Subject: Lead bioremediation in gardens

From: [email-masked] (Rachel Freifelder)
Date: Fri, 9 Apr 1999 03:30:47 -0800

I'm helping to start a garden on a site that was a parking lot.  After
depaving, we got the soil tested for lead and it came back with 700 ppm.
Some extension services say this is "safe to garden" as long as you wash
everything with soap and don't grow roots or greens - in other words almost
no cool-season vegetables.

We're going to do more detailed spot testing to see if it's only in certain
areas, and if it's just one spot we'll probably dig that out and fill it
with city compost.  In the meantime I am trying to find out what we can do,
particularly what crops are safe to eat, and what we can grow that would
accumulate/concentrate the stuff that we could then harvest and landfill
(or smelt!).  I heard of one person who grew a particular variety of corn
on a lead-contaminated site, then smelted the corn to obtain a lead ingot
(it was an art project).  The extension services all say corn, like other
fruit/seed crops, is safe, but maybe the lead accumulates in the stalk and
husks.  I would love to find out what variety of corn this is.

  If you have any advice, contacts, books, etc, to suggest, I would be grateful.

Thank you,
Rachel Freifelder
Mariposa Grove Community Garden
828 59th St
Oakland, CA 94609
510-655-2936
[email-masked]

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From: [email-masked]
Date: Sat, 10 Apr 1999 08:31:37 EDT

Well, Rachael, I'm afraid there are no generalities one would want to trust.  
Around 1980, Clark Nickelow, then (and maybe still) of the Waltham Field 
Station, Cooperative Extension Service, Waltham, Massachusetts, had 
opportunity to do analysis of soil and tissue of crops grown on the soil.  He 
was keeping records, but so far as I know he never published.  Maybe y ou can 
run down Clark, or see if the field station still has the records.  (You can 
probably get your local extension service to run down an adress, or maybe 
that is enough info for a phone call.)  We (Massachusetts Food and 
Agriculture Coalition) has pushed through the legislature funding so that 
inner city gardeners could get spectrographic analysis of soil and crop 
tissue for $5/test.  (The rest of us paid $20 or something like that.)  So he 
had the opportunity to test many samples of both.  Moreover, Ted Live, who 
worked in one of the State community agencies (forget the name) was 
distributing seed to people in standard assortments (also state funded 
courtesy of MassFAC) so there were a lot of the same varieties comming up 
that helped a lot in getting trends.
	Clark determined that lead uptake of vegetables differs markedly not 
only by species, and by plant part, but also by VARIETY!  So variety X of 
tomatoes will always take up less lead than variety Y.   I don't remember any 
of the details.  Also, certain root crops take up lead in the main tissue 
while others take it up mainly in the peel.  So the food is safe if  you peel 
it.  Beets and carrots were the comparison Clark used (this is all from one 
conversation I had with him incidental to the main business of my visit), and 
I THINK I remember that it was beets that you peel.  But I wouldn't bet my 
health, or anyone elses, on the recollection.   If all that data has been 
thrown away, which is the most likely scenario, then you need to start over.  
This time publish results in our journal (The International Permaculture  
Solutions Journal), where it will be ever available to people.

