A Novel Method for Phytoextraction and Phytostabilization of Environmental Mercury

Because environmental mercury poses significant challenges to global public health, reducing mercury levels in air, soil, and water is an international priority. However, the widespread distribution of mercury (Hg) through the atmosphere makes current methods of addressing Hg contamination ¿ such as excavation and replacement of soil, or pump-and-treat techniques for water ¿ too expensive to be practical, due to the typically large scale of remediation activity required. This project will develop an innovative, low-cost method of extracting Hg from soil and water, using two recently-identified Hg-hyperaccumulating plant species, one terrestrial and one aquatic. The Hg stored in the plant leaves and stems may then be harvested for disposal, or allowed to remain on-site in an extremely refractory (highly stable) chemical form that poses negligible health risks. Preliminary studies have demonstrated that Hg uptake by the terrestrial hyperaccumulator is greatly accentuated when soil is rich in Se, suggesting HgSe formation may be occurring. Phase I will attempt to demonstrate a high plant uptake of Hg and in planta conversion of environmental Hg to HgSe. Phase II will explore methods of increasing Hg uptake, confirm the low bioavailability under normal environmental conditions of the stabilized form, and conclude with a field demonstration. Commercial Applications and other Benefits as described by the awardee: The technology should establish the foundation for a low-cost, solar powered method of removing and stabilizing mercury over large areas of soil and large volumes of water.