Uneven distribution of inorganic pollutants in marine air originating from ocean-going ships.

The distribution of mass, water-soluble inorganic salts and mineral elements of size-segregated aerosols (PM1, PM2.5-1 and PM10-2.5), precursor gaseous pollutants, black carbon, and nanoparticles (10-300 nm size range) at the Southern Bight of the North Sea has been studied. The concentrations of air pollutants peaked over shipping lanes, open-water anchorage areas and frequently navigated waters, due to the presence of mobile emission sources. A considerable decrease in air pollutant levels was seen when diverting from these marine areas towards remote or coastal banks. These findings showed the rapid dispersion of pollutants in the marine air. The nano-aerosol count, originating from ocean-going ships, peaked at lower average aerodynamic diameters (e.g., ≈28 nm) than those, observed from low-displacement vessels (45-50 nm, e.g., for fishing boats). The average diameter of nano-PM depended also on weather conditions, e.g., it was higher (≈50 nm) in air of higher humidity.

Major ionic species in size-segregated aerosols and associated gaseous pollutants at a coastal site on the Belgian North Sea.

The chemical composition of airborne particulate matter (PM) was studied at a coastal region near De Haan, Belgium, during a winter-spring and a summer campaign in 2006. The major ionic components of size-segregated PM, i.e. NH(4)(+), Na(+), K(+), Mg(2+), Ca(2+), Cl(-), NO(3)(-), and SO(4)(2-), and related gaseous pollutants (SO(2), NO(2), NH(3), HNO(2), and HNO(3)) were monitored on a daily basis. Air mass backward-trajectories aided in evaluating the origin of the diurnal pollution load. This was characterised with high levels of fine secondary inorganic aerosols (NH(4)(+), NO(3)(-), and non-sea-salt SO(4)(2-)) for continental air masses, and sea-salts as the dominant species in coarse maritime aerosols. Seasonal variations in the level of major ionic species were explained by weather conditions and the release of dimethyl sulfide from marine regions. This species was responsible for an increased sea-salt Cl(-) depletion during summer (56%), causing elevated levels of HCl. Neutralisation ratios for the coarse fraction (0.6-0.8) suggested a depleted NH(4)(+) level, while that for the fine fraction (1.1-1.3) had definitely an excess of NH(4)(+), formed by the neutralisation of HCl. The results of factor analysis and the extent of SO(2) oxidation indicated that the major ionic species originated from both local and remote sources, classifying the Belgian coastal region as a combined source-receptor area of air pollution.