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Harvesting Toxins

Article #124 • Written by Cynthia Wood

If you talk to employees at one of the US Governments nuclear facilities long enough, you’re likely to hear a lot of interesting stories about the early days of dealing with nuclear materials. One, apparently originating in Oak Ridge, TN, involves an underground tank and a tree.

Apparently during a regular check of the site some radioactive contamination was found in the ground near one of the storage tanks. The area was promptly cleaned up, the soil carted away and replaced, but the people assigned to figure out how the ground became contaminated in the first place were stumped. They found no leaks, no spills, nothing that could have caused the radioactive material to escape. They checked over the spot for several months to see if the contamination recurred, which it did not, then finally shrugged and called it a mystery.

But a year later the contamination was back.

The second time was much like the first. The clean-up went smoothly, the investigation did not. It was not until the third time the same contamination recurred in the same place that the investigators found the culprit – an oak tree. The tree had sunk its roots into the tank, and was pulling up contaminated material. While one would expect the whole tree to become radioactive, that wasn’t the case. Instead the oak preferentially shunted the contaminants to its leaves. Every fall a new crop of radioactive leaves would hit the ground to mystify the workers at Oak Ridge, and every winter while they were investigating, there would be no sign of anything amiss with the tree.

It’s an amusing story, but the ability of that tree has become a major weapon in the efforts to clean up contaminated soil. You see, trees aren’t the only plants that can pull contaminants from the ground. There are a slew of others that can do it too, and they are becoming more and more valuable in places where the ground has become polluted or contaminated.

The process is called phytoextraction, and it’s one of a number of ways ecologists are beginning to use plants in bioremediation – the treatment of environmental problems. There are plants that can pull lead, uranium, arsenic, and any number of other contaminants out of the soil. They can then be harvested, a new crop planted, and the process repeated until the soil is sufficiently recovered.

The process has already been used with great success. At Chernobyl, genetically altered sunflowers have been used to clean up two ponds heavily contaminated with both cesium and strontium, while hemp plants are being used to clean up the soil. Various companies and institutions are beginning to jump on the bandwagon. Dr. Ilya Raskin of Rutger’s University, one of the field’s pioneers, has been working with members of the Brassica family (mustards), which tests have shown effective at removing a number of heavy metals. Dupont has found corn useful for lead, while Phytokinetics, a company in Ohio, is using trees to clean up deeper soil contamination.

All in all, the field of phytoextraction seems to be one of the most promising in the efforts to clean up the hundreds of thousands of sites worldwide (30,000 in the US alone, according to the EPA), that require hazardous waste treatment. Even if only modestly successful, the use of plants as contaminant removers could reduce cleanup costs considerably. Even more promising, phytoextraction is only one aspect of the whole field of phytoremediation, in which plants are being used not only to remove toxins, but sometimes to break them down (phytotransformation), enhance microbial activity (phytostimulation), or prevent leaching of contaminants in the first place (phytostabalization).

Perhaps if they had known where it would lead, the site workers at Oak Ridge might have been less frustrated when they finally found their answer.

Article written by Cynthia Wood, published on 24 February 2006. Cynthia is a contributing editor for DamnInteresting.com.

Article design and artwork by Alan Bellows. Edited by Alan Bellows.
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26 Comments
megzee
Posted 24 February 2006 at 09:46 pm

I've always been into using trees to clean up the environment. My focus lies in using trees in reducing air pollution. In my studies, I've learned that for every tree we cut down, we need to plant 10 in its place, so in about 50 years or so the air environment will be in better shape than it has in a long time. The amount of carbon dioxide removal itself would lower atmospheric temperatures, and reduce the threat of the ever-ambiguous "global warming" problem. I realize that this would only happen in a dream-world, but it's nice to know the idea is really working in a big way.


MaddMan
Posted 24 February 2006 at 10:42 pm

Cynthia Wood said: "while hemp plants are being used to clean up the soil."

I wonder what radioactive marijuana would be like?


ForestGrump
Posted 25 February 2006 at 05:09 am

Radioactive marijuana glows green in the dark...much like the BBs in my BB gun.

