Thesis supervisor: Jerald L. Schnoor. Thesis supervisor: Craig L. Just. Includes bibliographic references (p. 186-196).

Thesis (M.C.E.)--University of Delaware, 2006. / Principal faculty advisor: William Ritter, Dept. of Civil & Environmental Engineering. Includes bibliographical references.

Nutrients are of critical concern in water quality assessment. The development of empirical models to estimate mean nutrient concentrations, based on satellite derived land use, could aid water resource managers. Models using land use acreages outperformed those using percentages, and discrete urban land uses were superior to lumped urban. Regressions of the combinations of two, three and four of the eight possible land use variables were investigated. Sensitivity analyses, with one stream deleted each series, identified robust combinations of variables at each level. Although uncertainty exists regarding the final regression coefficients, five of the six actual measured nitrate and total phosphorus mean concentrations were within the 95 percent confidence limits.

Interactions between cyanobacteria and herbivorous grazers play an important role in mediating the responses of freshwater phytoplankton assemblages to nutrient enrichment and top-down manipulation. Negative consequences associated with these interactions include dangerous blooms of harmful blue-green algae that have been implicated in the sickness and death of fishes, livestock, and, in extreme cases, humans. Frequently cited mechanisms influencing the interactions between grazers and cyanobacteria include cyanobacterial toxicity and morphology. To tease apart the importance of these mechanisms, I used meta-analysis to quantitatively synthesize the available literature on this topic. In addition, I conducted several experiments using novel techniques to determine the effect that cyanobacterial secondary metabolites from the bloom-forming cyanobacterium,

This study investigated temporal changes in nutrient concentrations and other water quality parameters at one sampling location at Muncie, Indiana in the Upper White River Watershed. Baseline sampling was conducted weekly over a six-month period in 2012 and focused on the analysis of total suspended solids and different forms of nitrogen and phosphorus. Three storm events were also investigated to understand how storm water runoff affected nutrient concentrations and other water quality parameters. It was hypothesized that storm events would temporarily increase nutrient concentrations in the river. Overall, nutrient concentrations increased during the initial stages of storm events and subsequently decreased at a rate slower than discharge. Concentrations measured exceeded recommended limits suggesting that these contaminants could cause eutrophication at downstream locations. These data suggest that improved or increased best management practices should be implemented in the Upper White River Watershed to control the inputs of nutrients into the river. / Department of Natural Resources and Environmental Management

The Prairie Creek Reservoir, located in east central Indiana in an agricultural watershed, serves as a secondary drinking water source as well as a recreational facility. Limited research of water quality performed at the reservoir has affected management decisions over the past years, threatening its future.. Consequently, additional investigation was necessary to examine the reservoir dynamics, and continue to provide data to determine long-term water quality trends. Basic water quality parameters were measured using a Hydrolab Sonde, nutrients were measured spectrophotometrically, and a Secchi disk was used to determine water transparency. The Prairie Creek Reservoir was categorized as an eutrophic water body. Concentrations of the measured nutrients were higher in the hypolimnion and increased as summer progressed. Concentration of ammonia and soluble reactive phosphorus exceeded the recommended water quality guidelines. Increased concentration of phosphorus has resulted in nitrogen limitation in the reservoir. Internal loading of nutrients, especially phosphorus, was found to deteriorate water quality. Dissolved oxygen concentrations varied vertically and anoxic conditions frequently reached 50% of the total reservoir depth. Reservoir restoration and watershed protection programs need to address internal P load and nitrogen limitation to prevent development of toxic algal blooms and eutrophication in the future. / Department of Natural Resources and Environmental Management

Prairie Creek Reservoir in east central Indiana serves as a secondary water supply for the city of Muncie and is also used as a recreational facility. Due to water quality concerns, this study was conducted to characterize spatial and temporal variability of physical and chemical parameters, specifically nutrients, in the sediment interstitial (pore) water at three reservoir locations. The pH, temperature, specific conductivity, ammonia, nitrates, total nitrogen, orthophosphates and total phosphorus, were monitored twice per month from June through September 2006. Spatial variations in the sediment interstitial water were evident for all water quality parameters, except phosphorus and orthophosphates. Variability in temporal nutrient concentrations in pore water was most likely affected by decomposition of organic matter and presence of anoxic conditions in the overlying water. The results showed high internal nutrient loading, especially from phosphorus, in the sediment interstitial water. Under anoxic conditions, these excessive nutrient concentrations within the sediment can be released into the water column and exacerbate eutrophication of the reservoir. This study provides useful assessment of internal nutrient loading in the Prairie Creek Reservoir sediment that should be considered in the implementation of land management strategies and future land development practices in the reservoir watershed. / Department of Natural Resources and Environmental Management

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.

Thesis (M.E.S.)--The Evergreen State College, 2007. / Title from title screen (viewed 1/24/2008). "MES thesis." Includes bibliographical references (p. 51-54).

Thesis (Ph. D.)--University of North Texas, Dec., 2007. / Title from title page display. Includes bibliographical references.