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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
541

Bodenfruchtbarkeit im Öko-Betrieb: Untersuchungsmethoden

Kolbe, Hartmut, Schuster, Martina January 2011 (has links)
Die Broschüre gibt einen Überblick zu Methoden, mit denen die Bodenfruchtbarkeit von Ackerflächen bewertet werden kann, sowie Hinweise zu deren Anwendung. Dazu gehören unter anderem die Spatendiagnose, Bodenuntersuchungen und Nährstoffbilanzierungen.
542

Análise do histórico de impactos antrópicos em reservatórios do estado de São Paulo com base nos estoques de metais, pigmentos e nutrientes em sedimento /

Mizael, Juliana de Oliveira Soares Silva January 2019 (has links)
Orientador: Viviane Moschini Carlos / Resumo: Por meio de uma abordagem paleolimnológica este projeto teve o intuito de 1) estabelecer valores de referência para os metais Cu, Cr, Ni, Pb, Zn, Mn, Fe e Al; 2) investigar a qualidade dos sedimentos dos reservatórios através do histórico de acumulação desses metais, da geocronologia com 210Pb e do fator enriquecimento; 3) quantificar as concentrações de nutrientes fósforo total (PT) e nitrogênio total (NT), matéria orgânica (MO) e pigmentos fotossintetizantes (clorofila-a , luteína , zeaxantina , fucoxantina e betacaroteno) nos testemunhos sedimentares localizados na área da barragem de sete reservatórios do estado de São Paulo (Broa , Barra Bonita , Salto Grande , Itupararanga, Igaratá , Rio Grande e Atibainha). Foram estabelecidas condições de referências para todos os metais e os índices ecológicos não apresentaram sinais de contaminação antrópica significativos. Somente o reservatório Rio Grande apresentou aumento para metais associados direta (Mn) e indiretamente (Cu) ao lançamento de efluentes e aplicação de sulfato de cobre no tratamento de água. Os teores de matéria orgânica indicaram predomínio da fração orgânica (> 10%) para todos os reservatórios. Observou-se variabilidade das concentrações de pigmentos e nutrientes no perfil sedimentar em todos os reservatórios, evidenciando o aumento e maior presença dos pigmentos nas camadas superficiais. Os aumentos ao longo do tempo nos teores de pigmentos estiveram provavelmente associados às atividades antrópicas. A análise... (Resumo completo, clicar acesso eletrônico abaixo) / Doutor
543

INVASIVE SPECIES AND PANNE ECOSYSTEMS: THE EFFECTS OF ATMOSPHERIC POLLUTION

Nazareth, Cheryl 10 April 2008 (has links)
Pannes are rare intradunal wetlands. Though small, they are known to exhibit extremely diverse and sensitive vegetation and are home to a number of reptile and amphibian species. In the United States, pannes are known to occur only around the Great Lakes Basin and Cape Cod. At Indiana Dunes National Lakeshore, the fifteen known pannes have an unusually large variety of plant species for such a small geographic area and provide habitat for plant species found nowhere else in Indiana. However, these sensitive ecosystems have been exposed to over a century of atmospheric pollutants from the surrounding steel and coal industries. Since 1986, the native vegetation of the area is slowly being replaced by invasive species like Phragmites australis and Typha spp. This study attempts to explain the shift in vegetation. Pannes in two other locations, at a distance from the industrial complex, were used as control sites as they were not expected to be exposed to the same levels of heavy metal concentrations. Four of the fifteen pannes at the Indiana Dunes National Lakeshore, two of the four pannes at Sleeping Bear Dunes National Lakeshore, Michigan, and two of the three pannes at Warren Dunes State Park, Michigan, were studied, resulting in a total of eight pannes. The pannnes were stratified and sampled by hydroperiod. Surface soil samples and sediments at depth, were recovered from each of the pannes considered in this study and analyzed for heavy metal, phosphorus, carbon and nitrogen content. Results show that high levels of organic matter coupled with high nutrients and high metals, in the soil, are a combination that may be considered a risk factor for future invasion of pannes by invasive species. It appears to be difficult for the native vegetation to deal with the high metals and high nutrients which are deleterious to the native vegetation and facilitate establishment of invasive vegetation which is more tolerant to the altered geochemical conditions.
544

SOIL WATER AND NUTRIENT MANAGEMENT FOR IMPROVING SORGHUM PERFORMANCE IN DRYLAND AREAS OF TANZANIA / タンザニア乾燥地におけるソルガム生産向上を目指した土壌養水分管理の確立

Mahinda, Athuman Juma 23 January 2020 (has links)
京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第22163号 / 農博第2377号 / 新制||農||1074(附属図書館) / 学位論文||R2||N5243(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 舟川 晋也, 教授 縄田 栄治, 准教授 真常 仁志 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM
545

