Microplastic pollution is an escalating threat to marine ecosystems, with recent studies showing that stormwater runoff transports the majority of terrestrial microplastics to the ocean. While long-term solutions such as upstream source control and green infrastructure are essential, their widespread implementation will take decades, highlighting the need for immediate interception strategies. The Clean Streets, Clean Seas project, funded by NOAA/National Sea Grant's Marine Debris Competition, investigates whether non-structural and structural best management practices (BMPs) commonly used by municipalities for sediment, trash, and pollutant removal can also effectively capture microplastics. This presentation will provide an update on the project’s research findings as well as its outreach and education initiatives. Results from four street sweeping and stormwater interception studies studies will be presented, including 1) a pilot study using simulated rainfall events that demonstrated reductions in microplastic concentrations following street sweeping; 2) a field study comparing estimated microplastic removal by street sweeping to estimated microplastic loads entering Mission Creek in Santa Barbara, CA during rain events, supporting the role of street sweeping in reducing tire wear particle discharges to the ocean; 3) a controlled pickup-efficiency study testing six street sweeper models, which found that microplastic particles across multiple size ranges and material classes were removed with the same or greater efficiency as simulated street dirt; and 4) a study evaluating the effectiveness of full-capture trash devices and catch basin cleaning for intercepting microplastics. In addition, the presentation will highlight the work of the project’s Education and Engagement Working Group, which is adapting existing K-12 microplastics curricula to incorporate education on street sweeping, stormwater runoff, and microplastics prevention. To date, findings indicate that street sweeping is a promising and practical strategy for intercepting microplastics from urban surfaces and reducing pollutant loads discharged to storm drains, creeks, and the ocean.  

Workshop Host: USC Sea Grant