Assessing the impact of ship emissions on the atmospheric chemical composition in the Eastern Mediterranean and the Piraeus port (Greece)

This study examined the impact of shipping emissions on the atmospheric composition and oxidation capacity in the Eastern Mediterranean, focusing on Greece and the Piraeus port. The analysis used CAMx air quality modeling (simulations for January and July 2019), Positive Matrix Factorization (PMF) receptor modeling, and ship emission inventories from CAMS-REGv6.1 and the "Flexible Emission Inventory for Greece and the Greater Athens Area" (FEI-GREGAA). Zeroing out shipping emissions within Greek maritime waters resulted in substantial reductions in monthly concentrations of pollutants in major Aegean Sea shipping corridors, becoming largest in the Piraeus port. PMF and CAMx estimations for the net shipping contribution to fine particulate matter (PM₂.₅) in the Piraeus passenger port area showed good correlations. However, CAMx average estimates were higher compared to PMF (1.1 µg m^-³ (4.9%) by CAMx and 0.6 µg m^-³ (2.7%) by PMF for January 2019; 2.7 µg m^-³ (20.9%) by CAMx and 1.7 µg m^-³ (11.2%) by PMF for July 2019), partly due to higher CAMx-simulated shipping impact on elemental carbon (EC). More refined ship emission inventories and air quality modeling, optimized chemical speciation of ship emissions, and more experimental data are necessary, while considering also the changing regulations on ship fuels and their future climate implications.