Brazil are examples of hydrologically-controlled ecosystems. In hydrologically-controlled ecosystems water sources, the availability of nutrients, and the patterns of water movement play important roles in determining vegetation structure and function. The main objective of this study was to understand ecosystem level processes that shape different physiognomies in two hydrologically-controlled ecosystems. I conducted field work at the IBGE ecological reserve, a field experimental station located in Brasilia, Brazil. I also worked at the Everglades National Park in an area located near the south entrance of the Park in Homestead, Florida. I carried out three interconnected studies investigating water and nutrient dynamics: (1) In a Brazilian savanna I manipulated levels of litter input and measured changes to soil properties, organic matter decomposition and tree growth. I found that changes in litter input affect soil physicochemical properties and soil biochemical processes. I also found that litter dynamics influence tree growth through their effects on soil physicochemical properties. (2) I also studied the effect of water table depth and its temporal variation on spatial patterns of vegetation distribution in the cerrado landscape. I monitored diurnal and seasonal changes in water table depth along two tree-density and topographic gradients. In addition, I measured woody species composition, growth rates of four tree species, litter production, soil nutrients, and nutrient resorption efficiency along those two gradients. I found that water table depth has an important role in determining the spatial distribution of cerrado physiognomies; it also affects tree growth, species composition and nutrient resorption efficiency. (3) In the Everglades I studied patterns of underground water uptake by two vegetation types. I monitored seasonal and diurnal changes in water table depth in a Hammock forest, in a stand dominated by the invasive woody species Schinus terebinthifolius, as well as the water level in an adjacent lake. I estimated stand level transpiration using two different approaches: with sap flow measurements and diurnal oscillations in water table levels. Then, I calculated the total quantity of groundwater withdrawn by evapotranspiration for the wet and dry seasons in the Hammocks and in the exotic invaded site and then compared the results. I found that water uptake by Everglades trees is well coupled to diurnal changes in water table depth and that the amount of water withdrawn from the groundwater was larger during the wet season than during the dry season. Finally, I detected hydrological feedbacks between different vegetation types and nearby bodies of water. Results of this study contributes to the current knowledge of ecosystem level processes in tropical and subtropical ecosystems where water circulation and water availability play a dominant role in shaping vegetation structure and function.
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Walker, Carolyn Faye, and n/a. "Nutrient dynamics during winter convection in the North Atlantic Subtropical Gyre." University of Otago. Department of Chemistry, 2009. http://adt.otago.ac.nz./public/adt-NZDU20090825.142702.
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Storm-induced open-ocean convective mixing is one of the primary processes controlling the supply of nitrate to the sunlit layer of the oligotrophic North Atlantic Subtropical Gyre (NASG). Yet, the magnitude and timing of nitrate fluxes during winter convection is poorly understood due to an absence of targeted process studies. In the northwest NASG, multiple quasi-Lagrangian studies were conducted during the boreal winters of 2004 and 2005 in an effort to sample strong winter convection. During each of the time-series studies, inventories of vertically fluxed nitrate were quantified approximately every twelve hours using the distribution of helium isotopes ([delta]�He) and nitrate in the water column. This method is known as the Helium Flux Gauge Technique (HFGT).
Large variability in surface forcing and density structure of the upper ocean was observed between the two years; however, only winter 2005 experienced convective mixing to depths greater than 150 m. In winter 2004, mild atmospheric conditions coincided with a positive phase in the winter North Atlantic Oscillation (NAO), consistent with the dominant regime experienced during the previous decade. On average 36 � 9 mmol m[-2] of fluxed nitrate was inferred by excess �He in the mixed layer of the ocean during the winter 2004 study period. This inventory of physically transported nitrate is attributed to the sampling of waters laterally advected from nearby eddy features. The sampling of multiple water masses is likely due to the inability of the drogue to persistently follow water masses efficiently. Although physical evidence indicates spatial variability within the time-series data, the length scales of convective mixing appear to be greater than those associated with spatial aliasing as a result of drogue performance. This observation provides us with increased confidence that the objectives for the present study are not compromised by spatial variability in the data.
