CHARACTERIZATION OF INDIVIDUAL GIANT AEROSOL-PARTICLES ABOVE THE NORTH-SEA

In order to investigate the importance of giant airborne particles, air sampling was carried out using an aircraft which flew at different altitudes over the southern bight of the North Sea. A set of 25 samples was collected with a steel rod on top of the airplane. Some 12 500 individual particles were analyzed using electron probe X-ray microanalysis. Principal factor analysis allowed identification of four sources of giant aerosol particles: aluminosilicates, combustion processes, industrial processes, and marine sources. Hierarchical and nonhierarchical cluster analysis enabled us to classify the analyzed particles. A clear distinction was found between flights for which the associated air masses were marine or continental. The experimentally found size distributions for sea salts, sea salts enriched with sulfur, and organic, CaSO4, and Fe-rich particles were fitted well by the log-normal distribution, and average sizes of these particle types were found to be approximately 3-mu-m. Aluminosilicates had a bimodal size distribution with average size maxima at 4 and 15-mu-m.