Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 24 for “"Dissolved nitrogen"”.
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THE STUDY OF THE DISSOLVED NITROGEN CONTAINING MACROMOLECULES IN THE MARINE ENVIRONMENT
… developed for the direct determination of the dissolved combined amino acid (DCAA) content of seawater involving the acid hydrolysis of seawater under specified conditions, followed by the determination of the amino acids by reverse phase liquid chromatography (RPLC). No preconcentration or …
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Titanium dioxide dielectric layers made by anodization of titanium: the effect of dissolved nitrogen and oxygen
… and properties of TiO2formed by anodization of nitrogen-and-oxygen-infused Ti substrates for electrolyticcapacitors. The controllable parameters of the diffusion process and the anodizationwere studied to evaluate the effect of nitrogen and oxygen dissolved in the Ti substrateon the formation of …
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Modeling nitrogen transport with the ANSWERS model
… has been identified as the primary source of nitrogen and sediment, and a significant source of phosphorus in the Chesapeake Bay. These pollutants, whether from point or nonpoint sources, have been found to be the primary cause of declining water quality in the Bay. Numerous studies have …
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The fate of anthropogenic nitrogen in a redox stratified pond: an isotopic approach
… biogeochemical effects accompanying increased nitrogen pollution. Cape Cod is home to roughly 1,000 ponds and lakes which play an important role in local ecosystems, but the cycling of nitrogen in these waters is not well understood. The goal of this research is to identify the major …
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Comparison of Water Quality, Rainbow Trout Production, and Economics in Oxygenated and Aerated Raceways
… State Fish Hatchery (WSFH) for 270 days. Mean dissolved oxygen (DO) concentrations and delta DO were significantly higher (P < 0.001) in the oxygenated raceways (9.5 and 2.75 mg/L, respectively) compared to aerated raceways (7.4 and 0.57 mg/L). Total settleable solids loads were significantly …
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Carbon and Nitrogen Dynamics in High Intensity Minimal Exchange Shrimp (<i>Litopenaeus vannamei</i>) Raceways
… 2 density treatments, (2) construct carbon and nitrogen budgets to see where the carbon and nitrogen went in the system for all growouts, (3) determine if plastic media had any effects on water quality parameters and shrimp production, (4) determine if plastic media allowed for a nitrifying …
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Reservoir Management Techniques to Enhance Biological Productivity and Protect Water Quality
… seasonally with water temperature and initial dissolved nutrient concentrations. Few interannual effects from whole-lake manipulation were observed in the treatment lakes due to the `pulse' nature of nutrient additions. However, the short-term data revealed increased concentrations of total …
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A computer model for circular and linear bubble plumes
… method. Knowledge of ambient temperature, dissolved solids, dissolved oxygen, and dissolved nitrogen profiles as well as gas input rate, diffuser dimensions, and initial bubble size are required to implement the models. The implementation of the circular model was successful as the results …
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Factors Affecting Phytoplankton Biodiversity and Toxin Production
… analyzed for pH, electrical conductivity, total dissolved solids, dissolved oxygen, alkalinity, chlorophyll–a, total phosphorous, phosphate, total dissolved phosphorous, dissolved organic and inorganic phosphorous, particulate phosphorous, total nitrogen, total dissolved nitrogen, dissolved …
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Evolution of chemical composition along river drainage networks
… in the Bagmati were extraordinarily high for nitrogen and phosphorus, and both nutrients and major ions were found in proportions similar to those in raw domestic sewage. The contribution of chemical weathering processes to water quality of the Bagmati does not seem to be significant within …
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NUTRIENT RETENTION BY RIPARIAN FORESTED BUFFERS IN WESTERN MARYLAND: DO THEY WORK AND ARE THEY WORTH IT?
… riparian buffer’s nutrient removal function of dissolved nitrogen and phosphorus in the R&V to understand the hydrologic controls further. Throughout western Maryland, we conducted two synoptic stream chemistry studies that contained forest buffers planted under CREP and a range of pre-existing …
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On-shelf nutrient trapping enhances the fertility of the southern Benguela upwelling system
… continental shelf. We present the first nitrate nitrogen (N) and oxygen (O) isotope data (δ15N and δ18O, respectively) from the SBUS, generated for samples collected along four hydrographic lines in February (summer) and May (early winter) of 2017. During summer upwelling, a decrease in nitrate δ …
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Constructed Floodplain Wetland Effectiveness for Stormwater Management
… 73% total suspended solids (TSS), 54% ammonia-nitrogen (NH3-N), 16% nitrate-N (NO3-N), 16% total nitrogen (TN), 23% orthophosphate-phosphorus (PO4-P), and 37% total P (TP) in the fall, and 69% TSS, 58% NH3-N, 7% NO3-N, 22% TN, 8% PO4-P, and 25% TP in the spring. Linear regression of mass flux …
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Land Cover Influences on Stream Nitrogen Dynamics During Storms
… on the effects of land cover influence on stream nitrogen have focused on base flow conditions or were conducted specifically within urbanized or primarily agricultural watersheds. While these studies have shown relationships between land cover and nitrogen, this relationship and the scale of …
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Causes of temporal variations in N species transformations and mobility under acid grassland in York: The multi-functional role of plant litter
Nitrogen cycling has been studied in soils from Hob Moor, an unimproved, unfertilized and N-impacted acid grassland near York, UK. Preliminary assessment of 7 soil profiles sampled to 60 cm depth indicated considerable N mineralization and nitrification in sub-soils. Later soils from a freely …
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NUTRIENT IMPACT OF SWINE CAFO WASTE ON SURFACE WATER AND GROUNDWATER IN EASTERN NORTH CAROLINA
… to facilitate plant uptake by crops; however, nitrogen and/or phosphorus may leach into groundwater or run off into streams, potentially degrading water quality located hydraulically downgradient of SFs. The goal of this study was to analyze nutrient concentrations, transport, and …
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Winter dynamics in mountain lakes and impacts of an introduced species to the endangered Devils Hole pupfish
… nutrient concentrations, and hypolimnetic dissolved oxygen of 10 global mountain lakes in ice-covered (winter) and ice-free (summer) seasons. Productivity was 44% lower in winter compared to summer but varied in magnitude by lake. Winter phytoplankton biovolume and zooplankton abundance …
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<i>Trichodesmium</i> spp.: Numerical Studies of Resource Competition, Carbohydrate Ballasting, and Remote-Sensing Reflectance
… <p>The first study focuses on issues of nitrogen and phosphorus competition and ecosystem structure. It utilizes a simple ecosystem model that includes dissolved nitrogen and phosphorus plus two classes each of primary producers, grazers, and particulate detritus. In a monoculture …
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Stormwater and organic matter in the urban stream continuum
<p>Dissolved organic matter (DOM) is present in all natural waters and modulates</p><p>aquatic ecosystems by absorbing light and heat, and because it comprises a complex</p><p>mixture of organic molecules including amino acids, sugars, fulvic acids, and humic</p><p>material. DOM is derived from …
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An analysis of solute transport on a harvested hillslope in the southern Appalachian Mountains
Interest in transport of dissolved nitrogen (N) and carbon (C) in forested ecosystems is growing because of potential effects of these solutes on streamwater quality and implications for C sequestration. Additional research will further the understanding about the dynamics of these soil solutes, …
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