High-Time-Resolution Analysis of Organic and Inorganic Trace Gases and Particles in a Major European Port Using Mobile and Stationary Measurements

Port environments are characterized by complex and highly variable emissions from shipping, industrial and traffic activities, which results in distinct spatial and temporal heterogeneity in air pollutant concentrations. Fuel cells used in port activities, whether stationary or mobile, can be adversely affected by elevated pollutant concentrations. Therefore, we investigate the concentrations of volatile organic compounds (VOCs), trace gases, and ultrafine particles in the Port of Rotterdam as part of the KaLiBer joint project. MOBILAB serves as the mobile measuring platform equipped with state-of-the-art instrumentation for particle and gas-phase analysis, enabling both mobile transects and stationary monitoring. VOCs were measured using proton-transfer-reaction mass spectrometry (PTR-MS), capturing a wide range of oxygenated and non-oxygenated species, alongside simultaneous observations of CO, CO₂, NOₓ, SO₂, NH₃, and ultrafine particle (UFP) number concentrations. The mobile measurements were conducted over 10 days along selected routes in the port area and subsequent 30 days of stationary monitoring during summer. PTR-MS measurements covered approximately 130 masses, allowing a detailed characterization of both oxygenated and non-oxygenated VOCs.

The mobile measurements capture distinct spatial gradients and short-lived concentration spikes linked to local emission plumes. In contrast, the stationary data set reveals long-term variability and background conditions with additional plumes from ships passing by. Average concentrations and prominent diurnal patterns suggest distinct emission sources from shipping, heavy-duty traffic, and industrial activities. Spatial analysis reveals elevated VOC concentrations accompanied by high UFP and CO₂ levels, along port roadways. This suggests a dominant contribution from traffic-related sources. In the urban background, mixing ratios decreased due to chemical transformation and atmospheric dilution. The aromatic-to-oxygenated VOC (OVOC) ratios reveal distinct differences between fresh emissions along traffic-affected routes and more chemically aged air masses at the stationary site. This emphasizes the dynamic interplay between primary emissions and atmospheric processing. Although toluene/benzene ratios were comparable during mobile and stationary periods, they reflect mixed contributions from traffic, shipping, and industrial sources.

The combined mobile–stationary dataset demonstrates the significance of high-time-resolution measurements for capturing emission variability, chemical processing, and source contributions in complex port environments. Such insights are vital for quantifying transport-sector contributions to urban air pollution. They are essential for assessing potential health impacts, and effective emission mitigation and air quality management. Beyond atmospheric characterization, the observed concentration ranges, variability, and occurrence of short-lived pollutant peaks are important for designing and optimizing air filtration systems that protect fuel cell technology. In particular, understanding the temporal occurrence of VOCs and acidic gases is essential for minimizing catalyst poisoning, membrane degradation, and performance losses. This, in turn, improves fuel cell durability and operational lifetime under real-world port conditions.

This work is funded by the Federal Ministry for Economic Affairs and Energy based on a resolution of the German Bundestag under funding code 03EN5043D.