|MadSci Network: Environment & Ecology|
There is a big difficulty with this question. It has to do with the way that chemists use their terms. Chlorine means two quite different things! In the first case "chlorine" means a very poisonous greenish yellow gas, Cl2. Chlorine gas is one of the more reactive substances that chemists come across. It reacts directly with about 80 out of 90 other simple substances (elements), and with a good proportion of known compounds as well. But the second and more important meaning that chemists attach to the word chlorine is that of chlorine as an element -- a particular type of atom. Now in any type of chemical reaction, atoms are conserved. You cannot get rid of a chlorine atom in a reaction. All you can do is to arrange for it to be bonded in a more reactive or a less reactive compound. The particular CFC compounds that are responsible for the thinning of the ozone layer and the Antarctic ozone hole are things like dichlorodifluoromethane, CF2Cl2. These chlorine-containing compounds simply do not react with *ANYTHING*, and certainly not with anything in the natural environment. There have been several proposals for possible ways to "scrub" chlorine compounds out of the atmosphere, including a few from leading atmospheric scientists. All have so far proved, on deeper examination, to be impractical. Because of the scale that would be required for any such solution, even if it were found, there would be a very large danger of the "solution" producing its own adverse and unforeseen environmental effects. The atmosphere is a very delicate environment.
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