Seasonal and diurnal characteristics of water soluble inorganic compounds in the gas and aerosol phase in the Zurich area R. Fisseha1,*, J. Dommen1, L. Gutzwiller2, E. Weingartner1, M. Gysel1,3, C. Emmenegger4, M. Kalberer4, and U. Baltensperger1 1Paul Scherrer Institut (PSI), 5232 Villigen, Switzerland 2Bundesamt für Energie BFE, 3003 Bern, Switzerland 3School of Earth, Atmospheric and Environmental Sciences, Univ. of Manchester, P.O. Box 88, Manchester M60 1QD, UK 4Laboratory of Organic Chemistry, ETH Hönggerberg, CH8093 Zürich, Switzerland *now at: ICG-II: Troposphäre, Forschungszentrum Jülich, 52425 Jülich, Germany
Abstract. Gas and aerosol samples were taken using a wet effluent diffusion
denuder/aerosol collector (WEDD/AC) coupled to ion chromatography (IC) in the city
of Zurich, Switzerland from August to September 2002 and in March 2003.
Major water soluble inorganic ions; nitrate, sulfate, and nitrite
were analyzed online with a time resolution of two hours for the gas and
aerosol phase. The fraction of water soluble inorganic anions in PM10 varied
from 15% in August to about 38% in March. Seasonal and diurnal
variations of nitrate in the gas and aerosol phase were observed with more
than 50% of the total nitrate in the gas phase during August and more
than 80% of nitrate in the aerosol phase during March exceeding the
concentration of sulfate by a factor of 2. Aerosol sulfate, on the other
hand, did not show significant variability with season. However, in the gas
phase, the SO2 concentration was 6.5 times higher in winter than in
summer. Nitrous acid (HONO) also showed a diurnal variation in both the gas
and aerosol phase with the lowest concentration (0.2–0.6 µg/m3) in
the afternoon. The primary pollutants, NO, CO and SO2 mixing ratios
were often at their highest between 04:00–10:00 local time due to the build
up of fresh vehicle emission under a nocturnal inversion.
Citation: Fisseha, R., Dommen, J., Gutzwiller, L., Weingartner, E., Gysel, M., Emmenegger, C., Kalberer, M., and Baltensperger, U.: Seasonal and diurnal characteristics of water soluble inorganic compounds in the gas and aerosol phase in the Zurich area, Atmos. Chem. Phys., 6, 1895-1904, doi:10.5194/acp-6-1895-2006, 2006.