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<p>Excess nutrients are currently impacting the ecosystem, fisheries, and recreational use of Lake Simcoe. The objective of this study was to determine the importance of groundwater as a pathway for nutrient input during base flow periods to a landfill impacted urban stream in Barrie, Ontario, which flows directly into the lake. A characterization of a 28 m reach was created using sediment and water level data, and a groundwater flux map of the stream was creating using heat tracer methods. This data was combined with the shallow groundwater nutrient concentration distribution measured with multi-level piezometers and diffusion samplers to calculate nutrient discharge. Such fine-scale measurements of nutrient discharge using groundwater-based data like these have not previously been reported. The water flux results were then extrapolated to a larger 460 reach (Site B) of Dyment’s Creek, and combined with groundwater contaminant data from that reach to derive a crude estimate of nutrient discharge at a larger scale. Groundwater soluble reactive phosphorus (SRP) and ammonium concentrations were much higher than stream concentrations. Estimates of total SRP discharge ranged from 3.6 to 8.1 g/d at Site A and 38 to 108 g/d at Site B, and ammonium discharge ranged from 66 to 218 g/d at Site A and 757 to 2043 g/d at Site B. This study showed that groundwater is an important pathway for nutrients to enter Dyment’s Creek, and this pathway that must be considered when addressing nutrient input to Lake Simcoe.</p> / Master of Science (MSc)

Advanced oxidation of organic pollutants with TiO2 photocatalysts is limited due to the wide bandgap of TiO2, 3.2 eV, which requires ultraviolet (UV) radiation. When nanosized TiO2 is modified by carbon doping, charge recombination is inhibited and the bandgap is narrowed, allowing for efficient photodegradation under visible light. Here, we propose a flame spray pyrolysis (FSP) technique to create TiO2. The facile process of FSP has been successful in preparing highly crystalline TiO2 nanoparticles. Using the same procedure to deposit TiO2 onto biochar, the photocatalyst was doped by the carbonaceous material. The morphology, crystalline and electronic structure of the FSP TiO2 and TiO2-decorated biochar (TiO2-BC) were characterized by SEM, XRD, TGA, DLS, and diffuse reflectance UV-vis spectroscopy. Photocatalytic performance of TiO2 and TiO2-BC was investigated for model organic contaminants in an aqueous solution under UV and visible light, which will be compared to that of Degussa P25 TiO2 as a control.

Over the past century, the world's rivers have become increasingly impounded to combat water scarcity and fossil-fuel reliance. Large dams have faded from popularity due to their adverse environmental effects, but small ponds and reservoirs continue to be constructed at high rates. Due to limited data regarding their size and flow, it has been difficult to assess how these smaller impoundments impact rivers. This study combined rainfall runoff data from the Chesapeake Bay Model with the unique routing framework of VA Hydro to create a simplistic hydrologic model capable of analyzing impoundment-induced flow alteration. Using standard design techniques and satellite imagery, a methodology was developed to build realistic stage-storage-discharge relationships for small and large impoundments. Eleven impoundments of the Difficult Run watershed were modeled within VA Hydro to assess their cumulative impact on downstream flow. Multiple models were created with different active impoundments and run for the full model period, 1984 - 2005. Flow alteration increased significantly with additional impoundments. Peak flows were attenuated as water was stored behind outlets, but median flows were increased as this water was slowly released. Average storm duration increased due to extended rising and falling limbs caused by impoundment outlets. Headwater channels increasingly ran dry, decreasing extreme low flows due to impoundment evaporation. Large reservoirs had a greater impact on median flows, but smaller ponds dominated low flow alteration. These results suggest that traditional hydrologic assumptions and metrics may be incapable of analyzing a changing flow regime without explicitly considering small and large impoundments upstream. / Master of Science / At first look, dams are an excellent solution to water scarcity and energy independence. They trap clean water and direct it through turbines. Unfortunately, their installation and operation creates many negative environmental impacts by fundamentally altering downstream channels, leading to a loss of fish vitality and river function. Large dam construction has decreased in the US because of these effects, but small dams continue to be built at high rates due to growing agricultural and stormwater demands. Their impact on rivers is less understood due to limited data availability regarding their size and function. This experiment used standard design techniques and widely available satellite data to create a representative model for dams of all size. Multiple tests were run, progressively increasing the number of dams within a watershed and analyzing their impact on downstream flow. With increased impoundment, high floods decreased in magnitude. However, more-typical medium flows increased. River flow became more static, with less extreme floods and more medium flows. The modeled dams greatly decreased drought flows as trapped water evaporated and decreased outflow. This impact was particularly noticeable in ponds that drained only a small area as they took longer to refill after drying. Larger dams more greatly impacted medium flows. These results contribute significantly to water availability prediction by more realistically representing dam processes. Although more work is needed to refine the impoundment modeling strategy, this study has effectively demonstrated that small and large dams affect flow in different manners and need to be accounted for accordingly.

Lake Eola is an eutrophic, land-locked lake located in downtown Orlando, Florida. It has a surface area of approximately 27 acres (11 .0 Ha) and a maximum water depth of 22 feet (6.7 meters) near the center. Sediment samples were collected from the lake bottom at various water depths and analyzed for physical characteristics and phosphorus content. Lake water samples were collected and analyzed for selected parameters as related to sediment phosphorus dynamics. Phosphorus release from agitated, aerobic sediment samples was measured in laboratory batch experiments. Phosphorus release from anaerobic hypolimnetic sediments was measured by utilizing~ situ isolation chambers. Results indicate that phosphorus release from anaerobic Lake Eola sediments can be described by the Freundlich isotherm, indicating that release may be a desorption process. Phosphorus budget calculations indicate that the phosphorus that accumulates in the hypolimnion of Lake Eola has the potential for increasing productivity when overturn occurs.

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