Laser microprobe mass analysis of individual North Sea aerosol particles

Some 6000 individual aerosol particles in the 0.5-4-µm aerodynamic diameter range, collected from an aircraft at different heights above the North Sea, were analyzed using laser microprobe mass analysis (LAMMA). In this way, various well-separated particle types could be defined. Many of these particles appeared to occur as internal mixtures. Several definite trends in particle type abundances as a function of wind direction during sampling and of particle size could be observed. This helped in identifying source processes of the aerosol. Obtaining conclusive results as a function of sampling height, on the other hand was much less straightforward. This is not surprising, since most samples were collected under the inversion layer where extensive mixing is likely to take place.