CAREER: CAS: Discovering the Early Stages of Photodegradation of Emerging Contaminants in Marine Relevant Environments

About This Grant

With support from the Environmental Chemical Sciences (ECS) program in the Division of Chemistry and the Established Program to Stimulate Competitive Research (EPSCoR), Professor Tolga Karsili of the University of Louisiana at Lafayette is investigating the UV-induced breakdown of Contaminants of Emerging Concerns (CECs) in marine environments. CECs include chemicals that are found in everyday products like cosmetics, pharmaceuticals, and cleaning products and end up in oceans through wastewater or recreational activities. Their photodegradation mechanisms in saltwater environments, particularly in the sub-nanosecond timescales on which environmentally toxic intermediates are expected to form, remain largely elusive. Professor Karsili and his team will use quantum chemistry and ultrafast pump-probe spectroscopy to investigate how common CECs photodegrade in bulk seawater solutions and at the air-sea interface. Their studies could contribute to the fundamental understanding of the photodegradation mechanisms of common CECs in marine relevant environments and could provide detailed information on the environmental impact of CECs when discharged into surface waters. The educational and outreach efforts of the project include the use of virtual reality to help undergraduates visualize complex chemical concepts and hosting a computational chemistry summer camp for local high school students. CECs are mostly lipophilic, meaning they preferentially accumulate at the air-water interface as well as within the bulk aqueous phase. The Karsili research group will develop machine-learning (ML) potentials trained using high-level GPU-accelerated quantum chemical data. These ML potentials will be integrated with ab initio molecular dynamics to predict Henry’s law solubility constants for a range of common CECs in seawater and to simulate the excited-state dynamics of photoexcited CECs both in bulk seawater and at the air-seawater interface. To validate and these results, the team will conduct femtosecond pump-probe laser spectroscopy experiments on representative CECs in both synthetic and natural seawater – focusing on the vital femtosecond to nanosecond timescale on which potentially toxic intermediates are formed. Fieldwork in collaboration with NOAA’s Southeast Fisheries Science Center will involve seawater sample collection along the U.S. Gulf Coast. Educational efforts include integrating the simulations into virtual reality (VR) platforms to produce interactive, open-source teaching tools that visualize abstract physical chemistry concepts. The project will also establish a summer boot camp in computational chemistry for high school students, promoting early STEM engagement and supporting transitions to college-level science education. 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.