Originally Posted by
Mike Alexander '59
I am not sure what the significance of the hydroxyl article is. This is my understanding.
Ozone (O3), water and sunlight react to form oxygen and hydroxl radical (OH). Water is present in enormous excess and when sunlight is adquate the progress of this reaction should be limited by ozone level. (This is an overall reaction comprising two subreactions).
Carbon monoxide (CO), oxygen (O2) and sunlight react to form carbon dioxide and ozone. This overall reaction consists of three subreactions and is catalyzed by hydroxyl radical. That is, the hydroxyl radical is not consumed (actually it is consumed in one subreaction and regenerated in another for no net consumption).
Hydoxyl radical removes itself from the atmosphere though a third reaction. The rate of its removal depends on its level.
The net effect is the rate of CO removal is dependent on the level of CO and the level of OH. The level of the latter is dependent on the level of O3, which itself is made by CO and so is ultimately dependent on the amount of CO.
What this amounts to is the more CO (pollutants) pumped into the atmosphere the more oxidation (atmospheric cleansing) occurs, and the higher the level of ozone. This is why pollution by volatile organic compounds (VOCs) is associated with ozone and why in "ozone non-attainment regions" we see those special gas pumps with the emission controls on them (to reduce the emission of hydrocarbons, the atmospheric cleansing of which creates ozone).
Now methane (other hydrocarbons too?) is a potent greenhouse gas. Were large quantities of methane to get into our upper atmosphere they would serve to significantly exacerbate global warming. But as long as atmospheric cleansing mechanisms are working, CH4 is converted into carbon dioxide, another greenhouse gas, but much less potent. (The probably explains why all the methane produced by cattle and similar animals hasn't been a global-warming problem)
If something were to effect the level of OH (a marker for the efficiency of atmospheric oxidation reactions) this would imply that more pollutants are leaving the troposhere, which means less ozone (a good thing for public health) but more hydrocarbons moving upstairs (a bad thing for global warming). On the other hand if OH levels aren't falling (which I think is what the article says) then that means we still need to worry about ozone but less about non-CO2 greenhouse gases.
Exactly, but far and away from the implied point of Marc's article - that the increased presense of hydroxyl ions somehow is the ultimate ecological palliative.
Unlike politics, science is incapable of comromise. Physics and chemistry are what they are - no more; no less. 8)
Marx: Politics is the art of looking for trouble, finding it everywhere, diagnosing it incorrectly and applying the wrong remedies.
Lennon: You either get tired fighting for peace, or you die.