Hartikainen, A.* ; Ihalainen, M.* ; Shukla, D. ; Rohkamp, M.* ; Mukherjee, A.* ; He, Q.* ; Piel, S. ; Virkkula, A.* ; Li, D.* ; Kokkola, T.* ; Jeong, S. ; Koponen, H.* ; Etzien, U.* ; Das, A. ; Luoma, K.* ; Schwalb, L. ; Gröger, T.M. ; Barth, A.* ; Sklorz, M. ; Streibel, T.* ; Czech, H. ; Gündling, B.* ; Kalberer, M.* ; Buchholz, B.* ; Hupfer, A.* ; Adam, T.* ; Hohaus, T.* ; Johan Øvrevik,* ; Zimmermann, R. ; Sippula, O.*
Photochemical aging of aviation emissions: Transformation of chemical and physical properties of exhaust emissions from a laboratory-scale jet engine combustion chamber.
Atmos. Chem. Phys. 25, 9275 - 9294 (2025)
Aviation is an important source of urban air pollution, but the impacts of photochemical processing on the exhaust emissions remain insufficiently characterized. Here, the physical-chemical properties of fresh and photochemically aged emissions from a laboratory-scale jet engine burner operated with JP-8 kerosene were studied in detail with a range of online and offline methods. The fresh emissions contained high amounts of organic matter present predominantly in the gaseous phase. Photochemical aging in an oxidation flow reactor caused substantial formation of oxidized organic aerosol, increasing the particle mass approximately 300-fold. During aging, aromatic hydrocarbons and alkanes in the gas-phase decayed, while gas-phase oxidation products, such as small carbonyls and oxygenated aromatics, increased. The composition of organic matter became more complex by photochemical processing, with the average particulate carbon oxidation state increasingly growing throughout the addressed exposure range (equivalent to 0.2 to 7 d in the atmosphere) with a Delta H:C/Delta O:C slope of -0.54. Simultaneously, the near-UV wavelength absorption by the particles increased due to enhanced particulate mass. The imaginary refractory indices of organic particulate matter were 0.0071 and 0.00013 at the wavelength of 520 nm for the fresh and photochemically processed particles, respectively, indicating secondary production of weakly absorbing brown carbon. The direct radiative forcing by the exhaust particles was estimated by a Mie model, which revealed a prominent shift from a warming to cooling climate effect upon photochemical aging. The results highlight the importance of considering secondary aerosol formation when assessing the environmental impacts of aviation.
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Publication type
Article: Journal article
Document type
Scientific Article
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Keywords
Jet Engine ; Jet Fuel; Organic Aerosol Formation; Particulate Matter Emissions; Oxidation Flow Reactors; Optical-properties; Ultrafine Particles; Commercial Aircraft; Mass-spectrometry; Effective Density; Refractive-index; Light-absorption
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Language
english
Publication Year
2025
Prepublished in Year
0
HGF-reported in Year
2025
ISSN (print) / ISBN
1680-7316
e-ISSN
1680-7324
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Volume: 25,
Issue: 16,
Pages: 9275 - 9294
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European Geosciences Union (EGU) ; Copernicus
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Bahnhofsallee 1e, Gottingen, 37081, Germany
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Reviewing status
Peer reviewed
POF-Topic(s)
30202 - Environmental Health
Research field(s)
Environmental Sciences
PSP Element(s)
G-504500-001
Grants
Helmholtz International Lab aeroHEALTH
Research Council of Finland project "Black and Brown Carbon in the Atmosphere and the Cryosphere" (BBrCAC)
European Union
Copyright
Erfassungsdatum
2025-10-13