Emissions of Size-Segregated Aerosols from On-Road Vehicles in the Caldecott Tunnel

1. Emissions of Size-Segregated Aerosols from On-Road Vehicles in the Caldecott Tunnel Jonathan O. Allen Civil and Environmental Engineering Department, Arizona State University Lara S. Hughes Chemistry Department, University of California, Riverside • Paul R. Mayo, Lynn G. Salmon Environmental Engineering Science Department, California Institute of Technology Glen R. Cass School of Earth and Atmospheric Science, Georgia Institute of Technology SCOS97 -- NARSTO Data Analysis Conference 15 February 2001

2. Motivation • Vehicle emissions are large contributors to ambient aerosol concentrations • Los Angeles aerosol in September 1996 study was composed of • 9-11% primary particles emitted by vehicles • 37-65% gas-to-particle conversion products from NOx, NH3, SO2, organic compounds • Actual on-road vehicle fleet emissions can be measured in tunnels including • high emitters • non-tailpipe emissions

3. Caldecott Tunnel Study • Bore 1 - HDV and LDV • 5-6% Heavy Duty • Nov 17 and 18 • noon to 3 p.m. • Bore 2 - “LDV Only” • 0.24% Heavy Duty • Nov 19 and 20 • 3:30 to 6:30 p.m. HDV - Heavy Duty Vehicles LDV - Light Duty Vehicles

4. Aerosol Measurements Mass Fine Particle Filters PM10 Filters Trace Metals (V,Fe,Br,Mg,…) Impactors 1.0 - 1.8 mm 0.56 - 1.0 0.32 - 0.56 0.18 - 0.32 0.10 - 0.18 < 0.10 Carbon (Elemental, Organic) Ions (NO3-, SO4=, Cl-, NH4+) Samplers Analytes Organic Tracers (PAHs, Hopanes, …) Electronic Particle Counters Particle Size Distribution Reactive Gases HNO3, HCl, NH3

5. 100 ) 80 -3 g m Unidentified m - 60 Cl + Na = SO 40 Concentration ( 4 + NH 4 - NO 20 3 Metals and Metal Oxides Organic Compounds 0 Bore 1 Bore 2 Elemental Carbon (HDV and LDV) ("LDV Only") PM1.9 Concentrations • Carbonaceous emissions are most important • Higher emissions in HDV than LDV Tunnel Bore

6. D Ci EC,i = SD CC,j Emissions Calculations • Gas phase carbonaceous species (CO2, CO, CH4, NMHC) measured • Calculate aerosol emissions based on fuel consumption as EC,i Emission of species i on carbon consumption basis D Ci Concentration increase in species i SD CC,j Sum of carbon emissions in tunnel

7. Unidentified - Cl + Na = SO 4 + NH 4 - NO 3 Metals and Metal Oxides Organic Compounds Elemental Carbon PM1.9 Emissions

8. 400 ) -1 300 Unidentified (mg kgC - Cl + Na = SO a 200 4 + NH log D 4 - NO 3 Metals and Metal Oxides D 100 Organic Compounds E / Elemental Carbon D 0 0.02 0.05 0.1 0.2 0.5 1 m Aerodynamic Diameter, D ( m) a Size-Segregated Emissions in Bore 1 (HDV and LDV)

9. 100 ) -1 80 Unidentified (mg kgC - Cl + 60 Na = SO a 4 + NH 40 log D 4 - NO 3 Metals and Metal Oxides D Organic Compounds 20 E / Elemental Carbon D 0 0.02 0.05 0.1 0.2 0.5 1 m Aerodynamic Diameter, D ( m) a Size-Segregated Emissions in Bore 2 (“LDV Only”)

10. LDV and HDV Fleet Emissions Estimate emission rates of LDV and HDV fleets by linear regression EC,ik = fk EC,i(HDV) + (1-fk) EC,i(LDV) + eik fk Fraction of carbon emitted by HDV fleet in experiment k • fk calculated from • vehicle counts • fuel consumption estimates • fuel properties

11. 2500 ) -1 2000 1500 Mass Emissions (mg kgC 1000 500 0 0 0.2 0.4 0.6 0.8 1 Fraction Carbon Emitted by HDVs, f Linear Fit of Mass Emissions

12. 1500 Unidentified 1000 - Cl + Na Emission Rate (mg kgC-1) = SO 4 + NH 4 - NO 500 3 Metals and Metal Oxides Organic Compounds Elemental Carbon 0 HDV Fleet LDV Fleet (x 10) PM1.9 Emissions by HDV and LDV Fleets HDV emissions 25 times greater than LDV emissions

13. 1500 ) -1 (mg kgC 1000 Unidentified - a Cl + Na log D = SO 500 4 + NH D 4 - NO E / 3 Metals and Metal Oxides D Organic Compounds 0 Elemental Carbon 0.02 0.05 0.1 0.2 0.5 1 m Aerodynamic Diameter, D ( m) a Size-Segregated HDV Emissions Size-segregated LDV emissions are indistinguishable from zero Maximum LDV emissions are those for Bore 2

14. Emission Source Measurements • Kleeman, Schauer, and Cass (Environ. Sci. Technol., 34:1578–1587, 2000) measured the emissions of • Catalyst-Equipped Gasoline Vehicles • Noncatalyst-Equipped Gasoline Vehicles • Medium Duty Diesel Trucks • Size-segregated emission profiles agree with tunnel measurements • Note: no afterfilter analyses on these source samples

15. 2 Unidentified 1.5 - Cl + Na = SO 4 DM / Dlog Da Mtot 1 + NH 4 - NO 3 Metals and Metal Oxides Organic Compounds 0.5 Elemental Carbon 0 0.1 1.0 Da (mm) Medium Duty Diesel Emissions

16. 1.4 1.2 Unidentified 1 - Cl + Na DM / Dlog Da Mtot 0.8 = SO 4 + NH 4 - 0.6 NO 3 Metals and Metal Oxides 0.4 Organic Compounds Elemental Carbon 0.2 0 0.1 1.0 Da (mm) Catalyst-Equipped Gasoline Vehicle Emissions

17. 2 Unidentified 1.5 - Cl + Na = DM / Dlog Da Mtot SO 4 1 + NH 4 - NO 3 Metals and Metal Oxides Organic Compounds 0.5 Elemental Carbon 0 0.1 1.0 Da (mm) Noncatalyst-Equipped Gasoline Vehicle Emissions

18. Comparison of Laboratory and Tunnel Emissions Measurements • Medium duty diesel truck emissions profile similar to HDV emissions profile • Relatively more HDV emissions of particles larger than 0.2 mm — due to • heavy duty trucks (source sample was medium duty) • non-tailpipe emissions • Organic compounds emissions in Bore 2 similar to profiles for gasoline powered vehicles • Elemental carbon emissions in Bore 2 due to • few trucks • non-tailpipe emissions

19. Conclusions • Emission rates measured were comparable with other tunnel studies • Size-segregated emission profiles are comparable to those from source tests possible additional emissions from untested sources • heavy duty trucks • gasoline powered trucks • non-tailpipe emissions • Ammonia emissions were 194 and 267 mg l-1 fuel consumed

20. Acknowledgement This work was supported by the Coordinating Research Council, Inc., and the U.S. DOE Office of Heavy Vehicle Technologies through the National Renewable Energy Laboratory under CRC Project No. A-22.