"Jo Schaper" wrote in
message ...
hanson wrote:
element or compound in tree bark that it burns with too much ash
"Bob" wrote in message
...

"Farooq W"
| More surprising the uptake of heavy metals especially
| Th and U by the plants...Barium is abnormally high or the
| soil on which that tree grew was rich in barium ores!

On Sat, 11 Mar 2006 02:27:31 GMT, "donald haarmann"
wrote:
The up take of uranium by plants is well know. See for example :-
Botanical Prospecting for Uranium on La Ventana Mesa, Sandoval
County New Mexico. US Geological Survey Bulletin 1009-M. 1956.
Some plants uptake serious amounts of selenium.

[Bob]
A Berkeley group is developing the use of a plant for Se
decontamination of soil. It is in field testing. (I could probably
find a ref if someone wants it.)
Then there are the Ni accumulators, which have several percent Ni in
their sap, nicely chelated (citrate, I think).
bob

[hanson]
=1= I posted this into sci.geo.geology in hope to get some views
from the geos' camp about the popularity & effectiveness of BP.
=2= As what/which compound does Si get into solution from the
calcogen silicates, considering that SiO4-- is stable only at
pH 11 in aq?
=3= in what soluble or sol-gel form is Silicon taken up
and transported in/to the plant (at a pH range ~ 7)
=4= As what/which compound is Si stored in the plant?
=5= and what function does the Si have in the plants?

[Jo]
I don't know the answer to your question, but I would look at
Equisetum -- aka scouring rushes. They have extremely high
Si uptake. [1] As a primitive plant whose chlorosphyll is incorp'd
in the stems, the Si, is used as a supporting structure. [2]
Also, the Na, K, Ca group are also metals utilized by plants. [3]

[hanson]
Thanks Jo. AFAYK, is [1], such a high Si uptake, common to
all such primitive plants (Fern, Lichen etc)? If yes, then there's
here an interesting link to the origin of multi-cellular plant life.
In marine plankton, the radiolarians, all do have skeletons made
of beautiful microscopic SiO2 structures.
What Si chemistry and physics is involved in their existence &
growth? -- How & in what form do they extract Si from sea water?
What chemical Si-reactions are involved in this transport?
What soluble silicates are there in ocean water?

I have no problems with [3] presence at all, not even with [2]
using the rigid SiO2 networks as a the basic inorganic frame
around which the "living" CHNO networks grow and harden
(a bit like in a fiber-glass analogy)... But what I have not seen
a good/elegnat explanation yet for in what form this Si4+ or
H4SiO4 is transported into and through the plant.
hanson