HR: 0830h
AN: A51F-0742    [PDF]
TI: Release of dicarboxlic acids by uptake of nitric acid into mixed inorganic/organic aerosols
AU: * Henk, H
EM: h.henk@fz-juelich.de
AF: ICG-II: Troposph\"are, Forschungszentrum J\"ulich, J\"ulich, NRW 52425 Germany
AU: Folkers, M
EM: m.folkers@fz-juelich.de
AF: ICG-II: Troposph\"are, Forschungszentrum J\"ulich, J\"ulich, NRW 52425 Germany
AU: Mentel, T F
EM: t.mentel@fz-juelich.de
AF: ICG-II: Troposph\"are, Forschungszentrum J\"ulich, J\"ulich, NRW 52425 Germany
AU: Tillmann, R
EM: r.tillmann@fz-juelich.de
AF: ICG-II: Troposph\"are, Forschungszentrum J\"ulich, J\"ulich, NRW 52425 Germany
AU: Wahner, A
EM: a.wahner@fz-juelich.de
AF: ICG-II: Troposph\"are, Forschungszentrum J\"ulich, J\"ulich, NRW 52425 Germany
AU: Otjes, R P
EM: r.otjes@ecn.nl
AF: Energy research Centre of the Netherlands, P.O. Box 1, Petten, ZG 1755 Netherlands
AU: Blom, M J
EM: m.blom@ecn.nl
AF: Energy research Centre of the Netherlands, P.O. Box 1, Petten, ZG 1755 Netherlands
AU: Ten Brink, H M
EM: tenbrink@ecn.nl
AF: Energy research Centre of the Netherlands, P.O. Box 1, Petten, ZG 1755 Netherlands
AB: Tropospheric particles contain both organic and inorganic components. Not much is known about the processing of the organic components through heterogeneous reactions and the effects of the latter on the hygroscopicity and surface reactivity of the aerosol. In the Large Juelich Aerosol Chamber we conducted several experiments on mixed aerosols consisting of ammonium sulfate or ammonium bisulfate and the dicarboxylic acids C2 -C7. For these studies we utilized ECN's Steam Jet Aerosol Collector (SJAC). The output of the SJAC is an aqueous solution of the dissolvable particulate matter which is analyzed by ion chromatography. We optimized a set of isocratic conditions to quantitatively determine the dicarboxylic acids in presence sulfate and nitrate in mixed organic-inorganic aerosols. The analysis times range between 10 and 25 minutes and the detection limits are in the order of magnitude of a few $\mu$moles/$\rm m^3$. The results are compared with measurements of the total organic carbon (TOC) in the aerosol phase, which were conducted by ECN as well as measurements with an Aerosol Mass Spectrometer (Aerodyne AMS). The mixed aerosol was then processed by heterogeneous hydrolysis of $\rm N_2O_5$, which was produced in situ by oxidation of $\rm NO_2$ with $\rm O_3$. The uptake of the hydrolysis product $\rm HNO_3$ into the particulate was measured. As result of the acidification the organic acid was partially or completely forced out of the particulate phase. An interpretation of these observations based on the thermodynamic modelling of mixed organic/inorganic aerosols will be given. The experiments are part of the EC project CASOMIO.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0365 Troposphere--composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting