Plastics for Life
This is no news flash, but plastics don't biodegrade. And yet almost 50% of it never sees a landfill. Worse, approximately 80% of the plastic debris in our oceans comes from the land. Plastics inevitably become part of our ecosystem from top to bottom. Of course, we think of the most pure environments as those in the highest mountaintops. The springs percolate into the headwaters on our mountain peaks, cascade down, hopping rocks and tumbling through forests into lakes, eventually emerging into larger rivers and ultimately out into the oceans. Along the way human influence affects their purity. Generally, we have hypothesized that water starts pure and becomes more polluted with each tier of drainage but recent research suggests that we are not starting with as clean a slate as we thought.
Researchers have recently found an alarming number of microplastics in Lake Garda, a subalpine lake located in the Adamello-Presanella Mountains, a part of the Italian Alps. The microplastics found in Lake Garda were a surprise because of its elevation; researchers had anticipated pure unpolluted waters.
Microplastics, small pieces of plastic, typically less than 5 millimeters (0.2 inches) in size come from a variety of man-made sources. Some of it is produced when large pieces of plastic breakdown in the environment. Other types come from synthetic fibers broken down from clothing, other consumer and personal care products as well as construction materials.
Researchers led by Christian Laforsch of the University of Bayreuth in Germany conducted the Lake Garda study and found the numbers of microplastic particles in sediment samples from Lake Garda were similar to those found in studies of marine beach sediments. Laforsch said, "The mere existence of microplastic particles in a subalpine headwater suggests an even higher relevance of plastic particles in lowland waters." Ingestion into the food chain is likely to blame.
"Next to mechanical impairments of swallowed plastics mistaken as food, many plastic-associated chemicals have been shown to be carcinogenic, endocrine-disrupting, or acutely toxic," said Laforsch. "Moreover, the polymers can adsorb toxic hydrophobic organic pollutants and transport these compounds to otherwise less polluted habitats. Along this line, plastic debris can act as vector for alien species and diseases."
Half a world away other microplastic studies are being conducted on the Great Lakes. Sherri Mason, Associate Professor of Chemistry at the State University of New York (SUNY) is measuring the incidence of microplastics in the Great Lakes. Initial studies on Lakes Superior, Huron and Erie were completed in 2012. The remaining two, Lakes Ontario and Michigan will be complete this year. The highest number of microplastic particles so far has been found in Lake Erie where more than 600,000 pieces per square kilometer were found in parts of the lake.
Because microplastics are not biodegradable, they persist in the environment for many years. When entrapped within the sediment they are likely to persist for decades. Clearing the pollution is likely to be expensive and difficult.
Regardless of which body of water is being tested though, all of the contributing scientists are concerned that ingested microplastics may impair the ability of organisms to feed, leading to disruptions in aquatic food webs. Additionally, microplastics are likely to play a role in the transfer of chemical contaminants into aquatic biota affecting all of the world's ocean and watersheds.
Reefs of Lake Garda photo via Shutterstock.