Polycyclic aromatic hydrocarbons as fuel-dependent markers in ship engine emissions using single-particle mass spectrometry

We investigated the fuel-dependent single-particle mass spectrometric signatures of polycyclic aromatic hydrocarbons (PAHs) from the emissions of a research ship engine operating on marine gas oil (MGO), hydrotreated vegetable oil (HVO) and two heavy fuel oils (HFO), one with compliant and one with non-compliant fuel sulfur content. The PAH patterns are only slightly affected by the engine load and particle size, and contain sufficient dissimilarity to discriminate between the marine fuels used in our laboratory study. Hydrotreated vegetable oil (HVO) produced only weak PAH signals, supporting that fuel residues, rather than combustion conditions, determine the PAH emissions. The imprint of the fuel in the resulting PAH signatures, combined with novel single-particle characterization capabilities for inorganic and organic components, opens up new opportunities for source apportionment and air pollution monitoring. The approach is independent of metals, the traditional markers of ship emissions, which are becoming less important as new emission control policies are implemented and fuels become more diverse. Single-particle mass spectrometric information on PAHs in ship emissions can indicate the type of fuel used.