Dear Andre:
Your design is very simmilar to measuring contamination in big cities.  Try
contacting universities in the very polluted ones, such as Mexico D.F. They
use specific methods, filters and vaccuum equipment for particles, gases.
They could recommend you where to purchase equipment and reagents.  There is
also the AOAC handbook which describes in detail methodologies for
gravimetric, volumetric, spectrophotometric and other quantitative analysis.
Best regards, Ronaldo.
 
At 01:41 PM 13/07/98 +0200, you wrote:
>I plan to conduct a field experiment with maize and I am interested to
>quantify the amount of N, P and K and perhaps other elements such as
>heavy metals or acidifying agents during no rain periods (dry periods)
>as well as periods of rain (wet periods).  I am therefore looking for
>a procedure or a method to measure the deposits of these elements from
>the atmosphere.  Can you please help me in this regard by giving me
>any information you have about methods or instruments that can be used
>for this purpose, or even if you know of any similar studies that have
>been carried out.  I would also like to know the addresses of possible
>suppliers of such instruments
>
>Regards
>Andre
>
>
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