WATER RESOURCES RESEARCH GRANT PROPOSAL
Project ID: 2004WA75B
Title: Phosphorus Contamination of Surface Waters
Project Type: Research
Focus Categories: Surface Water, Groundwater, Water Quality
Keywords: ground and surface water quality, phosphorus, field drainage, solute transport
Start Date: 03/01/2004
End Date: 02/28/2005
Federal Funds: $24,000
Non-Federal Matching Funds: $48,000
Congressional District: Washington Fifth
Washington State University
In northwestern Washington State, dairy manure spreading has been common for at least 30 years. At the present time, manure management is of particular concern among farmers due to increasing environmental regulations. Dairies are often located on flat soils where flooding commonly occurs during winter. During flooding, the redox potential of the soil decreases, and Fe can be reduced from Fe(III) to Fe(II). This reductive dissolution of Fe is likely associated with a release of sorbed P into the soil solution. We hypothesize that during periodic flooding of soils, P leaching into tile drains will be significantly increased and may cause surface water eutrophication. The goal of the proposed research is to study fate and transport of phosphorus in soils characterized by periodic anaerobic conditions. Specifically, we address the following objectives:
(1) Acquire relevant field data to understand the dynamics of dissolved phosphorus in tile effluents.
(2) Explore the effect of the soil redox potential on phosphorus release and transport in soils.
(3) Develop a tile drain filter to reduce the concentration of dissolved phosphorus in tile effluents to comply with EPA water quality criteria.
This is an experimental study and consists of field and laboratory experiments. In the field experiments, we will monitor tile drain outflow on selected farms to obtain information on phosphorus concentrations in tile drains. In the laboratory experiments, we will study phosphorus release from idealized porous media under oxidized and reduced conditions. We will use dynamic column flow-through systems to assess phosphorus leaching as affected by redox potentials in the columns. Finally, we will use the information obtained from field and laboratory experiments to design and test a filter methodology to reduce phosphorus concentrations in tile-drain outflow.
The results of this project will provide a better fundamental understanding of an important aspect of phosphorus transport through the subsurface. We will provide, on a mechanistic level, information on when phosphorus transport can occur in soils affected by periodic flooding. Results of this project will help to determine strategies for reducing the risk of phosphorus losses in tile-drained soils impacted by high phosphorus loadings.