Plant this Fern to Remove Arsenic from Soil

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Healthy Child Healthy World

Monday, July 30, 2007

Now there's a truly "green" solution to remove highly toxic arsenic from contaminated soil. A plant, Pteris genus, actually pulls significant amounts of arsenic out of soil.

If your deck, playset or garden beds are made with pressure-treated wood, the soil in your yard could be contaminated with arsenic, a known human carcinogen. Pressure-treated wood sold for home use prior to 2004 contained chromated copper arsenate, or CCA, which prevented insect damage and rot. CCA can leach out of treated wood into surrounding soil.

A researcher at the University of Florida found that the fern removes arsenic from contaminated soil at a rate more than 200-times any other plant tested. Through a process called phytoremediation, the fern pulls as much as 10-15 parts per million of arsenic from contaminated soil. The fern is patented by Edenspace and is marketed at nurseries around the country as edenfernTM.

Last year, the U.S. Environmental Protection Agency (EPA) announced an agreement with manufacturers to ban CCA-treated wood for all consumer uses by the end of 2003. However, treated wood already in use will continue to release arsenic. The Environmental Working Group discovered that even old pressure-treated decks continued to emit arsenic for many years.

Children are especially at risk of arsenic exposure because they are more likely to put their hands in their mouths after touching the treated wood. If children play underneath or around a deck made of CCA-treated wood, they may be exposed to arsenic by eating the dirt (which kids are known to do).

In gardens surrounded by pressure-treated wood, vegetables and fruits can absorb arsenic the leaches into the soil. If you eat plants grown in soil contaminated with arsenic, you may be eating arsenic, too.

To get the most out of the ferns, Edenspace recommends planting the ferns one foot apart. Arsenic is removed during the plant's growing season and concentrated in the leaves and stems. The ferns will live for several seasons in areas that don't get colder than 20 degrees Fahrenheit. If the plants die, you can dispose of them in the trash (which only moves the arsenic to a landfill) or send them back to Edenspace, who will extract the arsenic for industrial purposes. DO NOT COMPOST THE PLANTS! The arsenic will contaminate the compost.

Resources:

Bloom River Gardens, sells the ferns for $15 each. They're in Oregon, but ship nationwide.

Raintree Nursery

Healthy Building Network and Environmental Working Group sell arsenic test kits for both soil and wood.