Microplastics in Urban Watersheds, Southern California, USA

Globally, fluxes of microplastics to marine environments are thought to be dominated by stormflow from urban environments, which may be moderated by storage in estuaries. Fluvial transport of microplastics is primarily a supply-limited phenomenon, but flow field and particle characteristics can result in a wide range of transport modes, from surface load to bedload, with potential ramifications for estuarine transport and fate. Here we report preliminary findings from microplastic monitoring campaigns conducted in a number of streams draining urban watersheds in Southern California, and estuarine wetland and benthic sediment deposits. These studies will serve as the basis for microplastic flux, accretion, and composition evaluation, and inform the optimization of microplastic monitoring in urban systems.