from drinking water to clouds in the atmosphere - but scientists have yet to fully uncover how severely they impact the environment or the precise factors driving their buildup. A new study published by researchers at Penn State offers a fresh view of how microplastics traverse and influence watersheds, such as rivers and streams, across Pennsylvania and the world at large.
The team collected sediment samples from several freshwater ecosystems across Pennsylvania, comparing those readings to data previously taken from six sites in New York and New Jersey, as well as countries around the world. Modeling this data revealed more about how pollutants move through freshwater environments and the potential roles humans play in rising levels of plastic content, even in remote areas, but the researchers said the work also raised more questions. They recently detailed their findings in Science of the Total Environment.
Nathaniel Warner, associate professor of environmental engineering, said much is unknown about microplastics - slivers of plastic that can range in size anywhere from one micrometer, a fraction of the width of a single human hair, to five millimeters, about the size of an M&M candy cut in half. What is known, however, is that more microplastics are in the environment every year.
Previous research from Warner's lab had correlated the growth of these synthetic materials, which the Environmental Protection Agency recently moved to classify as contaminants, in the environment with increasing plastic production over the course of the last century.
"Plastics are in the environment everywhere you look," Warner said. "Many studies have examined how microplastics interact with marine environments, but there has been much less research studying the concentrations of microplastics inland, and how these plastics move through freshwater environments like rivers and streams."
This motivated the team to collect sediment samples from three watersheds across Pennsylvania - the Conemaugh watershed in the southwest, the French Creek watershed in the northwest and the Spring Creek watershed towards the center of the state. They collected samples from several points at each site, starting at the headwaters, or upstream source, of the watershed and moving downstream. This data, combined with existing measurements taken from 45 sites in drainage basins of the Oswego, Delaware, Susquehanna and Allegheny rivers, offered a comprehensive view of microplastic content in mid-Atlantic freshwater, Warner said.
