Native grasses an explosive idea for cleaning contaminated soil

Ron Tarver/Philadelphia Inquirer/NEWSCOM/file
Switchgrass is being studied as a possible biofuel. But it also has been proven to clean up ground contaminated with TNT.

You hear a lot these days about the benefits of native plants, but here's a new one: Certain native grasses can convert the toxic leftovers from atrazine – second most common herbicide in the US and a stubborn pollutant in the nation’s waterways – into harmless carbon dioxide, reports the Kansas City Star.

But there's more.

Three researchers – Robert Lerch of the Agricultural Research Service of the USDA, Chung-Ho Lin of the University of Missouri at Columbia, and John Yang of Lincoln University – thought that if native grasses worked for atrazine, why wouldn't they clean up soils contaminated with TNT and another explosive, RDX, which are chemically similar?

It turns out that two common native grasses – switchgrass and Eastern gamma grass – do.

This is a big deal, because "The U.S. Army has identified more than 538 sites contaminated by explosives, including 20 EPA-designated Superfund sites," says Dr. Yang.

The grasses work by nourishing microorganisms in the soil that work to break down the explosives into harmless components. The advantage to using grasses is that they're natural and cost effective, says Yang in an interview with the Columbia Daily Tribune.

Research shows using native grasses to clean up a site costs only $200 to $10,000 for 2-1/2 acres — a fraction of cost of the traditional method of phytoremediation, reports the Tribune.

Compare those small amounts to the estimated cost of $100,000 to $1 million per acre that, the Star reports, it typically costs to haul away the soil in a field contaminated by TNT or RDX and incinerate it.

And the researchers think there may be many more potential uses for grasses in cleaning up contaminated areas.  “We really haven’t looked at that,” Dr. Lerch says. “I think it’s fair to say there is a lot more potential.”

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