Impact of ship emissions and harbour activities on gas pollutants and size segregated particles concentrations

Harbours are important hubs for social and economic development of coastal Mediterranean areas. However, ship emissions are also a significant source of atmospheric pollution in port-cities with potential effects on both human health and climate. At European level (Viana et al., 2014), the impact of shipping to particulate matter (PM) concentrations is larger in Mediterranean area with respect to Northern Europe. Further, information on impact on ultrafine and nanoparticles is still fragmentary and not sufficient to have a global picture on this metric. International legislations to reduce ship emissions, both at Worldwide and European levels, are mainly based on the use of low-sulphur content fuel that is effective also in reducing primary impact of shipping to atmospheric aerosol (Contini et al., 2015). In the framework of POSEIDON project, a measurement campaign was performed between 27th June and 15th October 2014, in the harbour area of Brindisi (SE Italy, 40° 38? 43.32? N - 17° 57? 36.39? E). A mobile laboratory was used to investigate the contribution of ship traffic and harbour activities (hotelling, loading and unloading of ships) to gaseous pollutants and to concentrations of atmospheric particles of different sizes. The mobile laboratory was equipped to measure, at high temporal resolution, gaseous pollutants (NO2, NO, O3, SO2 at 5 minutes resolution), total particle number concentrations (Grimm CPC 5.403 at 1 minute resolution), particle size distribution in the range 0.25-34 µm using a Grimm OPC 1.109 (1 minute resolution) and further, a DOAS (Differential Optical Absorption Spectroscopy) remote-sensing system was employed for detection of NO2 and SO2 fluxes from ships in harbour (Premuda et al., 2011). Ship traffic details were collected from Brindisi Port Authority and arrival and departure times were synchronised with concentration measurements using a night & day video camera. A low-volume PM2.5 sequential sampler was used to collect 24-hour samples using the gravimetric method to calibrate optical measurements. Collected data allowed to individuate short-term concentration peaks associated with ship traffic and concentration increases associated with correlated harbour activities. An example is reported in Figure 1. Measurements show that SO2 presents brief concentration peaks associated with the manoeuvring phase and lower concentrations during the hotelling phase. This is compatible with the use of low-sulphur content fuel in European harbours (European Directive 2012/33/EC). Nitrogen oxides concentrations show a significant contribution, especially for NO, for both manoeuvring and hotelling, loading/unloading phases. Simultaneously, a depletion of O3 (not shown) was observed. Particle concentrations show a dynamics that is strongly depending on particle size. Ultrafine particles (diameter Dp<0.25 µm) show peaks well correlated with nitrogen oxides peaks. Instead, accumulation mode particles (0.25 µm<Dp<1 µm) show concentration peaks mainly in manoeuvring phase correlated with SO2 concentrations. Coarse fraction (Dp>1 µm) appears to be marginally influenced by the manouvering phase but it presents increases during the hotelling phase likely associated with the resuspension and mechanical generation of dust during the activities of loading/unloading of ships. Further, an analysis of the inter-annual trends of ship traffic and of its contribution to primary PM2.5 will be performed considering the results obtained in the same area in 2012 (Donateo et al., 2014).