"Micro- and Nanoplastics: A Potential Threat to Agroecosystems"

This event is sponsored by FAMU-FSU Engineering Department of Chemical & Biomedical Engineering.

Abstract: Microplastics (MP) and Nanoplastics (NP) are an “emerging pollutant of concern” (European Environment Agency) that serve as a potential threat to food production and water systems globally, hence to human health. M/NPs reside in agricultural soils to a significant extent (~4400 particles/kg), where they reduce soil quality, harm soil biota, including microorganisms and plants, and serve as a reservoir of M/NPs, the latter of which can undergo transport into waterways and air. Measuring, characterizing, and investigating dynamics of M/NP in soil environments is challenging due to the former’s small concentrations and the heterogeneity and complexity of the particles and the ecosystem. The behavior and toxicity of M/NPs is strongly related to the presence of an adsorbed or “corona” layer of natural organic matter, extracellular polymeric substances, heavy metals, and hydrophobic minor components (e.g., pesticides and plasticizers). This presentation will focus upon our recent research involving NP behavior near water-soil interfaces. Using wet grinding as a surrogate method to mimic the low-energy processes that slowly degrade MPs in soil, we found that NPs formed are bimodal in their size distribution (500-1200 nm and < 200 nm, respectively) and that minor components in the M/NPs leach out. Our studies using small-angle neutron scattering (SANS) and batch tests demonstrate that collisions between soil particles and NPs reduce the occurrence of homoaggregation of NPs and the size of the larger NP subpopulation. Collectively, these results demonstrate the importance of electrostatic attractive and hydrophobic interactions in controlling the behavior of M/NP at interfaces and the complexity of the systems involved.

Douglas G. Hayes

Institute Professor of Biosystems Engineering

University of Tennessee

Speaker Bio: Dr. Douglas Hayes, Institute Professor of Biosystems Engineering at the University of Tennessee (UT), received his BS from Iowa State University in 1986 and his PhD in 1991 from the University of Michigan, both degrees in Chemical Engineering. He also earned an Executive MBA- Strategic Leadership degree from UT in 2022. He served as a postdoctoral research scientist for the US Department of Agriculture from 1991-1993 and then a Professor of Chemical Engineering at the University of Alabama in Huntsville from 1994-2003, before joining UT in 2004. He currently serves as Editor-in-Chief of Journal of Surfactants and Detergents and is on the editorial board for three other journals. He has received several awards, including being named Fellow of the American Oil Chemists’ Society. He has coauthored over 115 journal articles, 24 book chapters and co-edited 3 books. His research interests include biodegradable plastics, environmental impacts of micro- and nanoplastics, surfactant self-assembly systems, and enzymatic reactions in nonaqueous media.