Mitigating Nonpoint Source Nutrient Pollution in Urban Runoff with Floating Treatment Wetlands

Abstract

Floating treatment wetlands (FTWs) are a promising new approach for mitigating the harmful effects of urban pond eutrophication due to stormwater nutrient pollution. However, nature-based treatment systems such as FTWs have inherent uncertainties due to uncontrollable factors present during operation. Thus, it is vital that FTW research fill critical knowledge gaps so emerging data sets can be strengthened and evidence-based design can ensure successful implementation. We performed experiments over the summer growing season for three years. Experimental goals were to (1) evaluate nutrient fate and perform a phosphorus mass balance in FTW mesocosms planted with Pontederia cordata, (2) evaluate effects of Pontederia cordata, Schoenoplectus tabernaemontani, and Iris virginica on nutrient removal efficiency compared to controls, and (3) assess nutrient removal efficiency of Pontederia cordata using three different harvesting strategies compared to controls. Preliminary results indicate Pontederia cordata potted with coir fiber filler showed greater nutrient removal from mesocosm water than Pontederia cordata with no coir fiber filler, coir fiber filled pots without plants, and controls. Mass balance assessment indicates phosphorus uptake by plants and periphyton attached to coir fiber were responsible for a significant majority of phosphorus removal. Preliminary also results suggest both Pontederia cordata and Schoenoplectus tabernaemontani would perform strongly in FTWs in a central Midwest climate. Both species showed greater nutrient removal from water than Iris virginica. In an experiment evaluating harvesting strategies, preliminary results indicate nutrient removal was comparable for all harvesting schemes during peak growing season. Schemes evaluated were mid-season aerial harvest followed by end-of-peak-growing-season whole plant harvest, end-of-peak-growing-season whole plant harvest, passive management, and controls. Mesocosms containing senescing plants (passive management) and controls were continued through mid-December and observed nutrient levels remained low during this time. Preliminary results from a separate nutrient leaching experiment indicate nutrient resorption for Pontederia cordata may potentially be significant during senescence.

Meeting Name

AGU Fall Meeting 2022

Department(s)

Biological Sciences

Second Department

Civil, Architectural and Environmental Engineering

Document Type

Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2025 The SAO Astrophysics Data System, All rights reserved

Publication Date

December 2022

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