[USCC] Contaminated park brings end to community garden plan

[Chaney, Rufus]

Dear Colleagues:

First, imagine trying to grow mushrooms on a contaminated urban soil to remove soil Pb. Mushrooms are not a practical phytoextraction crop.

Second, although some mushrooms may accumulate some Pb, they do not accumulate over 1% Pb which is the level needed to make phytoextraction begin to be practical. 

Please note an older paper which showed the potential for Hg accumulation by mushrooms when grown on media containing much Hg, and some horse manure composts have produced mushrooms with high Hg because of medicinals used in veterinary medicine of horses (this is rare). Although I did not summarize the Pb information, it showed low accumulation of Pb compared to garden vegetables that are our usual concern with Pb contaminated soils.

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Domsch, K.H., K. Grabbe, and J. Fleckenstein.  1976.  Schwermetallgehalte im Kultursubstrat und Erntegut des Champignons, Agaricus bisporus (Lange) Singer, beim Einsatz von Müllklärschlammkompost (Heavy metal contents in the culture substrate and in the mushroom, Agaricus bisporus, grown in composts mixed with municipal waste and sewage).  Z. Pflanzerern. Bodenk. 1976:487-501.  
	"The addition of increasing quantities of municipal waste compost to conventional horse manure compost resulted in a proportional increase in the heavy metal content of the mixture.  The increases ranged between 250% (zinc) and 900% (mercury).
	"94-99% of the heavy metals in municipal waste compost are bound in compounds from which they can not be extracted using CaCl2 solution.  The amounts extractable from horse manure compost with CaCl2 solution are from 1.5 (zinc) to 33 (mercury) times higher.
	"The influences of the increasing quantities of heavy metals in municipal waste - horse manure composts are demonstrable in the content of these metals in harvested mushrooms.  This, in turn, corresponds to the availability of the metals.  The relative enrichment is greatest with mercury, and least with cadmium.  The quantities found in mushrooms, with the exception of mercury, fall within the normal range detected in vegetable groups." 
	Compost contained 0, 25, 50, 75, or 100% sludge/refuse compost; the 100% compost medium contained 2.40 mg Hg/kg DW, Zn=1390, Cd=11.1, Pb=625, Cu=197, and As=33 mg/kg DW.  Mushrooms contained 0.13, 0.32, 0.52, and 0.53 mg/kg FW for the 0, 25, 50, and 75% compost media (100% not reported or not grow), and were significantly increased in Hg.  Methyl-Hg not analyzed.  Cu, Cd, and Zn were significantly increased in the mushrooms also, but Zn only slightly.   

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Regards,

Rufus Chaney
USDA-ARS
Beltsville, MD

-----Original Message-----
From: compost-bounces at mailman.cloudnet.com [mailto:compost-bounces at mailman.cloudnet.com] On Behalf Of Heide Hermary
Sent: Saturday, May 09, 2009 12:02 AM
To: Compost Discussion List
Subject: Re: [USCC] Contaminated park brings end to community garden plan

Here is the list provided by Joshua,taken from "Mycelium Running" by  
Paul Stamets:

Numbers represent the bioaccumulation factor which indicates how many  
times more concentrated the metal is compared to the background level.
Note: mushrooms listed without accumulation number have no research to  
tell us the bioaccumulation factor, just that they do concentrate lead.
Factors may vary between samples, this is only to be used for further  
comparison or further research.

Agaricus bitorquis  23X
Agaricus campestris  10X
Boletus edulis  X
Chlorophyllum rachodes  X
Lycoperdon perlatum
Morchella spp  70-100X
Morchella atretomentosa  X
Suillus tomentosus  67X

Obviously many variables can affect the mushroom's ability to  
hyperaccumulate toxins, and results could vary substantially between  
sites. I suggest that anyone wanting more information read the book,  
or contact Paul Stamets directly (www.fungiperfecti.com). This is a  
new field of research and practice.

Cheers, Heide

Heide Hermary
Gaia College
http://www.gaiacollege.ca