German Title: Heterogene Reaktionen von Salpetersäure und Distickstoffpentaoxid auf Mineralstaub: Eine Knudsen-Reaktor-Studie
Translation of abstract (English)
The heterogeneous reactions of nitric acid and dinitrogen pentoxide with various authentic dust, mineral and clay mineral surfaces has been investigated my means of the Knudsen reactor techique at room temperature. Authentic dust surfaces from the Saharan, the Chinese and the Arizona dust regions were used as substrates, as were the minerals and clay minerals: aluminium oxide, calcite, dolomite, feldspar; kaolinite, chlorite, illite, smectite, montmorillonite and palygorskite. The uptake of both trace gases was investigated at concentrations as low as 10^9 cm^-3 (HNO3) and 10^10 cm^-3 (N2O5) and found to be large and irreversible. For HNO3 uptake coefficients of the order of 0.1 werde determined. Uptake coefficients of N2O5 were between 0.02 and 0.001. Water was found to have some influence onto the uptake coefficient, though this depended on the substrate used. It was observed that diffusion into the pores of the sample bulk can be relevant for N2O5; this has to be considered in the calculation of the uptake coefficient. For HNO3 pore diffusion is unimportant. These results strongly suggest that mineral aerosol can redistribute nitrate from the gaseous to the particulate phase, modifying tropospheric photochemical cycles involving NOx and NOy.
|Supervisor:||Platt, Prof. Dr. Ulrich|
|Date of thesis defense:||27 June 2001|
|Faculties / Institutes:||The Faculty of Physics and Astronomy > Institute of Environmental Physics|
|Uncontrolled Keywords:||Knudsen-Reaktor , Knudsenzelle , Mineralstaub , DistickstoffpentaoxidKnudsen reactor , nitric acid , dinitrogen pentoxide , mineral dust|