MICROPLASTICS IN BEACH SEDIMENT ALONG SOUTHERN SHORES OF LAKE MICHIGAN

The presence of microplastics in marine coastal environments has been a concern since the mid to late 1970s, however it was not until recent years that much thought had been given to microplastics within the Great Lakes environment. Recent studies suggest that the concentration of microplastics within the Great Lakes may be equal too, or even greater than that within marine environments. The objective of this study is to determine the amount and types of microplastics along four Indiana beaches of southern Lake Michigan and see how these quantities compare with microplastics from beaches of other Great Lakes, and with microplastics from marine beaches. We used two methods – 1) volume reduced, swash line (5 m²) collection, and 2) bulk sampling of quadrats (625 cm²) perpendicular to shoreline – to determine amount of microplastics on four Lake Michigan beaches (Porter, Dunbar, Marquette, and Whihala). Microplastic (< 5mm) was classified into five categories: film, foam, fragments, fiber (line), pellets (beads). The most common type of microplastic found along the southern Lake Michigan shoreline was pellets/beads (44%), followed by foam (42%), fragments (12%), film (0.66%) and line (0.44%). Of the beaches studied, the beach with the most amount of microplastic was found to be Whihala with an average of 49.15 particles of microplastic per m². The beach with the least amount of microplastic was Porter with only 5.7 particles of microplastic per m². The average amount of microplastic contained per m² along the four beaches studied is 27.59. This number is five times higher than that found on the shoreline of Lake Huron by other researchers (5.43); it is even higher than that when compared to Lakes Erie and St. Clair. It is important to point out that factors such as plastic density, as well as natural factors such as currents, may cause variations in quantities amongst the different locations. This study will contribute to the growing body of knowledge on the presence of microplastics within the Great Lakes, an important part of communicating the problem to the general public, as well as addressing it. Further work will consist of studying different parts of the coastal system.