|MadSci Network: Environment|
What happened....? The answer to your question is that the particulate matter from the Desert Storm fires in many cases was of sufficient mass that it did indeed fall to the ground within days of formation. As such the ultimate chemical fate would be a function of the particular chemical make-up of the soot particles. Some would degrade rather rapidly either by chemical or biological pathways and some would persist for years, as does soot in chimneys. Those particles that were too small for immediate deposition would in many cases be spread over thousands of miles, conceivably even around the entire earth and ultimately become very dilute formations before they, too, would ultimately be deposited on the earth and ultimately be degraded by physical, chemical, or biological means.
Yes, our atmosphere does indeed clean itself through many pathways, some of which are very complex. Consider the case of Freons... Freons have been released into the air and some of the freon molecules ultimately find their way into the upper atmosphere where they interact with ozone molecules and destroy the ozone, thus depleting the atmosphere of the ultraviolet radiation shielding properties of the ozone. The observation of this phenomena and the subsequent determination of Freon's chemical pathways were of sufficient importance that Professors Rowland and Molina co-won the Nobel Prize in chemistry.
The various insults we fling into the air sometimes are rendered innocuous nearly immediately and others persist for years. Consider the methane that results from landfill biodegradation over the years. It is a major contributor to "global warming", much more than the contribution of carbon dioxide that we have heard so much about. This is a potential problem that mankind is rather slow in confronting yet it is one of potential disastrous proportions. Imagine global warming occurring, melting Arctic and Antartic ice packs and the resultant waters causing the flooding of coastal cities.
I trust this will provide information that will help to satisfy your curiosity. The ultimate complexity of the question is resulting in many, many years of research effort by scientists around the world.
Thank you for asking.
Try the links in the MadSci Library for more information on Environment .