DURHAM, N.H. In a mud flat at the edge of the Cocheco River, just outside downtown Dover, scientists from the University of New Hampshire's Contaminated Sediments Center are testing an innovative way to treat polluted sediment in coastal waterways.
Rather than dredging up the problem, or burying it under several feet of sand, they've created a patch black geotextile mats designed to cap and stabilize pollution in place. Over the next two years, UNH associate professor Kevin Gardner, research assistant professor Jeffrey Melton, and a team of UNH students will monitor these mats to evaluate the effectiveness of this new approach.
"We need to know how these mats behave when they're buried under mud for a few years, compared to how they performed in the lab," says Melton. "What will happen to them in this intertidal zone with boats, waves, birds, and weather? How will they impact bugs and other aquatic life in the sediment?"
The mats are six feet square and one inch thick. They consist of a mixture of reactive materials sandwiched between two layers of geotextile fabric, creating a sort of quilt that traps pollutants but allows water to flow through. The reactive "filling" of this quilt contains three different substances that bind and stabilize different pollutants. One such substance a UNH-patented technology based on a natural form of phosphorus treats toxic heavy metals associated with industrial pollution such as lead, copper, zinc and cadmium.
"But you don't just find one pollutant at a site," says Melton. "Everything is all mixed up in the sediment." So he and his colleagues added organoclay and activated charcoal ("like in your Brita filter," he says), which adhere to and treat toxic chemicals such as polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons, (PAHs), and petroleum products that routinely enter waterways through stormwater runoff.
The project is funded by the Cooperative Institute for Coast
|Contact: Beth Potier|
University of New Hampshire