Aerosol and trace gas vehicle emission factors measured in a tunnel using an Aerosol Mass Spectrometer and other on-line instrumentation

• Published in: Atmospheric environment (1994) Vol. 45; no. 13; pp. 2182 - 2192
• Main Authors: Chirico, Roberto, Prevot, Andre S.H., DeCarlo, Peter F., Heringa, Maarten F., Richter, Rene, Weingartner, Ernest, Baltensperger, Urs
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.04.2011; Elsevier
• Subjects: absorption; Aerosol mass spectrometer; Aerosols; Applied sciences; atmospheric chemistry; Atmospheric pollution; Black carbon; carbon dioxide; Density; diurnal variation; Emission; Emission factor; emissions factor; Exact sciences and technology; Gubrist tunnel; hydrocarbons; Instrumentation; Mass spectrometers; Organic aerosol; Phase composition; Pollution; temperature; traffic; Tunnels (transportation); Vehicles; Switzerland; Europe; Organic aerosol; Emission factor; Aerosol mass spectrometer; Black carbon; Gubrist tunnel; High resolution; Carbon compound; Gas emission; Carbon dioxide; Emission content; Nitrogen compounds; Instrumentation; Motor vehicle; Pollutant emission; Concentration measurement; Working days; Microparticle; Phase partition; Organic compounds; Nitrogen oxide; Carbonaceous materials; Carbon black; Phase composition; Hydrocarbon; Pollutant behavior; Trace compound; Diesel engine; Diurnal variation; Organic loading; Aerosols; Air pollution; Road traffic; Mass spectrometry
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2011.01.069

In this study we present measurements of gas and aerosol phase composition for a mixed vehicle fleet in the Gubrist tunnel (Switzerland) in June 2008. PM 1 composition measurements were made with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (AMS) and a Multi Angle Absorption Photometer (MAAP). Gas-phase measurements of CO, CO 2, NO x and total hydrocarbons (THC) were performed with standard instrumentation. Weekdays had a characteristic diurnal pattern with 2 peaks in concentrations for all traffic related species corresponding to high vehicle density (∼300 ± 30 vehicles per 5 min) in the morning rush hour between 06:00 and 09:00 and in the afternoon rush hours from approximately 15:30 to 18:30. The emission factors (EF) of OA were heavily influenced by the OA mass loading. To exclude this partitioning effect, only organic aerosol mass concentrations from 60 μg m −3 to 90 μg m −3 were considered and for these conditions the EF(OA) value for HDV was 33.7 ± 2.3 mg km −1 for a temperature inside the tunnel of 20–25 °C. This value is not directly applicable to ambient conditions because it is derived from OA mass concentrations that are roughly a factor of 10 higher than typical ambient concentrations. An even higher EF(OA) HDV value of 47.4 ± 1.6 mg km −1 was obtained when the linear fit was applied to all data points including OA concentrations up to 120 μg m −3. Similar to the increasing EF, the OA/BC ratio in the tunnel was also affected by the organic loading and it increased by a factor of ∼3 over the OA range 10–120 μg m −3. This means that also the OA emission factors at ambient concentrations of around 5–10 μg m −3 would be 2–3 times lower than the emission factor given above. For OA concentrations lower than 40 μg m −3 the OA/BC mass ratio was below 1, while at an OA concentration of 100–120 μg m −3 the OA/BC ratio was ∼1.5. The AMS mass spectra (MS) acquired in the tunnel were highly correlated with the primary organic aerosol (POA) MS from a EURO 3 diesel vehicle with a speed similar to the average tunnel speed. ► Measurements of gas and aerosol phase composition in a tunnel are presented. ► PM 1 measurements were made with a HR-ToF-AMS and a MAAP. ► Among the species analyzed, OA and BC were the main constituents of PM 1. ► The emission factors for OA and the OA/BC ratio were affected by the organic mass loading. ► At higher OA concentration more organics in the gas phase will condense producing more OA mass.