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The Dance of the Mud Particles

Sediment-laden plumes of water around the Chesapeake Bay Bridge following flooding and extensive rains of June-July 2006. ©Jane Thomas, Integration and Application Network, University of Maryland Center for Environmental Science (ian.umces.edu/imagelibrary/).

Sediment-laden plumes of water around the Chesapeake Bay Bridge following flooding and extensive rains of June-July 2006. ©Jane Thomas, Integration and Application Network, University of Maryland Center for Environmental Science (ian.umces.edu/imagelibrary/).

Sediment-laden plumes of water around the Chesapeake Bay Bridge following flooding and extensive rains of June-July 2006. ©Jane Thomas, Integration and Application Network, University of Maryland Center for Environmental Science (ian.umces.edu/imagelibrary/).

A fellow models sunlight-blocking sediment in Chesapeake Bay

By Chris Patrick, science writer

Looking at sand and mud on the ground, it might be difficult to imagine there’s an entire field devoted to studying how water, wind, and ice transport sediment. But there is. And sediment dynamics is actually really important—especially in the Chesapeake Bay. If too many fine-grained sediment particles are suspended in the water they can block out the sun, and deprive underwater plants of light. If the plants die, fish and other critters that use them for shelter may also be adversely affected.

Rae Kuprenas. Courtesy of Rae Kuprenas.

Rae Kuprenas. Courtesy of Rae Kuprenas.

Scientists model sediment’s movement to predict and monitor how much is floating in the water versus how much has settled on the Bay’s floor. Most of the sediment is a fine-grained mud, which can stick together to form clumps called flocs. In this process, known as flocculation, mud particles coalesce and separate.

This dance of the mud particles makes predicting their movement tricky. While scientists suspect environmental conditions modulate the dance, determining floc sizes and settling rates, they’re unsure exactly how. Which is why Rae Kuprenas, a graduate student studying engineering at Virginia Tech, will model flocs as a Virginia Sea Grant graduate research fellow.

“I want to advance flocculation models and ultimately improve the understanding of how sediment moves in the Bay,” she says.

To do so, she’s embarking on what she calls a “perfect trifecta” of research, which includes field work, lab experiments, and modeling. This tripartite undertaking will begin with Kuprenas wearing waterproof boots to wade through the Bay and two of its tributaries, the York and Elizabeth Rivers, to collect mud samples from the waterways at different times of the year.

In the lab, Kuprenas will look at how different environmental conditions, like varying levels of turbulence and salinity, affect floc sizes in the mud samples. She will use a special camera to measure the miniscule mud clumps, which range between 6 and 1,000 micrometers in size. For perspective, one micrometer is one thousand times smaller than a sharpened pencil point. Kuprenas will use the data she generates to improve flocculation models, which will more accurately predict how mud moves in the Bay. Better models can bolster basic sediment understanding, and eventually improve its management.

While her research has three parts, there’s another component to Kuprenas project: outreach. Kuprenas will work with Virginia Tech’s Museum of Geosciences to create programs that educate educator, professionals, and children about Chesapeake Bay sediment dynamics.

“I’m most excited about the outreach plan—to work with children, and get them excited about science,” Kuprenas says. “From my experience with both research and teaching, I know that I want to help others get involved in creating new knowledge for the field of engineering.”

Kuprenas received her bachelor’s from University of South Carolina Honors College in 2015, majoring in civil engineering and minoring in mathematics. She is currently earning her doctorate in civil engineering from Virginia Tech. She hopes to teach at a university one day.