Final Report: Improving chemical transport model predictions of organic aerosol: Measurement and simulation of semivolatile organic emissions from mobile and non-mobile sources

EPA Grant Number: RD834554
Title: Improving chemical transport model predictions of organic aerosol: Measurement and simulation of semivolatile organic emissions from mobile and non-mobile sources
Investigators: Robinson, Allen , Donahue, Neil
Institution: Carnegie Mellon University
EPA Project Officer: Chung, Serena
Project Period: April 1, 2010 through March 31, 2013
Project Amount: $500,000
RFA: Novel Approaches to Improving Air Pollution Emissions Information (2009) RFA Text |  Recipients Lists
Research Category: Air Quality and Air Toxics , Air

Objective:

Organic material contributes a significant fraction of PM2.5 mass across all regions of the United States. However, the sources of ambient organic aerosols are not well understood; for example, state-of-the-art chemical transport models often substantially underpredict measured organic aerosols concentrations. To improve model performance, emissions inventories must explicitly account for the emissions of all low-volatility organic species. This project is characterizing these emissions for important classes of mobile sources. The new emissions data, inventories and other products developed by this project will allow the next generation of chemical transport models to directly simulate gas-particle partitioning of primary organic aerosol and to account for secondary organic aerosol production from emissions of low-volatility organic vapors.

Specific technical objectives include to:

1. Investigate methodologies for routine measurement of the volatility distribution of emissions of low volatility organics from combustion systems.

2. Measure emission factors for and volatility distributions of low-volatility organics emitted by on-road and non-road mobile sources, including high and low emitting gasoline powered vehicles and diesel vehicles.

3. Quantify the effects of emission control technologies such as diesel particulate filters on emissions of low-volatility organics.

4. Develop techniques to efficiently update existing emission inventories for use with the volatility basis set approach and the next generation of chemical transport models.

5. Conduct PMCAMx simulations to evaluate updated inventories in the eastern United States and California.

Summary/Accomplishments (Outputs/Outcomes):

Mobile sources can be a major source of organic aerosols and secondary organic aerosol precursors in urban areas. In this project, we characterized the tailpipe emissions from 64 unique light-duty gasoline vehicles (LDGVs) spanning model years 1987-2012, two mediumduty diesel vehicles and three heavy-duty diesel vehicles with varying levels of aftertreatment. Each vehicle was tested on a chassis dynamometer using constant volume sampler, commercial fuels and standard duty cycles at the California Air Resources Board Haagen-Smit and Heavy-Duty Engine Testing Laboratories. A suite of instrumentation was utilized to measure regulated pollutants such as carbon monoxide (CO), non-methane organic gases (NMOG), nitrogen oxides (NOx), and particulate matter (PM). Off-line analyses were performed to speciate gas- and particle-phase emissions. Quartz filter and Tenax™ TA sorbent samples were collected to characterize low-volatility organic emissions. Comprehensive speciation was performed on the organic emissions, including quantification of carbonyls, C2 to C30 hydrocarbons, and many commonly used molecular markers (e.g., hopanes, steranes, and polycyclic aromatic hydrocarbons). These datasets were used to investigate trends in emissions with vehicle age and to quantify the effects of different aftertreatment technologies on diesel vehicle emissions (e.g., with and without a diesel particulate filter).

Newer LDGVs that met the most recent emissions standards had substantially lower emissions of regulated gaseous pollutants (CO, NMOG and NOx) than older vehicles. For example, NMOG emissions from LDGVs that met the LEV2 standard were roughly a factor of 10 lower than pre-LEV vehicles; similarly, there were substantial reductions in NOx (factor of ~100) and CO (factor of ~10) emissions from pre-LEV to LEV2 vehicles. However, there were not as clear reductions in PM mass emissions. LDGVs manufactured over 20 years ago had the highest PM emissions, but there has been essentially no change in PM emissions over the last 20 years. Diesel particulate filters reduced CO, NMOG and PM emissions one to two orders of magnitude. Comprehensive organic speciation was performed to estimate emissions of air toxics and secondary organic aerosol (SOA) formation potential; preliminary findings indicate that SOA production from cold-start LDGV exhaust may be substantially greater than SOA from on-road diesel vehicles.

