Daily News Archive
From February 6, 2001

Fern Found to Soak Up Arsenic

The brake fern, a common fern native to the Southeast and California, has been found to soak up extraordinary amounts of arsenic. According to The Association for the Environmental Health of Soils, this fern has an extraordinary capability to uptake a large quantity of arsenic from soils and translocate them to aboveground biomass. In laboratory studies conducted by Lena Q. Ma, Cong Tu, and Elizabeth Kennelley of the University of Florida, fern samples were both collected from an arsenic contaminated soil and grown in a greenhouse in artificially contaminated soils for up to 8 weeks, and then analyzed for arsenic concentrations. The ferns harvested from the arsenic contaminated soil were shown to have an arsenic concentration in the aboveground biomass of up to 7,500 parts per million (ppm), a concentration up to 200 times greater than those of the contaminated soils. In greenhouse soils spiked with 500 ppm arsenic, the concentration in the aboveground biomass reached over 2% after 4 weeks.

The process by which vegetation is used for treatment of contaminated soils, sediments, or waters to degrade, assimilate, metabolize, or detoxify inorganic and organic chemicals is called phytoremediation. It is considered an attractive technology because of its relatively low cost and aesthetic nature of using plants to clean up sites. The brake fern is the first arsenic hyperaccumulating plant to be discovered.

Arsenic is a naturally occurring element in rocks, soils, and the waters in contact with them. Before 1968, inorganic forms of arsenic were used extensively in agriculture as insecticides and herbicides. Frequent applications of these chemicals at high rates have resulted in significant arsenic accumulation in soils. Arsenic is also a major contaminant of the surface, ground, and drinking water in the United States abroad. Arsenic contamination poses a significant health risk to humans and animals. It is a known carcinogen, contributing to skin, lung, bladder, and other cancers, a known mutagen, and has adverse effects on the heart, lungs, and immune system.