Phosphorus Water Quality Model Evaluation and Comparison for Natural and Constructed WetlandsEPA Grant Number: U914937
Title: Phosphorus Water Quality Model Evaluation and Comparison for Natural and Constructed Wetlands
Investigators: Paasch, Mary M.
Institution: Texas A & M University
EPA Project Officer: Carleton, James N
Project Period: January 1, 1996 through January 1, 1998
Project Amount: $68,000
RFA: STAR Graduate Fellowships (1996) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Engineering and Environmental Chemistry , Fellowship - Agricultural Engineering
The objective of this research project is to develop various numerical models to predict total phosphorus outflow concentrations and annual phosphorus retention within treatment wetlands.
Constructed and natural wetlands have been used to treat wastewater from both point and nonpoint sources. Phosphorus concentrations in receiving waters are a prime concern because of the role phosphorus plays in freshwater lake eutrophication. Three phosphorus models, the mass balance model with first-order areal uptake, the Vollenweider-based wetland model, and the detailed ecosystem model, were evaluated at three wetland sites across the United States. The three sites were Boney Marsh Experimental Area, Florida; Jackson Bottom Experimental Wetlands, Oregon; and the Des Plaines River Wetland Demonstration Project, Illinois. The mass balance model with first-order areal uptake provided the smallest average percent error for outflow concentration, with percent error ranging from -6.8 percent to 6.0 percent. Although the Vollenweider-based wetland model consistently over-predicted annual phosphorus retention, the model provided the smallest average percent error for annual retention, with percent error ranging from 0.1 percent to 6.9 percent. The detailed ecosystem model yielded the highest average percent error in both outflow concentration and annual phosphorus retention. However, the detailed model most accurately predicted total phosphorus outflow concentration trends at all three of the wetland sites.