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 51 for “"Nutrient loads"”.
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Calculating nutrient loads from four tributaries of the Cedar River in Iowa
1 PDF file (ix, 77 pages)
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An Assessment of Floating Treatment Wetlands for Reducing Nutrient Loads from Agricultural Runoff in Coastal Virginia
… retention ponds by increasing removal of the nutrients nitrogen (N) and phosphorous (P). FTWs consist of floating rafts on which wetland plants are planted, allowing the roots to be submerged below the water surface while the shoots remain above. A growing body of research has documented FTW …
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Development and analysis of the measured annual nutrient loads from agricultural environments (manage) drainage nutrient concentration database
… to understand the mechanisms responsible for nutrient transport from this land use leading to the eutrophication of surface waters and the hypoxic zone in the Gulf of Mexico. It is also vital to understand the effects of management practices in drained systems, as subsurface drains are …
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Restoring freshwater quality: an integrated environmental, economic and ecosystem services assessment of reducing nutrient loads to Lake Rotorua
… health. Land use has played a major role in nutrient enrichment of this lake. Restoration actions have been targeted at limiting nutrient loss from land, and reducing internal loading of the lake through engineering solutions. The aim of the research here was to analyse historical management …
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Understanding the role of scale in assessing sediment and nutrient loads from Coastal Plain watersheds delivered to the Chesapeake Bay
… are available that focus on prediction of nutrient and sediment runoff loads from Coastal Plain watersheds. The overall goals of my dissertation are to assess the effect of urban and agricultural watershed on coastal waters through monitoring and modeling, and to characterize treatment …
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GIS for source water assessment and nonpoint source modeling in the Las Vegas Valley
… protection zones and to estimate nonpoint source loads for the entire watershed; The extent of the source water protection zones is represented by the valley's dry weather flows. After source water protection zones were defined, field work and GIS defined the potential contaminant sources and land …
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Quantifying the Effects of Watershed Size and Land Development on Stream Nutrients
Excessive nutrient loading from watersheds causes nutrient enrichment and water quality issues in very small streams to large rivers. Nutrient enrichment is exacerbated by urbanization and agricultural land use; however, the magnitude of the problem differs by regional landscape and environmental …
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Development of error correction techniques for nitrate-N load estimation models
Excess nutrient loads carried by streams and rivers are a great concern for environmental resource managers. In agricultural regions, excess loads are transported downstream to receiving water bodies, potentially causing algal blooms, which could lead to numerous ecological problems. To better …
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New applications of STEPL watershed modeling of CAFO feedlot runoff and implications of surface water impacts
… Load (STEPL). STEPL estimates the annual nutrient load of nitrogen and phosphorus, among other pollutants, by land use for a watershed. The Dry Creek Watershed Basin of Sioux County, Iowa, is delineated to capture runoff from large CAFO cattle feedlots. Feedlots are classified by …
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Lake remediation by top-down and bottom-up management : an ecosystem-scale experiment in the English Lake District
… against the desired impact of reduced external nutrient loads. Analysis of contemporary surface sediments revealed a legacy of phosphorus enrichment from years of high external loading, including from aquaculture cages previously installed on the lake. Much of the sediment phosphorus was …
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Assessing biofilm and epiphytes on seagrass leaves as bioindicators of environmental change
… events are a consequence of increased nutrient loads entering the coastal environment. Light reduction can occur from a number of processes including eutrophication, but also increased sediment loads entering the water column through anthropogenic activities on the land and in the sea. …
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A Complex, Linked Watershed-Reservoir Hydrology and Water Quality Model Application for the Occoquan Watershed, Virginia
… temporal distribution of hydrology processes, nutrient detachment and transport, stream temperature and dissolved oxygen were well reproduced by HSPF submodels. By using the outputs generated by HSPF submodels, the CE-QUAL-W2 submodels adequately captured the water budgets, hydrodynamics, …
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Measuring and modeling suspended sediment and nutrient yields in a mixed-land use watershed of the central United States
… contributions of suspended sediment and nutrient loads to receiving water bodies. Water samples were analyzed for suspended sediments and nutrients using a nested-scale experimental watershed study design (n=836 samples x 5 gauging sites) in an urbanizing mixed-land use watershed of the …
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Spatial and Temporal Variability of In-Stream Functioning within a Forested, Headwater Piedmont Watershed
As anthropogenic nutrient loads threaten the health of the Chesapeake Bay, lotic processes throughout its headwaters may buffer increased nitrogen inputs by converting them to stable forms, ultimately through denitrification to N2 gas. However, the temporal environmental factors controlling …
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Bioproducts and environmental quality: biofuels, greenhouse gases, and water quality
… other parts of biogeochemical cycles, notably nutrient loads in the aquatic environment. In three essays, this dissertation explores the tradeoff between GHG emissions and nitrogen leaching associated with biofuel production using general equilibrium models. The first essay develops a …
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Two analyses of costs of agricultural NPS pollution: Transactions costs of expanding nutrient trading to agricultural working lands and Impacts of TCs and differential BMP adoption rates on the cost of reducing agricultural NPS pollution in Virginia
… on reducing delivered nitrogen and phosphorus loads. However, achievement of water quality objectives remains elusive. In Virginia, agriculture represents the single largest source of nutrient loads to the Chesapeake Bay. Despite aggressive regulatory efforts in other nutrient source sectors, …
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Evaluation of agricultural beneficial management practices: Cattle access restriction to surface waters subsurface tile drainage management
… as: indicator bacteria, pathogens, parasites and nutrients between treatments. Microbial source tracking indicated that livestock was the main source of fecal contamination in the stream. Greater bacteria and nutrient loads were observed in the unrestricted pasture system than the excluding …
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Modeling Farm-Level Costs of the Yield Reserve Program
… Known as the Yield Reserve Program, or Enhanced Nutrient Management, this policy could possibly help to reduce the nutrient loads. The objective of this study was to evaluate the effects of a Yield Reserve Program on farm yields and net revenues. Costs were estimated for different policy …
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Phycoremediation of meat processing wastewater by using microalgae scenedesmus sp.
… Meat Processing Wastewater (MPWW) contains high nutrient loads which can induce eutrophication and cause water quality to deteriorate as it has been claimed that this type of wastewater is difficult to treat due to different types of processed meat and factory activities. The objective of this …
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Costs of Meeting Water Quality Goals under Climate Change in Urbanizing Watersheds: The Case of Difficult Run, Virginia
… identified as a non-point source contributor of nutrient loadings into watersheds. Interannual surges of nutrient loadings into local water systems are more damaging than mean interannual nutrient loadings. Virginia has outlined the need to reduce urban nutrient loadings. Mean interannual …
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