In-situ real-time mass spectrometric measurements of the chemical aerosol composition of traffic emissions

Transcription

1 ISEEQS Conference, NO 1123, Rehovot, 30 May 2005 In-situ real-time mass spectrometric measurements of the chemical aerosol composition of traffic emissions Stephan Borrmann Institut für Physik der Atmosphäre, Universität Mainz Abteilung für Wolkenphysik und chemie, MPI für Chemie

2 Outline 1. Particle emissions and health 2. Aerosol mass spectrometry 3. Small car Diesel-exhaust particles 4. Aircraft emissions 5. Outlook

3 Human respiratory system O 2 alveoli bronchioli Ultrafines CO 2

4 Pulmonary tissues Carbonaceous particles of µm free and inside phagocytes

5 Deposition of aerosol-partices within the lung > 5 µm, Impaction 1-5 µm, Sedimentation < 0.2 µm, Diffusion Pleura << 0.1µm, Permeation, Penetration into cells+organs

6 Health effects of nano-particles (1.) Stress on phagocyte-system to clean allows for infections. (2.) Inflammations of lung alveoli (3.) Increase of viscosity of the blood plasma probable (4.) Penetration into organs, even the brain, and into cells has been proven (2004). (5.) Possible cancerogenic effects still are subject of medical research. (6.) Whether particle size, surface area, chemical composition are the cause of the health effects is unknown. (7.) BUT: Harmless composition of large particles turns adverse if in ultrafines.

7 Outline 1. Particle emissions and health 2. Aerosol mass spectrometry 3. Small car Diesel-exhaust particles 4. Aircraft emissions 5. Outlook

8 Real-time in-situ online particle mass spectrometry: Transformation of aerosol particle material into molecule ions? NH 4 + SO 2 + NO + CO 2 +? OH + C 2 H 6 + N 2 + Transfer of aerosol particles into vacuum Vaporization of the particulate material Ionisation of the vapor molecules/clusters Mass spectrometric analysis of ion-cloud

9 Aerodyne Aerosol Mass Spectrometer Particle size diameter range: 20 nm to 2 µm

10 Aerodyne Aerosol Mass Spectrometer Aerodyne AMS modified for use in trucks and aircraft

11 Aerodyne Aerosol Mass Spectrometer Time-of-flight mode Mass m(s) present in spectral line S as function of vacuumaerodynamic diameter (D va ) Mass-spectra mode Continuous analysis of the entire particle beam => masses of all lines detected but no size info available 5 S 10 6 Signal der Masse 73 dm/dlog(d va ) Ion Rate (Hz) Ion Rate (Hz) vakuum-aerodynamischer Durchmesser d va in nm Vacuum aerodynamic diameter m/z m/z

12 Aerosol-Mass-Spectrometer 18= H 2 O +, NH 4 + MINOS 2001, Eastern Mediterranean campaign 48 = SO + 64 = SO = CO = O = SO = H 2 SO 4 +

13 Aerosol-Mass-Spectrometer What is it, that is actually measured? substances which evaporate at C => no metals, soot-bc not, => for these laser ablation instrument Substances which ionize at 70 ev ion impact energy.... these are sulfate, nitrate, ammonia, H 2 O within limits... organics = up to now, everything which is not sulfate, nitrate, ammonia, chloride, other anorganic salts.... particles with size diameters between 20 nm and 2000 nm size resolved composition measurements only with one selectable mass number possible THIS PRESENTATION: Not SOOT ITSELF, but what is ON THE SOOT PARTICLES

14 Outline 1. Particle emissions and health 2. Aerosol mass spectrometry 3. Small car Diesel-exhaust particles 4. Aircraft emissions 5. Outlook

15 Soot particles of traffic emissions M. Ebert, TU Darmstadt PKW-Diesel î Aircraft emissions 10km cruise altitude (NASA Ames) <- Diesel-soot, TEM&ESEM TU Darmstadt

