What fern loves arsenic?
By Chelsie Vandaveer
November 15, 2001
killerPlants Tendrils: ~~1~~2~~3~~4~~5~~
Suggested Reading—>Click here.
The Chinese ladder brake (Pteris vittata Linnaeus) [ter' is vi tat' ah] is one of those ferns that does not live like a fern. The brake prefers full sun and rocks, not minding alkaline limestones or concrete rubble. Native to China, the brake is an escapee and is now found in most of the warm areas of the world. In Florida, it has picked some unusual places to habituate.
Arsenic is a highly toxic metal that is used as an herbicide and insecticide. From 1923 to 1943 in Florida, large amounts were used on ranches to kill ticks on cattle. It is used today as chromated copper arsenate (CCA) to pressure-treat lumber against termites and rot and in herbicides for golf courses and lawns. Arsenic is an element, it does not go away. Worldwide, it is estimated there are tens of thousands of sites contaminated with arsenic from mining, industrial, and farming operations.
The University of Florida Institute of Food and Agriculture Sciences is studying Florida's arsenic problem. At an abandoned wood treatment facility, the IFAS research team sampled the plant life on the property to determine the effects of the arsenic on the growth. One plant in particular was doing well on the contaminated soil.
The Chinese ladder brake had concentrations of arsenic at 7,526 parts per million (ppm); the soil beneath the brake had 38.9 ppm arsenic. The ladder brake was pulling arsenic from the soil at an amazing rate. When the team sampled Chinese ladder brake on the UF campus growing in soil 0.47 ppm arsenic, they found the ferns had accumulated 136 ppm arsenic.
In greenhouse testing, the team added arsenic to the Chinese ladder brakes' potting mix. The fronds accumulated 22,630 ppm; 2.3 percent of the leaves were composed of arsenic. The ferns appeared to grow better with additional arsenic in the soil. Interestingly, the fern deposits 90 percent of the arsenic in the stipe and frond, the biomass above the ground.
The Chinese ladder brake may become useful in phytoremediation, the use of plants to clean up contaminated soils. The fronds could be harvested at the end of the growing season and hauled off to hazardous waste facilities. The rhizome and roots would be left to continue growing; the remediation site would not need replanting.
To learn more about phytoremediation, the Chinese ladder brake, and to view a photograph of the fern, click on the link:
http://www.napa.ufl.edu/2001news/fern.htm
killerPlants Tendrils: ~~1~~2~~3~~4~~5~~
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