	Meanwhile, back at what you absolutely can do, there are several 
fail-safe remedies.  
	1)  Import soil for raised beds.  Far fetched?  Boston Urban 
Gardeners were getting contractors to do this for their gardeners at least as 
far back as the 1970s.  They also get organic matter and even manure hauled 
for free, often as backhauling so the added energy cost is much less.  BUG is 
a non-profit, so there are tax writeoffs for contributions of goods and 
services.
	2)  Build soil-less gardens.  There are two or three basic types.  
	One is basically gardening in mulch.  Barbar Daniels of CA has done 
this with rooftop gardens and using containers.  Basically, she applies deep 
mulch to a surface, usually an impervious surface, and innoculates it with 
some topsoil (very little, a sprinkling).  She sets out plants in pockets of 
soil and fertilizes and irrigates everything with dilute urine.  Her method 
was written up in a back issue of the Activist and we  have an article on 
file to publish in an upcoming isue of TIPS   journal, too.
	A very similar method is what I call dryland chinampas.  This is 
written up in Vol. I, No. 3 of TIPS (The International Permaculture Solutions 
Journal).  Again, this would require much less imported soil than regular 
raised beds.  Basically, you make a bed of any shape you like (can be a 
spiral or concentric circles or straight beds, etc) using thick layers of 
mulch alternated with thin layers of soil, topping the whole mess with about 
2 inches of soil.  Plants can be seeded or transplanted into this.  In 
Wichita, Kansas, we built a whole system of these beds using yard waste we 
picked up by beating the city truck on trash day.  Grass clippings are 
especially useful, and I like green matter for these beds when I can get it.  
I take clippings next to lawns with weeds--no herbicides.  A certain amout of 
brush trimmings with green leaves attached are ok for the bottom layer.
	3)  Straw-bale gardens.  These are described by Robert Kourik in 
DESIGNING AND MAINTAINING YOUR EDIBLE LANDSCAPE, NATURALLY.  The bad news is 
that this book is out of print.  The good news is that we bought out Bob's 
inventory of damaged copies (very slightly damaged).  Inthis method, a high 
nitrogen fertilizer is placed on the surface of straw bales and then they are 
covered by 4-6 inches of soil and planted in.  Regular watering is critical.  
I like to soak the bales down before I start.  (Did these in Kansas too.)   
Don't use hay--it will rot too fast and you will have an awful mess.  (I made 
that mistake when I couldn't get straw in Georgia.) It also heats up too fast 
an cold cook your seedlings.  You can skip the N if you plant legumes that 
you innoculate.  We got phenomenal crops of Christmas limas this way.  
(That's a variety, not the harvest season.)
	All methods of soilless gardening require rigorous attention to 
watering.  This is at odds with realities of urban gardens of this type, 
which are always in zone 3 or 4 for the residents, when ideally they should 
be no further than zone 2.  If you have no capacity to irrigate at will, 
forget it.  And only DEDICATED gardeners should use this system out in zone 3 
or further.  Just because you want a zone 1 garden in zone 3 doesn't make it 
a zone 1 garden.  The zone system does not slide to accomodate the 
inconveniences of urban living. This is the commonest mistake in what 
sometimes passes (alas) for urban permaculture.
	For anyone else out there contemplating such a situation, this 
project would be way better off if they had NOT removed the tarmac, which 
sealed off the toxic soil (you can remove a few small areas for tests of 
course), and used soilless techniques.  
	Finally, the application of all this organic matter will definitely 
reduce lead uptake.  Also try to keep soil pH between 6.5 and 7, again to 
reduce lead uptake.  Happily, most garden crops like this pH best anyway.  
	I hope I've been helpful.  I don't have time for a continuing dialog 
on this (unless you have consulting funds), but I think I've given you enough 
information to dig out any further data that you need.  Try to get a local 
college to take this on as a research project and generate your own lead 
uptake data.  (You do have to throw away some crop.)
	OK, one more point.  Back sometime prior to 1980, when I heard about 
it, a graduate student at Columbia University did a study of heavy metal 
uptake in NYC urban gardens.  As a "control" s/he measured heavy metals in 
supermarket produce.  S/he found that the supermarket vegetables were 
"heavey" in cadmium and the garden produce "heavy" in lead.  Given different 
forms of toxicity, it was a toss-up as to which vegetables are more toxic.  
In that situation, why not grow your own, improving the soil (which makes it 
less toxic), gaining a measure of self-reliance, and making the urban 
environment more liveable.  But steer clear of carrots.
	By the way, CA has a huge surpluse of rice straw.
For Mother Earth, Dan Hemenway, Yankee Permaculture Publications (since 
1982), Elfin Permaculture workshops, lectures, Permaculture Design Courses, 
consulting and permaculture designs (since 1981), and annual correspondence 
courses via email.  Copyright, 1998, Dan & Cynthia Hemenway, P.O. Box 52, 
Sparr FL 32192 USA  Internships. [email-masked]  

We don't have time to rush.

