More than 70% of United States arsenic consumption, representing approximately 37 million pounds of arsenic per year, is used to produce chromated copper arsenate (CCA), a wood preservative. Weathered lumber in decks, docks, playground equipment and garden construction can leach significant amounts of arsenic into soil and water, where it poses health risks to humans and animals. Although the use of CCA to treat wood for use in residential areas is being reduced, the existing stock of CCA-treated wood products will continue to leach arsenic for years to come. At present there is no cost-effective method to clean arsenic-contaminated soils. This research seeks to demonstrate the feasibility of using a recently discovered arsenic-hyperaccumulating fern to provide a cost-effective remediation alternative for CCA-contaminated soils in residential and industrial settings. Preliminary data demonstrate that when grown on arsenic-contaminated soils, this fern accumulates sufficient arsenic and biomass in its fronds to effectively reduce soil arsenic concentrations.

Growth chamber studies were conducted to evaluate arsenic removal by the fern from six different CCA-contaminated site soils, assessing the effects of soil pH and light intensity on the efficiency of arsenic phytoextraction. A small field demonstration was also conducted concurrently at a CCA-contaminated field site to demonstrate arsenic uptake and biomass production. The potential to further concentrate and refining recovered arsenic for storage and future recycling, as well as the ability of the fern to reduce chromium (VI) in the CCA soils to chromium (III) was also evaluated.

The anticipated result of this research is a demonstrated arsenic phytoextraction technique, accessible to homeowners as well as to environmental professionals, that uses commercially-available plants to provide cost-effective remediation of contaminated soils associated with the use of CCA-treated wood products. The results of these and other studies with CCA contaminated soils will be presented.