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The Resilience Hub & Portland Maine Permaculture Message Board › Using Spinach to Remove Lead

Using Spinach to Remove Lead

Lisa F.
Group Organizer
Portland, ME
Post #: 179
I'm not sure if I can make it to this event, but I am VERY interested. If someone can go and report back with a few notes on this message board, it would be fabulous...


USM Phytoremediation in Urban Gardens talk
Posted by: "Justine Roths"
Fri Oct 12, 2007 10:19 am (PST)
There's a free talk coming up at USM that may be of interest to a few
folks. It will be a scientific talk but on a topic that's quite
interesting. Dr. Langley-Turnbaugh uses spinach to remove lead from
soil, returning the soil to health. She's been working in Portland's
neighborhoods for some years now. Her faculty page is at http://...­ I hope to see a few of you
there! (If you're not familiar with USM's Portland campus, just email
me directly and I'd be glad to give you directions.)

Announcement: "Dr. Samantha Langley-Turnbaugh of the Department of
Environmental Sciences and Policy at USM will present a seminar titled:

"Phytoremediation of lead in urban gardens of Portland

Please join her on Thursday, October 18, from 2:00 to 3:00 p.m. in
the Luther Bonney Auditorium."

-Justine Roths
A former member
Post #: 24
I'll try to go. Our house is being re-roofed this week but I should be able to slip away during that time. My husband knows her--she's a very respected faculty member in the environmental science dept. out in Gorham. I'll post anything I can gleen.

Merry & Burl H.
Portland, ME
Post #: 23
Field Notes on Speech of Samantha Langley-Turnbaugh
Phytomediation of Lead in Urban Gardens of Portland, Maine
Department of Environmental Science

Portland has two major problems that combine to poison children. First, it has Maine's worst urban poverty, with more than 40% of black refugees living in such poverty that 78% of the children do not eat enough fruits and vegetables to be healthy. To fight this problem, many immigrant households practice "gypsy gardening" in defiance of a city ban on urban gardening. That brings us to the second and related problem. Why would the city have such a ban? Because they know that most of Portland?s soil is highly contaminated with lead. Lead poisoning is the #1 environmental health threat for children. Over 1000 Maine children per year are identified with elevated levels of lead in their blood. Soil in their yards is potentially a major contributor and largely unregulated. Although most adults are affected by inhalation of soil when they garden, most children are poisoned by ingestion. While the EPA says levels >375 (parts per ?) are unacceptable even though Europe, Canada, and even Russian allow far less, samples in Portland were often >500 with some >20,000. 98% of the 500 yards tested had some areas >1000.

How did Portland?s soil get so contaminated by lead when the background levels throughout the State are well below the EPA?s (admittedly high) maximum allowable standards?

  • The Great Fire of 1866 burned thousands of lead painted buildings to rubble, which was plowed as landfill into low-lying areas like Bayside and Parkside. That layer of ash remains there and toxic to this day.
  • A tannery and a paint factory in the area both emitted huge amounts of lead.

  • Flaking paint, from before the 1970s when the 1959 ?suggestion? that we not use lead-based paints finally became mandatory, got into the soil where it doesn?t biodegrade.
  • Incinerators give off lead.
  • Emissions from leaded gasoline before it was banned remain in the soil, and virtually all Portland buildings are immediately roadside.
  • Much of the landmass of the Portland Peninsula is landfill of wetlands, essentially built on garbage dumps.

    Dr. Langley-Turnbaugh studied the intensive planting of spinach in the lead polluted spots on 500 properties on the Portland Peninsula in the areas of Bayside, Parkside, East End and West End. Such use of plants to take up the heavy metals contaminating the soil is called ?phytomediation?. She regrets that she was unable to access some of the most important areas. Rental landlords wouldn?t allow her on their properties; and neither would the government let her on public lands such as schoolyards, with the exception of parks. Why? Liability! As long as they don?t "know" that their land is polluted by lead, they cannot legally be held liable. The fact that their ignorance is intentional, since they have been offered the opportunity to have their soil tested free, doesn?t make them culpable. Effectively, this absurdity prevented Dr. Langley-Turnbaugh from testing or treating the soils of the most vulnerable of the poor. Very few immigrants from war-torn African nations have the resources to own property. Schoolyards, because of heavy foot traffic, have lots of exposed dirt.

