Tabatha Lewis is handling lots of beads these days, but they’re not the kind on necklaces.
The University of Rhode Island senior is using microscopic glass beads to track the path of storm water runoff—sediment and grime—that washes off roads and can damage the environment.
Lewis is teaming up with Engineering and Geoscience Professor Thomas Boving to conduct the study. Her preliminary results were presented recently at the Showcase of Undergraduate Research, Scholarly and Creative Works on the Kingston campus.
With more than 4 million miles of roads in the United States, it’s critical to know what contaminants are in road runoff, and how far they’re traveling on abutting land. Lewis says there is no reliable system in place now to track runoff.
“We intend to change that through our experiment,” says Lewis, of Brookfield, Conn. “And, so far, it looks promising that we’ve come up with a method that works.”
“Colored Glass Microbeads for Tracing Roadside Sediment Transport” has captured the attention of the Rhode Island Department of Transportation, which is funding the project, along with the URI Transportation Center.
The project started in July, when Lewis placed the microbeads—in three different sizes—at six sites along Plains Road, near URI’s Greene H. Gardner Jr. Research Building. The microbeads are the size of natural soils and mimic their movements, which allowed Lewis to track the microbeads in ditches along the road.
“The number of microbeads we released was about 130,000 at each site,” says Lewis, an environmental science major. “We take samples every two or four weeks to determine how far the beads moved.”
So far, Lewis has collected five sample rounds from the ground. The data is translated into computerized “plume maps” that visually show what’s happening.
“I’m very excited about our results,” says Lewis. “The plume gets bigger as the microbeads move across the land. This is what we predicted might happen.”
Lewis says the project will continue with other URI students for the next few years.
In the future, engineers could use the microbeads to trace runoff that is potentially hazardous to streams or lakes nearby. Microbeads could also be used to trace oil spills on roads and highways.
“People don’t realize how damaging road runoff can be to surrounding waterways and lands,” says Lewis. “Road toxins can kill fish, harm plants and leach into the groundwater, so it’s important we understand the movement of these contaminants and sediments to protect the environment.”
Lewis’ interest in the environment was nurtured in high school. She recalls a paper she wrote involving the 2010 BP oil spill in the Gulf of Mexico, recognized as the worst oil spill in American history.
“We came up with a way to clean oil off the seabirds,” says Lewis. “We suggested dry shampoo. It didn’t work that well, but it gave me a taste of what I could do to preserve nature.”
One of her highlights at URI was a two-week trip to Goa, India, to create riverbank filtration systems that bring clean drinking water and irrigation water to nearby villages.
After graduation this spring, she hopes to join the Peace Corps and serve for two years as a water sanitation and hygiene education engineer in Panama. Her many projects at URI, including her microbeads study, have prepared her for new challenges.
“I’m so thankful to my professors—who are devoted teachers—and for the opportunity to do practical field work,” says Lewis. “I’m ready to jump into a job and do my part to protect the world.”
Photo above: Tabatha Lewis, a URI senior majoring in environmental science, holds a container of microbeads. Photo by Michael Salerno.