Abstract
The use of filter packs and a cascade impactor during a series of research cruises in the southern area of the North sea yielded detailed spatial distribution patterns of aerosol concentrations, chloride, nitrate, sulphate and ammonium, and gaseous concentrations, hydrogen chloride, nitric acid and ammonia. The overall distribution of the atmospheric concentrations closely parallels published modelled results for metallic species. The chemical transformation of these aerosols and gases were investigated together with their interactions with the seasalt aerosol. Aerosol chloride loss was greatest in the more polluted areas, whilst concentration products of ammonia and HNO3 and hydrogen chloride seemed insufficient to sustain the existence of ammonium nitrate and ammonium chloride. Nitrate was associated predominantly with larger particles and appeared to be present substantially as a surface coating on marine aerosol. The total dry deposition input for nitrogen species was calculated for the southern sector with extrapolation to the whole of the North sea, using particle size weighted deposition velocities of 0.63 and 0.21 cm per second for nitrate and ammonium, respectively, and literature-derived values for the gaseous constituents. Finally the use of air-mass back trajectories illustrates the role of source regions in influencing the chemical composition of the North sea atmosphere. There are 53 references.