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Theses/Dissertations

2018

Biogeochemistry

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Full-Text Articles in Physical Sciences and Mathematics

Evaluating Sediments As An Ecosystem Service In Western Lake Erie Through Quantification Of Nitrogen Cycling Pathways, Ashlynn Rose Boedecker Jan 2018

Evaluating Sediments As An Ecosystem Service In Western Lake Erie Through Quantification Of Nitrogen Cycling Pathways, Ashlynn Rose Boedecker

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Lake Erie experiences annual cyanobacterial harmful algal blooms (HABs), comprised mostly of non-nitrogen-fixing Microcystis, due to excess nitrogen (N) and phosphorus (P) inputs (eutrophication). Lake Erie's watershed is mostly agricultural, and fertilizers, manure, and drainage practices contribute to high nutrient loads. This study aimed to clarify the role of Lake Erie sediments in either exacerbating or mitigating conditions that fuel HABs via recycling and/or removal, respectively, of excess N and P. Sediment-water interface N dynamics were evaluated in low HAB (2016, dry) and high HAB (2017, wet spring and early summer) years. Intact sediment cores and overlying water were collected …


Geochemical And Microbiological Controls On Mercury Methylation In Natural Waters, Alison M. Agather Jan 2018

Geochemical And Microbiological Controls On Mercury Methylation In Natural Waters, Alison M. Agather

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Mercury (Hg) is a global pollutant toxic to humans and wildlife. Monomethylmercury (MMHg) is a bioavailable compound that bioaccumulates and biomagnifies in food webs. Humans are primarily exposed to MMHg from seafood consumption (Sunderland 2007), and high quantities of the neurotoxin lead to reduced neurocognitive functioning in adults and the children of exposed mothers (Cohen et al. 2005, Yokoo et al. 2003). Negative effects from MMHg accumulation on the health of humans and wildlife requires a more complete understanding of the chemistry and microbiology driving Hg methylation in both marine and freshwater systems. This work focuses on water column distribution, …