Comparison of emissions from on-road sources using a mobile laboratory under various driving and operational sampling modes
Open Access
- 6 January 2009
- journal article
- Published by Copernicus GmbH in Atmospheric Chemistry and Physics
- Vol. 9 (1), 1-14
- https://doi.org/10.5194/acp-9-1-2009
Abstract
Mobile sources produce a significant fraction of the total anthropogenic emissions burden in large cities and have harmful effects on air quality at multiple spatial scales. Mobile emissions are intrinsically difficult to estimate due to the large number of parameters affecting the emissions variability within and across vehicles types. The MCMA-2003 Campaign in Mexico City has showed the utility of using a mobile laboratory to sample and characterize specific classes of motor vehicles to better quantify their emissions characteristics as a function of their driving cycles. The technique clearly identifies "high emitter" vehicles via individual exhaust plumes, and also provides fleet average emission rates. We have applied this technique to Mexicali during the Border Ozone Reduction and Air Quality Improvement Program (BORAQIP) for the Mexicali-Imperial Valley in 2005. We analyze the variability of measured emission ratios for emitted NOx, CO, specific VOCs, NH3, and some primary fine particle components and properties by deploying a mobile laboratory in roadside stationary sampling, chase and fleet average operational sampling modes. The measurements reflect various driving modes characteristic of the urban fleets. The observed variability for all measured gases and particle emission ratios is greater for the chase and roadside stationary sampling than for fleet average measurements. The fleet average sampling mode captured the effects of traffic conditions on the measured on-road emission ratios, allowing the use of fuel-based emission ratios to assess the validity of traditional "bottom-up" emissions inventories. Using the measured on-road emission ratios, we estimate CO and NOx mobile emissions of 175±62 and 10.4±1.3 metric tons/day, respectively, for the gasoline vehicle fleet in Mexicali. Comparisons with similar on-road emissions data from Mexico City indicated that fleet average NO emission ratios were around 20% higher in Mexicali than in Mexico City whereas HCHO and NH3 emission ratios were higher by a factor of 2 in Mexico City than in Mexicali. Acetaldehyde emission ratios did not differ significantly whereas selected aromatics VOCs emissions were similar or smaller in Mexicali. Nitrogen oxides emissions for on-road heavy-duty diesel truck (HDDT) were measured near Austin, Texas, as well as in both Mexican cities, with NOy emission ratios in Austin < Mexico City < Mexicali.Keywords
This publication has 29 references indexed in Scilit:
- A Decade of On-road Emissions MeasurementsEnvironmental Science & Technology, 2008
- Long-term changes in emissions of nitrogen oxides and particulate matter from on-road gasoline and diesel vehiclesAtmospheric Environment, 2008
- Real-World Vehicle Emissions: A Summary of the Sixteenth Coordinating Research Council On-Road Vehicle Emissions WorkshopJournal of the Air & Waste Management Association, 2007
- Real-world European driving cycles, for measuring pollutant emissions from high- and low-powered carsAtmospheric Environment, 2006
- Large eddy simulation of flow structures and pollutant dispersion in the near-wake region of a light-duty diesel vehicleAtmospheric Environment, 2006
- Chase Studies of Particulate Emissions from in-use New York City VehiclesAerosol Science and Technology, 2004
- On-road remote sensing of petrol vehicle emissions measurement and emission factors estimation in Hong KongAtmospheric Environment, 2004
- The Effects of Altitude on Heavy-Duty Diesel Truck On-Road EmissionsEnvironmental Science & Technology, 2001
- On-Road Remote Sensing of Vehicle Emissions in MexicoEnvironmental Science & Technology, 1997
- Effects of Grades and Other Loads on On-Road Emissions of Hydrocarbons and Carbon MonoxideJournal of the Air & Waste Management Association, 1997