Harmful algal blooms caused by eutrophication from fertilizer runoff carrying excess nutrients such as phosphorus have plagued natural water systems for over a century devastating a wide range of ecosystem services such as drinking water supplies, aquatic habitats, aquaculture, and recreational activities. The dissolved oxygen content of water controls many functions of a natural water system and can influence the speciation and bioavailability of phosphorus, particularly at the sediment-water interface. The impact of phosphorus internal loading to a Central Florida lake was examined seasonally using phosphorus speciation data collected. Phosphorus speciation in lake sediment was primarily controlled by sediment type and organic carbon content. Correlations between iron and phosphorus within the sediment indicated that anaerobic respiration and iron reduction was a factor in phosphorus speciation suggesting that oxygen content in the overlying water column was a primary factor in controlling internal loading. To prevent the release of phosphorus from sediments, oxygenation at the sediment-water interface is vital. Collagen, whey protein concentrate, and a composite were fabricated by electrospraying into core-shell micromaterials for the encapsulation of calcium peroxide as an oxygen releasing compound and characterized by SEM, FTIR, UV-Vis, and fluorescence spectroscopy. The micromaterials were soluble in water and released oxygen as a function of time at neutral pH. The micromaterials were used to treat anoxic lake water and sediment spiked with phosphate adsorbed to goethite in order to determine the effects of oxygen on the release of iron-bound phosphorus into the overlying water through controls on reductive iron dissolution. Systems remained oxygenated for 75-100 hours before returning to anoxic conditions. Evidence of iron dissolution was observed, but the reason as to why was indeterminant. Results indicated that multiple mechanisms were controlling phosphorus speciation and that dissolved oxygen was but one factor affecting phosphorus cycling in the benthic sediments.
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Doctor of Philosophy (Ph.D.)
College of Sciences
Length of Campus-only Access
Doctoral Dissertation (Campus-only Access)
McCormac-Miller, Kathleen, "The Effects of Dissolved Oxygen on Phosphorus Cycling in Benthic Freshwater Systems" (2020). Electronic Theses and Dissertations, 2020-. 255.
Restricted to the UCF community until August 2025; it will then be open access.