The distribution of nitrogen species and adsorption of ammonium in sediments from the tidal Potomac River and estuary

Estuarine, Coastal and Shelf Science
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Abstract

The distribution of dissolved ammonium, adsorbed ammonium and residual, organic and total nitrogen was measured in Potomac River tidal, transition zone and lower estuary sediments to a depth of 66 cm. For these sediments, exchangeable ammonium, and thereby adsorbed ammonium concentrations, were determined directly using an ammonia electrode in alkaline sediment suspensions. Ammonia electrode data were comparable to data obtained by KCl extraction of fresh sediment. The conventional unitless ammonium adsorption coefficient, calculated as the slope of the regression line drawn when sediment-adsorbed ammonium (μmol g−1 dry wt of sediment) is plotted against interstitial water ammonium (μmol g−1 dry wt sediment), is 1·5 for this system. When a modified ammonium adsorption coefficient is calculated from sediment-adsorbed ammonium concentrations and a ratio of interstitial water ammonium and potassium concentrations, the regression equation through the data has a zero intercept and is more nearly linear than the regression equation of data based on conventional calculations. The use of a ratio including ammonium and potassium concentrations in the interstitial water term takes into account ionic strength variations in the estuary and competition between ammonium and potassium for adsorption sites.

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Publication type Article
Publication Subtype Journal Article
Title The distribution of nitrogen species and adsorption of ammonium in sediments from the tidal Potomac River and estuary
Series title Estuarine, Coastal and Shelf Science
DOI 10.1016/0272-7714(87)90022-9
Volume 25
Issue 1
Year Published 1987
Language English
Publisher Elsevier
Description 16 p.
First page 11
Last page 26
Country United States
State Maryland, Virginia
Other Geospatial Potomac River
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