[Terrapreta] char & vascular systems

[Lloyd Helferty]

Thank you Philip, this is what I essentially concluded as well.  You
summarized it better, however.
I've passed this information along to my group.
 
    Lloyd Helferty
    Thornhill, ON, Canada
    905-707-8754
    647-886-8754


  _____  

From: e.philip.small at gmail.com [mailto:e.philip.small at gmail.com] On Behalf
Of Philip Small
Sent: June 15, 2008 4:28 PM
To: Richard Haard
Cc: mark at ludlow.com; Lloyd Helferty; terra pretta group;
biochar-ontario at googlegroups.com
Subject: Re: [Terrapreta] char & vascular systems


I did find a pdf by Frank
<http://cru.cahe.wsu.edu/CEPublications/eb1884/eb1884.pdf> Peryea for
gardening on arsenic contaminated soils, which says:



Plants absorb soil ... arsenic through their roots; hence, all plants
contain small amounts 

of both elements. ... Plant arsenic concentrations tend to increase with
increasing soil arsenic, then 

stabilize at some maximal value at higher concentrations in soil. The exact
relationships between 

plant and soil ... arsenic vary with factors ranging from chemical forms of
the elements in 

soil, soil properties, climate, soil and plant management practice, to plant
species and varieties.

 

The Washington State Department of Health estimates soil arsenic
concentrations below 37 mg/kg 


should protect the health of children having frequent exposure to
contaminated soils.


Reading between the lines in this pdf as a whole, as well as supporting
references, one is left with the impression that arsenic acts in  very
complex ways chemically.  Because of this complexity, there is no clean
linear relationship between simple arsenic content and simple effects,
physical (like plant uptake) or health-wise. I don't believe we will be able
to come up with a clear direction regarding plant uptake and accumulation of
char-derived arsenic.  From what I read, I conclude that:
1) direct ingestion/inhalation of char derived arsenic will cause more
health effects than ingestion of plants grown on char amended soils and 
2) Worst case scenario for plant uptake of arsenic is on acidic sandy soils
where arsenic is most likely to be mobile. 
3) 10 ppm As in char doesn't appear to be worth worrying about. -philip

 

On Fri, Jun 13, 2008 at 4:33 PM, Philip Small <psmall2008 at landprofile.com>
wrote:




On Fri, Jun 13, 2008 at 2:40 AM, Richard Haard <richrd at nas.com> wrote:



 There must be a body of research on uptake.....

I am at my daughter's college graduation (go Gooey Ducks!) so short
response: WSU has extensive studies on arsenic and plant uptake, Soil sci
Frank Peryea at WSU in wenatchee wa is the primary source.  I will google
when  get a chance... -philip





-- 
Philip Small, RPSS
Land Profile, Inc. * PO Box 2175 * Spokane, WA 99210
509-844-2944 cell * 509-838-4996 fax * 509-838-9860 office
Profile: http://www.linkedin.com/in/philipsmall 

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