Volatility of Primary Organic Aerosol Emitted from Light Duty Gasoline Vehicles

Abstract

Primary organic aerosol (POA) emitted from light duty gasoline vehicles (LDGVs) exhibits a semivolatile behavior in which heating the aerosol and/or diluting the aerosol leads to partial evaporation of the POA. A single volatility distribution can explain the median evaporation behavior of POA emitted from LDGVs but this approach is unable to capture the full range of measured POA volatility during thermodenuder (TD) experiments conducted at atmospherically relevant concentrations (2-5 μg m(-3)). Reanalysis of published TD data combined with analysis of new measurements suggest that POA emitted from gasoline vehicles is composed of two types of POA that have distinctly different volatility distributions: one low-volatility distribution and one medium-volatility distribution. These correspond to fuel combustion-derived POA and motor oil POA, respectively. Models that simultaneously incorporate both of these distributions are able to reproduce experimental results much better (R(2) = 0.94) than models that use a single average or median distribution (R(2) = 0.52). These results indicate that some fraction of POA emitted from LDGVs is essentially nonvolatile under typical atmospheric dilution levels. Roughly 50% of the vehicles tested in the current study had POA emissions dominated by fuel combustion products (essentially nonvolatile). Further testing is required to determine appropriate fleet-average emissions rates of the two POA types from LDGVs.

Simulating secondary organic aerosol in a regional air quality model using the statistical oxidation model – Part 3: Assessing the influence of semi-volatile and intermediate volatility organic compounds and NO<sub>X</sub>

“…Phys. on eight light-duty gasoline vehicles, Kuwayama et al (2015) found that the POA volatility for their vehicles was 265 consistent with that determined by (May et al, 2013a) for about half the vehicles but substantially lower for the other 266 half. They hypothesized that the lower POA volatility could be attributed to fuel oxidation products.…”

“…They hypothesized that the lower POA volatility could be attributed to fuel oxidation products. The findings of 267 Kuwayama et al (2015) suggest that the volatility distribution used in this work may overestimate the evaporation of 268 POA with dilution. We assumed all on-and off-road diesel exhaust POA to have the same hydrocarbon/linear alkane 269 distribution as the volatility distribution determined by May et al (2013b) from data for two medium-duty diesel 270 trucks, three heavy-duty diesel trucks, and a single off-road diesel engine.…”

Downwind evolution of the volatility and mixing state of near-road aerosols near a US interstate highway

“…Although a number of laboratory and field studies have investigated the volatility (Kuwayama et al, 2015;May et al, 2013a, b;Li et al, 2016;Biswas et al, 2007;Grieshop et al, 2009) and mixing state (Tiitta et al, 2010;Liu et al, 2014;China et al, 2014;Willis et al, 2016) of traffic-emitted particles using various techniques, they have largely focused on source characterization or measurements at a fixed ambient location. To the best of our knowledge, no studies have been conducted to systematically explore the evolution of volatility and mixing state of near-road aerosols at different distances from the roadway under diverse environmental conditions.…”

Organic PM Emissions from Vehicles: Composition, O/C Ratio, and Dependence on PM Concentration

“…The SDS was used primarily to dilute the emissions to atmospherically relevant concentration but was also used to perturb the environment into which the emissions were sampled and to simulate different environmental conditions (Kuwayama et al 2014). The AMS sampled at high time resolution (10 s) to acquire high mass resolution (HMR) spectra of nonrefractory organic matter in submicron particles (thereof referred to as POM) from vehicles running on a chassis dynamometer at atmospherically relevant dilution.…”