Title: Anthropogenic Litter and Microplastic in Urban Streams: Abundance, Source, and Fate

Introduction The abundance of anthropogenic litter (i.e., garbage; AL) in marine ecosystems has received attention from researchers, the public, and the media. AL has many detrimental ecological effects such as ingestion and entanglement by animals and assistance in invasive species dispersal (Moore 2008). Accumulation of AL in the environment also presents an economic burden from costs related to clogged sewers and AL removal, and may represent potential hazard to human health (i.e., injury). Rivers transport materials such as organic matter, nutrients, and pollution between terrestrial and marine ecosystems. While many studies suggest rivers are an important source of AL to marine habitats (Stefatos 1999, Galgani et al. 2000, Hammer et al. 2012), the abundance, movement, and ecosystem effects of AL in rivers are unknown.