Scientists may have a powerful new tool for clearing soil of deadly arsenic--one that comes not from a laboratory, but from the great outdoors. According to a report published today in the journal Nature, the brake fern, Pteris vittata, soaks up arsenic from contaminated soils with incredible efficiency. It may thus prove useful in cleaning up sites sullied by industrial, mining and agricultural operations.

Lena Ma of the University of Florida, a specialist in trace metal chemistry, and her colleagues discovered brake fern growing on an arsenic-contaminated site in Central Florida. Of 14 species analyzed from the site, only the brake fern exhibited the large amounts of the carcinogenic heavy metal. Indeed, the fern frond arsenic concentration measured up to 200 times higher than that found in the surrounding soil.

Although arsenic is frequently used to kill weeds and other unwanted plants on lawns and golf courses, the brake fern may actually fare better when the toxin is present: Ma's team found that increasing soil arsenic by 100 parts per million (ppm) yielded a 40 percent increase in biomass as compared with the control plants grown in six ppm soil arsenic. Exactly why the brake fern absorbs the arsenic is unclear, but Ma and her colleagues hope to get to the bottom of that with future research.