Date of Award


Degree Type


Degree Name

Master of Science (MS)




The accumulation and ecological effects of anthropogenic litter (AL) and microplastic are well-documented in marine ecosystems, but these materials’ abundances in rivers is unknown. AL enters rivers from recreation, runoff, and illegal dumping. Microplastic fibers and pellets are abundant in wastewater treatment plant (WWTP) effluent which enters rivers. Our objectives were to: (1) quantify AL abundance and composition in urban streams, (2) measure AL flux, accumulation, and export, and (3) measure riverine microplastic concentration and analyze its bacterial communities. We collected AL from 5 urban streams and observed greater AL density in riparian habitats and greater mass in benthic habitats. We monitored AL flux and demonstrated that material type and hydrology mediate AL’s movement. Surface water samples collected upstream and downstream of 9 WWTPs revealed higher microplastic concentrations downstream at all but 2 streams. Analyzing 16S rRNA next-generation sequencing data demonstrated that microplastic selects for plastic-degrading, biofilm-forming, and pathogenic bacteria.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.