Blue Sky Science
PTR-TOF-MS takes a trip on NASA Flying Lab to analyse South Korea’s atmosphere
South Korea is a heavily industrialized and densely populated country – and the combination of local pollutant emissions and transported pollution from China means the country suffers from increasingly poor air quality. The Koreans are making efforts to clean up the air – yet to be successful, scientists first need to understand exactly how different sources, transport and transformation of air pollution contribute to the problem.
Enter: NASA’s DC-8 Flying Laboratory.
NASA monitors the atmosphere of Earth using satellites, research aircraft and ground-based observatories. The research planes move at a speed of 100-200 m/s, requiring them to carry very fast chemical sensors. This latest campaign involved 20 research flights over the Korean peninsula and the Yellow Sea. Twenty-four teams from renowned universities and research institutes contributed their instruments to create “the most advanced chemical laboratory in atmospheric science”, including a group of physicists and chemists from the Universities of Innsbruck and Oslo, and company Ionicon.
“South Korea is one of the countries that will, in the near future, monitor its air quality from space using satellite-based spectrometry,” says Armin Wisthaler, Instrument Principal Investigator and Adjunct Professor, Institute for Ion Physics & Applied Physics, University of Innsbruck. “However, satellite remote sensing data are difficult to interpret – which is why in situ data from the atmosphere need to be collected beforehand.”
The Innsbruck/Oslo/Ionicon team flew a prototype of an improved proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF-MS) – described by Wisthaler as “the world’s fastest and most sensitive sensor for volatile organic compounds in the Earth’s atmosphere.” The instrument drew air from outside the aircraft into an ion drift tube, where organic analytes were protonated by gaseous hydronium ions. “The resulting analyte ions are then analyzed in a medium mass resolution orthogonal acceleration TOF-MS, which collects data at a frequency of 10 Hz,” says Wisthaler. The prototype includes an RF ion funnel and an RF ion guide, both developed by Ionicon, which boost the instrument’s sensitivity by almost one order of magnitude. “If we integrate the mass spectra for 1 second, we reach detection limits on the order of 10 ppt (pmol/mol).”
They have come back from the field with 250 GB of data in the form of raw mass spectra, but, says Wisthaler, it is too early to make any qualified statements. “During the forthcoming months, we will analyze and quality assure our data – which will then become publicly available on a NASA data archive along with the data from the other instruments,” he says. “Only then can a comprehensive analysis begin.” The team’s collaborators will use this data to feed their air quality models and to improve the interpretation of satellite data. And in the meantime? Wisthaler and crew are getting ready for NASA’s next aircraft mission over the North Atlantic.
Wisthaler was “very proud” to be part of the project, despite having to work under demanding conditions. “It was a unique experience to fly over the Yellow Sea in this highly instrumented aircraft, tracing the pollution outflow from China. However, 150 hours in the air, most of the time spent in the turbulent boundary layer at a cabin temperature of 35ºC, is definitely a challenge for both the instrument and the operators …”
More information: http://blog.ionicon.com/2016/06/nasa-campaign-korus-aq-ionicon-ptr-tof-monitor-vocs-smog-korea
A former library manager and storyteller, I have wanted to write for magazines since I was six years old, when I used to make my own out of foolscap paper and sellotape and distribute them to my family. Since getting my MSc in Publishing, I’ve worked as a freelance writer and content creator for both digital and print, writing on subjects such as fashion, food, tourism, photography – and the history of Roman toilets.
