Superfund Research Program
Rabbit-foot grass (Polypogon monspeliensis) has been shown to efficiently remove mercury from contaminated soils, according to a new study by Edenspace Systems Corporation, funded by the Superfund Research Program (SRP) Small Business Innovation Research Grant (SBIR).
Mercury remediation is an important step to reduce human exposure to mercury and subsequent health effects. Mercury in soil, generally occurring as a result of anthropogenic sources such as coal-burning power plants, can be easily converted in the environment to methyl mercury, a potent neurotoxin. Once converted, methyl mercury may enter waters and bioaccumulate in the fish we eat, leading to dangerous exposures. This is of particular concern for pregnant women and small children.
Using physical and chemical remediation methods, decontamination of mercury in soil is difficult and expensive. However, Edenspace has investigated a less-expensive biological method to remove mercury from soil. Focusing primarily on wet ecosystems, researchers at Edenspace tested the ability of rabbit-foot grass to take up mercury and sulfur from soil and convert the elements to mercury sulfide (HgS), which has high stability and low solubility, into its plant tissue. Using this method, researchers correlated mercury accumulation with HgS formation, and demonstrated hyperaccumulation of mercury, with concentrations up to 110 times that of the control plant.
Currently, phytoremediation, a process where plants remove, detoxify, or stabilize toxic substances, is not widely used for mercury. This study reveals that phytoremediation is a viable, low cost alternative for remediation of mercury at contaminated sites. The phytoremediation method has the potential to improve our ability to remove mercury from the global cycle and reduce possible human exposure. Edenspace is currently assessing the potential ecological risks of HgS-containing biomass and plans to perform field demonstrations at two mercury-contaminated sites.