Electric sparks from plants during thunderstorms may affect air quality, study finds
These gaseous molecules are vital “cleaners” of our atmosphere. They can degrade greenhouse gases like methane, however hydroxyl radicals can also be unhelpful, producing high levels of ozone when they encounter oxygen.
The study estimates that thunderstorms may account for 16 percent of all atmospheric OH globally. Follow-up work led the researchers to investigate other ways thunderstorms might trigger the formation of hydroxyl radicals.
“Hydroxy radicals contribute to the overall oxidation of many atmospheric pollutants, including the greenhouse gas methane, improving air quality, and slowing climate change,” explains Brune. “However, these reactions can also lead to the formation of ozone and small aerosol particles, and negatively impact air quality and climate. Therefore, understanding all potential sources of OH is important for predicting future air quality and climate.”
The researchers studied a phenomenon whereby thunderstorms can induce small electrical discharges on objects on the ground. These discharges are called crowns and may be especially prominent on plant leaves with sharp corners.
The question the researchers wanted to answer, therefore, was whether plant crowns produced measurable OH chemicals.
Under laboratory conditions, the researchers tested eight different types of leaves and found that the plant crowns did produce extremely high amounts of hydroxyl groups. While the total amount of OH produced by the plant canopy was significantly lower than in thunderstorms, the researchers speculate that the size of large forests may have contributed to the extreme OH levels before and after thunderstorms.
“Even though the corona produces a weaker charge than the sparks and lightning we’ve seen before, we’re still seeing extreme amounts of this hydroxyl radical,” said Jana Jenkins, another researcher on the project. There are probably two trillion trees in the area of the thunderstorm, and there are 1800 thunderstorms going on at any one time. It’s definitely an ongoing process, and based on what we can do so far, we think it can affect the forest and the inside of the trees and surrounding air quality.”
While the researchers know that the newly discovered mechanism is unlikely to be related to global hydrogen production, it may be that these waves of atmospheric oxidation can affect tree and forest ecology. Jenkins also suggested that as climate change increases the amount of thunderstorm activity, understanding these processes is critical, especially in terms of the impact on local air quality in these places.