ARS | Publication request: SEDIMENT PHOSPHORUS DYNAMICS IN TILE-FED DRAINAGE DITCHES

Submitted to: International Symposium on Sediment Dynamics and the Hydromorphology of Fluvial Systems Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 1, 2006
Publication Date: July 1, 2006
Citation: Smith, D.R., Warnemuende, E.A., Haggard, B.E., Huang, C. 2006. Sediment phosphorus dynamics in tile-fed drainage ditches. In: International Symposium on Sediment Dynamics and the Hydromorphology of Fluvial Systems Proceedings. Sediment Dynamics and the Hydromorphology of Fluvial Systems, July 3-7, 2006, Dundee, UK, IAHS Publ. 306, 2006.

Interpretive Summary: Stream sediments may regulate aqueous phase phosphorus (P) concentrations. The objectives of this work were to study the equilibrium P concentrations between the aqueous phase and sediments in tile-fed drainage ditches. Sediments from three ditches in Indiana, USA, were sampled and evaluated as P sources or sinks. Sediments that potentially release P to aqueous solutions could be chemically amended to sequester labile P. Sediment deposition from episodic storm events could increase the P buffering capacity of drainage ditches. In fluvarium studies (initial concentration of 0.55-mM P), aqueous P concentrations after 120-h were 0.075-mM and 0.111-mM for pre-dredged and dredged sediments, respectively. Phosphorus release from sediments to the aqueous solution was greater from the dredged sediments. These studies are helping to expand our understanding of the dynamic nature of P in agricultural ditches, and aiding in the development of ditch management practices that could be used to reduce downstream P transport. The impact of this work is to form a basis for utilization of drainage ditches in the management system to reduce non-point source pollution from agriculture.

Technical Abstract: Phosphorus (P) losses from agriculture have been linked to eutrophication. The objectives of this work were to study the relationship between P in the water column and sediments in tile-fed drainage ditches, and determine if these ditches can be used in the management system to reduce downstream delivery of anthropogenic sources of P. To accomplish this, three tile-fed drainage ditches in Northeast Indiana, USA, were monitored. Sediments in these ditches act as sources or sinks for P in the water column. Sediments that release P to the water column can be treated with chemicals, such as aluminum sulfate, to sequester the labile P in the sediments, and remove P from the water column. Dredging of the ditches is a common practice to remove sediments and optimize the rate of water removal from agricultural fields. This practice has a detrimental impact on contaminant transport though. Pre-dredged and dredged sediments were placed in a fluvarium with an initial P concentration of 0.55 mM, final P concentrations after 120 h were 0.075 mM and 0.111 mM for pre-dredged and dredged sediments respectively. Release of P to the water column by P-saturated sediments was greater from the dredged sediments. Deposition of fresh sediments following severe storms can increase the P removal from the water column. Data from these studies are helping to expand our understanding of the dynamic nature of P in agricultural ditches, and aiding in the development of practices that could be used to reduce downstream delivery of this contaminant.