In addition to the testing of on-road vehicles, the project also characterized the emissions from nonroad sources. A total of seven small off-road engines (SORE) were tested: six gasoline engines from a variety of applications (backpack leaf blower, soil tiller, string lawn trimmer and lawnmower) and a larger diesel engine for a transportation refrigeration unit (TRU). The SORE were taken from the inventory at the CARB Haagen-Smit Laboratory. Both gasoline and diesel SORE are high emitters of primary gas- and particle-phase pollutants relative to their fuelconsumption. Two- and 4-stroke gasoline SOREs emit much more (up to 3 orders of magnitude more) non-methane organic gases (NMOG) than newer passenger cars (per kg of fuel burned).

These results provide important new data to update and test emission inventories. In particular, this project added considerably to the emissions data for late model light duty gasoline vehicles that meet Tier 2/LEV2 emission standards.

A major objective of this project was to investigate the gas-particle partitioning of primary organic aerosol emissions from combustion sources. We developed a new technique for measuring the primary organic aerosol emissions from internal combustion engines. The method combines thermal-optical OC/EC analysis and thermal desorption gas chromatography mass spectrometry (TD-GC-MS) of quartz filter samples collected using a dilution sampler to quantify the total emissions of low-volatility organics and to distribute them across the volatility basis set. These data can be used in conjunction with partitioning theory to predict the gas-particle partitioning and thus the total amount of primary organic aerosol over the entire range of atmospheric conditions. To evaluate the new method, we directly measured the effects of temperature and concentration on gas-particle partitioning of the primary organic aerosol emissions from two gas-turbine engines, 62 light duty gasoline vehicles, and five diesel vehicles. Predictions based on the volatility distributions derived from the filter analyses are consistent with the direct partitioning measurements. The new approach represents a major improvement over the traditional assumption of nonvolatile primary organic aerosol emissions, which overpredicts actual primary organic aerosol emissions from these sources by a factor of 2-4 at typical ambient concentration and temperature. By using quartz filter samples, this new technique is designed to be applied to routine source test data. Volatility distributions derived using this new approach can also be applied to the large catalog of quartz filter data used by existing emission inventories and models. The emissions data derived from this approach are designed for use in the next generation of chemical transport models and emissions inventories that employ the volatility basis set approach to explicitly track the gas-particle partitioning of primary organic aerosol emissions.

The practical implications of this work are that emerging techniques may provide a quick and relatively simple way to measure the volatility distribution of all low-volatility organics emitted by combustion systems.

As part of the on-road vehicle testing, four independent yet complementary approaches were used to investigate gas-particle partitioning of the emissions: sampling artifact correction of quartz filter data, dilution from the constant volume sampler into a portable environmental chamber, heating in a thermodenuder, and thermal desorption/gas chromatography/mass spectrometry analysis of quartz filter samples. This combination of techniques allowed partitioning measurements to be made across a wide range of atmospherically relevant conditions – temperatures of 25 to 100 °C and organic aerosol concentrations of < 1 to 600 g m-3. These data were used to test the hypothesis that the majority of primary organic aerosol emissions from on-road vehicles are semivolatile and to develop parameterizations to quantitatively predict the gasparticle partitioning of these emissions for the next generation of chemical transport models.

For the LDGV, the gas-particle partitioning of the POA emissions varied continuously over this entire range of conditions and essentially none of the POA should be considered nonvolatile. Furthermore, for most vehicles, the low levels of dilution used in the constant volume sampler created particle concentrations that were a factor of 10 or more higher than typical ambient levels. This resulted in large and systematic partitioning biases in the POA emissions factors compared to more dilute atmospheric conditions.

For diesel vehicles not-equipped with diesel particulate filters (DPF), about 80% of the POA emissions that are collected on quartz filters from the CVS were semi-volatile. During tests of these vehicles, particle concentrations inside the CVS were a factor of ten greater than ambient levels, which created large and systematic partitioning biases in the POA emissions data. For low-emitting DPF-equipped vehicles, as much as 90% of the POA collected on a quartz filter from the CVS were adsorbed vapors (positive sampling artifact).