And if anyone was wondering what leaching is...It's when materials (such as salts, minerals, contaminants) are moved from one soil layer to another.
For example, salt is applied on the soil surface (such as during the winter onto the road). It rains/snow melt and the salt is dissolived into the water. When the water percolates through the soil layers, it leaches the salt down along with it.

And now...my rant.
If my memory serves me right...Erin brockovich (http://www.imdb.com/title/tt0195685/) is more than just a movie I've never seen.
From what I understand, PG&E were using underground caverns out in the desert for natural gas storage. To cool the pumps, they used water treated with chromium as a growth inhibitor in the water.

When the coolant wore out, it was dumped into evap ponds. Due to the sandy nature of desert soil, the coolant quickly reached groundwater, contaminating it. The problem was that resdents used groundwater for their water supply.

Now what to do?
1. do nothing and let the residents suffer. (somewhat unethical)
2. ban all use of groundwater and truck in water. (short term solution, long term has very high cost)
3. Remidiate the groundwater so it can once again be usable in the future

To remediate the site, they could do it with a costly "laboratory" setup where water could be extracted from the ground and run through treatments (high operation cost).
Or use bioremediation where plants/microbes would neutralize the chromium somehow.

So what happened is that a plant was found that could convert the toxic chromium in the water to a form of chromium that isn't toic (and is the stuff you get in multivitmins).

So yep, that's another example of using plants to remediate a contaminated site.

And I apologize if my facts are a bit off. A professor I had last quarter worked on this project, and brought it up to us as a sidebar to his lecture. (actually, he's very proud of this...probably. I've taken 2 classes with him and he brought it up in both classes.)

END OF RANT.


Anthony Kendall
Posted 25 February 2006 at 07:17 am

One of the projects I first worked on when I started research in my current field (groundwater hydrology), was using bacteria to consume carbon tetrachloride (the contaminant in A Civil Action) in Schoolcraft, MI. What was so remarkeable about this was that bacteria were able to remove something like 99% of the CT. Comparatively, the "pump and treat" method where groundwater is pumped out of the ground, treated, and replaced, is inefficient and expensive.

The power of biology is just amazing in this regard. Most of it comes from the fact that it operates on the nano-scale. Perhaps nanotechnology will offer us capabilities beyond even what plants and bacteria are capable of.


Furnace
Posted 25 February 2006 at 07:56 am

I'd like to know more about the leaves after contamination. Is the radiation within the leaves contained within specific parts/areas? What happens when it breaks down? What happens if caterpillars eat those leaves? What about food produced by these radiation cleaning plants? I'm thinking about an earlier story on this site about the coffee beans passing through an animals digestive system to become "improved", so I'm curious if these new items would have some sort of use afterward.

I've never heard of this process before, and would have completely dismissed the idea of plants removing radioactive contaminants as a myth.


Josh Harding
Posted 25 February 2006 at 10:05 am

It's already part of a major animated movie. Check out Miyazaki's Nausicaa of the Valley of the Wind.


JustAnotherName
Posted 26 February 2006 at 07:02 am

Josh Harding said: "It's already part of a major animated movie. Check out Miyazaki's Nausicaa of the Valley of the Wind."

I assume you are answering Furnaces quote. Does the contaminent ALWAYS go away or converted into something else? Because I gotta tell you, I am not sitting through a movie for the answer. Yes. I'm lazy.


Pascal Leduc
Posted 26 February 2006 at 08:01 pm

It dosent get converted, it gets moved to the plant.

Then you harvest the plant and the toxins with them.

Trees naturaly move toxins in their systems to their leaves so you harvest those. but in the end the toxins are still ther, they just got moved to a more convenient vessel


Cynthia Wood
Posted 27 February 2006 at 06:42 am

Some contaminants are simply pulled from the soil by the plant, some are converted, either by being inserted in a larger molecule (like the chromium), or by being broken down. It's more useful to render the contaminants harmless, but being able to recover useful soil is in and of itself a tremendous accomplishment. Don't underestimate the value of a more convenient vessel when you're talking about things as toxic as radioactives and heavy metals.


