Microplastic pollution in the surface waters of the Laurentian Great Lakes

Neuston samples were collected at 21 stations during an ~700 nautical mile (~1300km) expedition in July 2012 in the Laurentian Great Lakes of the United States using a 333μm mesh manta trawl and analyzed for plastic debris. Although the average abundance was approximately 43,000 microplastic particles/km², station 20, downstream from two major cities, contained over 466,000particles/km², greater than all other stations combined. SEM analysis determined nearly 20% of particles less than 1mm, which were initially identified as microplastic by visual observation, were aluminum silicate from coal ash. Many microplastic particles were multi-colored spheres, which were compared to, and are suspected to be, microbeads from consumer products containing microplastic particles of similar size, shape, texture and composition. The presence of microplastics and coal ash in these surface samples, which were most abundant where lake currents converge, are likely from nearby urban effluent and coal burning power plants.