    Moreover, property that had been used as ?gypsy gardens? was the least responsive to the phytomediation. The lime, compost, and water used for gardening had ?bound? the lead, so that the spinach could not absorb it. Therefore, as the study progressed, the scientists concentrated more and more on non-garden exposed soil, thereby getting more significant results. Also, the funding, which Dr. Langley-Turnbaugh is grateful to have received from the EPA, Healthy Communities, and Environmental Justice, only allowed for one year of spinach planting in each of the four communities. It is entirely possible that more gains could be made with repeat remediations.

    These problems aside, the experiment had some significant findings, suggesting the advantages of using high-biomass plants, such as spinach, in intensive plantings (much denser than crop plantings) to remove toxic lead from urban soil.
  • The finding that the spinach plants did absorb significant and toxic amounts of lead makes the appropriate labeling of such plots with the skull and crossbones used to label poisons, which the experimental team used, crucial. People need to be warned and discouraged from eating these plantings.
  • The finding that much more lead was taken up by the spinach in soil not recently gardened suggests that such mediation should precede planting gardens for food.
  • The finding that far more lead was found in the roots than in the leaves of the spinach suggests two things: a) that the entire plant, roots and all, should be harvested and disposed of after such phytomediation; and b) that root vegetables should be grown in planters, not in contaminated urban soil.
  • Spinach worked better than (some kind of) mustard, the plant used in most laboratory phytomediation studies and better than sunflowers, although it was hoped their deeper roots would absorb more. Whatever plant is used in Maine?s climate needs to put most of its energy into growing lots of leaves fast.
  • The study found that seedlings grown organically and transplanted into the lead-polluted soil grew far better and sequestered more lead than seeds started in the lead-polluted soil. In this case, a healthy start in life gave the plants an advantage that persisted, even when later exposed to the stressors of heavy metal. (I am tempted to over-generalize from this finding.)
  • Bare soil in polluted areas should be covered either with vegetation or concrete to protect children, adults, and other creatures from the lead.

    It is very promising to realize that cover cropping with spinach or some other fast-growing leafy crop can reduce lead levels. If repeated applications of this procedure, in fact, further reduced the levels and then good farming practices "bound" what remained, urban gardening could help the urban poor obtain the vegetable and fruit nutrients their diets so sorely lack. Such research as Dr. Langley-Turnbaugh?s, though it doesn?t offer a panacea, suggests a vital first step toward urban food security in Maine and elsewhere.
A former member
Post #: 28
Hi Mary

Nice to have run into you at Samantha's presentation! As I promised you that I would, I am chiming in with a couple of additions. You put a lot into your summary...thank-you for writing it up for us!

1. EPA levels of unacceptable lead is > 375 mg/kg. (of soil) I believe that
the upper range of lead levels in Portland is 2000 mg/kg not 20,000. 91% of their samples in their study area
(Portland peninsula) had lead levels over 400mg/kg

2. Indian mustard is one of the other plants that has been widely used for 'phytoremediation' studies.
Spinach was chosen because it was familiar to the immigrants. Any leafy weeds also work.

3. Lead is a neurotoxin and impairs brain function. It has been found to contribute to ADD and ADHD in children.
It also affects hearing and speech function and has been found to lower IQ and contribute to lower test
scores. The incarceration rate of prisoners with lead contamination is higher than the general population.
Parkinson's patients have a higher lead level in their bones. People with osteoporosis have sequestered
lead from their deteriorating bones leaching back into their blood.

4. Lead does not (naturally) degrade (in soil) over time. There is more lead accumulation around the drip line of
houses. All houses built before 1986 had lead-based paint.

5. 'Gyspy gardening' can be defined as gardening in areas despite regulations saying not to do so/unsafe to do
so ( in an effort to get food on the table by any means)

6. Adding ammendments such as lime and manure raises the pH of the soil making the lead LESS able to dissolve
into solution for uptake by plants. In other words remediation in acid soils works better than in soils with a
higher pH because the acid helps dissolve lead. Test plots required increased irrigation to help put lead into
solution. Those families whose plots were tested received individualized recommendations for how to
proceed. e.g. how long to keep throwing away plants and when or whether to add ammendments.

7. As far as plant uptake goes, lead molecules are similar to calcium molecules and enter the plant because they
are perceived to be similar. Leafy greens contain more calcium and have a high growth/biomass rate. which is
one reason why weeds/spinach make good phytoremediators

8. The reduced levels of lead in her study only involved six weeks of actually growing spinach. Further
funding would allow replanting plots to see how much further lead levels could be reduced.

