OH is an important oxidant inside water droplets and the main assumption in the models is that OH comes from the air, it is not generated directly in the droplets.
A key player in atmospheric chemistry, the researchers said a deep and complete understanding of OH sources and sinks is critical to reducing air pollution.
Despite the absence of sunlight, special atmospheric conditions can produce hydroxide (OH) molecules, which power the atmosphere’s self-cleaning mechanism by reacting with pollutants and eliminating them, according to a new study.
The study’s researchers, including one from the University of California, Irvine (UCI), US, report that the presence of a strong electric field at the interface of airborne water droplets and the surrounding air can create OH by a previously unknown mechanism.
“You need OH to oxidize the hydrocarbons, otherwise they will remain in the atmosphere indefinitely,” said Sergei Nizhkorodov, professor of chemistry at UCI. nitric oxides, which are toxic gases, from the atmosphere,” said Christian George, an atmospheric chemist at the University of Lyon in France and lead author of the study.
A key player in atmospheric chemistry, the researchers said a deep and complete understanding of OH sources and sinks is critical to reducing air pollution. The newly uncovered mechanism is published in the journal Proceedings of the National Academy of Sciences. Previously, researchers assumed that sunlight was the main driver of OH formation.
“The conventional wisdom is that you have to make OH by photochemistry or redox chemistry. You have to have sunlight or a metal acting as a catalyst,” Nizkorodov said.
“What this paper says in a nutshell is that you don’t need any of it. In
Pure water
OH can be created spontaneously by special conditions on the droplet surface, Nizhkorodov said.
Scientists at Stanford University previously reported the spontaneous formation of hydrogen peroxide on the surface of water droplets. The current research, building on this, helps explain their unexpected results. The team tracked OH production in the dark by studying vials of different OH concentrations, some containing an air-water surface and others containing only water without air. They included in the vials a “probe” molecule that fluoresces when it reacts with OH. The researchers found that OH production rates mirror those in the dark and even exceed rates from drivers such as exposure to sunlight. “Enough OH will be created to compete with other known OH sources,” Nizhkorodov said.
“At night, when there is no photochemistry, OH is still produced and at a higher rate than it would otherwise be.”
While changing the current understanding of OH sources, the researchers expect these findings will lead to changes in how other researchers create computer models of air pollution.
“OH is an important oxidant inside water droplets and the main assumption in the model is that OH comes from the air, it is not generated directly in the droplet,” Nizkorodov said.
He said the next step to determine whether this OH production mechanism played a role was to conduct carefully designed experiments in real environments in different parts of the world.
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(This story has not been edited by News18 staff and is published from a syndicated news agency feed)
