CAREER: An Investigation of Microplastics Fate and Contaminant Transport in Storm Runoff, The Nexus of Environmental Engineering and Material Sciences

The use of plastics in consumer products and materials results in the release of small particles of plastic known as “microplastics” that can pollute the environment. These microplastics are persistent in the environment and will typically take hundreds of years to decompose completely. Microplastics can be transported through water, air, and through the food web following ingestion and uptake by animals and other organisms.

In addition, microplastics can also absorb toxic pollutants, causing them to spread further and faster in the environment, including the world’s oceans. Although a majority of microplastics in marine environments originate from inland sources, the relative importance of microplastic pollutants released in urban storm runoff to surface waters is still poorly understood.

The goal of this CAREER project is to close the critical knowledge gap on the environmental degradation of microplastics and how they facilitate the transport of heavy metals in urban stormwater. Successful completion of this research will greatly advance our understanding of microplastic sources in urban environments and how they mobilize heavy metals.

Such knowledge will greatly aid the development of effective stormwater management strategies. Additional benefits to society will result from advancing scientific literacy and improving the Nation’s STEM workforce through the development of educational materials for K-12 teachers to educate their students on plastic pollution and inspire them to pursue careers in environmental engineering and science.

The goal of this CAREER project is to utilize material science and environmental engineering interdisciplinary research to understand processes controlling the fate and transport of microplastics in urban stormwater. This will be achieved through the specific research objectives to elucidate the roles that intrinsic and extrinsic material properties play in influencing the kinetics of microplastic photodegradation and particle fragmentation, and examine how aqueous physiochemical processes impact microplastic facilitated transport of heavy metals present in stormwater.

The fundamental knowledge developed in this research will provide a better conceptual understanding of the mechanisms controlling microplastics persistence and contaminant transport within the urban environment, which is crucial to estimating their negative impacts on the ecosystem and developing effective control measures and remediation strategies. This investigation represents one of the first efforts to develop a comprehensive mechanistic understanding of the physical and chemical processes that control microplastic fate and contaminant transport in stormwater.

A key novelty of the proposed research addresses the mismatch between laboratory experiments that generally use virgin plastic pellets and beads by using environmentally relevant degraded secondary microplastics generated through the disintegration of larger plastic segments. This approach using microplastic fragmentation under abrasive tension will facilitate the development of dynamic models to predict microplastics disintegration under various mechanical loadings and physical conditions.

The integrated educational plan will benefit society by providing professional development for K-12 educators through annual workshops to increase the recruitment of underrepresented students into environmental engineering. Additional benefits will result from dissemination of results to inform water managers, practitioners, policymakers, and other stakeholders in Tennessee on the presence of microplastics in stormwater, and ways to combat the problem.

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.