Phytoremediation of Lead Polluted Soils

[Nathaniel Page]

I have this little science fair project in mind in which I hope to clean up some lead pollution in my friend's back yard with mustard plants. This is a little spot of ground about 20'x20' in Clinton Hill, Brooklyn. The soil has been tested and found to contain pretty high levels of lead (not sure on the exact numbers), probably from paint.

From my initial research, it looks like I will need to apply fertilizers and a chelating agent to the soil to help the mustard plants pick up the lead. It looks like the chelate I'll need is Ethylenediaminetetraacetic acid. This is where my expertise runs out, though. I'm hoping someone who is familiar with these agents may be able to talk to me briefly by phone about the application process. My main questions are: How much EDTA do I need to apply, and in what is the application medium, and what is the application timing? And is there a certain form in which I should buy my EDTA?

Thanks.

[Avery louie]

EDTA is a pretty commonly used buffer, and can probably be purchased from carolina biological.  Just order online.

--Avery

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[Cathal Garvey]

Aim for a low sodium content. EDTA is commonly sold as a tetrasodium salt, but you can get disodium or maybe less. Don't want to salt the earth, after all! Come to that, you might find an alternate salt like calcium or potassium if you look; much better!

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[Jeswin]

On Tue, May 8, 2012 at 9:36 AM, Nathaniel Page <nathan...@gmail.com> wrote:

> application process. My main questions are: How much EDTA do I need to
> apply, and in what is the application medium, and what is the application
> timing? And is there a certain form in which I should buy my EDTA?
>

How much? This article is good:
http://www.plantphysiol.org/content/117/2/447.full.pdf+html
Seems 0.5 to 0.75 mM EDTA is best for maximum absorption.

I attached another article, haven't read it yet

[Chris Templeman]

Nathaniel,

I have nothing technical to add, but please keep us updated on how this goes.  I think its a great project!

Thanks,
Chris

[Dakota Hamill]

I'm meeting with my analytical chem professor today to discuss some things and I'll ask her when I go.  I know she did a project on using a plant (I'm pretty sure mustard plant) to test for lead remediation near our school.  Right down the road from campus on the water there was this site for 50+ years that said LEAD CONTAMINATION site because it used to house some old pottery place.  Just this past year they cut down all the trees, flattened it, and put up some houses.  

Maybe the lead levels were back to an acceptable level, or maybe the construction site hired some people that specialize in remediation of heavy metals.

For our sophomore project we did a bunch of metal tests around that area using Flame Atomic Absorption, but the plant project was before our class so I don't know all the details.  I'll write back if she has kept any of the files or data from it.

-Dakota 

[Jeswin]

How do you extract the heavy metals from the plant matter? What are
the DIY methods to check for their presence? It would be interesting
to go around the yard and check if my plants are collecting these
metals.

[Dakota Hamill]

This is what my professor said 

"As for mustard plants...it's mentioned in a text box in the Harris book we used for Quant. I tried using peas instead of indian mustard..the book mentions indian mustard and that the lead needs to be made soluble w/ EDTA...then the plants can sequester it...the only issues is that once it's able to move more freely w/ the EDTA it has the chance to leech away to other areas as well. We planted peas in the lead contaminated area and watered w/ EDTA water and after they grew but before we removed the plants [waiting for them to die in the fall before pulling them] they closed the area for remediation before building so we never got to test them. There's got to be a reference in that text box in the book though...direct them to that reference is my  advice."

http://i.imgur.com/G7uGU.jpg

That's the picture I just took out of my old quantitative chem book, too bad it doesn't list any reference.

I'm sure "remediation of lead" will give you tons of results, as I know I've seen a lot about mustard/pea plants.  The only thing I don't know is the concentration of EDTA.

As for testing, Flame Atomic Absorption is no doubt your best bet.  It's simple, easy, cheap, and fast if you have the machine (which costs a lot) but most universities have.  For DIY ways, no idea, probably some terribly boring and complex titration.

Testing for metals is so cheap with AA...if I was still at school I'd do it for a large pizza.  The machine is very cool, brilliant acetylene oxygen flame that turns colors depending on the metal ions present in your sample, but it just doesn't do it for me.  I like HPLC/LCMS/GCMS stuff more because it's like solving a puzzle, whereas AA is just plug in your metal detector lamp, run it, and get a readout.  

[Nathan McCorkle]

My Quantitative Chemical Analysis book by Daniel C Harris (seventh
edition) has a similar box on phytoremediation in the EDTA Titration
section, and also mentions EDDS (ethylenediamine disuccinic acid, a
biodegradable alternative to EDTA)

http://en.wikipedia.org/wiki/EDDS

My book has a reference section, and lists these references

S. Tandy, K. Bossart, R. Mueller, J. Ritschel, L. Hauser, R. Schulin,
and B. Nowack, "Extraction of Heavy Metals from Soils Using
Biodegradable Chelating Agents", Environ. Sci. Technol. 2004. 38, 937

B. Kos, and D. Lestan, "Induced Phytoextraction/Soil Washing of Lead
Using Biodegradable Chelate and Permeable Barriers", Environ. Sci.
Technol. 2003, 37, 624

S.V. Sahi, N.L. Bryant, N.C. Sharma, and S.R. Singh, "Characterization
of a Lead Hyperaccumulator Shrub", Environ. Sci. Technol., 2002, 36,
4676

On Sun, May 13, 2012 at 7:19 PM, Dakota Hamill <dko...@gmail.com> wrote:
> http://i.imgur.com/G7uGU.jpg

Check your reference section for the EDTA chapter, Note 14


--
Nathan McCorkle
Rochester Institute of Technology
College of Science, Biotechnology/Bioinformatics