Scientists have identified a new type of extremely reactive substance in the Earth’s atmosphere that could pose a threat to human health and the global climate. University of Copenhagen researchers have shown that trioxides, that is, chemical compounds with three oxygen atoms bonded together, form under atmospheric conditions.
Trioxides are even more reactive than peroxides, which have oxygen atoms attached to each other and are highly reactive and often flammable and explosive. Peroxides are known to exist in the air surrounding us, and trioxides were presumed to be present in the atmosphere as well, but have not been conclusively proven until now.
Professor Henrik Grum Kjærgaard, from the Department of Chemistry at the University of Copenhagen, says, “We’ve now been able to prove it,” and continues: “The type of compounds we discovered are unique in their structure. And because they’re extremely oxidizing, they probably have a bunch of effects we haven’t discovered yet.”
Detected trioxides, a completely new class of chemical compounds called hydrotrioxides (ROOOH). Hydrotrioxides are formed in the reaction between two types of radicals (molecules containing at least one unpaired electron).
In laboratory experiments using a free jet flow tube at room temperature and 1 bar air pressure in conjunction with highly sensitive mass spectrometers, the researchers demonstrated that hydrotrioxides are formed during the atmospheric decay of many known and widely emitted substances, including isoprene and dimethyl sulfide. . It is produced by many plants and animals, and isoprene, whose polymers are the main component of natural rubber, is one of the organic compounds most frequently emitted into the atmosphere.
The study shows that about one percent of all released isoprene is converted to hydrotrioxides.
However, researchers estimate that nearly all chemical compounds will form hydrotrioxides in the atmosphere, and their lifetimes can range from minutes to hours. This time allows them to be stable enough to react with many other atmospheric compounds.
Researchers estimate that the concentration of hydrotrioxide in the atmosphere is about 10 million per cubic centimeter. For comparison, OH (peroxide) radicals (one of the most important oxidants in the atmosphere) are present in concentrations of about one million per cubic centimeter.
Jing Chen, a PhD student in the Department of Chemistry and the study’s second author, said, “We can now show, through direct observation, that these compounds actually form in the atmosphere, that they are surprisingly stable, and are composed of almost any chemical compound.” must end.”
The research team says hydrotrioxides can penetrate tiny airborne particles known as aerosols, which pose health hazards and can lead to respiratory and cardiovascular diseases.
Prof. “They will likely enter the aerosols and form new compounds here with new effects. It is easy to imagine that new substances are formed in aerosols that are harmful when inhaled. However, more research is needed to address these potential health effects,” says Kjærgaard
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As co-author and PhD student Eva R. Kjærgaard explains, “Since sunlight is both reflected and absorbed by aerosols, , this affects the Earth’s heat balance, i.e. the rate of sunlight that the Earth absorbs and sends back into space. When aerosols absorb substances, they grow and contribute to cloud formation, which also affects Earth’s climate.”
The researchers hope the discovery of hydrotrioxides will help scientists learn more about the impact of the chemicals we emit. Published in Science
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