A sludgy mess sits a couple hundred yards from the Pasquotank River near Elizabeth City. Over the years, fuel has leaked out of underground storage tanks used to gas up boats, contaminating the soil. To Dr. Elizabeth Nichols, an assistant professor of environmental technology in the College of Natural Resources, it’s the perfect place to do some landscaping.

Nichols doesn’t landscape with showy annuals and flowering perennials. She practices phytoremediation, concentrating on plants that thrive in the toxic grounds sometimes left behind by former manufacturing plants, abandoned gas stations, and closed military bases. Her efforts in this growing field could soon offer government and the private sector an alternative to the more costly approaches of excavating and burning contaminated soil. “Financial resources are too limited to clean every contaminated area,” she says, “and some sites are ideal for longer-term remediation approaches.”

Building on the concept of riparian buffers that filter urban and agricultural runoff from streams, scientists in the late 1980s began experimenting with plants as a way to prevent underground contamination from spreading. At Elizabeth City, for example, Nichols, NC State graduate students, and collaborators from state and federal agencies this spring will plant a mix of deep-rooted shrubs and fast-growing trees like poplars, river birches, and willows to surround the contamination plume before it reaches the river. “There is still a lot to learn about how trees can impact residual, aged contamination,” she says, “We don’t yet know how much of the chemicals are absorbed by the trees and what effect it has on them.”

Nichols’ research has shown that some vegetation actually cleanses tainted soils. At an old refinery site in Gary, Indiana, where she has worked for two years, a reed-like plant, Phragmites australis, has been especially adept at growing in the petroleum-laden sediments along a creek. About 40 percent of the carbon the plant fixes during photosynthesis is released into the soil, she says, feeding bacteria that then break down the contamination. Because Phragmites is considered an invasive species across much of the U.S., Nichols is examining characteristics of the plant that help it thrive in such harsh conditions to determine if plants more suitable to various habitats could also be used for phytoremediation. “It’s a slow-moving process that can’t be used everywhere,” she says. “But it could be an effective, affordable approach for many small sites that have been left unattended while more critical sites were cleaned.”