Publication Date


Document Type


Committee Members

Chad R. Hammerschmidt (Advisor), Mark J. McCarthy (Committee Member), Silvia E. Newell (Committee Member)

Degree Name

Master of Science (MS)


Human activities have increased nutrient loadings to aquatic ecosystems during the past century. During low river flow in late summer and early fall, excessive concentrations of phosphorus (P) are present in the Lower Great Miami River (LGMR) and contribute to its eutrophication. Although wastewater treatment plants are suspected of being major point sources of P to the LGMR during low river flow, riverbed sediment has not been examined as an additional potential source of P. Benthic P fluxes were measured at 11 representative locations along the LGMR during late summer and early fall of 2015. Sediment and overlying water sampled from the LGMR were incubated in laboratory flux chambers, and total and filtered P were measured over time in overlying water to estimate fluxes. Concentrations of P in river water and benthic fluxes of filtered total P (range from -50 to 390 µmol m-2 d-1) varied considerably among sites and sampling periods. Benthic fluxes of filtered total P were inversely related to filtered total P concentrations in overlying river water (p = 0.002, r = -0.60). This relationship suggests that elevated concentrations in river water inhibit mobilization of P from sediment, likely by minimizing the concentration gradient between pore and overlying water. Accordingly, upstream sources that increase concentrations of P in river water, including wastewater treatment plants, could inhibit the potential for P to be remobilized from, as opposed to temporarily stored in, downstream sediment.

Page Count


Department or Program

Department of Earth and Environmental Sciences

Year Degree Awarded