Anthropogenic litter and plastics across size classes on a mechanically groomed Great Lakes urban beach

Abstract

Anthropogenic litter and plastic pollution are well-recognized global and Great Lakes stressors, but the distribution of plastic pollution on shorelines is uneven. Beaches in urban areas are close to many potential sources of plastic pollution and often heavily visited, so are likely exposed to high litter inputs. Conversely, beach maintenance activities, including mechanical grooming, may lower litter concentrations. In the summer of 2021, surface litter and > 2 mm anthropogenic materials within the top 5 cm of beach sediment were repeatedly measured along 10 transects at Euclid Beach, in Cleveland, Ohio. Plastics comprised 79 % of litter > 50 mm and 100 % of smaller visible litter on the beach surface. Surface litter concentrations (0.279 pieces m⁻²) were relatively low compared to previously studied Great Lakes strandlines, with mechanical grooming and beach visitor usage influencing litter distribution. However, when plastics within the top 5 cm of the beach sediment were included, Euclid Beach microplastics (54.7 pieces m⁻²) and mesoplastics (45.0 pieces m⁻²) concentrations were among the highest in the Great Lakes. Plastic production pellets were the most common microplastic morphology, while foamed plastics were the most common mesoplastics. Most plastics in the sediment were too small to be removed by mechanical grooming, but fragmentation of larger, weathered plastics is a potential concern deserving further investigation. Overall, our results suggest that urban, mechanically-groomed beaches can have high plastics loads. Such beaches should be strategically included in larger scale studies of plastic pollution along shorelines, especially when considering issues of environmental justice.