Audrey E. McGowin, Ph.D. (Advisor); Steven Higgins, Ph.D. (Committee Member); Stephen Jacquemin, Ph.D. (Committee Member)
Master of Science (MS)
Caesar Creek Lake (CCL) in Warren County, OH has recently been experiencing harmful algal blooms (HABs) which are most likely attributed to an excess of phosphorus (P) from fertilizers and manures applied to surrounding fields. Sediments act as a sink for P later supplying a source of P in lakes for HABs when waters become thermally stratified and anoxic. This study seeks to determine the relationship between HABs in CCL and riparian cover at the main tributaries, Anderson Fork and Caesar Creek. In order to do this, sediment samples were collected from four sample sites along Anderson Fork and three sample sites along Caesar Creek in which there were varying amounts of riparian cover. Sediment samples were digested using concentrated nitric and hydrochloric acids following EPA method 3050B. Digested solutions were analyzed for total phosphorus (TP) and total iron (TFe) at wavelengths 213.618 nm and 238.204 nm, respectively, using Inductively Coupled Plasma – Atomic Emission Spectroscopy (ICP-AES). Types and percentage of riparian cover at each site were determined and quantified using QGIS 3.14. To determine statistical relationships between sedimentary TP concentrations and predictor variables such as riparian cover and TFe concentrations, a mixed effects ANCOVA was carried out. Results revealed no significant statistical relationship (p-value>0.1) between sedimentary TP concentrations and percentages of tree cover (TC), grass cover (GC), and urban cover (UC). A significant positive relationship (p-value<0.0001) was observed between sedimentary TP and TFe concentrations likely indicating a large concentration of iron-phosphate (Fe-PO43-) complexes due to phosphate’s affinity for iron oxides. Distance from the Anderson Fork and Caesar Creek confluence was found to be statistically significant (p-value=0.0321) due to finding higher TP concentrations at downstream sites suggesting that P moves downstream by sorption to suspended solids in streambeds during stormwater runoff events. A significant interaction variable between stream and location was investigated to reveal that there was a significant difference between sedimentary TP concentrations at Anderson Fork LDB and center. Overall, streambank TP concentrations were higher than streambed concentrations revealing that P is deposited on the streambanks contributing to the legacy P pool.
Department or Program
Department of Chemistry
Year Degree Awarded
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