9. There are studies being done using fast-growing hybrid poplars for lead uptake for the purpose of reclaiming
the lead from the harvested trees for recycled useage.

10. It's LEGAL to dispose of contaminated plants in the trash although I think she said it needs to be treated as a
toxic waste.

user 4058763
Hollis Center, ME
Post #: 20
So my question is: How do you dispose of the spinach properly...where it isn't just moving the lead elsewhere.

Any data on how much lead is removed from the soils? How many years does this process take, in other safe is the soil after one crop of spinach is grown?

Thanks, very interesting.

Merry & Burl H.
Portland, ME
Post #: 24
Thanks, Winnie. I'll incorporate your info into my writeup and send it to Samantha for refinement.

Hi, Tree. I'm not too happy with the answers to your questions, but here they are. As Winnie pointed out to me on the way out of the session, when I grumbled about these things, "At least it's a good first step." Yes. Also it illustrates what good friends and physicians plants can be to humankind when we are willing to cooperate receptively with them. This is an important permaculture lesson.

So my question is: How do you dispose of the spinach properly...where it isn't just moving the lead elsewhere.

Samantha indicated that removed contaminated soil had to be treated as toxic waste, but the spinach plants removed roots and all can safely (?) go to a landfill where it will be burned.

Any data on how much lead is removed from the soils? How many years does this process take, in other safe is the soil after one crop of spinach is grown?

Yes, it was "significant" scientifically, but not terribly much to my eye on the bargraphs she showed. Certainly, after one year's mediation, the level of lead remained above "acceptable" standards of the EPA which are high by international standards. Samantha was not able to research further years, because the funding only allowed for one year at each site. I doubt very much that hungry people are willing to wait years to plant their "gypsy gardens" so it might be a moot point anyway.

Many blessings, BeMerry
David S.
Washington, ME
Post #: 69
I should be noted here that for lead contamination, mycoremediation is also a possibility. A number of different mushrooms extract heavy metals. Mushrooms found in downtown Portland sound dangerous to me.

Once again, I refer you to "Mycelium Running" by Paul Stamets for information on this. I get the idea no one has purchased this book but it also has info on remediation of hydrocarbons as well which may be a more widespread problem than lead. As I said, this book would change the way you think about virtually everything. This book should be on the permaculturist's shelf.

A former member
Post #: 29
I have Paul Stamet's book and I agree that he and it is incredible. I don't know how you could conclude that no one else has his book though, as Dr. Langley-Turnbaugh's research concerns a specific target group of people, in a specific area using one specific plant that was chosen because it was already familiar to the people who would be using it--mainly low income residents in food insecure households who live mostly in the contaminated areas. She said that 40% of the children in Maine come from food-insecure households and that 78% of them don't eat fresh fruit or vegetables.

David S.
Washington, ME
Post #: 71
Much of what I say passes without comment. I guess I should not assume.

I did actually write to Dr. Langley-Turnbaugh and she is not familiar with mycoremediation but then she is not a mycologist either. All strategies that work are good and spinach is easy. That said, I would not feel comfortable eating garden products after the spinach treatment without some serious testing.

I'm guessing all those 3 deckers on Munjoy Hill were painted with lead paint. There is probably still plenty around and the water table likely moves downhill. It's too bad to find out that most city gardening can be risky. I have a friend that did a plant/soil study of roadside gardens. He found easily measurable amounts of rubber dust 50 feet from the road and some evidence as far as 150 ft. away. Not good.

It should be noted here that oyster mushrooms and others can remediate hydrocarbons. They don't suck them up and require disposal. The create enzymes that actually deconstruct hydrocarbon molecules. PCBs gasoline, diesel fuel, transmission fluid etc. actually no longer exist after treatment. Pretty amazing.

That said, oysters do uptake heavy metals as spinach does and require similar disposal if used for that purpose.
Lisa F.
Group Organizer
Portland, ME
Post #: 183
My guess is that your friendly neighborhood transfer station attendant would look at you as if you had three heads if you asked how to dispose of your "hazardous waste spinach." smile

Thanks to all for the notes/comments on this. I think it's an extremely important issue for permaculturists who want to make the most of edible growing potential on their lots - esp up close to structures, whether that's urban, suburban or rural. Get that soil tested!


Hopefully more funding or empirical evidence will answer some lingering questions on all of this...

David - not everyone comments but I'm certain ALOT of people read what you have to say on this forum - your experience and knowledge on many topics is appreciated.
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