Plant Extracts Arsenic from Polluted Soil

In an effort to clean up arsenic-polluted sites, scientists are really going green.

A new technique modifies plants to take up the poison in their roots and transport it all the way to the leaves for easy harvesting. The plants can be incinerated or dried and shrunk to store.

Arsenic is a poisonous semi-metal commonly used in pesticides, insecticides, and herbicides. High levels are found in some soil and drinking water.  Long-term exposure can cause cancer of the skin, lungs, urinary bladder, and kidney, according to the World Health Organization.

The common practice of excavating and reburying arsenic is too expensive for sites that need remediation, said Richard Meagher, a geneticist at the University of Georgia.

"As a result, the overwhelming majority of arsenic-contaminated sites are not being cleaned up," he said.

The technique of using plants to clean up polluted soil in order to make poisons less harmful is called "phytoremediation," and has proven viable for removing arsenic. But arsenic collected from the soil is stored in the plant root, which makes safe harvesting and disposal a challenge.

Meagher and his team genetically modified Arabidopsis, a small member of the mustard family, to be arsenic-resistant and to move the arsenic collected in its root up to its shoots. The new method is much more efficient, too, soaking up 16 times more arsenic than normal Arabidopsis plants. 

"We want a 35- to 50-fold increase in these plants' ability to sequester arsenic, and now that we understand the mechanism, we believe that is possible," Meagher said.

The findings were detailed in current issue of the journal for the Proceedings of the National Academy of Sciences.

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