A new type of highly reactive substance has been discovered in the atmosphere

For the first time in the atmosphere, a completely new class of superreactive chemical compounds was discovered. Researchers from the University of Copenhagen, in close collaboration with international colleagues, have documented the formation of so-called trioxides – an extremely oxidative chemical compound that is likely to affect both human health and our global climate.

Hydrogen peroxide is widely known chemical compound. All peroxides have two oxygen atoms attached to each other, making them very reactive and often flammable and explosive. They are used for everything from teeth and hair whitening to cleaning wounds and even as rocket fuel. But peroxides are also found in atmosphere.

In recent years, there have been speculations as to whetherchemical compounds with three oxygen atoms connected to each other and thus even more reactively active than peroxides are also found in the atmosphere. But so far this has never been unequivocally proven.

“This is what we have achieved now,” says Professor Henrik Groome Kiergaard of the Department of Chemistry at the University of Copenhagen. Kiergaard is the senior author of a study just published in Science. “The type of compounds we have discovered are unique in their structure. And because they are extremely oxidizing, they are likely to bring many effects that we have not yet discovered.

Hydrotrioxides (ROOOH), as they are known, are a completely new class of chemical compounds. Researchers from the University of Copenhagen (UCPH) together with colleagues from the Leibniz Institute for Tropospheric Research (TROPOS) and the California Institute of Technology (Caltech) have demonstrated that these compounds are formed when atmospheric conditions.

Researchers have also shown that hydrotroxides are formed by the decomposition in the atmosphere of several known and widely emitted substances, including isoprene and dimethyl sulfide.

“It is very important that we can now show through direct observations that these compounds are actually formed in the atmosphere, that they are surprisingly stable and are formed from almost all chemical compounds. Now all speculation must be abolished, ”said Jing Chen, a Ph.D. student in chemistry and co-author of the study.

Hydrotroxides are formed in the reaction between two types of radicals. Researchers expect that almost all chemical compounds will form hydrotroxides in the atmosphere, and have estimated that their lifespan is from minutes to hours. This makes them stable enough to react with many other atmospheric compounds.

Presumably absorbed in aerosols

The research team also believes that trioxides are able to penetrate tiny particles in the air, known as aerosols, which pose a health hazard and can lead to respiratory and cardiovascular disease.

“They are likely to end up in aerosols, where they will form new compounds with new effects. It’s easy to imagine that aerosols form new substances that are harmful by inhalation. But to investigate these potential health effects, further investigation is needed,” he said. Henryk Grum Kjergaard.

Although aerosols also affect the climate, they are one of the things that is most difficult to describe in climate models. And, according to researchers, it is likely that hydrotroxide affects the amount of aerosols produced.

“Because sunlight is reflected and absorbed by aerosols, it affects the Earth’s heat balance – that is, the ratio of sunlight that the Earth absorbs and sends back into space. When aerosols absorb substances, they grow and contribute to cloud formation.” climate, ”says the co-author and PhD. student, Eva R. Kjergaard.

The effect of the compound needs to be studied further

Researchers hope that the discovery of hydrotroxides will help us learn more about the effects of the chemicals we emit.

“Most human activity leads to the release of chemicals into the atmosphere. Therefore, knowing the reactions that determine atmospheric chemistry is important so that we can predict how our actions will affect the atmosphere in the future,” said co-author and postdock Christon H. Moeller. .

However, neither he nor Henrik Groom Kiergaard are worried about the new discovery: “These compounds have always been – we just did not know about them. But the fact that we now have evidence that compounds are formed and live a certain amount of time means that it is possible to study their action more purposefully and react if they turn out to be dangerous, ”says Henrik Groome Kiergaard.

“The discovery suggests that there may be many other things in the air that we don’t yet know about. Indeed, the air around us is a huge tangle of complex chemical reactions. As researchers, we must be open if we want to improve. in search of solutions, ”concludes Jing Chen.