A list by topic of all Yankee Permaculture titles may be found at 
http://csf.colorado.edu/perma/ypc_catalog.html
Elfin Permaculture programs are listed at the Eastern Permaculture Teachers 
assn home page: http://home.ptd.net/~artrod/epta/eptahmp.html

In a message dated 4/9/99 7:24:39 PM, [email-masked] wrote:

<<

  If you have any advice, contacts, books, etc, to suggest, I would be 
grateful.

Thank you,
Rachel Freifelder

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From: fbanks <[email-masked]>
Date: Mon, 12 Apr 1999 12:53:49 -0700

Hello ~

I'm not a certified permaculturalist or anything fancy....   I  happened to read an article just last night that may help in this situation....   from  National Geographic, August 1993, "Bacteria:  Teaching Old Bugs New Tricks"....  

    "Lethal cyanide poured daily from the Homestake Mine's gold processing plant into South Dakota's Whitewood Creek.  Mercury, arsenic, and sewage thickened the toxic flow....   A Homestake biochemist said "I thought bacteria could do it [clean up the cyanide].  I collected samples of water exposed to the poison.  They held cyanide-tolerant bacteria that actually feed on the poison's carbon and nitrogen.  We designed...  a series of tanks in which the cyanide effluent moves slowly past feeding bacteria.  It worked."
    
    "....Groundwater Technology, Inc. of Norwood, Mass [are] specialists in treating polluted groundwater and soil.  They have used the technology of bioremediation to clean up hundreds of sites around the world...
    
    ".....[The author] sought out some sore spots...  a Superfund project on the lower Mississippi...  the soil [was] black with contaminants --- more than 200 toxic compounds....  [A biochemist with Louisiana St. University] identified bacteria that were already eating the pollutants and encouraged them to reproduce.  [They were] applied to a contaminated test site.  In nine months they cleaned it up.
    
    "....Aviation fuel had been leaking from [a Traverse City, Michigan Coast Guard] station's underground tanks, maybe for decades.  Its invisible plume had moved a mile with the groundwater [contaminating wells].  Traverse Group, Inc, a bioremediation firm, drilled interdiction wells to pump out the fuel at the station boundary.  The effect on the plume was astonishing.   With the  spread of the spill halted, the indigenous soil microbes quickly did their work, and the plume collapsed on itself.  After 18 months no trace of it was found beyond the station."  [End of excerpt]
    
Why not try a cheaper easier solution to your lead-infested parking lot soil first, before buying expensive topsoil.....    Till or plow deeply, adding copious amounts of compost and rough, rotting organic matter like moldy hay or straw....    Water the soil thoroughly and keep it moist for several weeks.....  then have it retested and see if the lead levels are dropping...   It seems to me that since the soil had been sealed off from the air by the asphalt pavement, helpful bacteria had no opportunity to flourish....   Perhaps all they need is some air (deep rototilling and coarse organic additions), micronutrients (compost and water), and some innoculation (compost and moldy hay).....   and the dormant, lead-eating bacteria will clean up this site FOR you...??

Why not be a "test case" for this method, since you already have an investment in one official lead test....  Your results could be very helpful for others encountering the same problem.....  If it doesn't work, you can always resort to  the more expensive methods (imported soil, raised beds, etc.)  I'm betting  your soil cleans itself up....

Could I be mistaken?  I'm no biochemist, either...   But it sounds reasonable, even with heavy metals....  Bioremediation works on industrial sewage full of heavy metals.....  Harwich, Mass. has a sewage treatment facility that turns the town's residential and industrial sewage into clean water, using only biological processes....

