(ORDO NEWS) — Scientists have long known that plants and trees can emit small, visible electrical discharges from the tips of their leaves.
This usually happens when plants become trapped under the electrical fields created by thunderstorms. These discharges, known as coronas, are sometimes visible as faint blue sparks that glow around charged objects.
A new study suggests that these sparks can change the quality of the surrounding air. But it remains unclear whether the effects of these atmospheric discharges are positive or negative.
In a study published in the Journal of Geophysical Research: Atmospheres, researchers recreated the electrical fields from thunderstorms in the lab and analyzed the coronas emitted by eight plant species under various conditions.
The results showed that all coronas created large amounts of radicals, chemicals containing unpaired electrons that react strongly with other compounds that can significantly change the quality of the surrounding air.
“While little is known about how widespread these discharges are, we believe that the crowns that form on trees during a thunderstorm can have a significant impact on the surrounding air,” said Jen Jenkins, lead author of the study from Pennsylvania State University.
The two radicals given off by plant crowns are hydroxyl (OH) and hydroperoxyl (HO 2 ), both of which are negatively charged and are known to oxidize or steal electrons from a number of different chemical compounds, thereby converting 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 general atmospheric oxidation of many atmospheric pollutants,” said co-author of the study, meteorologist William Bruhn of Pennsylvania State University.
For example, if the hydroxyl radical reacts with greenhouse gases such as methane, it could remove harmful molecules from the atmosphere and help fight climate change, Brune said.
But if the same radical reacts with oxygen, it can lead to the formation of ozone, which, despite its 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 researchers have shown a link between thunderstorms and hydroxyl radicals.
In September, another team led by Brune published the results of a study published in Earth, Atmospheric and Planetary Science s, showing that coronas formed from metal objects such as telephone poles and power poles produce slightly higher levels of hydroxyl radicals. than plant crowns.
However, the levels of radicals produced by plant and artificial crowns are significantly lower than those generated directly from lightning.
“Even though the charge generated by the [vegetal] corona was weaker than the sparks and lightning we had seen before, we still saw huge amounts of this hydroxyl radical being generated,” Jenkins said.
Given the vast number of trees that grow in lightning-prone areas, plant crowns can represent a largely understudied source of radicals with highly unpredictable effects on air quality, she added.
“In areas where thunderstorms are most likely, there are about two trillion trees worldwide, and there are 1,800 thunderstorms at any given time,” Jenkins said.
The researchers intend to continue studying these coronas in more detail to fully understand the impact they have on global air quality.
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