Phytoremediation

Mr.Intel writes "Wired has an article up about an 18 year old biology whiz who has done some very interesting research on phytoremediation (plants used to clean contaminated soil). This type of soil remediation is very eco-friendly compared to traditional methods but requires about 10 to 20 years to be effective. Marc Burell (the kid who did the experiments) used wheat to remove lead from soil in Mississippi."

Fungi have this property, too

[Deagol]

Check out this link on mycoremediation [fungi.com].

Overall, very cool stuff. Check out this site. It's great if you're into mushrooms (no, not those kind!).

Re:Fungi have this property, too

[bhima]

Yes, THOOSE kinds too!
Read his page, buy his books!, Grow Shrooms!

Great, but...

[fluffhead]

then what do you do with the wheat? You can't eat it, and if you bury it you are back to square one.

Re:Great, but...

[Jeremy Gray]

A quick read of the article gives the obvious answer: the plants are harvested and either the contaminants are extracted or the plants are disposed of as hazardous waste.

The benefits of this procedure over excavation and contaminant extraction should be equally obvious.

Re:Great, but...

[NaturePhotog]

From the article:

"If you have enough plants, you can recover the metal through a smelting procedure, or you can simply dispose of (the metal) in a hazardous waste site," Burrell said.

No, you can't eat it. You can either smelt it to recover the metal for other uses, or bury it properly, instead of scattered across a former industrial site. The latter doesn't get rid of it, but it does (in theory) keep it from continuing to contaminate the environment.

Re:Great, but...

[nucal]

you can recover the metal through a smelting procedure

I find it hard to believe that you can recover any metal from plants effectively. It's not like the wheat is going to turn into rebar.

Re:Great, but...

[j_w_d]

At the dawn of the Chalcolithic, the old timers probably had a hard time believing you could extract metal from rock too. After all, it wasn't as if the rock would turn into copper tools on its own.

You really weren't serious about that question, were you?

Re:Great, but...

[nucal]

From this report from the EPA(PDF file) [clu-in.org] : Baker (1995) found 80 species of nickel-accumulating plants in the Buxaceae (including boxwood) and Euphoribiaceae (including cactus-like succulents) families. Some euphorbs can accumulate up to 5% of their dry weight in nickel.

That's close enough to rebar for me - I stand corrected, next time I'll keep my yap shut.

Birds?

[Mr.Ned]

From the article:
{snip}
Burrell used wheat for his experiments, planting the crop in lead-contaminated soil. The roots accumulated the metal, which moved to the shoots -- the portion of the plant above the ground. The plants were then harvested.
{/snip}

So I'm assuming the basis of this is to have plants "soak" up the metals as they grow. The plants would then be smelted or dumped somewhere else.

What happens to the critters that eat the plants? Wouldn't it be just as bad for the animals to eat toxic metals as them live in them? Biological magnification would still take place.

Well, its not just soaking up contaminents.

[Veramocor]

One of the things that phytoremediation does is soak up metals and organic compound.

It also can have the effect of converting either the metal or organic chemical to a different form.

Say converting lead from its soluble Pb2+. To its reduced mettalic form Pb which isn't as toxic.

Or in organic chemical say PCBs, ploychlorinated biphenols, the plant may break off a few clorines off the phenol chain, again making it less toxic (or at least easier to break down).

So with the correct choice of organisms this should be a safe way of cleaning up things.

Works for gold as well...

[cp99]

This sort of stuff is pretty interesting. At my old university, there was a Prof. who was looking at taking up gold from the soil. You just need to add a simple chemical to the soil, then grow your plants (making sure that you get the species right), and get ready to harvest and extract the gold. While it isn't as cheap as some gold extration methods, it can be used in areas where the gold concentration is too low for other means of extration. Plus you don't have to go pouring tonnes of cyanide into the soil.

The Russians are doing it too

[Slashamatic]

Many people may be aware of the environemntal chaos left during earlier years in Russia. Well at least one company in St. Petersburg is using Phytoextraction as pat of the soil decontamination process, especially at oil petrochemical plants. The process takes some time and the oil industry has got the money to pay for it (although not always the inclination).

Note that plants are just part of the process, someone else here mentioned Fungi as well as other treatments.