Thanks for listening...
Mrs. Joy Banks in AZ

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From: [email-masked]
Date: Mon, 12 Apr 1999 16:57:00 EDT

I am not going to reproduce the long post about bioremediation, in part 
because it is so long.  However I want to point out that cyanide removal is 
unrelated to the question of heavy metals.  Cyanide is an organic compound 
(HCN) so common that it is found in interstellar gas.  It was undoubtedly 
common in the atmosphere of primordial earth, and HCN energy pathways where 
the first used by life on this gob of mud and muck covered nickle/iron.  It 
is small wonder that organisms still know how to do it.  Even the human body 
can go into an anerobic phase under stress, for limited periods.

Unlike HCN, which needs merely to be taken apart to be detoxified (nothing 
wrong with hydrogen, carbon and nitrogen individually--togethere with oxygen 
and bits of this and that they make up protein in our own bodies, after all), 
well anyway, unlike HCN, heavy metals are elements and not likely to be 
changed by biological activity, despite far-fetched claimes at the far fringe 
of airey-fairey land.  (Not refering to the post in this exchange, but other 
claimes which strongly suggest use controlled substances.)  

Reduction of heavy metals in wastewater is done by holding them in or at 
least on plant tissue.   The issue of urban gardens is to keep the poison OUT 
of plant tissues.  This is done by the methods I posted earlier.

It is probably possible to come up with some superfund-type bioremediation 
program that willextract the nutrients.  But people who use urban gardens 
have few funds, let alone superfunds, and want to garden, not conduct bizzare 
experiments in element translocation.  You don't have to have credentials in 
permacuture, or to understand it much at all, to understand that before all 
else it is PRACTICAL.  Raising soil organic matter, keeping pH between 6.5 
and 7, and using various kinds of raised beds (with imported soil or soilless 
media) are methods ordinary people can put into effect, plant their seeds, 
and be eating from them in a few months.  It is not reasonable to expect 
urban gardeners to become leading edge soil biochemists and to treat soil 
with various advanced technologies so that in some years it will be fit for 
them to grow their lettuce and zuchinni.  The solution is out of scale with 
the problem.  

I think it is u seful to remind us of the fact that great strides are being 
made in bioremediation.  These should always be funded by the corporation or 
individuals who caused the pollution.  However in some cases, such as 
ubiquitous lead due to paint and gasoline, that means the taxpayer.  Since 
the urban environment is continually re-polluting itself, it seems not the 
first place to spend such money.  Not when the strip mines, superfund sites, 
Great Lakes, Chesapeake Bay, ad infinitum of the country can be cleaned and 
kept clean thereafer.  It is easier and cheaper to keep away from poison than 
to try to extract it from the environment after it is fully dispersed.  It is 
like pissing in a lake and then trying to get the fertilzer back.  Tilting at 
windmills is reasonable compared to tilting against such entropy.

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From: [email-masked]
Date: Wed, 14 Apr 1999 05:53:15 EDT

what about yes, incorporating the lead into timber through growing trees, 

but

continuing to grow gardens, but MAKING SURE to post -- in wood, and with 
lasting paint, where the lead concentrations are?

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From: [email-masked] (Harold Waldock)
Date: Wed, 21 Apr 1999 14:04:34 -0700

>lasting paint, where the lead concentrations are?

Cast the sign in stone or iron big and deep so nobody can move it.  But the
real issue is that you are playing on the edge of high levels.    I said
don't.  Your real problem is a) lead is mobile in the water table  b) there
is no safe dose  c) you can't print enough signs because there is somebody
bound to have a language you did not print a sign for.  Painted signs on
wood outdoors usually only last a few years unless very carefully done.
d)The problem in community gardens is that people usually avoid mulch and
grow annuals and leaves such as lettuce. e) people steal fruit ie tomatoes
or cucumber so gardeners don't grow fruit. f) Community gardeners don't
like people telling them what to do.They do what they want to do and there
is usually no way to stop them. Even you seem resistant to my suggestions
for example.

It is only useful to grow food in such a situation (high levels) if it
meant that people would starve on the short term with out it.  My garden
will not have high levels only low levels (I have 3x your rainfall and 2x
my normal rainfall in the last 2 years)  But I will test for hot spots such
as paint chips near the house.

Harold Waldock
Edible Landscape Creations
Vancouver Permaculture Network

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