Equilibrium Phosphorus Concentrations and Phosphorus Forms of Sediments in Walnut Creek, Iowa.

To determine how adsorption processes regulate phosphorus (P) mobility in stream water and to characterize the composition of P sorbents in the sediments, isotherm adsorption experiments and a P fractionation were conducted for 12 sediment samples from the Walnut Creek watershed, Iowa. We learned from adsorption experiments that lowering redox potential as well as increasing shaking energy resulted in higher value of Equilibrium P Concentration (EPC). The higher the EPC value, the more likely stream sediments can act as a P source by favoring phosphate desorption into stream water. The P fractionation study indicated that the distribution of P among different organic and inorganic solid phases varied among the stream sediments.