16 Exhaust pipe processes known processes process under discussion

17 Chassis dynamometer tests Das Aerosolmassenspektrometer Diesel exhaust: Ford Research Center test facility in Aachen, Germany Chemical composition AMS Number density CPC SMPS Size distribution

18 Volatile exhaust components Chassis dynamometer mass spectrum 600 second average 360 ppm fuel sulfur content, 120 km/h, level drive: NOTE: No sizes, but all spectral lines

19 Effects of engine load dm/dlogd va (µg/m³) kw 700x dv/logd mob (nm³/cm³) dm/dlogd va (µg m -3 ) kw 700x dv/logd mob (nm³/cm³) dm/dlogd va (µg m -3 ) kw 700x dv/logd mob (nm³/cm³) D va, D mob (nm) D va, D mob (nm) D va, D mob (nm) * With load the diameters of sulfate and organic Particles increase. Electrical mobility diameter remains constant. * Mass concentration of sulfate particles increases with engine load.

20 Engine load EXPLANATION: The oxidation-catalyzer oxidizes CO to CO 2 and HC to H 2 O and CO 2. BUT: SO 2 is converted to SO 3 forming H 2 SO 4 => rapid particle nucleation. AND: The higher the exhaust temperature, (i.e. engine load) the more efficient the oxi-cat operates. downhill 6% uphill

21 Weird result Particle diameter [nm] Durchmesser (nm) Downhill Lastzustand (kw) 40 Engine load in Kilowatts 6% uphill Massenverhältnis D va D mob Massenverhältnis Sulfat/Organics Mass ratio of sulfate to organics Vacuum diameter increases BUT Mobility diameter is constant EXPLANATION: Shape factor χ decreases with engine load as particles get less fractal and more spherical. PLUS density ρ p increases with growing sulfur content (i.e. engine load) D va = ρ p /ρ 0 1/χ² D mob K

22 Nucleation particle formation 360 ppm sulfur, no TD 360 ppm sulfur PLUS TD 2 ppm no TD * Nucleation particles of H 2 SO 4 and H 2 O at 50 nm * Low fuel sulfur avoids H 2 SO 4 particle formation * Thermodenuder at 280 C removes nucleation peak

23 Measurements at Autobahn A4 and in the background Februar 2003

24 Automobile-Ensemble measurements directly at autobahn Sulphate Organics Ammonium Nitrate background at 5 km distance Sulphate Organics Ammonium Nitrate dm/dlogd va (µg m -3 ) dm/dlogd a (µg m -3 ) Vacuum Aerodynamic Diameter (nm) Vacuum Aerodynamic Diameter (nm) Traffic emission contribution

25 Measurements behind single car on Ford-test-tracks in Belgium

26 Volatile Diesel-exhaust dm/dlogd a (µg m -3 ) Speeds of 120 km/h with different fuel sulfur contents sulphate 120 km/h: Sulphate Chasing ppm Chasing - 30 ppm Background dm/dlogd a (µg m -3 ) organics 120 km/h: Organics Chasing - 360ppm Chasing - 30ppm Background Vacuum Aerodynamic aerodynamic Diameter diameter (nm) (nm) Vacuum aerodynamic diameter (nm) Sulfuric acid nucleation particles only if fuel sulfur content is high. Starting 2005 this issue is resolved due to 10 ppm EU legislation

27 dm/dlogd a (µg m -3 ) Volatile Diesel-exhaust Speeds of 50 km/h with different fuel sulfur contents sulphate 50 km/h: Sulphate Chasing ppm Background dm/dlogd a (µg m -3 ) organics 50 km/h: Organics Chasing - 360ppm Background Vacuum aerodynamic diameter (nm) No nucleation-mode at 50 km/h at sulfate lines, Vacuum aerodynamic diameter (nm)...but interestingly at the "organics???

28 Volatile Diesel-exhaust At 10 m distance two modes appear with high sulfur content. These disappear right after event.

