This project aims to evaluate the effectiveness of best management practices (BMPs) in capturing microplastics from surface runoff and percolated stormwater, and to investigate the extent to which microplastics that are associated with per- and polyfluoroalkyl substances (PFAS) contribute to PFAS release through various processes, including fragmentation into nanoplastics. The specific objectives of this project are to:

• Compare and optimize methods to measure microplastics in stormwater and sediments and quantify microplastic accumulation in stormwater treatment systems by analyzing deposited sediments and stormwater in outfall to surface waters.
• Identify the major transport pathways where microplastics accumulated in stormwater BMPs may re-enter downstream water bodies and carry PFAS along with them.
• Evaluate the fragmentation of microplastics to nanoplastics accumulated in stormwater BMPs and resulting leaching of PFAS during the fragmentation processes.

This project will utilize advanced spectroscopical tools to quantify microplastics from stormwater and sediments collected from different locations . A combination of controlled laboratory and field studies will quantify the transport and retention mechanism of microplastics in BMPs and examine the impact of accumulated microplastics on PFAS release and biotransformation. Advanced analytical tools will be used to compare the concentration of microplastics in the same sample and variability between samples and develop a standard protocol to inform how to best quantify microplastics. Controlled laboratory column experiments will be conducted to simultaneously compare microplastics mobilized by resuspension and infiltration. The results of the laboratory study will be validated from field observation by analyzing microplastic concentrations in filter media depth profile and comparing influent and effluent concentrations of microplastics in BMPs during storm events. Fragmentation of microplastics into nanoplastics and its effects on plastic surface properties and binding or leaching of PFAS will be examined by exposing microplastics to stressors including ultraviolet light and common enzymes found in root zones.

This research will provide tools to predict microplastic-mediated PFAS transport in stormwater BMPs or conveyance systems. The results will not only help develop an improved method for microplastic characterization, but also inform how to best capture microplastics by implementing the most effective BMP per cost of design and operation/maintenance. Eventually, the results will inform how to best utilize the existing stormwater conveyance and treatment systems to minimize any potential impacts of microplastics on PFAS-impacted downstream waterbodies. (Anticipated Project Completion – 2028)