Source Apportionment and Composition Characterization of Transport-Related Aerosols in the Port of Rotterdam during the MI-TRAP Campaign

The Port of Rotterdam is Europe’s largest maritime hub and a major hotspot of transport-related air pollution, influenced by intensive shipping activity, and port-related industry. Within the Horizon Europe project Mitigating Transport-related Air Pollution in Europe (MI-TRAP), a comprehensive atmospheric measurement campaign was conducted in this area to improve the quantification and source attribution of transport emissions in the complex port environment. A high-resolution stationary monitoring site was deployed at Hoek van Holland, strategically located to detect emissions from shipping traffic, port operations, and surrounding industrial and urban sources. The measurement setup combined state-of-the-art aerosol chemical, physical, and optical instrumentation with advanced data analysis approaches, enabling detailed characterization of particulate matter.This contribution presents key results from the Rotterdam campaign with a focus on source apportionment and particle volatility. Positive Matrix Factorization (PMF) applied to Aerosol Chemical Speciation Monitor (ACSM) and Xact Ambient Metals Monitor data reveals distinct factors associated with shipping emissions and industrial activities, alongside contributions from local sources and secondary aerosol formation. In addition, a catalytic stripper was employed upstream of particle and black carbon measurements to quantify the solid particle fraction. Apart from long-term statistics, three characteristic pollution episodes are examined in detail: (i) a summer period dominated by elevated organic aerosol concentrations during high-temperature conditions, (ii) a pronounced ultrafine particle number episode, and (iii) a high nitrate episode.Overall, the MI-TRAP Rotterdam results show that combining receptor modelling with volatility-resolved measurements and targeted episode analysis helps to separate different emission sources and to better describe their contribution to urban air pollution.