MICROPLASTIC CONCENTRATION AND TYPE IN A CENTRAL ILLINOIS URBAN STREAM

Microplastics have become an increasingly pervasive problem in many aquatic ecosystems. To date, most microplastic research has focused on marine systems as well as larger lakes and rivers. Studies conducted in the Chicago, Seine, and Danube Rivers respectively found the mean microplastic concentrations to be: 1.94 microplastics per m³, 30 microplastics per m³, and 0.32 microplastics per m³. We investigated the microplastic concentrations and types in a small urban stream and its tributaries. We also considered watershed- and reach-scale characteristics in order to determine the relationship between the characteristics and microplastic content. Grab samples were collected from Sugar Creek and respective tributaries during summer and early fall. The samples were processed using a standard method. We found that microplastic concentrations in a small urban stream can be orders of magnitude greater than those found in larger rivers. Upstream samples had an average concentration of 1,300 microplastics per m³ while the downstream average was 2,000 microplastics per m³. Land use is expected to influence the types and concentrations of microplastics. Our results indicate that urban landscapes may be major contributors to microplastics in freshwater environments.