Bioremediation can refer to the use of microbes, fungi (mycoremediation) or plants (phytoremediation) that have the ability to remove pollutants from the environment. Microbes and fungi generally accomplish this through breaking down toxic substances into benign byproducts, which is highly effective with things like petroleum products, chlorinated solvents and even radioactive substances. It is less effective with heavy metals, however, which is where plants enter the picture. In this case, the contaminants (lead, mercury, cadmium, etc.) are absorbed in the plant’s tissues, which are then removed and incinerated to recover the metals.
We may enjoy eating oyster mushrooms in omelets, but they also have another, incredibly profound quality: they enjoy eating diesel fuel and other petroleum products for breakfast. In one study, soil contaminated with diesel oil was inoculated with oyster mushroom mycelia, resulting in a 95 percent reduction of toxic compounds after a one-month period. The resulting byproducts were nothing
more than carbon dioxide and water. Other related fungal species are known to break down chemicals such as polyurethane and many common pesticides and herbicides.
Image via Pensoft
Some plants specialize in eating just one type of pollutant. This is a result of having evolved in rare terrestrial habitats where the soil is naturally high in certain compounds that would be toxic to most plants, such as the case with Rinorea niccolifera, a distant relative of violets from an island in the Philippines, where nickel levels in the soil are off the charts. Scientists are looking at this species as an agent to clean up industrial sites contaminated with nickel, but also as a non-invasive, “green” mining technique. Rinorea absorbs up to 1,000 times as much nickel as most other plants, making it theoretically possible to plant fields of it in nickel-rich soils and then extract the metal from the harvested crop. Rinorea was just discovered in a remote area last year and is now undergoing testing for it metal-eating abilities.