Influence of Land Cover, Stream Discharge, and Waste Water Effluent on Suspended Sediment and Nutrient Concentrations in Southwest Ohio Streams

Spahr, Rachel Elizabeth 01 July 2019 (has links)
No description available.
546

Implication Of Inorganic Nitrogen And Phosphorous Species As A Cause Of A Harmful Algal Bloom Event In Caesar Creek Lake, Ohio And Its Tributaries

Foskuhl, Baxter Jeffrey January 2019 (has links)
No description available.
547

Bacterial Community Succession during Soil and Ecosystem Development

Ganapathi Shanmugam, Shankar 11 May 2013 (has links)
Organism succession during ecosystem development has been well studied for aboveground plant communities while the associated pattern of change in microbial communities remains largely unknown. A study was conducted along developmental sand-dune chronosequences bordering Lake Michigan at Wilderness State Park and Altamaha river valley of southeast Georgia with the hypothesis that soil bacterial communities will follow a pattern of change that is associated with soil, plant, and ecosystem development. This study site included 5 replicate sites along 14 dunes ranging in age from 105 to 500,000 years since deposition. The microbial composition and diversity in the soil was studied using bacterial tag-encoded FLX amplicon pyrosequencing of the 16S rRNA gene. As hypothesized, Bray-Curtis ordination indicated that bacterial community assembly changed along the developmental gradient at both sites. However, there was no seasonal effect at Michigan sites despite likely differences in plant carbon inputs. At the Michigan site, soil Ca, Mg levels and pH showed a significant log-linear correlation with soil development (r = 0.83, 0.84 and 0.81, respectively). Bacterial diversity represented by Simpson’s reciprocal index (Simpson’s 1/D) showed a steady decline from the youngest to the oldest dunes with the largest decline (212 to 58) during the initial stages of soil development (105 to 450 years). The change in plant species abundance was higher in the youngest sites than the older sites. This change was significantly correlated with the change in microbial community distribution (p < 0.0001; r = 0.56). Similarly, at Georgia sites, soil development showed significant log-linear correlation with soil base cations (Ca and Mg) (r = 0.93and 0.95). However, diversity indices and PLFA failed to show any particular change in trend across the developing chronosequences. When the results from both sites were used to study bacterial spatial patterns, local geochemical features were found to be a dominant factor in driving bacterial community structure, while geographic distance as a single factor could contribute to some community variation at a scale (50 – 1700 km). The results suggest that soil nutrients and plant community could be a strong driving force in shaping microbial community assembly across a developing soil ecosystem.
548

The Ecological Significance of Phyllosphere Leaf Traits on Throughfall Hydrology, Biogeochemistry, and Leaf Litter Quality among Oak (Quercus Spp.) Species in the Southeastern United States

Limpert, Katy Elizabeth 12 August 2016 (has links)
Oaks (Quercus spp.) are a dominant genus in forests across the United States that have been declining due to fire suppression and forest mesophication. The reduction of these species may alter forest hydrologic and biogeochemical cycling. Canopy-derived nutrients and interspecific temporal distribution of leaves were quantified under oak and hickory (Carya spp.) species in Mississippi during 2014-2016. Throughfall quantity and chemistry were measured during every storm event under oak and hickory species. Interspecific leaf litter was collected weekly to quantify the timing of leaf fall and leaf litter nutrient content. Throughfall volume and solute fluxes were impacted by seasonality. Mg2+ and DOC were greater in throughfall than precipitation. Leaf loss was slower in oak species during leaf fall. Slower decay in oak litter may correlate with higher C/N ratios compared to hickory species. Results of this study indicate oak species are an important contributor to forest hydrology and nutrient cycling.
549

Urban Flow-Through Facilities' Media Compositions for Stormwater Quality and Quantity Improvements

Overbey, Emily Gwynne 14 December 2013 (has links)
Urban stormwater management is evolving toward sustainable approaches which rely on dispersed small-scale bioretention BMPs. One such BMP is the flow-through planter, commonly applied in areas where infiltration into in situ soil is restricted or not possible. A project was developed to evaluate 18, vertically scaled flow-through mesocosms. Three replicates of six treatments, including four soil mixtures containing varied percentages of sand, compost and topsoil, were tested for orthophosphate and nitrate removal, volume reduction capabilities, and peak flow attenuation through the application of a synthetic solution over a simulated 2-inch, Type II storm event. Runoff volume was significantly (p < 0.05) reduced compared to controls. Nutrient levels observed along the hydrograph at different time-steps and flow rates revealed patterns not apparent in cumulative results. The observation of preferential flow patterns along with variability in nutrient removal across treatments highlights the need for design modifications of flow-through facilities.
550

Size variation of planktonic diatoms on glacial-interglacial time scales in the sediment record of Lake El'gygytgyn, north-east Russia

Phillips, Katie Lynn 26 August 2013 (has links)
No description available.

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