Plant-Based Removal of Emerging Contaminants and Pesticides from Contaminated Surface Water

University Of Florida, Gainesville FL

Investigators

Abstract

1435522 Wilson Plant-Based Removal of Emerging Contaminants and Pesticides from Contaminated Surface Water Water quality throughout the United States and elsewhere in the world is a major concern. Non-point source contaminants originate from many different land-use activities, and include organic pesticides used in landscape maintenance as well as contaminants of emerging concern associated with use of reclaimed water for irrigation. Methods are needed to remove these bioactive compounds from contaminated surface water. Stormwater retention ponds were originally designed to reduce sediment discharges from watershed drainage basins by slowing the flow of the drainage water. These systems remove sediment-associated contaminants, but are not designed for removal of dissolved contaminants. Floating bioremediation islands planted with emergent macrophytes may provide an innovative option for adding organic contaminant removal functions to stormwater retention ponds. Emergent plants grow on a mat floating on the water surface, rather than rooted in the bottom sediments. Unlike in constructed wetlands, these emergent plants can tolerate wide fluctuations in water depth that are typical of stormwater retention ponds. Such systems have been used for removal of nutrients and heavy metals from stormwater. However, no information is available regarding the removal of organic pollutants. This project has the potential to provide dissolved organic contaminant removal options to every community in the United States and the world, where they are present in stormwater retention ponds. This could reduce ecological risks and develop higher quality water sources. This project will also provide an educational opportunity for a doctoral student, who will learn and routinely practice critical thinking skills, chemical extraction and analysis methods, trouble-shooting and operational principles, and statistical analysis. In addition to providing tangible improvements in water quality where implemented, results from the studies will be also packaged in written and video format for incorporation into the PI's extension program at the University of Florida/IFAS. Materials will be used to train extension agents, students, environmental managers, teachers, agency staff, and any other stakeholders who can use the information. The overall objective of this project is to evaluate the potential for enhancing the removal of harmful organic contaminants from contaminated surface water using emergent wetland plants grown on floating islands. The plants essentially function as biological pumps and as a substrate for possibly synergistic, contaminant-degrading microflora to attach and grow. Specific aims are to characterize the kinetics of pollutant removal, the fate of the contaminants within the phytoremediation system, and the effects of plant density and type on phytoremediation efficiency. This project focuses on eight surrogate contaminants with Log Kow values ranging from 1.4-4.2, the optimal range for plant uptake. Additionally, two emergent wetland plant species are evaluated. These are hearty plants that have been shown to remove organic herbicides from hydroponic solutions. The fate and possible degradation of contaminants by the plants will be evaluated using non-radiolabeled standards and Gas Chromatography-Mass Spectrometry analysis. Mass-balance studies to measure the kinetics of uptake and accumulation sinks will be conducted using radiolabeled contaminants and mass-balance chambers. Predictions of potential mass uptake relative to cumulative water volume transpired through the plants will be made. These predictions will be validated using mesocosm-scale field studies. Results will define expectations for removal efficiencies and will be useful for designing systems targeting specific contaminants based on their properties.