DELINEATING THE SOURCE AND POTENTIAL ECOSYSTEM IMPACTS OF MACROPLASTICS IN SUBURBAN AND URBAN FIRST ORDER STREAMS

Aquatic plastic pollution can have a wide range of negative ecological impacts, including harming the digestive health of aquatic organisms and increasing the potential bioaccumulation of heavy metals. Few studies have investigated the distribution of macroplastics in riverine environments, with even fewer studies focused in upstream areas, despite its substantial role in the delivery of plastics to the ocean. Yet, understanding the sources of plastics to headwater systems could help society take meaningful measures to prevent its introduction to waterways. We collected and categorized litter, including macroplastics (>4mm in diameter), from 20 suburban and urban headwater streams in southeastern Pennsylvania to gain greater insight into its abundance and potential ecosystem impacts. Litter was collected from both the stream channel and banks along a 50-m longitudinal transect immediately downstream of stormwater outlets where streams daylighted. Litter was categorized in accordance with the National Oceanic and Atmospheric Administration (NOAA) Marine Debris Shoreline Survey Field Guide. In total, over 1,000 macroplastics were collected. Plastic film fragments (n = 304), plastic bags (n = 153), and food wrappers (n = 132) were the three most commonly identified items. Subcategory and absolute totals of macroplastics were compared to potential controlling parameters such as relative land cover, population density, and socioeconomic variables in the upstream area. Finally, select plastic litter items were analyzed for metal bioavailability (Al, Ba, Cd, Cr, Cu, Pb, Sb, and Zn) using acetic acid extractions and inductively coupled plasma mass spectrometry. Collectively, the data suggest the need for public education campaigns, municipal plastic ordinances, and other litter prevention measures to protect the ecosystem health of suburban and urban riverine ecosystems.