Chemical Characterization of Photochemical Aging of Ship Particulate Matter Emissions - Determination of Marker Compounds and PAH Decay Rates

SANDRA PIEL, Nadine Gawlitta, Deeksha Shukla, Ellen-Iva Rosewig, Hendryk Czech, Jürgen Schnelle-Kreis, Thorsten Streibel, Johannes Passig, Helena Osterholz, Jan Hovorka, Thomas Adam, Uwe Etzien, Bert Buchholz, Mika Ihalainen, Olli Sippula, Thomas Gröger, et al., Ralf Zimmermann, Mass Spectrometry Centre;Rostock University/Helmholtz Munich

     Abstract Number: 325
     Working Group: Aerosol Chemistry

Abstract
Emissions from ships contribute significantly to the release of aerosols into the environment and have adverse effects on climate, marine ecosystems, and health. During atmospheric transport, aerosol emissions from ship traffic undergo chemical transformations involving oxidative gas-to-particle conversion and complex multiphase chemistry (“atmospheric aging”). As ship traffic mainly occurs distant to populated regions, aged aerosols may be of greater relevance for public health.

Within the ULTRHAS project (ULtrafine particles from Transportation – Health Assessment of Sources), fresh emissions from a 1-cylinder 4-stroke marine engine on a test bench, running on heavy fuel oil (0.5 % sulfur) or marine gas oil (0.1 % sulfur), were aged in the Photochemical Emission Aging flow tube Reactor (PEAR) to an equivalent photochemical age of 2 to 7 days. Filter samples of particulate matter were analyzed by comprehensive two-dimensional gas chromatography coupled with high-resolution time-of-flight mass spectrometry. The statistical evaluation based on Fisher ratios (ChromaTOF Tile) revealed the substances most affected by aging, categorized into those experiencing decay (e.g., all classes of hydrocarbons), those increasing (e.g., oxygenated classes and pyridines), and those showing intermediate peaking (e.g., furanones and long-chain acids). This allows a distinct clustering of the fresh, short, and long-term aged emissions in the principal component analysis. Furthermore, the study includes the quantification and determination of decay rates for individual polycyclic aromatic hydrocarbons (PAHs). Consequently, aging altered the PAH pattern, thus aggravating PAH-based source apportionment and the use of diagnostic ratios.

Overall, the study describes in unprecedented detail the molecular characterization of simulated photochemically aged ship emissions. The findings not only enhance the understanding of atmospheric processes but provide valuable insights for real-world emissions by tentatively identifying marker compounds for short- and long-term aging. In further studies, these results will complement toxicological data and be compared to real-world emissions from the Baltic Sea.