Atmospheric impact of ships emissions in two Adriatic harbours: Brindisi and Venice.

Emissions of atmospheric pollutants from shipping and harbour activities are a growing concern at International level and, specifically, in the Mediterranean area. The continuous increase of global trade and of harbour services made maritime transport a key contributor to atmospheric pollution. The objective of this work is to give a comparable assessment of the impact of ship traffic and harbour activities to atmospheric PM2.5 and particle number concentrations (PNC) in two important port-cities of the Adriatic Sea: Venice and Brindisi. In Venice area, measurements were taken in 2007, 2009 and 2012 during summer, when the tourist ship traffic is at maximum. In Brindisi, measurements were performed in summer 2012 and in summer 2014. The two harbours have significant differences in the typology of ship traffic as well as in the volume of traffic and in the layout and logistic organization that could influence the impact of pollutant emissions on nearby urban areas. High temporal resolution measurements, both for particle number and mass concentrations, were used for identification of single ship plumes and for quantitative statistical evaluation of primary contribution of ship emissions to atmospheric aerosol concentrations. Results show that, in 2012, the contribution of ships emissions to PM2.5 was 7.4 (±0.5) for Brindisi harbour and 3.5 (±1) for Venice harbour. The contribution to particle number concentration was 26 (±1) and 6 (±1), respectively, for Brindisi and Venice harbour. Results show that the ship traffic contribution increases when particle size decreases and it is significantly larger on particle number concentration with respect to PM2.5. The inter-annual trends of the impact of shipping to atmospheric particles concentrations were investigated in the two areas showing a decrease in Venice correlated with the use of low-sulphur content fuel.