God of Biscuits
Posted 27 February 2006 at 10:14 pm

Well to be honest with all of you fellow scholars i have known about the power of a tree to lift certain liquids from the soil in my case it was an experiment with several decaying bodies near a mass grave in my home town in Germany. You see after the war we wanted to hide the massive graves of jews and others that were out side of our town so we planted trees above the ground that the jews were buried under. These trees i believe they are called apple trees here but grew the most bitter fruit you could imagine but the fruit shown up more often. The university study it and said the decaying of the bodies tainted the nutrients that theses trees absorbed and thats why the fruit was so bitter. I have recenty read an article in which the same tactic was used in serbia but the global satalites of the fascist american president bill clinton discovered these and it did not accomplish the goal that it was intended to. Well i'm sorry i'm probally boring you with history my grandchildren hate my war stories too. If anyone read the study published by our university or the one in Time about the serbian mass graves please commit i'm interested in hearing more about this


Christiaan
Posted 28 February 2006 at 06:25 am

Another interesting thing, with regard to our infantile economic system, is that such contamination and shifting of contamination will all register as a "good thing" on the books. i.e. it increases the GDP.


Christiaan
Posted 28 February 2006 at 06:30 am

God of Biscuits, yes you are boring us, not with history lessons but conjecture. I'm sure such stories about mass graves and trees in Serbia will sooth your conscience however.


Pascal Leduc
Posted 28 February 2006 at 07:30 am

Christiaan said: "Another interesting thing, with regard to our infantile economic system, is that such contamination and shifting of contamination will all register as a "good thing" on the books. i.e. it increases the GDP."

Technicaly yes, GDP sees work of any kind as good. If you make a thousand windows, break them all then make a thousand others and sell those, the nations GDP will be for the better.

Now of course youl be prety screwed and if you continue to do this you'l eventualy go out of buisness which will have a negative effect on GDP.

This is know as the broken glass falacy http://en.wikipedia.org/wiki/Broken_window_fallacy

As for the GDP when the hidden effects take umm well effect the GPD suffers so it is not as innacurate as it is beleived. Most of the problems with the GDP calculater anyway is that people see much more in it then a simple economic calculator.


God of Biscuits
Posted 01 March 2006 at 12:19 am

Christiaan says:

God of Biscuits, yes you are boring us, not with history lessons but conjecture. I'm sure such stories about mass graves and trees in Serbia will sooth your conscience however.

Sticks and stones, Christiann. If you're trying to hurt my feelings, you'll have to do better than that.


username
Posted 01 March 2006 at 08:30 pm

MaddMan said: "I wonder what radioactive marijuana would be like?"

Talk about high!!!!!!!!!!!!!! Stick a lighter to and BOOOOOOOM!!!!!!!!!!! Anybody got any for sale? Might as well die high and glowing!


cosmos
Posted 14 March 2006 at 12:36 pm

Check out Paul Stamet's new book, Mycelium Running. He goes into a ton of detail about using mushrooms for mycoremediation and filtration. It's fascinating!


another viewpoint
Posted 17 March 2006 at 11:08 am

...and what type of plant should be used to absorb the crap that comes out of every federal, state and local government body that wants to take advantage of its constituents? and all the fortune 500 companies that believe it's okay to treat employees like a piece of meat and take advantage of them?

Whatever it is, it's probably extremely rare, 'cause there won't be enough of it to go around!


Tink
Posted 03 October 2006 at 02:48 am

Cynthia said: "At Chernobyl, genetically altered sunflowers have been used to clean up two ponds heavily contaminated with both cesium and strontium, while hemp plants are being used to clean up the soil." .Dr. Ilya Raskin of Rutger’s University, one of the field’s pioneers, has been working with members of the Brassica family (mustards), which tests have shown effective at removing a number of heavy metals. Dupont has found corn useful for lead,.."

MaddMan said: "I wonder what radioactive marijuana would be like?"