Although the POA emission factors varied by more than the order of magnitude across the set of test vehicles, the measured gas-particle partitioning of all the gasoline vehicles can be predicted using a single volatility distribution derived from TD-GC-MS analysis of quartz filters. The same is true for diesel vehicles. This project derived volatility distributions for each of these vehicles classes. These distributions are designed to be applied directly to quartz filter data that are the basis for existing emissions inventories and chemical transport models that have implemented the volatility basis set approach.

In addition to investigating the emissions of mobile sources, this project also analyzed data on the gas-particle partitioning of primary organic aerosol (POA) emissions from biomass burning emissions from common North American trees/shrubs/grasses. The data were collected during the third Fire Lab at Missoula Experiment (FLAME-III) in collaboration with Colorado State University. Fifty to 80 percent of the mass of biomass burning POA evaporated when isothermally diluted from plume to ambient-like concentrations; while ~80% of the POA evaporated upon heating to 100oC for a residence time of ~10 seconds. Therefore, the majority of the POA emissions were semivolatile. An evaporation kinetics model was used to derive volatility distributions and enthalpies of vaporization from the thermodenuder data. Thermodenuder measurements made at three different residence times indicated that there were not substantial mass transfer limitations to evaporation (i.e., the mass accommodation coefficient was greater than 0.01). A single volatility distribution can be used to represent the measured gasparticle partitioning from the entire set of experiments, including different fuels, organic aerosol concentrations, and thermodenuder residence times. This distribution, derived from the thermodenuder measurements, also predicts the dilution driven changes in gas-particle partitioning. This volatility distribution and associated emission factors for each fuel studied can be used to simulate the gas-particle partitioning of biomass burning POA emissions in chemical transport models.

These results support the hypothesis that the majority primary organic aerosol emissions from combustion systems are semivolatile. The volatility distributions derived by this project provide important data for emission inventories for next-generation chemical transport models.

To evaluate the new emissions data, we also collected and analyzed the filter and sorbent samples in a highway tunnel in Pittsburgh, PA (Fort Pitt Tunnel on Interstate 376) and on the California Institute of Technology campus in Pasadena California over a 4-week period during the CalNex air quality study (May/June 2010). The samples were analyzed using gaschromatography mass-spectrometry to quantify concentration of individual organic species and to characterize the unresolved complex mixture. The tunnel data are being compared with the dynamometer data. The ambient data have been combined with other data from the CalNex campaign to test chemical transport model simulations using the emission data collected by this project.


