Recent groundbreaking research by an international team of researchers found that Kryky intermediates play an important role in the formation of tropospheric secondary organic aerosols, suggesting that the impact of these processes is greater than previously thought, and highlighting areas that require further research.
An international team of researchers has succeeded in documenting the first clear evidence of a long-term hypothetical catalyst in the aerosol formation process. 85% of the Earth's atmosphere is located in the troposphere – the lowest layer of the atmosphere. Still, there is still a big gap in our understanding of the chemical processes that alter the composition of the troposphere.
The formation and ubiquity of secondary organic aerosols (SOAs) is a particularly important knowledge gap that affects the radiation balance of the planet, air quality, and human health. But thanks to breakthrough discoveries by an international team of researchers led by the U.S. Department of Energy's Argonne National Laboratory (DOE), Sandia National Laboratories and NASA's Jet Propulsion Laboratory (JPL), that gap is narrowing.
The scientists detail their findings in a new paper published in Nature Geosciences.
New research on kryki intermediates
The team focused on a class of compounds known as kryl intermediates (CIs). Researchers suspect that CIs play a crucial role in the formation of SOAs when they are held together through a process called oligomerization. But until now, no one in this field has directly identified the chemical characteristics of this process.
Using the most advanced atmospheric vapor phase molecule and aerosol detection methods available, the research team conducted field measurements in the Amazon rainforest, one of the most important regions on Earth for SOA. There, they found clear evidence consistent with the reaction of a kryl intermediate compound containing carbon, hydrogen, and oxygen (CH2OO).
"This discovery is significant because we were able to make a direct connection between what we saw in the field, what we expected about the oligomerization of CIs, and what we were characterizing and making theoretical judgments in the lab," explains Rebecca L. Caravan, first author of the paper and an assistant chemist at Argonne University.
These field observations are just one part of the innovative science that the laboratories are working on in collaboration.
Advanced methods and key findings
"In addition to field measurements, we have also used the world's most advanced experimental methods to directly characterize the Krigy intermediate reaction. We utilize state-of-the-art theoretical dynamics to predict reactions that we cannot measure directly. We also utilized state-of-the-art global chemical modelling to evaluate the impact of our expected oligomers in the troposphere based on these kinetics," said Craig A. Taatjes, combustion chemist at Sandia.
This combination has yielded some crucial findings. Carl Percival, a researcher at NASA's Jet Propulsion Laboratory, said: "First, we found that CI chemistry could play a larger role in changing the composition of the troposphere than current atmospheric models can explain, perhaps by an order of magnitude. Second, the updated modeling we did based on our work yielded only a fraction of the oligomerization features we observed in the field. "
This could mean that CI chemistry may be driving greater changes within the troposphere, or that other chemical mechanisms at play are at play.
Caravan concluded: "We still have a lot of work to do to fully determine the role of CI reactions in the troposphere. But these findings greatly expand our understanding of the potentially important ways in which SOA is formed in the most important layer of the Earth's atmosphere. "
编译来源：ScitechDaily
doi: 10.1038/s41561-023-01361-6