**Abstract Text**
Plastic production and pollution continues to increase and with it, microplastic presence in the environment. Microplastics can be transported by stormwater runoff to aquatic ecosystems. In a previous study, we demonstrated that a bioretention cell, a type of green infrastructure, worked effectively to remove microparticles larger than 106 µm from stormwater runoff. Microplastics, plastic particles 1 µm to 5 mm in size, are produced in this size range or consist of larger plastics which undergo wear from mechanical and biological stresses and sunlight exposure causing fragmentation into increasingly smaller sizes. These small sizes pose elevated health risks for humans and other organisms and increased concern for environmental transport. In a bioretention context, smaller size potentially risks microplastic transfer within media pores to connected surface water, groundwater, or underlying drains. Over 2 years in 2018-2019, a bioretention cell was monitored near Toronto, Ontario. Stormwater samples were collected from the inlet and outlet of the bioretention cell with a drainage area consisting of a parking lot made of recycled rubber pavers. Previous results for microparticles between 106 µm to 5 mm showed an 84 % concentration decrease from 186 to 31 microparticles/ L, on average, between the bioretention inlet and outlet. In this work, novel automated imaging spectroscopy techniques were used to analyze microplastics down to 25 µm and microplastic removal was observed at a rate of 79 %. These new results show microplastics down to 25 µm continue to be removed from stormwater by a conventionally-designed bioretention cell.



Bioretention cells remove microplastics in the 25 – 106 micron size fraction (Room 302 A, Monday 7th, 1:30pm-3:00pm)

The International Low Impact Development Conference highlights interdisciplinary practice, research, and implementation of Low Impact Development (LID), Green Infrastructure (GI), Sustainable Urban Drainage Systems (SUDS) and Water Sensitive Urban Designs (WSUD). The focus will be on using our past and present understanding of LID to tune management programs, design practice, and operation and maintenance into the future.