1Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
2Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
3Aerodyne Research, Inc., Billerica, MA, USA
Received: 12 Mar 2013 – Published in Atmos. Chem. Phys. Discuss.: 25 Mar 2013
Abstract. A detailed understanding of the climate and air quality impacts of aviation requires measurements of the emissions of intermediate-volatility and semi-volatile organic compounds (I/SVOCs) from aircraft. Currently both the amount and chemical composition of aircraft I/SVOC emissions remain poorly characterized. Here we characterize I/SVOC emissions from aircraft, using a novel instrument for the online, quantitative measurement of the mass loading and composition of low-volatility organic vapors. Emissions from the NASA DC8 aircraft were sampled on the ground 143 m downwind of the engines and characterized as a function of engine power from idle (4% maximum rated thrust) through 85% power. Results show that I/SVOC emissions are highest during engine idle operating conditions, with decreasing but non-zero I/SVOC emissions at higher engine powers. Comparison of I/SVOC emissions with total hydrocarbon (THC) measurements, VOC measurements, and an established emissions profile indicates that I/SVOCs comprise 10–20% of the total organic gas-phase emissions at idle, and an increasing fraction of the total gas-phase organic emissions at higher powers. Positive matrix factorization of online mass spectra is used to identify three distinct types of I/SVOC emissions: aliphatic, aromatic and oxygenated. The volatility and chemical composition of the emissions suggest that unburned fuel is the dominant source of I/SVOCs at idle, while pyrolysis products make up an increasing fraction of the I/SVOCs at higher powers. Oxygenated I/SVOC emissions were detected at lower engine powers (≤30%) and may be linked to cracked, partially oxidized or unburned fuel components.
Revised: 05 Jul 2013 – Accepted: 08 Jul 2013 – Published: 14 Aug 2013
Cross, E. S., Hunter, J. F., Carrasquillo, A. J., Franklin, J. P., Herndon, S. C., Jayne, J. T., Worsnop, D. R., Miake-Lye, R. C., and Kroll, J. H.: Online measurements of the emissions of intermediate-volatility and semi-volatile organic compounds from aircraft, Atmos. Chem. Phys., 13, 7845-7858, doi:10.5194/acp-13-7845-2013, 2013.