Contributions to OH reactivity from unexplored volatile organic compounds measured by PTR-ToF-MS – a case study in a suburban forest of the Seoul metropolitan area during the Korea–United States Air Quality Study (KORUS-AQ) 2016
oleh: D. Sanchez, R. Seco, R. Seco, R. Seco, D. Gu, D. Gu, A. Guenther, J. Mak, Y. Lee, D. Kim, J. Ahn, D. Blake, S. Herndon, D. Jeong, J. T. Sullivan, T. Mcgee, R. Park, S. Kim
| Format: | Article |
|---|---|
| Diterbitkan: | Copernicus Publications 2021-04-01 |
Deskripsi
<p>We report OH reactivity observations by a chemical ionization mass spectrometer–comparative reactivity method (CIMS-CRM) instrument in a suburban forest of the Seoul metropolitan area (SMA) during the Korea–United States Air Quality Study (KORUS-AQ 2016) from mid-May to mid-June of 2016. A comprehensive observational suite was deployed to quantify reactive trace gases inside of the forest canopy including a high-resolution proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS). An average OH reactivity of <span class="inline-formula">30.7±5.1</span> <span class="inline-formula">s<sup>−1</sup></span> was observed, while the OH reactivity calculated from CO, <span class="inline-formula">NO+NO<sub>2</sub></span> (NO<span class="inline-formula"><sub><i>x</i></sub></span>), ozone (<span class="inline-formula">O<sub>3</sub></span>), sulfur dioxide (<span class="inline-formula">SO<sub>2</sub></span>), and 14 volatile organic compounds (VOCs) was <span class="inline-formula">11.8±1.0</span> <span class="inline-formula">s<sup>−1</sup></span>. An analysis of 346 peaks from the PTR-ToF-MS accounted for an additional <span class="inline-formula">6.0±2.2</span> <span class="inline-formula">s<sup>−1</sup></span> of the total measured OH reactivity, leaving 42.0 % missing OH reactivity. A series of analyses indicate that the missing OH reactivity most likely comes from VOC oxidation products of both biogenic and anthropogenic origin.</p>