Photochemical aging of aviation emissions: transformation of chemical and physical properties of exhaust emissions from a laboratory-scale jet engine combustion chamber

Abstract. 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 ΔH:C/ΔO: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 Details

Journal
Atmospheric chemistry and physics
Published
2025-08-26
DOI
https://doi.org/10.5194/acp-25-9275-2025
Citations
2
Primary Topic
Advanced Aircraft Design and Technologies
Type
article
Field-Weighted Citation Impact
2.21

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article

Photochemical aging of aviation emissions: transformation of chemical and physical properties of exhaust emissions from a laboratory-scale jet engine combustion chamber

Markus Kalberer, Ralf Zimmermann, Johan Øvrevik, Seongho Jeong et al.
2 citations
Atmospheric chemistry and physics
Advanced Aircraft Design and Technologies
2.21
article

Photochemical aging of aviation emissions: transformation of chemical and physical properties of exhaust emissions from a laboratory-scale jet engine combustion chamber

Markus Kalberer, Ralf Zimmermann, Johan Øvrevik, Seongho Jeong, Sandra Piel, Bert Buchholz, Thorsten Streibel, Aki Virkkula, Krista Luoma, Alexandre Barth, Uwe Etzien, Olli Sippula, Thomas Adam, Deeksha Shukla, Anni Hartikainen, Thorsten Hohaus, Martin Sklorz, Mika Ihalainen, Arya Mukherjee, Lukas Schwalb, Hendryk Czech, Andreas Hupfer, Thomas Gröger, Quanfu He, Marius Rohkamp, Benedikt Gündling, Tuukka Kokkola, Hanna Koponen, Anusmita Das, Delun Li
article en
2 citations

Abstract

Abstract. 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 ΔH:C/ΔO: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.

Atmospheric chemistry and physicsVol. 25(16)
Finnish Meteorological Institute (FI), Norwegian Institute of Public Health (NO), Forschungszentrum Jülich (DE), University of Eastern Finland (FI), University of Oslo (NO), University of Basel (CH), Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR) (DE), Helmholtz Zentrum München (DE), Universität der Bundeswehr München (DE), Finland University (FI), University of Rostock (DE)
Academy of Finland, Horizon 2020
Openalex Percentile: Top 12%
Advanced Aircraft Design and Technologies
2.21
DOIOpen Access PDFOpenAlex
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