Phosphorus Content of Legacy Sediments in Lancaster County: Significance for Non-Point Source Pollution to the Chesapeake Bay
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This study chemically characterized stream bank sediments from two cores in Lancaster County, Pennsylvania, focusing on the total and sorbed phosphorus content. Denlinger’s Mill (DM) core was collected from stream bank sediments deposited behind a 5 m high dam, which served Stehman’s Grist mill in 1875. Big Spring (BS), a 1 m thick sediment core, was collected at the origin of Big Spring Run, a small tributary to Mill Creek. The geochemical characterization was done by X-ray fluorescence (XRF) for total elemental analysis, and Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES) for partial sediment digestion. There is a record of extensive accumulation of sediments in stream valleys in Lancaster County. These legacy sediments may be the source for trace metals, nutrients and toxins, which makes geochemical characterization important. This study focuses on phosphorus (P) in particular, as phosphorus is a limiting nutrient in primary productivity and contributes to eutrophication in water bodies such as the Chesapeake Bay. Our results show that total phosphorus (P) concentrations in sediments are overall high. Total P ranges from 400 to 1500 mg/kg sediment, and varies with sediment depth. The total environmentally available P (determined by EPA 3050 and 3051 partial digestion method) based on Big Spring Run represents about 60-70 % of the total P sediment content. These results suggest that legacy sediments may be a significant source of phosphorus, which can be released into streams as an environmentally available nutrients via bank erosion and sediment remobilization.
Franklin and Marshall College Archives, Undergraduate Honors Thesis 2006
- F&M Theses Collection