Re: Biology Question on Trees and Polution

In article <3kdp7e$dma@news.panix.com>, <jimcook@panix.com> writes:

> Simonich and Hites (1994) estimated that most of the atmosphere to soil
> flux of polycyclic aromatic hydrocarbons (PAHs) occurs via absorption 
> to plants.  They suggested that this may also be the case for other low
> vapor pressure and hydrophobic atmospheric pollutants -- such as 
> polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls.
> It's true that trees and other plants release hydrocarbons to the 
> atmosphere, and that these hydrocarbons contribute to the formation 
> of smog and haze.  However, the rate limiting reactant in this 
> photochemical reaction is NOx, which is largely anthropogenic in most
> urban areas.
> ....Simonich, S.L. and Hites, R.A. (1994) Importance of Vegetation
> in Removing Polycyclic Aromatic Hydrocarbons from the Atmosphere.
> Nature, 370, 49-51.

Thanks for the citation...always a help. 
I'm not in this field, but it seems to me what you are saying is that, as 
part of the process of transpiration, trees and other plants will carry 
hydrocarbons disolved in the ground water into the tree, and then it will 
blow off in to the air.
Is it therefore correct to say that trees are only responsible for moving 
the hydrocarbons from the soil to the air?  That is, they do not *create* 
any of these things?  If so, then the question really is, how did the 
hydrocarbons such as dioxins get into the ground?

I'm sure Mr. Reagan would blame the ground-hogs.  and that Mr Thorson 
would believe him.


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