Molecularly Resolved Composition of Ultra-Fine Particles in Aircraft Engine Exhaust Suggests Rapid Condensation of Lubrication Oil

ZACHARY DECKER, Peter A. Alpert, Markus Ammann, Julien Anet, Michael Bauer, Tianqu Cui, Lukas Durdina, Jacinta Edebeli, Martin Gysel, André S. H. Prévôt, Lu Qi, Jay G. Slowik, Curdin Spirig, Sarah Tinorua, Florian Ungeheuer, Alexander Vogel, Jun Zhang, Benjamin Brem, Laboratory of Atmospheric Chemistry, Paul Scherrer Institute

     Abstract Number: 513
     Working Group: Chemicals of Emerging Concern in Aerosol: Sources, Transformations, and Impacts

Abstract
Aircraft emit a large number of Ultra Fine Particles (UFPs, particles <100 nm) which degrade air quality. UFPs efficiently transport their chemical content into the body and it is known that UFPs near airports contain aircraft lubrication oil. However, knowledge of the relationship between aircraft operation and emission of oil-containing UFPs is poorly understood. Results here provide molecularly resolved composition of oil-containing UFPs from six in-service aircraft engines. The detection of 36 unique oil tracers confirms oil emissions from all engines. The UFP oil composition is thrust, particle size, and tracer volatility dependent. Lower volatility tracers are disproportionately present on particles < 30 nm. Particles <10 nm have the greatest oil mass to particle volume ratio. Both engine oil consumption and UFP oil content increase with engine thrust. Thrust-dependent UFP oil composition depends on tracer volatility suggesting rapid gas-to-particle partitioning and that a significant fraction of oil remains in the gas phase at least 50 meters behind the engine. The thrust-dependent oil consumption rate (~0.1 – 0.8 kg/hr) would, at most, represent an oil emission index at cruise altitude of 10 mg/kg similar to that of black carbon. For any flight >2 h the majority of oil emission will occur at cruise altitude highlighting the unknown importance of oil emission in the upper atmosphere.