Yields and stormwater loads of microplastics in five urban stormwater catchments (City of Kitchener, Ontario, Canada)

• MP concentrations, loads, and yields quantified across five stormwater catchments. • Hydrologic modeling coupled with sediment surveys and particle-mass balances. • Results reported in both particle- and mass-based units. • MP yields resolved by polymer type, size class, and particle shape. • Rubber and sediment yields covaried with MP yields and land use metrics. Urban stormwater runoff is a major pathway for microplastic (MP) pollution to aquatic environments. In this study, MPs from five st