Journal Articles on this Report : 24 Displayed | Download in RIS Format

Other project views: All 57 publications 24 publications in selected types All 24 journal articles
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Journal Article Ahmadov R, McKeen SA, Robinson AL, Bahreini R, Middlebrook AM, de Gouw JA, Meagher J, Hsie E-Y, Edgerton E, Shaw S, Trainer M. A volatility basis set model for summertime secondary organic aerosols over the eastern United States in 2006. Journal of Geophysical Research–Atmospheres 2012;117(D6):D06301 (19 pp.). RD834554 (Final)
R833748 (Final)
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  • Journal Article Bian Q, May AA, Kreidenweis SM, Pierce JR. Investigation of particle and vapor wall-loss effects on controlled wood-smoke smog-chamber experiments. Atmospheric Chemistry and Physics 2015;15(19):11027-11045. RD834554 (Final)
    R833747 (Final)
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  • Journal Article Bian Q, Jathar SH, Kodros JK, Barsanti KC, Hatch LE, May AA, Kreidenweis SM, Pierce JR. Secondary organic aerosol formation in biomass-burning plumes: theoretical analysis of lab studies and ambient plumes. Atmospheric Chemistry and Physics 2017;17(8):5459-5475. RD834554 (Final)
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  • Journal Article Gordon TD, Tkacik DS, Presto AA, Zhang M, Jathar SH, Nguyen NT, Massetti J, Truong T, Cicero-Fernandez P, Maddox C, Rieger P, Chattopadhyay S, Maldonado H, Maricq MM, Robinson AL. Primary gas-and particle-phase emissions and secondary organic aerosol production from gasoline and diesel off-road engines. Environmental Science & Technology 2013;47(24):14137-14146. RD834554 (Final)
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  • Journal Article Gordon TD, Presto AA, Nguyen NT, Robertson WH, Na K, Sahay KN, Zhang M, Maddox C, Rieger P, Chattopadhyay S, Maldonado H, Maricq MM, Robinson AL. Secondary organic aerosol production from diesel vehicle exhaust: impact of aftertreatment, fuel chemistry and driving cycle. Atmospheric Chemistry and Physics 2014;14(9):4643-4659. RD834554 (Final)
    R835873 (2017)
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  • Journal Article Gordon TD, Presto AA, May AA, Nguyen NT, Lipsky EM, Donahue NM, Guiterrez A, Zhang M, Maddox C, Rieger P, Chattopadhyay S, Maldonado H, Maricq MM, Robinson AL. Secondary organic aerosol formation exceeds primary particulate matter emissions for light-duty gasoline vehicles. Atmospheric Chemistry and Physics 2014;14(9):4661-4678. RD834554 (Final)
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  • Journal Article Jathar SH, Miracolo MA, Tkacik DS, Donahue NM, Adams PJ, Robinson AL. Secondary organic aerosol formation from photo-oxidation of unburned fuel: experimental results and implications for aerosol formation from combustion emissions. Environmental Science & Technology 2013;47(22):12886-12893. RD834554 (Final)
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  • Journal Article Jathar SH, Gordon TD, Hennigan CJ, Pye HO, Pouliot G, Adams PJ, Donahue NM, Robinson AL. Unspeciated organic emissions from combustion sources and their influence on the secondary organic aerosol budget in the United States. Proceedings of the National Academy of Sciences of the United States of America 2014;111(29):10473-10478. RD834554 (Final)
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  • Journal Article Jathar SH, Donahue NM, Adams PJ, Robinson AL. Testing secondary organic aerosol models using smog chamber data for complex precursor mixtures: influence of precursor volatility and molecular structure. Atmospheric Chemistry and Physics 2014;14(11):5771-5780. RD834554 (Final)
    R833748 (Final)
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  • Journal Article Jathar SH, Woody M, Pye HOT, Baker KR, Robinson AL. Chemical transport model simulations of organic aerosol in southern California: model evaluation and gasoline and diesel source contributions. Atmospheric Chemistry and Physics 2017;17(6):4305-4318. RD834554 (Final)
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  • Journal Article May AA, Saleh R, Hennigan CJ, Donahue NM, Robinson AL. Volatility of organic molecular markers used for source apportionment analysis: measurements and implications for atmospheric lifetime. Environmental Science & Technology 2012;46(22):12435-12444. RD834554 (2011)
    RD834554 (Final)
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  • Journal Article May AA, Presto AA, Hennigan CJ, Nguyen NT, Gordon TD, Robinson AL. Gas-particle partitioning of primary organic aerosol emissions: (2) diesel vehicles. Environmental Science & Technology 2013;47(15):8288-8296. RD834554 (Final)
    R833748 (Final)
