edu.ucar.opensky::articles:15227 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-26T14:59:58.526166 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d72r3spz New particle formation from the oxidation of direct emissions of pine seedlings 2009-10-28T00:00:00Z publication https://n2t.org/ark:/85065/d72r3spz https://doi.org/10.5194/acp-9-8121-2009 Hao, L. author Yli-Pirila, P. author Tiitta, P. author Romakkaniemi, S. author Vaattovaara, P. author Kajos, M. author Rinne, J. author Heijari, J. author Kortelainen, A. author Miettinen, P. author Kroll, J. author Holopainen, J. author Smith, James N. author Joutsensaari, J. author Kulmala, M. author Worsnop, D. author Laaksonen, A. author UCAR/NCAR - Library publisher Measurements of particle formation following the gas phase oxidation of volatile organic compounds (VOCs) emitted by Scots pine (Pinus sylvestris L.) seedlings are reported. Particle formation and condensational growth both from ozone (O₃) and hydroxyl radical (OH) initiated oxidation of pine emissions (about 20-120 ppb) were investigated in a smog chamber. During experiments, tetramethylethylene (TME) and 2-butanol were added to control the concentrations of O₃ and OH. Particle formation and condensational growth rates were interpreted with a chemical kinetic model. Scots pine emissions mainly included α-pinene, β-pinene, Δ³-carene, limonene, myrcene and β-phellandrene, composing more than 95% of total emissions. Modeled OH concentrations in the O³- and OH-induced experiments were on the order of ~10⁶ molecules cm⁻³. Our results demonstrate that OH-initiated oxidation of VOCs plays an important role in the nucleation process during the initial new particle formation stage. The highest average particle formation rate of 360 cm⁻³ s⁻¹ was observed for the OH-dominated nucleation events and the lowest formation rate of less than 0.5 cm⁻³ s⁻¹ was observed for the case with only O₃ present as an oxidant. In contrast to the particle formation process, ozonolysis of monoterpenes appears to be much more efficient to the aerosol growth process following nucleation. Higher contributions of more oxygenated products to the SOA mass loadings from OH-dominated oxidation systems were found as compared to the ozonolysis systems. Comparison of mass and volume distributions from the aerosol mass spectrometer and differential mobility analyzer yields estimated SOA effective densities of 1.34±0.06 g cm⁻³ for the OH+O₃ oxidation systems and 1.38±0.03 g cm⁻³ for the O₃ dominated chemistry. UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License. None eng geoscientificInformation