Scientists To Study Movement Of Plastic Pollution In Choptank River

Annapolis MD

28 February, 2022

1:30 PM

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By Whitney Pipkin, the Chesapeake Bay Journal Feb 24, 2022 Plastics swirling around in ocean gyres have garnered plenty of recent media and research attention. But what happens to the pieces that flow through rivers closer to home — or are trapped in marshes and washed up on shorelines along the way? Scientists at the University of Maryland Center for Environmental Science aim to answer that question through a two-year research project kicking off this year. The National Oceanic and Atmospheric Administration's Marine Debris Program chose the project as one of five to receive funding out of a nationwide pool of 72 applicants. The effort will focus on the Choptank River, the largest waterway on the Delmarva Peninsula, which runs through a relatively rural and agricultural region. With the university's Horn Point Laboratory sitting on its banks near Cambridge, on Maryland's Eastern Shore, the Choptank has been thoroughly studied, making it an ideal test case for understanding how microplastics move through river systems. A different microplastics project based in the Chesapeake Bay region recently received a federal grant, too. Last year, the National Science Foundation's Historically Black Colleges and Universities Research Infrastructure in Science and Engineering program awarded $1 million to Morgan State University to study the impact of microplastics on marine life. The work is based out of the university's estuarine lab in Calvert County, MD, with a focus on training students in microplastics research. Microplastics have been found everywhere scientists have looked for them — including in the air over the Pyrenees mountains. That's true in the Chesapeake region, too, where the U.S. Geological Survey has detected the small plastic particles at sampling stations throughout the Bay and its tributaries. The, the researchers in Cambridge want to know where they end up and what happens along the way. "We're looking at how microplastics flow through the system and how they're affected by the system," said James Pierson, a biological oceanographer and associate professor at Horn Point. "As the river is flowing, what happens when [microplastics] move past these marshes? How is that different from what happens in the middle of the channel?" Other research in the region suggests that Bay grass beds could be serving as catch basins for microplastics. One study found the particles in significantly higher concentrations in grass beds than in an adjacent water column in the Potomac River. The beds are also a hotbed of ecological activity where species such as blue crabs could mistake the tiny plastic bits for food. Working with fellow associate professor William Nardin, who specializes in hydrodynamic modeling at Horn Point, the Choptank researchers plan to use old and new tools to answer their questions. The $167,155 federal grant will support the research that could apply to other rivers in the Bay watershed and beyond. In addition to collecting microplastics with a net behind a boat, Nardin will use a drone with a special camera to locate larger plastic debris over a broad area. The work will analyze plastic samples of all sizes, from intact bottles and bags to pieces no larger than a pencil eraser. The scientists will also use microscope and camera technology that's more widely available — rather than what is only on hand in high-tech labs — to identify different types of microplastics gathered from the water. This could help set the stage for school groups or citizen scientists to participate in microplastics research if they can use equipment they have on hand to identify types of plastic. Experiments will look at how a half-dozen types of plastic polymers degrade and move downriver. Are plastics more likely to be trapped in the marsh during summer, when grass beds are thicker, then rejoin the stream channel in the winter? Are more dense plastics likely to sink to bottom sediment while lighter pieces flow farther from the shore? "This will help us make estimates of how the morphology of the river affects the flow of plastics through it," Pierson said. All of the data will feed a hydrodynamic computer model to explain and predict how plastics flow through the river and what factors determine where they land. The hope is to make this information applicable to a wide range of water bodies, informing policy decisions aimed at curtailing plastic pollution. Matt Robinson, environmental protection specialist with the District of Columbia's Department of Energy & Environment, said the work will help guide the Chesapeake Bay Program's Plastic Pollution Action Team, which he chairs. "Research such as this is vital to understanding the impacts of plastic pollution on the Chesapeake Bay and its watershed," Robinson said. His team has pointed to the need for this type of research in Bay waters "to understand the ecological risk of plastic pollution and how these pollutants could impact restoration success." The Chesapeake Bay Journal is a nonprofit news organization covering environmental issues in the Bay region. Sign up for a free subscription at BayJournal.com.