NSF Award
2404304
This project is jointly funded by the Environmental Chemical Sciences Program in the Division of Chemistry and the Established Program to Stimulate Competitive Research (EPSCoR). Professor Ann Ojeda at Auburn University and Professor Natalia Malina at Florida Atlantic University and their students will study how dissolved organic matter impacts the degradation of chlorinated organic contaminants when exposed to sunlight. Chlorinated organic contaminants are widely used in industry as solvents or chemical reactants and enter the waterbodies with accidental spills or municipal wastewater effluents. Surface water in streams, rivers, and lakes contains a wide range of dissolved organic matter, which is a complex mixture of molecules derived from plant material and microorganisms. When exposed to sunlight, chlorinated contaminants interact with dissolved organic matter and sunlight to degrade into a mixture of different compounds, called daughter products. The goal of this project is to investigate how the chemical composition of dissolved organic matter relates to the degradation pathway of chlorinated compounds and produces the cocktail of parent and daughter compounds that are detected in the environment. The data generated in this project will allow us to better understand the reasons behind the formation of toxic chemicals in water systems and ultimately help protect human and ecosystem health. The proposed research will also cultivate the next generation of researchers at both the graduate and undergraduate levels, who can work productively in teams and whose expertise covers a broad spectrum of environmental sciences.<br/><br/>This project will focus on the photodegradation pathways of 1,2-dichlorobenzene and triclosan in the presence of dissolved organic matter derived from two sources: algae and an isolate from Suwannee River. An array of mass spectrometric techniques will be combined to measure contaminant concentration, dissolved organic matter molecular composition, and degradation mechanisms of chlorinated organic contaminants. The quantum yield of the reactive oxygen species formed by dissolved organic matter under the light will be measured as well. Stable isotope enrichment factors will be first measured for 1,2-dichlorobenzene so that specific pathways of degradation can be established and then related to the chemical composition and the quantum yield of reactive oxygen species of each type of dissolved organic matter. This knowledge will be applied to study the photodegradation pathways of triclosan, a more complicated molecule with a wider range of potential degradation pathways. The focus of this project is to identify the molecular characteristics of dissolved organic matter that drive the formation of dioxins, a group of highly toxic daughter products produced from degradation of triclosan.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
