Plants Help Remove Toxic Materials from Old Mining Sites

First Posted: Feb 05, 2013 11:14 AM EST

There may be a new way to get rid of the toxic chemicals that leech their ways into soil after mining activities. Scientists from the Center for Functional and Evolutionary Ecology at Montpellier University are using flowers in order to combat the pollution found at old mining sites.

Only three species of plants can stand the high level of toxicity found at the bottom of a former tailing pond at Saint Laurent Lee Minier in the Cevennes. There, concentrations of zinc, lead and cadmium are between 500 and 850 times higher than European standards allow, according to The Guardian. Yet these three species of metallophyte, a type of small flower, can absorb between 7 to 8 percent of their dry weight in these poisonous materials.

In order to see exactly how effective these plants are at removing materials from soil, researchers transplanted 7,000 plants last summer to the site. Although metallophyte can store the toxic substances in vacuoles in their leaves, scientists estimate that it could take as many as 50 years to clean the site, according to The Guardian.

Already, similar experiments have been conducted at many different mining facilities, including sites in New Caledonia and China. In the U.S., environmental groups have worked together to try and clean up different mining sites, as well. An old coal mining site in Pittsburgh is slowly being turned into a botanic garden, and the EPA has recently tweaked environmental policy to make it easier for environmental groups to start cleaning up thousands of mines in the West. However, none of the current efforts have yet been able to find a way to remove the toxic materials on a large scale, or even dispose of the contaminated vegetable matter which itself becomes a form of toxic waste.

Mining can cause huge environmental issues, especially if not done properly. Early gold miners in California processed the metal with mercury and then dumped the excess material into nearby watershed. Although this happened more than a hundred years ago, some fish in San Francisco bay are still unsafe to eat.

Fortunately, the researchers in this experiment may have found a way to overcome this particular setback. They have discovered that they can extract the metal stored in the leaves of metallophyte by drying them and reducing them to powder. This powder can then be used to act as a catalyst in industrial applications, such as synthesizing drugs.

Although scientists still need to cover the rest of the mining site with plants over the next year, this technique could pave the way for detoxifying land that has been mined for centuries.

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