Riverine Microplastic Fluxes

Globally, rivers have been found to contain high concentrations of microplastics and are also the major conveyors of microplastic pollution to the ocean. This has engendered an increased focus on microplastic sources, transport, and fate in riverine systems. But how should we design microplastic monitoring plans for rivers if our goal is to quantify concentration, character, and flux? Here we present the results of microplastics monitoring campaigns conducted on several riverine systems draining coastal watersheds in Southern California and discuss lessons learned as well as future directions to support flux-based monitoring of microplastics. Key topics include consideration of microplastic distribution across the water column, sampler performance, concentration and character dependency on discharge/time, and by extension – effective discharge.