Author

Marc R. Owen

Date of Graduation

Fall 2003

Degree

Master of Science in Geospatial Sciences

Department

Geography, Geology and Planning

Committee Chair

Robert Pavlowsky

Subject Categories

Earth Sciences

Abstract

Eutrophic conditions in the upper James River Arm (JRA) of Table Rock Lake have been linked to phosphorus (P) inputs by wastewater treatment facilities and increasing urban development in the upper James River Basin (3,770 km2). Since the majority of P in aquatic environments is bound to sediments, bottom sediment can function as both a source and sink of P in lake systems. This study evaluates the spatial distribution, physical and chemical characteristics, and storage of sediment-P in the active layer ( < 5cm) of bottom sediments in the JRA. The JRA makes up about 20% of Table Rock Lake’s surface area, contributes about 30% of the inflow, and has the poorest water quality of the entire lake. For this study, grab samples were collected in the main arm and tributary coves at the deepest part of the lake and at several shallow sites along the main arm. Concentrations increase in a down-lake direction in the main arm ranging from 5 to >2000 ppm P. However, water-column P concentrations show a decrease down-lake, indicating that sedimentation is removing P from the water. Trap efficiency of the JRA of both natural and anthropogenic P is estimated at 91%. In the main valley of the JRA, P correlates with depth and iron concentration where these variables account for both down-lake deposition, sediment focusing, and changes in dissolved oxygen important to the spatial distribution in bottom sediments. Tributary cove sediments show no correlation with land-use characteristics, suggesting concentrations are close to background levels. Higher enrichment of P in bottom sediments in the deeper areas suggests that the ability of the JRA to trap P is correlated with sediment at depths greater than 12-15 meters where dissolved oxygen levels are seasonally low. Less P is stored in the upper section of the JRA below Galena, however, this shallower area is the transition zone between the river and lake has high deposition rates.

Copyright

© Marc R Owen

Open Access

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