INDIVIDUAL AEROSOL-PARTICLE COMPOSITION VARIATIONS IN AIR MASSES CROSSING THE NORTH-SEA

Single-particle analysis on North Sea aerosol and rainwater samples was performed by electron-probe X-ray microanalysis (EPXMA). The analysis was mainly focused on the determination of the inorganic composition of giant particles with diameters above 1 mum. Multivariate techniques were used for the reduction of the data set and for source apportion. Based on the relative abundances found by hierarchical cluster analysis according to the Ward error sum method, three to eight different aerosol types were distinguished. Crossing the North Sea, the changes in air mass composition appeared as a decrease in the abundance for the aluminosilicate particles and a relative increase for NaCl and seawater crystallization products. Principal factor analysis revealed four different aerosol sources: aluminosilicates and NaCl, seawater crystallization products as a marine source, and two industrial sources. Relations between the particle composition, origin, and shape were studied by manual EPXMA, and for most of the particle types, a characterization based on their shape was obtained.