LAUSR

Abstract. Secondary organic aerosol (SOA) is an important constituent of the atmosphere where SOA particles are formed chiefly by the condensation or reactive uptake of oxidation products of volatile organic compounds (VOC). The mass yield in SOA particle formation, as well as the chemical composition and volatility of the particles are determined by the identity of the VOC precursor(s) and the oxidation conditions they experience. In this study, we used an oxidation flow reactor to generate biogenic SOA from the oxidation of Scots pine emissions. Mass yields, chemical composition, and volatility of the SOA particles were characterized and compared with SOA particles formed from oxidation of α-pinene and of a mixture of acyclic/monocyclic sesquiterpenes (farnesenes and bisabolenes), which are significant components of the Scots pine emissions. SOA mass yields for Scots pine emissions dominated by farnesenes were lower than for α-pinene, but higher than for the artificial mixture of farnesenes and bisabolenes. The reduction in the SOA yield in the farnesenes and bisabolenes dominated mixtures is due to C=C bond scission in these acyclic/monocyclic sesquiterpenes during ozonolysis leading to smaller and generally more volatile products. SOA particles from the oxidation of Scots pine emission had similar or lower volatility than SOA particles formed from either of single precursor. Applying physical stress to the Scots pine plants increased monoterpene emissions, which further decreased SOA particle volatility and increased SOA mass yield. Our results highlight the need to account for the chemical complexity and structure of real-world biogenic VOC emissions and stress-induced changes to plant emissions when modelling SOA production and properties in the atmosphere. These results emphasize that simple increase or decrease of relative monoterpene and sesquiterpene emissions should not be used as indicator of SOA particle volatility.