AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Terpene Emissions and Their Oxidation Products in Forest Areas: Insight from Vocus PTR-TOF Measurements
HAIYAN LI, Pekka Rantala, Kaspar Daellenbach, Jordan Krechmer, Douglas Worsnop, Markku Kulmala, Matthieu Riva, Mikael Ehn, Federico Bianchi, University of Helsinki
Abstract Number: 432 Working Group: Aerosol Chemistry
Abstract On the global scale, biogenic volatile organic compounds (BVOCs) contribute a large fraction of secondary organic aerosol production. However, due to the complex characterization of organic mixtures, an incomplete understanding of BVOCs oxidation still exists and leads to large uncertainties in quantitative estimates of air quality and climate effects of atmospheric aerosol. In this study, the recently developed Vocus PTR-TOF (proton transfer reaction time-of-flight mass spectrometry) was deployed at the SMEAR Ⅱ station (Station For Measuring Forest Ecosystem-Atmosphere Relations), a boreal forest site in southern Finland. This station is known with high terpene emissions, thus providing a good opportunity to investigate the characterization of terpenes and their oxidation products. This work will give an overview of the ion molecules observed by Vocus PTR-TOF, and compare the results with those from the chamber study of α-pinene ozonolysis in the presence of NOx and the ambient observations in Landes forest in southwestern France. With a new chemical ionization source and focusing ion-molecule reactor, the Vocus PTR-TOF detected not only terpene precursors but also various terpene oxidation products and intermediates due to improved measurement precision and detection limits. The ambient behaviours of different terpenes and their oxidation products, including both non-nitrate organic compounds and organic nitrates, will be characterized in detail at SMEAR Ⅱ station, and compared with observations in Landes forest. The comparison among different environments will provide more insights into the complicated terpene chemistry.