| Abstract |
Old Woman Creek estuary (OWCE, Huron, OH) has been found to be an effective sink for phosphorus (P), which may contribute to eutrophication in Lake Erie. However, the mechanisms of P retention in wetlands are spatially and temporally variable, making predictions challenging. The quantity and mineralogy of iron (oxyhydr)oxides are key drivers of P sorption in mineral-rich wetlands such as OWCE. Wetland plants create oxidized microsites in reduced sediments due to leakage of oxygen from their roots, thereby potentially enhancing P retention. We assessed sediment Fe:P ratios, which have been found to negatively correlate with pore and surface water phosphate concentrations, and metal oxide quantity and mineralogy among four different plant types in OWCE that varied in hydrologic conditions and dominant plant type (Typha, Floating-leaf, Mudflat, and Open Water). I predicted that sediments in zones with plants that have a high-gas transport capacity (Typha) would contain higher Fe:P ratios and higher concentrations of metal oxides due to the bulk effect of oxidized microsites. Preliminary results from 2018 support my predictions and show that sediments dominated by Typha had higher Fe:P. Higher fractions of poorly-crystalline iron oxides provide further support that Typha-dominated sediments had higher P retention capacity.
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