CAS-MNP: Evaluating Degradation Products and Changes in Colloidal Properties of Microplastics During Photochemical Weathering

University Of Wisconsin-Milwaukee, Milwaukee WI

Investigators

Abstract

This award is supported by the Environmental Chemical Sciences (ECS) Program in the NSF Division of Chemistry. Professor Laodong Guo and his students in the School of Freshwater Sciences at University of Wisconsin-Milwaukee will study the weathering of microplastics / microfibers in aquatic environments. The kinetics, products, and mechanisms of these degradation processes will be determined. Microplastics and nanoplastics are ubiquitous, persistent, and toxic in aquatic environments and have been recognized as emerging contaminants. Nanoplastics are believed to have higher toxicity to organisms. The project will integrate research, education, and outreach through the participation of graduate and undergraduate students, especially underrepresented students and undergraduate research fellows, promote multidisciplinary collaborative research, and augment the training of graduate and undergraduate students in environmental chemistry and freshwater sciences. Microplastics are an important issue in the Great Lakes Region and subject increasing regulation by local and state ordinances. The project team will work with relevant federal/state agencies, stakeholders, and the general public, including K12 students, to share research findings on the fate and transport of microplastics in aquatic environments and their potential impacts on ecosystem and human health. Despite their importance, little is known about the fundamental environmental chemistry of micro- and nano-plastics (MNP), photochemical reactivities, and changes in their surface and colloidal properties and environmental behavior during and after weathering. To fill the knowledge gap, the project team will conduct research using controlled laboratory experiments on representative microplastics and microfibers. The degradation products from microplasics, including dissolved organic molecules and nanoplastics, will be characterized for chemical and optical properties using total organic carbon analyzer and ultraviolet-visible and fluorescence spectroscopy. Changes in surface and colloidal properties, such as zeta-potential and hydrodynamic size-distribution, will be determined using dynamic light scattering technique and asymmetrical flow field-flow fractionation coupled with multiple angles light scattering detectors. In addition, Fourier-transform infrared spectroscopy and Micro-Raman spectroscopy will be used to characterize plastic polymers and functional groups. 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.