Zone of Influence for Soluble Reactive Phosphorus in an Effluent Dominated River

by Miller, Joseph G

Abstract (Summary)
Benthic sediment and pore water from the Little Miami River (LMR) near Spring Valley, Ohio was sampled before and after three storm events to determine the zone of influence for soluble reactive phosphorus (SRP). The zone of influence is the area in a vertical cross section through the streambed where the pore water SRP concentration changes during the passage of a runoff event. Benthic sediment samples (d < 0.85 mm sieved coarse sand and finer) from three depths (z=0, 15, 30 cm) and five in-stream locations at a single transect were analyzed for their ability to adsorb and desorb SRP. The LMR stream bottom was surveyed during each sampling event to detect changes in the cross-sectional shape of the river. Laboratory analysis of benthic sediment and pore water showed a significant decrease (? =5%) in benthic SRP concentrations with the passage of storm events at all sample points except the 15 and 30 cm near-bank samples. The zone of influence for the SRP concentration was found to extend throughout the benthic zone examined except in areas that are "protected" by a layer of depositional silts near the edge of the LMR. The river cross-section profiles taken during sampling events showed a scouring and re-shaping of the river bottom. Following the storm event, water column SRP concentrations increase from upstream sources and subsequently benthic sediment SRP increases in the zone of influence. The benthic sediments may confound future improvements from TMDL controls and watershed improvements with regards to nutrient removal. While fine benthic material serves as a sink during periods of high SRP in the water column, it may also serve as a source of SRP as the river column phosphorus concentrations decline.
Bibliographical Information:


School:University of Cincinnati

School Location:USA - Ohio

Source Type:Master's Thesis

Keywords:little miami river soluble reactive phosphorus sediment sorption zone of influence nutrients


Date of Publication:01/01/2004

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