On-Road Spark Ignition and Compression Ignition Emission Factors for Vapor- and Particle-Phase Quinones
ARANTZA EIGUREN-FERNANDEZ (1), Emma di Stefano (1), Arthur Cho (1), John Froines (1) and Antonio H. Miguel (1*)
(1) Southern California Particle Center, University of California Los Angeles, Los Angeles, CA (1*) Current address: Cal/EPA - ARB, El Monte
Abstract Number: 800
Preference: Platform Presentation
Last modified: May 15, 2010
Working Group: Carbonaceous Aerosols in the Atmosphere
Aromatic and polar diesel exhaust particle fractions, which are enriched in polycyclic aromatic hydrocarbons and quinones can induce the expression of HO-1, GST, and other phase II enzymes in macrophages and epithelial cells (Li et al., J. Immun. 2004). The emission of quinones from compression ignition (CI) and spark ignition (SI) vehicles has been established for several decades. Recently, it has been demonstrated that quinones may be formed in via photochemical transformation of their parent compounds during atmospheric transport (Eiguren-Fernandez et al., AS&T, 2008). However, no prior studies have estimated quinone emission factors (emfs) for SI and CI vehicles. We report the results of a study conducted in the Caldecott tunnel (Berkeley, CA) designed to estimate the on-road, near-real-world driving conditions, emissions factors for four quinones present in the vapor-phase and in PM2.5 particles: 1,2- and 1,4-Naphthaquinone (1,2-NQ and 1,4-NQ), 9,10-PHenanthraquinone (PQ) and 9,10-Anthraquinone (AQ). The characteristics of bore 1 and bore 2 of the tunnel allow estimates of emissions for SI (gasoline) and CI (heavy duty diesel vehicles). Quinone concentrations were measured in the traffic tubes ~50 m before the tunnel exit and in the background air injected into the tunnel by the ventilations fans. All measurements were conducted from ~12:30 pm to 6:30 pm in summer of 2004 and winter 2005 using medium-volume samplers (Tish model 1220); the vapor-phase was collected using XAD-4 resin and PM2.5 using Teflon coated glass fiber filters. Quantification was conducted using the method reported by Cho et al. (2004). The emission factors were estimated following the equation established by Marr et al (1999). Quinone concentrations (V+P) vary from 0.20 to 10.4 ng/m3 in summer, and between 0.19 and 0.64 ng/m3 in winter, with higher levels found in bore 1 (SI and CI mixed fleet). No significant differences were observed in the average levels between winter and summer, suggesting a negligible effect of temperature in the vapor to particle conversion of these compounds. As previously shown by Eiguren-Fernandez et al (2007), 1,2-NQ and 1,4-NQ were mainly found in the vapor-phase, while the PQ was found associated with the particle-phase; AQ partitioned between the two phases.
In general, CI had higher emfs for all quinones, with higher values for summer while for SI the winter period was more important. Emfs for the vapor-phase quinones were highest for both SI and CI vehicles with factors varying from 0.26 to 14.0 ug/kg of fuel for SI and 0.63 to 60.5 ug/kg of fuel for CI. Particle-phase associated emfs were only significant for winter in the case of SI vehicles. These differences in emf patterns between engines may be due to changes in fuel composition between summer and winter.