The interaction of N2O5 with mineral dust: aerosol flow tube and Knudsen reactor studies
1Max-Planck-Institut für Chemie, Mainz, Germany
*now at: Bayerisches Staatsministerium für Umwelt, Gesundheit und Verbraucherschutz, Rosenkavalierplatz 2, 81925 München, Germany
**now at: International Laboratory for Air Quality and Health, QUT Gardens Point, 2 George Street, Brisbane, 4001 QLD, Australia
***now at: Unit Policy Studies of the Energy research Centre of the Netherlands, (ECN), VU University of Amsterdam (IVM), Radarweg 60 / P.O.Box 56890, 1040 AW Amsterdam, Netherlands
Abstract. The interaction of mineral dust with N2O5 was investigated using both airborne mineral aerosol (using an aerosol flow reactor with variable relative humidity) and bulk samples (using a Knudsen reactor at zero humidity). Both authentic (Saharan, SDCV) and synthetic dust samples (Arizona test dust, ATD and calcite, CaCO3) were used to derive reactive uptake coefficients (γ). The aerosol experiments (Saharan dust only) indicated efficient uptake, with e.g. a value of γ (SDCV)=(1.3±0.2)×10−2 obtained at zero relative humidity. The values of γ obtained for bulk substrates in the Knudsen reactor studies are upper limits due to assumptions of available surface area, but were in reasonable agreement with the AFT measurements, with: γ(SDCV)=(3.7±1.2)×10−2, γ(ATD)=(2.2±0.8)×10−2 and γ(CaCO3)=(5±2)×10−2. The errors quoted are statistical only. The results are compared to literature values and assessed in terms of their impact on atmospheric N2O5.