Nurdles: Impact of Primary Microplastic Sources on Their Presence in Great Lakes Beach Sediment

Nurdles, i.e., preproduction microplastics, are an emerging contaminant in aquatic environments. Improper management of nurdles at land-based facilities and offshore spills are responsible for an estimated 230,000 tons entering the world's oceans annually. A recent study found that Great Lakes coastal sediments contain an average of 19.1 nurdles/m 2 . Microplastics are highly mobile once released to aquatic environments, and migrate on the water surface, in the sub-surface, and in sediment. Polymers that have circulated in the environment for extended periods will display physical and chemical weathering that can be detected with light microscopy and Fourier-transform infrared spectroscopy (FTIR). Preliminary work using FTIR on nurdles collected along the shores of Lake Michigan found that they lack characteristic regions consistent with oxidation (weathering), i.e., between 1650 – 1750 cm -1 . The polymers in the Great Lake study and preliminary Lake Michigan data show little physical or chemical weathering, indicating limited environmental exposure. The objectives of this study are to: (1) review all potential sources (e.g., railroads, manufacturers, major ports, port facilities, known spills, landfills) for the presence of nurdles in the Great Lakes watershed within 10 km of shore; (2) assess if proximity to a known source increases the presence of nurdles detected in the environment; (3) evaluate if proximity to multiple sources increases the presence of nurdles; and (4) determine if proximity of sources to each other increases the presence of nurdles in the environment. Multidimensional Scaling will be used to construct a visual representation of the complex relationships between sources and contamination, ordinating possible source types to the presences/absence of nurdles in beach sediment where proximity will indicate similarity.