Three of the five Great Lakes—Huron, Superior and Erie—are awash in plastic. But it’s not the work of a Christo-like landscape artist covering the waterfront. Rather, small plastic beads, known as micro plastic, are the offenders, according to survey results to be published this summer in Marine Pollution Bulletin. “The highest counts were in the micro plastic category, less than a millimeter in diameter,” explained chemist Sherri “Sam” Mason of the State University of New York at Fredonia, who led the Great Lakes plastic pollution survey last July. “Under the scanning electron microscope, many of the particles we found were perfectly spherical plastic balls.”
Cosmetics manufacturers use these micro beads, or micro exfoliates, as abrasives in facial and body scrubs. They are too tiny for water treatment plants to filter, so they wash down the drain and into the Great Lakes. The biggest worry: fish such as yellow perch or turtles and seagulls think of them as dinner. If fish or birds eat the inert beads, the material can deprive them of nutrients from real food or get lodged in their stomachs or intestines, blocking digestive systems.
In early April, at the 245th National Meeting & Exposition of the American Chemical Society in New Orleans, chemist Lorena Rios of the University of Wisconsin–Superior, announced that her team found 1,500 to 1.7 million plastic particles per square mile (2.5 square kilometers) in the lakes, with the highest concentration in Lake Erie. Rios is collaborating on the study with Mason and 5 Gyres Institute, a Los Angeles-based research group studying garbage patches in five subtropical gyres in the Atlantic, Pacific and Southern oceans.
Typically, the oceans contain a higher percentage of debris in the one- to five-millimeter-diameter size, whereas, for unknown reasons, the three Great Lakes the team studied have a higher concentration, approximately 85 percent, of micro plastics measuring less than one millimeter in diameter.
Rios did not find any plastic in the fish samples she tested, but they were all from Lake Superior, which has less of a problem because of the way water flows through the lakes. “Lake Superior had a little less plastic than Lake Huron, which was far less than Lake Erie,” Rios says. “So, it will be really interesting to see [this summer] if the counts in Lake Ontario [downstream from Erie] are even higher.”
The Ohio Department of Natural Resources (ODNR) Fairport Fisheries Research Station has found plastic in yellow perch during their ongoing diet-analysis studies, according to Rios. Although they have not published any data about plastic in the fish guts, they will begin sending fish to her for analysis. “This summer, we’re going to look for the presence of plastics in the diet, and if we find any, send it to Dr. Rios to confirm the type of polymers in the plastics,” confirms fish biologist Ann Marie Gorman of the Fairport Harbor Fish Research Unit.
Rios’s background includes studying plastic debris and persistent organic pollutants (POPs) in the Pacific garbage patch. Her chemical analysis of the Lake Erie samples revealed varying levels of polycyclic aromatic hydrocarbons (PAHs), the product of incomplete combustion usually found near steel mill coking plants or from burning wood or petroleum products. In the mix was also polychlorinated biphenyls (PCBs) and other organochlorides such as the potent and poisonous insecticide DDT. PCBs were used in electric transformers and motors, until Congress banned them from production in 1979 because of their ability to cause cancer in humans.
Rios reports that the bits of plastic, essentially “solid oil,” absorb the chemicals like a sponge. The concentration of PAHs in Lake Erie is twice as high as that in the Atlantic because the ocean’s size dilutes the little pellets.
From Scientific American