In contrast, winter 2005 experienced a negative NAO, strong physical forcing and convective mixing to depths > 250 m. Two convectively modified water masses, most likely resulting from a single storm event, were sampled at different stages of development. These two water masses exhibit large variability in the magnitude of nitrate entrained in the convective layer from the thermocline. An average inventory of 247 � 56 mmol NO₃[-]m[-2] was entrained in the rapidly expanding convective layer of the first water mass in the first few days following the storm approach. In contrast, ongoing entrainment of nitrate was absent from the second water mass, sampled two weeks later when the depth of the surface mixed layer was consistently ~ 300 m. These results indicate that surrounding fluid is entrained into the convective layer when it is actively expanding in the vertical. On the other hand, significant fluid entrainment does not occur at the base of the plume once sinking waters have reached a level of neutral buoyancy. The persistence of elevated nitrate stocks (~ 100 mmol m[-2]) in the convective layer two to three weeks after the inferred injection event, suggests sub-optimal nitrate uptake by resident phytoplankton. Phytoplankton growth was most likely resource limited by light or a micronutrient such as iron. Despite the implied biolimitation, changes in chlorophyll-a, a proxy for phytoplankton biomass, indicate net production within the convective layer. On average, the convective layer was observed to support an inventory of 62 � 6mg chlorophyll-a m[-2], increasing at an average rate of 3.4mg m[-2] d[-1]. This inventory indicates a slow build-up of phytoplankton biomass to near bloom levels, ahead of the main spring bloom that typically follows formation of the seasonal thermocline near Bermuda. Net production in the convective layer was likely due to transient periods of increased (weak) surface stability that were observed to support high phytoplankton biomass, following the cessation of thermocline fluid entrainment.
When nitrate and excess �He in samples collected from the thermocline were regressed for the purpose of quantifying nitrate fluxes, the results showed that between 1.6 - 2.0 [mu]mol kg[-1] of dissolved nitrate was present during formation of the water mass. This suggests the source of this excess (above Redfield ratios) nitrate in the thermocline of the NASG is not local, and has ramifications for local nitrogen fixation budgets determined using geochemical approaches.
Thesis supervisors: William J. Jenkins, Senior Scientist, WHOI (United States of America); Philip W. Boyd, Senior Scientist, NIWA (New Zealand); Michael W. Lomas, Senior Scientist, BIOS (Bermuda)
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Wade, Jordon. "Soil Health and Nutrient Dynamics in Agroecosystems of the Midwestern US." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555334900543422.
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Lindsey-Robbins, Josephine C. "Effects of Detritivores on Nutrient Dynamics and Corn Biomass in Agroecosystems." Bowling Green State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1561588059374285.
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Nakata(Kobayashi), Shiho. "Density-driven circulation and nutrient dynamics in the Seto Inland Sea." Kyoto University, 2008. http://hdl.handle.net/2433/124016.
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Kyoto University (京都大学)0048
新制・論文博士
博士(農学)
乙第12254号
論農博第2690号
新制||農||963(附属図書館)
学位論文||H20||N4409(農学部図書室)
UT51-2008-L179
京都大学大学院農学研究科応用生物科学専攻
(主査)教授 藤原 建紀, 教授 山下 洋, 教授 白山 義久
学位規則第4条第2項該当
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Beckert, Kristen A. "Watershed land use and nutrient dynamics in Maryland Coastal Bays, U.S.A." College Park, Md.: University of Maryland, 2008. http://hdl.handle.net/1903/8966.
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Thesis (M.S.) -- University of Maryland, College Park, 2008.Thesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Herbert, Rachel Rosemarie. "Vegetation and nutrient dynamics of forested riparian wetlands in agricultural settings." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2547.
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Thesis (M.S.) -- University of Maryland, College Park, 2005.Thesis research directed by: Marine, Estuarine, Environmental Sciences Graduate Program . Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Kraus, Tamara Esther Caroline. "Tannins and nutrient dynamics in forest soils : plant-litter-soil interactions /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2002. http://uclibs.org/PID/11984.
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