In a twist on the old set a thief to catch a thief ploy, researchers at Michigan Technological University have found that a copper-loving bacteria can help corn suck copper contamination out of soil. The discovery could help clean up highly contaminated abandoned mining sites that have resisted other forms of “green” remediation. In addition to copper, a similar approach could be used to clean up sites polluted by other metals and toxic substances like zinc, lead, arsenic and mercury.
Green Remediation
Green remediation includes the growing trend of using plants, microbes, and other natural process to clean up contaminated sites. It can also include the use of solar power and other strategies that reduce the carbon footprint of site cleanup, which in the past has often involved the use of heavy machinery. However, when it comes to using plants (technically known as phytoremediation), there is one obvious limiting factor: if the soil contamination is too intense, little or nothing can grow on it.
Copper Country and Bacteria
That’s the situation besetting some abandoned mining sites in Michigan’s Copper Country, once among the world’s greatest copper producers. Though many areas have been restored, little has taken root at some sites, leaving large swaths of “moonscape expanses.” The Michigan Tech team, lead by biological sciences professor Ramakrishna Wusirika, tackled the problem by recruiting one of the few creatures that was managing to thrive in the contaminated sediment at Torch Lake, a copper-resistant strain of bacteria called Psuedomonas.
Bacteria and Phytoremediation
In a controlled laboratory experiment, the team introduced copper to pots of normal soil, then inoculated some of the pots with the bacteria. That made all the difference. Corn and maize planted in the contaminated soil did fine in the bacteria-added pots, and horribly in the pots with no bacteria. In fact, the bacteria were such a great help that plants grown in the bacteria-added, copper-tainted soil did almost as well as those grown in normal, healthy soil. In a conversation with CleanTechnica, Wusirika explained that the bacteria contributed growth hormones to the soil and rendered the phosphates soluble, making it easier for the plants to take these nutrients up. The next step is to grow plants in copper-contaminated soil gathered from a site near the village of Gay.
A Sustainability Twofer for Copper Sucking Plants
Though corn and maize grown on contaminated soil would be inedible (they were chosen for the experiment for their rapid rate of growth and large production of biomass), Wusirika’s team is already looking into the possibility of combining phytoremediation with biofuel operations. That would fit neatly in with President Obama’s rollout this summer of a comprehensive biofuel program, including the “Billion-Ton Update” that examines the nation’s potential for producing more biomass without impacting food crop production.
Image (altered): Corn by Way Tru on flickr.com
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