Comparison of spring and autumn time collected outdoor aerosol particles analyzed with depth-resolving SNMS

Aerosol particles were collected in a size-classified way at the Forschungszentrum Karlsruhe during two autumn days of fine weather in September 1997 in order to analyze the depth distribution of the chemical inventory. The fine particles -1 mm diameter. had a nitrogen- and sulfur-dominated shell with a thickness of 13 nm around a carbon core and mainly originate from traffic soot. The coarse particles )1 mm diameter.consisted of soil dust or fly ash and sodium salt containing particles. Again the particle composition in greater depth was found to be different to the surface region, where nitrogen and sulfur as well as carbon were enriched. The surface-near nitrogen and sulfur could be attributed to ammonium sulfate, maybe deposited by particulate material formed from ammonia and SO in the atmosphere. The results agree to a x large degree with the analysis of outdoor particles collected at the same location but in spring time four years ago. However, the autumn particles of 1997 exhibited with 600 nm twice the diameter for the most frequent size compared to the particles sampled in spring of 1993. q1999 Published by Elsevier Science B.V. All rights reserved.