HAMMOND, LA Rapid population growth and urbanization have raised concerns over stormwater runoff contamination. Studies on watersheds indicate that excess nutrients, specifically nitratenitrogen and soluble reactive phosphorus are found in stormwater runoff in many new urban areas. These pollutants degrade water quality and have an impact on the downstream ecosystem by contributing to the growth and decomposition of oxygen-depleting microorganisms.
A research team recently used a nutrient recirculation system (NRS) to assess the ability of four ornamental and three wetland plant species to remove nitrogen and phosphorous from stormwater runoff. The study showed that canna is a promising ornamental species for stormwater mitigation, and harvesting the aboveground biomass of canna can effectively remove nitrogen and phosphorous from the treatment system.
A variety of stormwater treatment technologies such as constructed wetlands and retention ponds have been developed in response to increasing regulatory pressures, but water quality issues are still found in many stormwater treatment structures. To meet increasingly rigorous EPA regulations, significant nitrogen and phosphorous reductions are necessary to improve water quality before it is discharged into the ecosystem from stormwater retention structures.
A relatively new technique using floating wetlands (also called "floating islands") for stormwater improvement has been tested in a wastewater treatment pond and a laboratory-scale constructed wetland; the results have suggested that the use of floating systems can increase mitigation capacity and provide efficient nitrogen and phosphorous removal in small treatment structures in urban areas. When ornamental plants are added to floating wetland systems, the benefits can be both aesthetic and environmental.
In a study published in a recent issue of the journal HortScience, a research team headed by Yan Chen of Louis
|Contact: Michael W. Neff|
American Society for Horticultural Science