10,000 metric tons of plastic debris enter Great Lakes every year – study
The study, conducted by Rochester Institute of Technology (RIT), used the population dynamics up to 62 miles (100 kilometers) from the shores of the Great Lakes, as well as hydrodynamic modeling to simulate the distribution of plastic debris from 2009 to 2014, the university’s news portal reports. Data from the National Oceanic and Atmospheric Administration Great Lakes Coastal Forecast System was used to simulate currents transporting plastic debris throughout the lakes.
The research determined that plastic accounts for approximately 80 percent of the litter on the shorelines of the Great Lakes.
The majority of the waste, 5,000 metric tons per year, enters Lake Michigan. Lake Erie takes second place, with 2,500 metric tons of plastic waste per year, and Lake Ontario places third with 1,400 metric tons. Lake Huron receives 600 metric tons, and Lake Superior receives 32 metric tons per year.
Highly populated areas in the US and Canada are mostly to blame for the waste, including Chicago, Toronto, Cleveland, and Detroit.
"Most of the particles from Chicago and Milwaukee end up accumulating on the eastern shores of Lake Michigan, while the particles from Detroit and Cleveland end up along the southern coast of the eastern basin of Lake Erie," lead author Matthew Hoffman, an assistant professor at RIT's School of Mathematical Sciences, told the university’s news portal.
"Particles released from Toronto appear to accumulate on the southern coast of Lake Ontario, including around Rochester and Sodus Bay," he added.
The research represents the first time that mathematical modeling has been used to study the scope of the issue over time and spatial scales.
"This study is the first picture of the true scale of plastic pollution in the Great Lakes," Hoffman said.
The research notes that plastics could be consumed by wildlife and potentially enter the food chain.
It also found that debris travels differently in the Great Lakes than in the ocean. Instead of the "garbage patches" that are found in the ocean, plastic in the lakes is carried by persistent winds and currents to the shore, often washing up in another state or country.
The Great Lakes form the largest group of freshwater lakes on Earth, containing 21 percent of the world's surface fresh water by volume and covering a total surface area of 94,250 square miles (244,106 square kilometers). They have long been referred to as inland seas, due to their sea-like characteristics including rolling waves, great depths, and strong currents.