UNDERSTANDING AND PREDICTING THE IMPACT OF AGRICULTURE ON THE ENVIRONMENTAL INTEGRITY OF MANAGED WATERSHEDS
Location: Water Quality and Ecology Research
Title: Inundation influences on bioavailable phosphorus in restored wetland sediments
Submitted to: Soil and Water Conservation Society Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: April 7, 2010
Publication Date: July 18, 2010
Citation: Kroger, R., Usborne, E.L., Lizotte Jr, R.E., Shields Jr, F.D., Moore, M.T. 2010. Inundation influences on bioavailable phosphorus in restored wetland sediments. Soil and Water Conservation Society Proceedings. pp. 7.
Interpretive Summary: Abstract Only - Interpretative Summary not required.
Agricultural surface runoff carries high nutrient loads to downstream receiving waters contributing to eutrophication. Used as part of best management practice efforts, restored wetlands can intercept non-point source nutrient pollutants before entering downstream aquatic systems. Due to the lack of information documenting sedimentary sorption and desorption of phosphorus during typical inundation cycles in primary aquatic systems associated with agriculture of the Lower Mississippi Alluvial Valley, this study seeks to quantify field sediment capacity to mitigate phosphorus. A restored wetland cell in Coldwater, Mississippi was subjected to increased agricultural runoff through a simulated storm event. Water extractable phosphorus (Pw), was monitored during the storm event as well as following the experiment in an inflow to outflow stratified manner. Preliminary data shows significant relationships between inundation and the amount of Pw desorbed from drainage sediments. Pw concentrations, at the most inundated site, significantly decreased over a 6 hour period (700m from inlet; r2=0.744; p=0.02). In contrast, the least inundated site (often dry) had a slight increase in Pw concentrations with time (100m from inlet; r2=0.11; p=0.45). Post manipulated flow (24h-5 months) sediment sampling show similar patterns of Pw concentration availability. This research puts forward preliminary data on how inundation with increased hydraulic residence time, in drainage systems associated with agriculture, can decrease the total bioavailable phosphorus in drainage sediments. This decrease in bioavailable phosphorus, with time, could reduce equilibrium phosphorus concentration and thus create drainage sediments acting as phosphorus sinks at lower water column phosphorus concentrations.