Ferns and Arsenic

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Joanne F.

Ferns may put brakes on arsenic

By kson

Parents don't want their children near it. Playgrounds across Central Florida are closed because of it. And scientists have clashed with the wood-treatment industry over whether it should be banned.

Ferns, however, love the stuff.

University of Florida researchers have discovered that a lush green fern, common to Florida, thrives on arsenic -- the more of the poison, the better.

Researchers who found the sun-loving plant growing in arsenic-tainted soil say the fern could be the solution to one of Central Florida's vexing environmental problems.

Federal regulators recently approved phaseout for the use of lumber treated with chromated copper arsenate, a poison that can leach into soil. But while the Environmental Protection Agency cautions people on the handling of treated lumber, it is not requiring playgrounds built with the wood to be pulled up.

That leaves recreation officials and parents wondering what to do with the treated wood in their parks and back yards.

Roy hopes the ferns are the answer.

"This could be huge, no question about it," said, looking out at a sea of green -- 10,000 of the ferns in 4-inch containers. "It sucks the arsenic right out of the ground."

sells the $2.45 plant, also known as Pteris vittata, or brake fern, from Milestone Agriculture, a nursery in Apopka. sells more than 80 types of ferns at Milestone.

He sells nationwide, but the soil-cleaning brake fern could really put his nursery on the map. For now, he has exclusive rights to grow the fern, thanks to a Washington lawyer who patented the fern after learning of the UF researchers' discovery.

The plant's sponge-like ability to soak up arsenic out of the ground could provide a less expensive and easier way to clean up hundreds of arsenic-contaminated sites across the state.

"There's tremendous interest in this, because worldwide arsenic contamination is a widespread issue," said Lena Ma, a soil chemist and UF associate professor. "Ideally, it would be a cost-effective solution."

In Central Florida, the playgrounds at several parks were closed in April after arsenic was found in the soil. Some cities have spent thousands of dollars removing and replacing soil.

Last week, companies that make chromated copper arsenate agreed to phase out most residential uses for the lumber by the end of next year. Even people who say arsenic-treated wood is safe in lumber form agree that the wood should not be mulched, burned or recycled. Most wood has been going to unlined landfills.

Ma, whose study was paid for by the Florida Center for Solid and Hazardous Waste, thinks scientists could clean up even heavy arsenic poisoning at a given site within 10 years.

has a contract to grow 20,000 of the ferns and ship them to the government in April. Knee-high ferns will be planted on an arsenic-contaminated Army base, and the soil will be periodically tested.

For quick treatment, researchers recommended planting one fern per square foot of contaminated soil.

Why the fast-growing plant absorbs the arsenic remains unclear.

"It's just amazing," said Ma, who hopes to find answers with more research. Several studies are under way.

Ma found the ferns, now patented under the name Edenfern, at an abandoned, arsenic-contaminated lumber mill near Archer. She found the thriving ferns while looking for trees that could soak up the poison.

The ferns had soaked up amounts of arsenic up to 200 times higher than in the surrounding soil. Lab tests showed that the fern can absorb arsenic quickly; arsenic quickly: Arsenic levels in the plants rose 126 times in just two weeks. Handling or smelling the firms would pose no health threat, but eating them would be dangerous. After ferns have soaked up arsenic, they would need to be pulled up and destroyed.

Researchers are trying to find a way to safely burn arsenic-laden ferns that have been grown on contaminated sites.

kson can be reached at serickson@... or 352-742-5921.

Copyright 2002 Orlando Sentinel