The Impact of Emissions from Ships in Ports on Regional and Urban Scale Air Quality

Ships emit considerable amounts of pollutants, not only when sailing, but also during their stay in ports. This is of particular importance for harbor cities because ship emissions contribute to regional and urban air pollution. However, only few studies investigated the specific effect of shipping emissions on air pollution in cities. It is difficult to estimate the emissions from ships in harbors only from the technical specifications of the ships because their activities during their stay at berth differ a lot and are not well known. A multi-level approach was used to calculate the total emissions of ship activities in the port of Hamburg. The resulting emission inventory served as input for the Chemical Transport Model systems TAPM and CityChem. To investigate the impact of ship emissions on air pollution in the Hamburg area two different model runs for January and July 2013 were performed; one model run including land-based emissions and the ship emissions and a model run just including the land-based emissions. The modeling outcomes are compared with air quality data and resulted in dispersion maps of pollutants (PM2.5 and NO2) from harbor related ships in the Hamburg metropolitan area. On the urban scale, the highest concentrations are located in the port area of Hamburg. The monthly averaged NO2 concentrations mostly remain within the harbor area and the southwest region of Hamburg. The regional background concentrations in the metropolitan area are only slightly increased by shipping emissions from the harbor.