Separation of Fine Particulate Matter Emitted from Gasoline and Diesel Vehicles Using Chemical Mass Balancing Techniques

Abstract

Samples of fine particulate matter were collected in a roadway tunnel near Houston, TX over a period of 4 days during two separate sampling periods: one sampling period from 1200 to 1400 local time and another sampling period from 1600 to 1800 local time. During the two sampling periods, the tunnel traffic contained roughly equivalent numbers of heavy-duty diesel trucks. However, during the late afternoon sampling period, the tunnel contained twice as many light-duty gasoline-powered vehicles. The effect of this shift in the vehicle fleet affects the overall emission index (grams pollutant emitted per kilogram carbon in fuel) for fine particles and fine particulate elemental carbon. Additionally, this shift in the fraction of diesel vehicles in the tunnel is used to determine if the chemical mass balancing techniques used to track emissions from gasoline-powered and diesel-powered emissions accurately separates these two emission categories. The results show that the chemical mass balancing calculations apportion roughly equal amounts of the particulate matter measured to diesel vehicles between the two periods and attribute almost twice as much particulate matter in the late afternoon sampling period to gasoline vehicles. Both of these results are consistent with the traffic volume of gasoline and diesel vehicles in the tunnel in the two separate periods and validate the ability for chemical mass balancing techniques to separate these two primary sources of fine particles.

Key Scientific Findings and Policy- and Health-Relevant Insights from the U.S. Environmental Protection Agency’s Particulate Matter Supersites Program and Related Studies: An Integration and Synthesis of Results

“…365 The Houston tunnel studies obtained estimates for gaseous species (CO, NO x , nonmethane hydrocarbons [NMHC]) 362 and PM 2.5 . 363 The NMOC emissions factor was slightly higher than ones obtained in previous studies conducted at least 5 yr earlier, suggesting the current Houston fleet was comprised of older, less 62 Christensen, 495 Magliano, et al, 496 Held et al, 497 Zhao and Hopke 498 Diesel estimated as 58-82% of mobile source apportionment Los Angeles 18 (62% of this from diesel)…”

The U.S. Environmental Protection Agency’s Particulate Matter Supersites Program: An Integrated Synthesis of Scientific Findings and Policy- and Health-Relevant Insights

“…365 The Houston tunnel studies obtained estimates for gaseous species (CO, NO x , nonmethane hydrocarbons [NMHC]) 362 and PM 2.5 . 363 The NMOC emissions factor was slightly higher than ones obtained in previous studies conducted at least 5 yr earlier, suggesting the current Houston fleet was comprised of older, less 338 ). 62 Christensen, 495 Magliano, et al, 496 Held et al, 497 Zhao and Hopke 498 Diesel estimated as 58-82% of mobile source apportionment Los Angeles 18 (62% of this from diesel)…”

“…Motor vehicle emissions measurements were made in tunnel studies in Houston, TX, 362,363 and Pittsburgh, PA. 364 In each case, fuel-based emissions factors (mass emitted/mass fuel burned) were developed. This approach is believed to vary less over the full range of driving conditions (e.g., vehicle attributes, operating mode) than emissions factors based on vehicle distance traveled (mass emitted/distance).…”

“…CAMx, GloBEIS, CMB, gas and aerosol composition, LIDAR, aircraft, reactive VOC; NH 3 Junquera et al, 373 Fraser et al, 363,393 Garnes and Allen, 74 Vizuete et al, 241 Ryerson et al, 397 Pavlovic et al 395 Modeling and atmospheric processes/process modeling issues to assess mechanisms CAMx; SAPRC with modified chemistry; supporting CAMx-PMF and CMB; FAC; NH 3 ; size distributions and hygroscopicity (DMA-TDMA) Junquera et al, 373 Buzcu et al, 525 Nopmongcol and Allen, 392 Dechapanya et al, 388,389,390 Russell and Allen, 179 Pavlovic et al, 395 401 Chang and Allen, 402,403 Gan and Hopke, 398 Zhao et al, 399 Kleinman et al, 396 Ryerson et al 397 Fresno, CA, and Central California 194 Rinehart et al, 409 Turkiewicz et al, 169 Park et al, 139 Watson et al, 6 Hering et al 410 Characterization-size distribution Nanoparticle (3-10 nm), UF PM (Ͻ100 nm), accumulation mode (0.1-2 m)…”

Temperature-induced volatility of molecular markers in ambient airborne particulate matter

“…Organic molecular markers have been especially useful for the source apportionment of carbonaceous aerosols (Schauer et al, 1996;Chow and Watson, 2002;Lin et al, 2010). Commonly-used organic molecular markers include hopanes and steranes for motor oil emissions (Simoneit, 1999, Phuleria et al 2007Riddle et al, 2008); heavy polycyclic aromatic hydrocarbons (PAHs) for gasoline exhaust and coal combustion (Robinson et al, 2006); light PAHs for diesel exhaust (Fraser et al, 2003;Riddle et al, 2008); cholesterol for food cooking (Rogge et al, 1991); nalkanes for vegetative detritus (Rogge et al, 1993); and levoglucosan for biomass burning (Simoneit, 2002). In general, the utility of a marker compound depends on how unique it is to a source, and how conserved it is in the atmosphere (i.e., its volatility and/or reactivity) relative to the other primary mass emitted from that source.…”