Microplastics: Investigating water pollution in an Anacostia River tributary

Microplastics are small (<5mm) plastic particles resulting from anthropogenic activity that pollutes freshwater and marine environments. Urban freshwater systems are in close proximity to microplastic sources. It is important, therefore, to quantify and categorize the microplastics present in these bodies of water to better understand the sources of these pollutants and the factors affecting their concentration. In this study, we analyze the microplastic content of water samples collected biannually in 8 transects of Nash Run, a tributary of the Anacostia River. Using water filtration coupled with microscopy, we investigate the density of microplastics along the transects by counting and classifying the pieces in each sample according to NOAA Marine Debris methods. Our preliminary analysis suggests that there are significant differences in the microplastic content between transects as well as between seasons, with the majority of the samples consisting of synthetic microfibers. The concentration for each transect ranges from 26 to 100 fibers/L for Spring 2019, while we have detected lower abundances in Fall 2019. Water samples were collected in late February 2020 as well. Additional analyses are ongoing for comparisons across seasons and transects, and chemical analyses will be conducted to identify the types of polymers present.