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1	Effects of a surface circulator on temperature, dissolved oxygen, water velocity, and photosynthetic yield in Falling Creek Reservoir Elam, Kevin Patrick 16 January 2009 (has links) Cyanobacteria are a naturally occurring component of reservoir aquatic ecosystems. Given that some species possess the ability to control their depth within the water column, they have a competitive advantage over other species of photosynthetic organisms. This leads to the potential for cyanobacteria blooms, and because of taste and odor problems, as well as possible toxin production associated with certain species of cyanobacteria, these organisms can cause major problems in drinking water production. The Western Virginia Water Authority installed a solar-powered circulator in Falling Creek Reservoir, located in Bedford County, Virginia, in an attempt to limit the growth of these organisms through limiting light exposure by circulating them deeper within the reservoir. Experiments were performed during the summer of 2008 to quantify the effect of the circulator on the reservoir. Temperature, dissolved oxygen, water velocity, and photosynthetic yield were monitored before and during operation of the unit. The overall effect of the mixer was limited to the first 10 m immediately adjacent to the unit during the afternoon. The effect was stronger during the morning when the difference in density between the intake water and the surface of the reservoir was smaller, allowing the water to travel up to 80 m away from the unit. Although the circulator was only intended to mix and possibly deepen the epilimnion, the entire reservoir became mixed about two weeks after the circulator was put into operation. The reservoir is quite shallow, leading to a weak stratification that is easily disrupted by the operation of the circulator. / Master of Science stratification mixing circulator cyanobacteria epilimnion odors
2	Mechanisms Causing Ferric Staining in the Secondary Water System of Brigham City, Utah Wallace, Robert Derring 26 May 2007 (has links) Water from Mantua reservoir has, during some years, exhibited reddish-brown staining when used by Brigham City for irrigation. I propose that seasonal fluctuations in the reservoir chemistry create an environment conducive to dissolving iron from the iron-rich sediments, which subsequently precipitate during irrigation, resulting in a staining event. These conditions are produced by chemical and biological decomposition of organic matter, coupled with isolation of the hypolimnetic waters, which results in seasonal low concentrations of dissolved oxygen in these waters. Under these specific circumstances, anaerobic conditions develop creating a geochemical environment that causes iron and manganese reduction from Fe(III) to Fe(II) and Mn(IV) to Mn(II), respectively. These reducing conditions facilitate reduction-oxidation (redox) chemical reactions that convert insoluble forms of iron and manganese found in the reservoir sediments into more soluble forms. Consequently, relatively high amounts of dissolved iron and manganese are generated in the bottom waters immediately adjacent to the benthic sediments of the reservoir. Water withdrawn from a bottom intake pipe during these periods introduces iron-rich water into the distribution system. When this water is exposed to oxygen, reoxidation shifts redox equilibrium causing precipitation of soluble Fe(II) and Mn(III) back to highly insoluble Fe(III) and Mn(IV). The precipitant appears on contact surfaces as the aforementioned ferric stain. This research focuses specifically on the iron chemistry involved and evaluates this hypothesis using various measurements and models including field data collection, computer simulations, and bench-scale testing to validate the processes proposed. anaerobic hypolimnion epilimnion stratification iron-staining reddish-brown staining hypereutrophic mesolimnion dissolved oxygen benchscale models iron reduction manganese redox potential Mantua Reservoir dissolved iron precipitate reoxidation aerobic PHREEQC benthic sediments seasonal fluctuations iron-rich sediments calibration curve spectrophotometer ICP Beer's Law EPA Methods thermal stratification Civil and Environmental Engineering

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Effects of a surface circulator on temperature, dissolved oxygen, water velocity, and photosynthetic yield in Falling Creek Reservoir

Mechanisms Causing Ferric Staining in the Secondary Water System of Brigham City, Utah