29 Summary: Volatile Diesel-exhaust The reduction of fuel sulfur content decreases production of ultrafine sulfate particles The production of ultrafine organics needs further research The real target for research should be trucks and ships Only volatile components can be measured with (our) current aerosol MS instrumentation => correlation with direct soot data is needed. How do Diesel-soot-filters enter? There is the possibility of homogeneous nucleation of nano-particles from hot exhaust BEHIND the filters after it cools.

30 Outline 1. Particle emissions and health 2. Aerosol mass spectrometry 3. Small car Diesel-exhaust particles 4. Aircraft emissions 5. Outlook

31 Aviation emissions are and continue to be an issue

32 Processes in aircraft exhaust at cruising altitude Isobaric mixing of cold, dry ambient air with hot, moist exhaust Soot H 2 SO 4 H 2 O n. H 2 O S SO 2 OH, H 2 O H 2 SO 4 X ± Ion cluster Ice formation H 2 SO 4 H 2 O H 2 SO 4 H 2 O n. H 2 O 0.01 s 0.1 s 1.0s Plume age

33 Commercial Airtraffic: Contrails Bild: WolkenBilderGalerie, Mainz Meteosat Image

34 Aircraft emissions at cruise altitude PAZI: PArtikel aus Flugzeugtriebwerken und ihr Einfluss auf Kondensstreifen, ZIrruswolken und Klima, Oberpfaffenhofen, Mai 2003 Particle mass spectrometer AMS Research aircraft DLR "Falcon"

35 Fotos: J. Curtius und DLR

36 SULPHUR IV, Size distribution measurements Schröder et al., JGR, 2000 Mass spectrometer size range

37 7. Tropospheric vertical profiles 10 5 PAZI Flight # Contrail encounters 13:06, 13:17, 13:20, 13:22 Contrail MS Noise level contrail MS Background MS Noise level background MS Gas phase signals 10 4 Ion Rate (Hz) m/z 12 (C + ) m/z 20 (?) m/z 23 (Na +?) m/z 30 (NO + ) m/z 39 (Ka +?) m/z 44 (CO2+ ) (N +, O +, N 2 +, 15 NN +, O2 +, 18 OO +, Ar +, Ar 2+ ) m/z 64 (SO2+ ) m/z 69 (C5 H 9+ ) m/z 71 (C5 H 11+ ) m/z 76 (?) m/z 80 (SO3+ ) m/z 86 (?) m/z 95 (?) m/z 96 (?) m/z 104 (?) m/z 113 (?) m/z (Daltons) In-situ measurements of chemical particle composition inside contrails at cruising altitude (May 2003)

38 Outline 1. Particle emissions and health 2. Aerosol mass spectrometry 3. Small car Diesel-exhaust particles 4. Aircraft emissions 5. Outlook

39 Aerosol mass spectrometry in Mainz Aerodyne Quadrupole <= AMS Ion-trap AIMS Single Particle Laser AblationTime-of-flight MS This presentation Time-of-flight AMS, Aerodyne

40 Acknowledgements: Johannes Schneider, Nele Hock, Frank Drewnick, Silke Hings, Silke Henseler, Joachim Curtius (UMAINZ/MPIC) Ulf Kirchner, Rainer Vogt, Volker Scheer (Ford FA) This work is from three accepted publications.

41 Idealized EC structure Morphology of combustion particles Ageing process of BC 0.12 nm H. Cachier (1989) nm From Carry et al., 2004

42 Effect of sample dilution dm/dlogd va (µg/m³) Verdünnung: 1:300 Sulfat Organics SMPS 800x dv/dlogd mob (nm³/cm³) dm/dlogd va (µg m -3 ) Verdünnung: 1:10 Sulfat Organics SMPS 200x dv/dlogd mob (nm³/cm³) D va, D mob in nm 0 high low dilution D va, D mob in nm 0 => Larger relative number/mass of nucleation particles at higher dilution

43 1E+4 1E+3 Kondensstreifen < 5 Sek., Partikelanzahl dn/d log(d) pro [1/cm³] Luft 1E+2 1E+1 1E+0 1E-1 1E-2 1E-3.. Dünne Cirren Cirrus Tropische Cirrus Partikeldurchmesser [µm]