It鈥檚 long been thought that emissions from things like coal-burning power plants need to react in sunlight to make sulfuric acid in the atmosphere. But a new discovery suggests there might be more to the story.
Scientists likeLee Mauldin, a researcher at the and the , thought they had the production of sulfuric acid in the atmosphere pretty much figured it out.
鈥淪unlight shines down and blows apart ozone,鈥漵ays Mauldin.
The broken ozone in turn creates hydroxyl radicals (OH) that are highly reactive and are the primary oxidant in the atmosphere.
Until recently, the hydroxyl radical was the only compound known to react with sulfur dioxide, or SO2, to make sulfuric acid. And because the sun sparks this reaction, it was thought that sulfuric acid could only be made during the daytime.
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But Mauldin and his colleagues saw plenty of sulfuric acid being made at night when they took measurements in a forest in Finland. Without the presence of hydroxyl radicals, how was the acid being made?
鈥淲e found a new oxidant that reacts all day long, 24/7, and is capable of turning SO2 into sulfuric acid,鈥� says Mauldin, who in the journal Nature on Aug. 9.
鈥淭o discover something that could open up a whole new arena in oxidation chemistry,鈥� says Mauldin, 鈥渋t鈥檚 a once in a lifetime kind of event or finding.鈥�
It looks like the hardworking oxidant is a result of ozone interacting with fragrant compounds made by spruce and pine trees called terpenes.But why would trees be capable of contributing to a such a chemical reaction? Mauldin thinks it could be part of a feedback mechanism to control climate.
鈥淪ulfuric acid is responsible for the formation of aerosols,鈥� explains Mauldin. 鈥淭he initial particles are like a nanometer or less in size, and then they will eventually grow up to be things that could form clouds.鈥�
And clouds can reflect light back to into space, which has a cooling effect on the environment. So as the climate gets hotter, Mauldin says trees may naturally be making more terpenes to knock down the temperature.
鈥淭he US over the last 100 years has basically kind of experienced a warming, overall,鈥� says Mauldin. 鈥淗owever in the Southeast there鈥檚 actually been a slight cooling.鈥�
Mauldin suspects the forests in the Southeast have actually driven this chill by increasing cloud cover using his newly discovered chemical reaction.
