Total Radical Production and Degradation Products from Alkene Ozonolysis (TRAPOZ) was a consortium project funded by NERC to investigate OH, HO2 and RO2 radical, and oxidation product yields from the reactions of ozone with a range of common anthropogenic and biogenic alkenes. Alkene-ozone reactions can constitute significant routes to radical formation in the contemporary urban environment and hence can be important in terms of overall atmospheric reactivity. Furthermore, the organic degradation products of alkene-ozone reactions can possess substantial affinity for the particle-phase and hence are able to contribute to Secondary Organic Aerosol (SOA) formation and/or growth. The TRAPOZ project, led by the Universities of Birmingham and Leeds, comprised two intensive field campaigns at the European Photoreactor (EUPHORE) facility, within the Centre for Mediterranean Studies (CEAM) in Valencia (Spain), and a comprehensive modelling study that employed the Master Chemical Mechanism (MCM v3.1) framework. During TRAPOZ we deployed Chemical Ionisation Reaction Time-of-Flight Mass Spectrometry (CIR-TOF-MS) and Peroxy Radical Chemical Amplification (PERCA) instrumentation, to measure organic oxidation products and S(HO2+RO2). From the execution of experiments investigating the ozonolysis of ethene, propene, 1-butene, but-2-ene, isoprene, alpha-pinene, beta-pinene, limonene, myrcene and methyl chavicol, we observed OH yields in-line with values previously reported within the literature and HO2 yields larger than those observed formerly, suggesting a potential underestimation in current mechanistic reactivity under certain scenarios. Furthermore, detailed observations of gas-phase oxidation products were employed alongside particle-phase composition measurements and MCM simulations, to improve our understanding of SOA formation, composition and evolution (including in-particle heterogeneous reactions).
