Shannon M. Meppelink, Dana W. Kolpin, David M. Cwiertny, Carrie E. Givens, James L. Gray, Lee A. Green, Grant R. Hemphill, Laura E. Hubbard, Luke R. Iwanowicz, Rachael F. Lane, Anlin J. Larson, Gregory H. LeFevre, Alyssa L. Mianecki, John W. Scott, Darrin A. Thompson, Michaelah C. Wilson

Potential sources of microplastics and per- and polyfluoroalkyl substances (PFAS) to rural streams include the recycling of livestock manure and municipal biosolids to agricultural fields. While these wastes may replenish organic matter and nutrients, application may also constitute a reservoir of microplastics and PFAS, a possible contaminant pathway to the environment. Plastics and PFAS have beneficial properties that led to their use in a myriad of household and industrial applications. The same properties that made them attractive for use has led them to be called “forever” contaminants due to persistence, mobility, and affinity for bioaccumulation in aquatic and terrestrial organisms (including humans). Mounting evidence indicates deleterious human and environmental effects from exposures to these contaminants (i.e., changing predator-prey interactions, cancer, and immune dysfunction). Research on microplastics and PFAS has accelerated recently with most research focused on urban aspects, thus limited data exist regarding exposures of microplastics and PFAS in small, rural agricultural streams. To fill this gap, 15 watersheds (varying from 5 to 333 square miles) in Iowa with a range of agricultural and urban land uses, livestock and human densities, and biosolid applications were studied. Importantly, this study has a multi-matrix approach. Water, bed sediment, and fish samples were analyzed for mass and counts of microplastics and concentrations of 34 PFAS compounds. Samples were collected at or near base-flow conditions April-June 2021. Multi-matrix sampling avoids focusing solely on stream water, which would likely lead to a substantial underestimation of contaminant exposures. Previous research has shown that bed sediment is an important exposure pathway for microplastics and PFAS. Thus, it is hypothesized that combining water and bed sediment results will lead to near ubiquitous exposures of aquatic and terrestrial organisms to microplastics and/or PFAS for this study. Additionally, fish tissue will provide a broader understanding of aquatic exposures that could be missed from a single water sample. Results of this study provide an increased understanding of microplastic and PFAS exposures and corresponding potential propagation within the riparian food web.