Mercury (Hg) is a globally distributed toxicant that has been shown to have negative effects on birds. in the United States, avian taxa have been shown to possess high Hg concentrations in the northeast, Great Lakes and Everglades ecosystems; however, few studies have measured avian Hg concentrations in other geographic regions. Previous studies have documented high Hg concentrations in multiple organisms in east Texas, but birds were not included in these studies. the main objective of the present study was to quantify Hg concentrations in birds in differing trophic levels at Caddo Lake and Lake Lewisville, TX. Results suggest that Hg concentrations may be high enough to negatively impact some bird taxa, particularly those at high trophic levels, residing at both Caddo Lake and Lake Lewisville.

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Located in Giles County, Virginia, Mountain Lake has a documented history of dramatic water level fluctuations. Previous water balance studies have documented that the main cause of water loss is outflow to groundwater. However, the flow paths of water exiting the lake are unknown. This study applied hydrologic, geophysical, and dye tracer methods to examine the pathways for water loss and the possible geologic controls on these flow paths. Continuous lake level monitoring data show seasonal trends of draining and filling over a three year period. Electrical resistivity profiles suggest the presence of a large low-resistivity zone beneath the northern end of the lake. A dye tracer study yielded limited positive results, but dye detection in one stream and within the lake suggest complex flow dynamics. The most likely reasons for the lack of dye recovery include dilution of the dye during lake recovery, seepage of water below monitoring site locations, or formation of a temporary seal in the depressions created by influx of sediment during periods of lake bed exposure. / Master of Science

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This thesis began with the goal of designing a bold house cantilevered over the edge of a cliff 120 feet above the water, and evolved into the study of how to design when starting with the primary form of a cube. The cube was chosen as representing the crystalline form of the rock upon which the house sits. The outside shell of the house is horizontal, board formed concrete, also in reference to the layered rock of the cliff face. There are two primary forces cutting away the mass of the cube to produce the final form of the house. The first force is of the site, and is generated by two spectacular views. These two views are used to cut through the house, forming an â Xâ shaped atrium eight feet wide and four storeys high, in the center of the house. The second force is generated by the desire to bring daylight into two opposite corners of the house. The southern corner of the house faces the lake. The bottom of that corner is cut out more than the top to admit direct sun in the winter, indirect sun in the summer, and reflected sun off the lake year round. The northern corner of the house faces the woods. The top of that corner is cut out more than the bottom to allow northern light into the top floors and maintain privacy on the lower floor, where the driveway approaches the house. / Master of Architecture