Erste atmosphärische Untersuchungen der Wechselwirkung von Mineralstaub mit den Spurengasen HNO₃ und SO₂: Einsatz einer hochempfindlichen CIMS-Sonde

Mineral dust is the single most abundant atmospheric aerosol by mass. In the presence of pollutants it could have a lasting effect on the earth's climate. This work deals with the interaction of mineral dust and the tropospheric trace gases sulfur dioxide, SO2, and nitric acid, HNO3. For this purpose, the CIMS technique (Chemical Ionization Mass Spectrometry) has been refined: A new inlet and filter system has been developed and employed successfully to perform calibrations and background measurements of the CIMS apparatus during the field campaign. Field measurements on the Monte Cimone in northern Italy showed a continuous decrease of HNO3 in dust loaded air masses, however HNO3 depletion was not com- plete. The atmospheric HNO3 mixing ratio decreased from 2 to 0.15 ppbv whereas the average concentration of HNO3 measured on Monte Cimone was about 1 ppbv or more. In contrast, there was no correlation between SO2 and mineral dust. The SO2 uptake depends strongly on the pH value of the mineral dust. Presumably the dust was suciently acidic to prevent SO2 uptak