Mass yields of secondary organic aerosols from the oxidation of α-pinene and real plant emissions

Abstract

Abstract. Biogenic volatile organic compounds (VOCs) are a significant source of global secondary organic aerosol (SOA); however, quantifying their aerosol forming potential remains a challenge. This study presents smog chamber laboratory work, focusing on SOA formation via oxidation of the emissions of two dominant tree species from boreal forest area, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies), by hydroxyl radical (OH) and ozone (O 3 ). Oxidation of α-pinene was also studied as a reference system. Tetramethylethylene (TME) and 2-butanol were added to control OH and O 3 levels, thereby allowing SOA formation events to be categorized as resulting from either OHdominated or O 3 -initiated chemistry. SOA mass yields from α-pinene are consistent with previous studies while the yields from the real plant emissions are generally lower than that from α-pinene, varying from 1.9% at an aerosol mass loading of 0.69 µg m −3 to 17.7% at 26.0 µg m −3 . Mass yields from oxidation of real plant emissions are subject to the interactive effects of the molecular structures of plant emissions and their reaction chemistry with OH and O 3 , which Correspondence to: L. Q. Hao (hao.liqing@uef.fi) lead to variations in condensable product volatility. SOA formation can be reproduced with a two-product gas-phase partitioning absorption model in spite of differences in the source of oxidant species and product volatility in the real plant emission experiments. Condensable products from OH-dominated chemistry showed a higher volatility than those from O 3 -initiated systems during aerosol growth stage. Particulate phase products became less volatile via aging process which continued after input gas-phase oxidants had been completely consumed.

Growth rates of nucleation mode particles in Hyytiälä during 2003−2009: variation with particle size, season, data analysis method and ambient conditions

“…Our results thus suggest that although light intensity and OH-oxidation are important factors controlling nucleation, the growth of the nucleated particles seems to be limited more by the concentrations of the precursor gases and their oxidation by ozone. This is in line with laboratory study by Hao et al (2011).…”

General overview: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) – integrating aerosol research from nano to global scales

“…Results from EUCAARI show that the yields of biogenic secondary organic aerosol (BSOA) from emissions of Boreal and Mediterranean trees were between 5 and 10 %, independent of the monoterpene mixture (Mentel et al, 2009;Lang-Yona et al, 2010;Buchholz et al, 2011), whereas Hao et al (2011) found a somewhat broader range for the yields (1.9-17.7 %). The formed particle mass and number concentration increased linearly with increasing monoterpene concentrations in accordance with the analysis of Boreal field data by Tunved et al (2008).…”

“…Kuopio showed that even if trace amounts of SO 2 had been present -the modelled peak OH concentration was 1.07 × 10 6 , and it is not likely that sulphuric acid would have been formed enough to produce the observed particle formation rate of 360 cm −3 s −1 without any contribution from the organics. In a later set of experiments (Hao et al, 2011) the ozonolysis products were somewhat surprisingly found to be less volatile than the OH products.…”

Temperature influence on the natural aerosol budget over boreal forests

“…1.9-17.7 % by Hao et al (2011), and 5-10 % from Mentel et al (2009). However, model studies on SOA yields have shown much higher variations and uncertainties, ranging from several percentages up to 70 % (Hallquist et al, 2009).…”