When lightning strikes overhead, plants on the ground may react in the same way.
Scientists have long known that plants and trees can emit small visible electrical discharges from the tips of their leaves when the plants are trapped under the electrical fields generated by thunderstorms overhead. These discharges, called coronas, are sometimes visible as faint blue sparks that glow around charged objects.
Now, new research suggests that these herbal sparks can alter surrounding air quality in ways never before recognized. But we do not know if the impacts of these minishocks in the atmosphere are positive or negative.
In the study, published August 9 in the Journal of Geophysical Research: Atmospheresthe researchers recreated the electrical fields of thunderstorms in a lab and analyzed the coronas emitted by eight plant species under a range of conditions.
The results showed that all the coronas created a great abundance of radicals – chemicals containing unpaired electrons that are highly reactive with other compounds – which can significantly alter the quality of the surrounding air.
“Although little is known about the extent of these releases, we believe that crowns generated on trees under thunderstorms could have substantial impacts on ambient air,” the author said in a statement. study lead Jena Jenkins, an atmospheric scientist at Penn State University.
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The two radicals given off by plant crowns are hydroxyl (OH) and hydroperoxyl (HO2), both of which are negatively charged and known to oxidize or steal electrons from a number of different chemical compounds, thereby turning them into other molecules.
The researchers were particularly interested in the concentrations of hydroxyl radicals because they have a greater impact on air quality.
“The hydroxyl radical contributes to the total atmospheric oxidation of many air pollutants,” study co-author William Brune, a meteorologist at Penn State University, said in the statement.
For example, if a hydroxyl radical reacts with greenhouse gases, such as methane, it can remove harmful molecules from the atmosphere and help fight climate change, Brune said.
But if the same radical reacts with oxygen, it can create ozone which, although it plays an important role in the upper atmosphere, is toxic to humans. The radicals can also create aerosol particles that harm air quality, he added.
This is not the first time that researchers have shown the link between thunderstorms and hydroxyl radicals.
In 2021, a research team led by Brune discovered that lightning was a major ancestor of hydroxyl radicals in the atmosphere. In their article published in the journal Sciencethe team hypothesized that thunderstorms could be directly responsible for one-sixth of the hydroxyl radicals in the atmosphere.
In September, another team led by Brune published a follow-up study, published in the journal Earth, Atmospheric and Planetary Sciencess, which showed that crowns produced by metal objects such as telephone poles and transmission towers produce a slightly higher level of hydroxyl radicals than plant crowns.
However, the levels of radicals produced by vegetative and artificial crowns are both significantly lower than those produced directly by lightning.
“Even if the load generated by the [plant] corona was weaker than the sparks and flashes we looked at before, we still saw extreme amounts of this hydroxy radical being made,” Jenkins said.
Given the large number of trees present in lightning-prone areas, the crowns produced by plants may represent a largely understudied source of radicals with a highly unpredictable effect on air quality, he said. she adds.
“There are about two trillion trees in the areas where thunderstorms are most likely to occur around the world and there are 1,800 thunderstorms in progress at any given time,” Jenkins said.
As a result, researchers want to continue studying these coronas in more detail to fully understand the effect they have on localized air quality and on a broader global scale.
“The hydroxyl radical is the most important cleaner in the atmosphere,” Jenkins said. “So having a better accounting of where these things are made can give us a more complete understanding of what’s going on in the atmosphere.”
Other studies suggest that thunderstorms could become more frequent and more powerful due to the effects of human-induced climate change, so understanding the effects of thunderstorms on air quality is critical, she said. added.
During the experiments, the team made another discovery that could help accelerate this area of research: leafy landfills emitted sharp spikes of ultraviolet radiation.
This could allow the team to indirectly study where coronas occur on the ground and measure their effects on nearby air quality.
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This article was originally published by Live Science. Read the original article here.
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