Hydroxyl (OH) radicals – known as the detergent of the atmosphere – decompose isoprene in the air. This leads to the creation of new OH radicals, which are then able to purify the air of other pollutants and trace gases. The scientific community had previously only been able to speculate about this mechanism.
The large atmosphere simulation chamber SAPHIR provides a platform for reproducible studies of well-defined atmospheric-chemical mechanisms.
Credit: Forschungszentrum Jülich
The atmosphere has an astonishing ability to cleanse itself. Chemical processes ensure that trace gases and pollutants are removed from the atmosphere – such as isoprene, which is largely produced by forests. Without these processes global warming would be even more severe and , air quality much poorer. Just a few years ago, scientists thought that the degradation of isoprene considerably reduced the concentration of OH radicals.
During studies in China, troposphere researchers from Jülich's Institute of Energy and Climate Research simultaneously determined high concentrations of both OH radicals and trace gases such as isoprene. Other research groups made similar observations in the air above North American forests and tropical rainforests. The obvious conclusion was that during isoprene degradation something happens to regenerate the OH radicals.
"In the past few years, there has been an intensive discussion in the scientific community about what this mechanism could be. But without actual proof this remained pure speculation. Now we have succeeded in demonstrating this process," says the Jülich troposphere researcher, Dr. Hendrik Fuchs.
The scientists recreated the natural conditions prevailing in the atmosphere above China and the tropical rainforests in the Jülich simulation chamber, SAPHIR. This chamber enables researchers to simulate the degradation of even slight quantities of trace gases. It is equipped with exactly the same measuring instruments as are used in field experiments. "It is only this particular combination that makes it possible to study the processes precisely. SAPHIR means that we enjoy unique conditions here at Jülich," says head of institute Prof. Andreas Wahner. Jülich scientists were indeed able to confirm the basic principles of this mechanism and to quantify its impact on OH regeneration. The process takes place much faster than thought before, but not so effectively as some researchers had assumed.
Since the degradation process is now understood for isoprene, scientists can begin to quantitatively investigate feedback effects. Relations between self-cleansing processes in the atmosphere and the climate are particularly interesting for the Jülich researchers. More OH radicals in the air mean that more greenhouse gases such as methane can be degraded. Furthermore, in contrast to all other known mechanisms for the degradation of isoprene, less climate-damaging ozone is produced in the atmosphere than previously assumed. Moreover, the effectiveness of the process increases with air temperature. "We may possibly have identified an important interaction between air quality and climate change leading to the accelerated degradation of trace gases in an atmosphere that is heating up," adds the deputy head of institute Dr. Andreas Hofzumahaus.
The Jülich investigations are part of the ongoing EU project PEGASOS (Pan-European Gas-AeroSOls-climate interaction Study) concerned with interactions between atmospheric chemistry, air quality and climate.
Original publication:Experimental evidence for efficient hydroxyl radical regeneration in isoprene oxidation.
Dr. Hendrik Fuchs | EurekAlert!
NASA finds newly formed tropical storm lan over open waters
17.10.2017 | NASA/Goddard Space Flight Center
The melting ice makes the sea around Greenland less saline
16.10.2017 | Aarhus University
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
18.10.2017 | Materials Sciences
18.10.2017 | Physics and Astronomy
18.10.2017 | Physics and Astronomy