Lets see, you smoke your radioactive weed, get this awful desire to listen to Heavy metal music, and make a necklace of pretty sunflowers, then you get the munchies.
So you eat a cornydog with mustard and there you are.
You got a bad case of lead posioning, while glowing in the dark and burning out your innerds.
I suppose you would eventually develop x-ray vision, but it would be hard to tell whether it was real or a halluciation from the brain damage from the insecticides.
Oh and then you would have mutant babies, just like your folks warned you about when giving you the don't do drugs talk in the 60's. LOL DI! Thank you Cynthia :)!


zachsauce
Posted 19 March 2007 at 07:10 pm

My only concerns is: would the oxygen that these plants and trees release be affected by the radiation they are collecting?


Mirage_GSM
Posted 23 May 2008 at 05:42 am

megzee said: "In my studies, I've learned that for every tree we cut down, we need to plant 10 in its place, so in about 50 years or so the air environment will be in better shape than it has in a long time. The amount of carbon dioxide removal itself would lower atmospheric temperatures, and reduce the threat of the ever-ambiguous "global warming" problem."

Actually... No.
Yes, trees metabolize Carbon Dioxide from the atmosphere into organic material. However they don't do that indefinitely. The amount of CO2 a tree takes from the atmosphere is equivalent to its mass (wood). By burning oil and gas we set free CO2 that was taken from the atmosphere over the course of millions of years. No single generation of trees will make up for this.
I do realize that the topic is even more complicated, I just wanted to denuk the myth that we just have to plant a few trees and global warming will go away.


Bob Nesbo
Posted 28 October 2008 at 02:00 pm

MaddMan said: "I wonder what radioactive marijuana would be like?"

Totally KILLER, dude!


ValiantDefender
Posted 16 December 2008 at 01:04 pm

Mirage_GSM said: "Actually… No.
Yes, trees metabolize Carbon Dioxide from the atmosphere into organic material. However they don't do that indefinitely. The amount of CO2 a tree takes from the atmosphere is equivalent to its mass (wood). By burning oil and gas we set free CO2 that was taken from the atmosphere over the course of millions of years. No single generation of trees will make up for this.
I do realize that the topic is even more complicated, I just wanted to denuk the myth that we just have to plant a few trees and global warming will go away."

I was under the impression that we've had very little overall effect on global warming and that volcanic activity spews out so much more greenhouse gas than Human activity that our is essentially negligible.

30,000 contaminated sites in the US alone? Are these all nuclear messes or all kinds of different things? And here I thought that the midwest was vastly UNDER populated. I'm thinking that a large portion of that 30,000 are in the nevada/utah/AZ deserts. Good lukc growing trees or mushroom in the environment.


kc-guy
Posted 14 March 2009 at 10:11 pm

ValiantDefender #22

THANK YOU for your Global Warming dose or reality.

Did anyone else know that the founder of The Weather Channel is SUING Al Gore?
http://en.wikipedia.org/wiki/John_Coleman_(news_weathercaster)#Views_on_global_warming


peace
Posted 02 February 2010 at 02:18 pm

Cynthia Wood said: "Some contaminants are simply pulled from the soil by the plant, some are converted, either by being inserted in a larger molecule (like the chromium), or by being broken down. It’s more useful to render the contaminants harmless, but being able to recover useful soil is in and of itself a tremendous accomplishment. Don’t underestimate the value of a more convenient vessel when you’re talking about things as toxic as radioactives and heavy metals."

I didnt understand if phytoremediation using agricultural crops is suitable for removing heavy metals from the contaminated soil or not because all the metals are accumulated in crop. but still many reserchers are using them in phytoremediation. If agricultural crops can be used for phytoremediation then what will be done for disposal of harvested plant parts.
Please experts in this field answer my query...


peace
Posted 02 February 2010 at 02:19 pm

I didnt understand if phytoremediation using agricultural crops is suitable for removing heavy metals from the contaminated soil or not because all the metals are accumulated in crop. but still many reserchers are using them in phytoremediation. If agricultural crops can be used for phytoremediation then what will be done for disposal of harvested plant parts.
Please experts in this field answer my query…


oscar
Posted 29 August 2014 at 04:45 pm

I know that lucerne grown to pull salts out of the ground are then sold to unsuspecting cattle grazers..


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