[permaculture] Study about lead in gardens (II)

Marimike6 at cs.com Marimike6 at cs.com
Thu Dec 11 12:02:28 EST 2003


In a message dated 12/11/2003 8:58:12 AM Eastern Standard Time, dtv at mwt.net 
writes: 
> Invariably, roots showed the highest lead concentrations, followed by 
> successively lower accumulations in stems, leaves, and the typically 
> edible portions. Root concentrations varied widely, even within a given 
> species. For instance, her team reports that one sample of soil with a 
> lead concentration of 1,600 parts per million (ppm) produced no 
> measurable lead anywhere in a grape plant. In another case, the roots 
> of grapes grown in soil with 944 ppm lead showed lead contamination of 
> 480 micrograms per gram (?g/g)-though there was no measurable 
> accumulation higher in the plant.

Great variability in the uptake is not surprising. Typically lead will occur 
in paint chips. If one plant's root system is touching a flake, it can take up 
a lot of lead into that side of the plant. The leaves on the other side, much 
less the leaves on the next plant over, may show no lead content at all. 

If you have a garden plot you're suspicious of, assume that lead is present 
anywhere the foundations of an old house can be seen. Most all of them got 
painted five or ten times before they were torn down. For a moderate expense you 
can gather samples and give them to a hazard assessment company to analyze. But 
either learn how to gather a good sample, or leave this step to the risk 
assessor.

I live in termite country, and old houses and barns collapse in a few years 
if they're not torn down first. All you have left is a pile of house-shaped 
brown dirt with tiny little flecks of white in it. These are what's left of the 
lead paint. Usually tobacco or cotton gets grown in such fields. 

Mike Elvin
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