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Public Radio's Environmental News Magazine (follow us on Google News)

Decontaminating Plants

Air Date: Week of

Nature's own ancient cures are being put to the test for the clean-up of chemical contaminant waste. The process of sun and plants purifying soil is called Phytomediation, and it's being put to use from New Jersey to Chernobyl, Ukraine. Jeff Rice reports from Salt Lake City, Utah.


CURWOOD: It's the fastest growing technology for the cleanup of chemical waste and contamination. It runs on little more than water and sun, and it's so advanced that it took billions of years to develop. The technology is nature's own plants. It's still in the experimental stage, but there are high hopes that in some cases the deliberate use of plants to remove contaminants from polluted soil and ground water will be cheaper and more environmentally friendly than present methods. From Salt Lake City, Jeff Rice reports.

(Highway sounds)

RICE: Just off the freeway in Ogden, Utah, a small fuel transfer station run by Chevron has been contaminating the soil with oil and diesel fuel since the 1950s. Two years ago, not even weeds would grow on this 5-acre lot.

(A sprinkler system)

RICE: Today, neat rows of green alfalfa are lined by barriers of poplar trees. Specially planted grass grows in abundance and birds can be seen skimming the fields for insects.

RICE: Doesn't look like an industrial waste site at all.

FERRO: Yeah. It looks a lot better. It was a real moonscape when we started.

RICE: But the landscaping isn't just an attempt to cover up the contamination problems, says Dr. Ari Ferro, President of the Utah-based clean-up company Phytokinetics. The extensive root systems are causing a massive chemical reaction in the soil that Dr. Ferro hopes will eventually turn the polluting petroleum into harmless organic elements.

FERRO: You have a root zone where you have a very -- a huge population of metabolically active microbes, and so they -- it's not so much that they're sucking up contaminants, but it's the fact that they stimulate soil microbes and that in turn stimulates biodegradation of the contaminants that -- the contaminated soil that the plants are growing on.

RICE: Normally, contaminated soil would be trucked away, an expensive proposition that simply moves the problem from one place to another. By using plants, Dr. Ferro was hoping to solve the disposal problem altogether.

RICE: So it just breaks it down.

FERRO: It just breaks 'em down, right, uh huh. Breaks 'em down in some cases all the way to carbon dioxide and water.

RICE: It's called Phytoremediation, and no, these aren't genetically altered super plants. Dr. Ferro uses commonly grown native plants chosen for thick or deep root systems to catalyze the microbes. He helps them out with a lot of fertilizer and intensive irrigation. It's a relatively low-tech system, but the potentials for this technology are vast. Companies like Phytokinetics are starting to spring up like wildflowers. Currently, plants are being used in experimental cases to treat contaminants ranging from petroleum spills to decaying TNT, nitrates, pesticides, heavy metals, and even radioactive waste. And if that weren't enough, Dr. Ferro and others say their methods are substantially cheaper. That's what led Chevron to take a chance on what might at first glance seem like just so much flower power. So far, says spokesman Walter Maguire, Chevron is happy with the results.

MAGUIRE: We were looking at anywhere from $800,000 to a million dollars to do this. But in this -- in this particular situation, I think to date we've spent about $70,000.

RICE: But does it work?

FERRO: We're kind of at an awkward position right now.

RICE: Dr. Farrell.

FERRO: We're right in the -- right between having evidence in the laboratory and having some solid evidence outdoors and we -- we don't have solid evidence outdoors yet. But --but every indication is that it'll -- it'll be effective.

RICE: The EPA is helping to sponsor a number of field studies, including the Chevron site, with an eye toward obtaining some solid objective data. Steve Rock is with the EPA's office in Ohio and has worked extensively in this area.

ROCK: There is still skepticism. That's why we're evaluating the field demonstrations. This is no -- not an accepted technology by any means, but there are some very interesting projects going on, and the results are very, real promising.

RICE: But Mr. Rock points out that in any case Phytoremediation is not a magic bullet. The contamination can't be too deep outside the range of the plant's roots. You also can't be in a hurry. Treatment necessarily takes a number of growing seasons. But for certain situations where low-level contamination is not an immediate hazard, it may be ideal. One of the main things, says Mr. Rock, is to ensure that at the very least the process doesn't do any harm. For example...

ROCK: And what happens if birds or grasshoppers come and eat the plants and then spread the contamination across the neighborhood? That's -- that's not what you want to do. We're trying to get the contamination away from the neighborhood, not spread it.

RICE: Early studies suggest that at sites with organic waste and contamination, such as petroleum spills for example, bugs and animals probably can eat to their heart's content. Plants don't seem to absorb the contaminants. It's a different story, however, when cleaning up another class of pollutants: heavy metals. In this case, plants do absorb the pollution. In fact, that's the whole point.

RASKIN: It's very important to understand that plants grow -- grow because they have this innate ability to accumulate the elements from the environment. They can't run around hunting for food. They have to sit there, and the only way they can grow is they accumulate elements from the environment.

RICE: Ilya Raskin is a Rutgers University biochemist and one of the founders of the New Jersey-based company Phytotech. His company deals primarily in cleaning up poisonous heavy metals, such as mercury, lead, and zinc. He was one of the first to study plants for clean-up 10 years ago.

RASKIN: Most of the things that accumulate are the essential elements for their growth minerals. Metals like iron, which they need for their own growth; copper; what they also need is manganese, magnesium. And now we won't have to trick most of the plants into accumulating things like lead and cadmium. In some cases over their naturally required minerals.

RICE: The plants are then disposed of in landfills, and in some cases the metals are actually removed and recycled. While the plants are growing they may be covered to keep them from entering the food chain. Phytotech is already working to clean up heavy metal sitesacross the East Coast and in Europe, including some of the nastiest stuff of all.

(Big Ben chimes. BBC announcer: "The Russians have revealed little during the day of the extent of the accident at a nuclear power station in the Ukraine, but it is clear that this is a major disaster. It's known that the Soviet Union...")

RICE: Ten years after the Chernobyl disaster, sunflowers planted at a pond just a mile away from the reactor are removing radioactive strontium and cesium from the water. Phytotech began experimenting with the possibilities of radioactive cleanup in the lab several years ago, and obtained startling results. Plants were able to remove 95% of radioactive elements under controlled conditions in just 24 hours. If Phytoremediation works at Chernobyl, Raskin's company hopes to gain a chunk of the $200 billion job of cleaning up low-level radioactive sites back in the US. Experts say cleaning up wastes with flowers may be a long shot, but the payoffs may be huge, both economically and environmentally. For Living on Earth, I'm Jeff Rice in Salt Lake City.



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