hanson wrote:

"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

hanson,
I am not a botanist, nor a botanic chemist. I would suggest you go to
a local botanical garden, or the botany section of a college library and
look up such things as 'natural terrestrial communities' 'acidic soil
ecosystems''alkaline soil ecosystem'(to see how the other half lives)
'sandstone glade' 'chert glade' 'igneous glade' and any other
combination of silic rock name plus landform (prairie, forest, savanna,
fen, bog, etc.)

As a generalization, more primitive plants do tend to populate more
silic environments, (pines on sandstone, deciduous trees on limestone)
but these are generalizations, with many exceptions as some trees and
plants (blackjack oak, post oak) do adapt to silic environments.

A good naturalist can walk through an area and accurately predict either
the rock or the plants if they know the other, plus the amount of
retained moisture and sun which an area gets.

I had to look up all this stuff when I did my thesis--in order to relate
water chemistry to some of the plants, and their possible interaction
with travertine deposition (i.e., was the water, the slope or the plants
controlling deposition) and I found more info than I could absorb or use
by just browsing in ecology,agronomy and silviculture texts.