AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
New Particle Formation in the Boreal Forest: Characterizing the Molecules Responsible for Growth
MICHAEL J. LAWLER, Nina Sarnela, Mikko Sipilä, Tuukka Petäjä, Douglas Worsnop, James N. Smith, National Center for Atmospheric Research
Abstract Number: 286 Working Group: Aerosol Chemistry
Abstract Size-resolved chemical composition measurements of recently formed ambient nanometer-sized particles were made during the spring 2014 Biogenic Aerosols: Effects on Clouds and Climate (BAECC) campaign in the Finnish boreal forest using the Time-of-Flight Thermal Desorption Chemical Ionization Mass Spectrometer (TOF-TDCIMS). Molecules and and fragments from recently formed 15-60 nm particles were observed during two new particle formation events. Collected particle samples were analyzed alternately in positive and negative polarity chemical ionization modes, enabling the detection of a diverse array of compounds. The observed molecular ions and fragments were primarily indicative of oxidized organics that were in many cases unsaturated or cyclic. These compounds were similar to those detected in TDCIMS observations of nanoparticles formed by the ozonolysis of alpha-pinene in a chamber study. Up to 47% of the detected ions from sampled nanoparticles were species with O:C ratios greater than 2:3. This result supports previous findings linking highly oxidized gas phase compounds with new particle formation in this environment. The observed nanoparticles also contained reduced nitrogen compounds that suggest the importance of biogenic sources of nanoparticle mass which have not been widely considered.