On-road emission measurements of reactive nitrogen compounds from three California cities.
The three California cities of San Jose, Fresno, and West Los Angeles (wLA) were visited during March 2008 to collect on-road emission measurements of reactive nitrogen compounds from light-duty vehicles. At the San Jose and wLA sites, comparison with historical measurements showed that emissions of carbon monoxide (CO), hydrocarbons (HC), and nitric oxide (NO) continue to decrease in the on-road fleet, yet the ratio of nitrogen dioxide (NO(2)) to NO in new diesel vehicles appears to be undergoing large increases. A small fleet of 2007 diesel ambulances measured in Fresno was found to have more than 60% of their emitted oxides of nitrogen as NO(2). Ammonia (NH(3)) emissions are shown to have a strong dependence on model year and vehicle specific power. NH(3) means are 0.49 +/- 0.02, 0.49 +/- 0.01, and 0.79 +/- 0.02 g/kg of fuel for San Jose, Fresno, and wLA, respectively, with the larger emissions at the wLA site likely due to driving mode. NH(3) at these locations was found to account for 25%, 22%, and 27% of the molar fixed nitrogen emissions, respectively. Using these mean values to construct a national fuel-based NH(3) inventory results in a range of 210000 to 330000 short tons of NH(3) annually from light-duty vehicles.
Bishop
Gary A
GA
Department of Chemistry and Biochemistry, University of Denver, Denver, Colorado 80208, USA. gbishop@du.edu
Peddle
Allison M
AM
Stedman
Donald H
DH
Zhan
Tao
T
D000393:Air Pollutants / Q000032:analysis*; D000641:Ammonia / Q000737:chemistry; D002140:California; D002947:Cities; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D018986:Motor Vehicles; D009584:Nitrogen / Q000737:chemistry; D052638:Particulate Matter / Q000737:chemistry; D026361:Reactive Nitrogen Species / Q000032:analysis*; D001335:Vehicle Emissions
D000393:Air Pollutants; D052638:Particulate Matter; D026361:Reactive Nitrogen Species; D001335:Vehicle Emissions; D000641:Ammonia; D009584:Nitrogen