München 2004 – wissenschaftliches Programm
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UP: Umweltphysik
UP 6: Aerosol und Mensch
UP 6.2: Fachvortrag
Montag, 22. März 2004, 18:30–18:45, HS 221
In-situ mass spectrometric analysis of diesel exhaust particles — •Nele Hock1, Johannes Schneider1, Silke Weimer1, Stephan Borrmann1,2, Ulf Kirchner3, Volker Scheer3, and Rainer Vogt3 — 1Abt. Wolkenphysik und -chemie, Max-Planck-Institut für Chemie, Mainz — 2Institut für Physik der Atmosphäre, Johannes Gutenberg-Universität Mainz — 3Environmental Science, Ford Research Center Aachen
We report on size-resolved measurements of the chemical composition of the volatile and semi-volatile fraction of exhaust particles, carried out with the Aerodyne Aerosol Mass Spectrometer (AMS). The instrument measures quantitatively the mass concentrations and size distributions of non-refractory aerosol compounds in a particle size range between 20 and 1500 nm. The project included measurements at the chassis dynamometer test facility at the Ford Research Center Aachen as well as field measurements near a German motorway and individual car chasing.
It has been observed that particle size and composition are a function of the engine load. At low power settings, the mass composition is dominated by organic species, while at high load (45 kW), corresponding to an uphill slope of 6% at 120 km/h, the composition is dominated by sulfate. This is most likely due to the conversion of SO2 into SO3 by the oxidation catalyst. The SO3 reacts fast to H2SO4 which can nucleate or condense on pre-existing particles, dependent on the dilution settings. However, the motorway measurements gave evidence that low volatile organic species are responsible for the existance of the observed small particle mode near the motorway.