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  • Journal Article May AA, Levin EJT, Hennigan CJ, Riipinen I, Lee T, Collett Jr. JL, Jimenez JL, Kreidenweis SM, Robinson AL. Gas-particle partitioning of primary organic aerosol emissions: 3. Biomass burning. Journal of Geophysical Research–Atmospheres 2013;118(19):11327-11338. RD834554 (Final)
    R833747 (Final)
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  • Journal Article May AA, Presto AA, Hennigan CJ, Nguyen NT, Gordon TD, Robinson AL.Gas-particle partitioning of primary organic aerosol emissions: (1) gasoline vehicle exhaust. Atmospheric Environment 2013;77:128-139. RD834554 (Final)
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  • Journal Article May AA, Nguyen NT, Presto AA, Gordon TD, Lipsky EM, Karve M, Gutierrez A, Robertson WH, Zhang M, Brandow C, Chang O, Chen S, Cicero-Fernandez P, Dinkins L, Fuentes M, Huang S-M, Ling R, Long J, Maddox C, Massetti J, McCauley E, Miguel A, Na K, Ong R, Pang Y, Rieger P, Sax T, Truong T, Vo T, Chattopadhyay S, Maldonado H, Maricq MM. Gas-and particle-phase primary emissions from in-use, on-road gasoline and diesel vehicles. Atmospheric Environment 2014;88:247-260. RD834554 (Final)
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  • Journal Article Presto AA, Miracolo MA, Kroll JH, Worsnop DR, Robinson AL, Donahue NM. Intermediate-volatility organic compounds: a potential source of ambient oxidized organic aerosol. Environmental Science & Technology 2009;43(13):4744-4749. RD834554 (Final)
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  • Journal Article Presto AA, Hennigan CJ, Nguyen NT, Robinson AL. Determination of volatility distributions of primary organic aerosol emissions from internal combustion engines using thermal desorption gas chromatography mass spectrometry. Aerosol Science and Technology 2012;46(10):1129-1139. RD834554 (2011)
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  • Journal Article Saleh R, Donahue NM, Robinson AL. Time scales for gas-particle partitioning equilibration of secondary organic aerosol formed from alpha-pinene ozonolysis. Environmental Science & Technology 2013;47(11):5588-5594. RD834554 (Final)
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  • Journal Article Saliba G, Saleh R, Zhao Y, Presto AA, Lambe AT, Frodin B, Sardar S, Maldonado H, Maddox C, May AA, Drozd GT, Goldstein AH, Russell LM, Hagen F, Robinson AL. Comparison of gasoline direct-injection (GDI) and port fuel injection (PFI) vehicle emissions: emission certification standards, cold-start, secondary organic aerosol formation potential, and potential climate impacts. Environmental Science & Technology 2017;51(11):6542-6552. RD834554 (Final)
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  • Journal Article Tkacik DS, Lambe AT, Jathar S, Li X, Presto AA, Zhao Y, Blake D, Meinardi S, Jayne JT, Croteau PL, Robinson AL. Secondary organic aerosol formation from in-use motor vehicle emissions using a potential aerosol mass reactor. Environmental Science & Technology 2014;48(19):11235-11242. RD834554 (Final)
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  • Journal Article Wang YJ, Yang B, Lipsky EM, Robinson AL, Zhang KM. Analyses of turbulent flow fields and aerosol dynamics of diesel engine exhaust inside two dilution sampling tunnels using the CTAG model. Environmental Science & Technology 2013;47(2):889-898. RD834554 (Final)
    R834561 (2011)
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  • Journal Article Zhao Y, Hennigan CJ, May AA, Tkacik DS, de Gouw JA, Gilman JB, Kuster WC, Borbon A, Robinson AL Intermediate-volatility organic compounds: a large source of secondary organic aerosol. Environmental Science &Technology 2014;48(23):13743-13750. RD834554 (Final)
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  • Journal Article Zhao Y, Nguyen NT, Presto AA, Hennigan CJ, May AA, Robinson AL. Intermediate volatility organic compound emissions from on-road diesel vehicles:chemical composition, emission factors, and estimated secondary organic aerosol production. Environmental Science &Technology 2015;49(19):11516-11526. RD834554 (Final)
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  • Journal Article Zhao Y, Nguyen NT, Presto AA, Hennigan CJ, May AA, Robinson AL. Intermediate volatility organic compound emissions from on-road gasoline vehicles and small off-road gasoline engines. Environmental Science & Technology 2016;50(8):4554-4563. RD834554 (Final)
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  • Supplemental Keywords:

    Airborne particulate matter, aerosol, emission characterization, atmospheric chemistry, regional modeling, source/receptor analysis, photochemistry

    Progress and Final Reports:

    Original Abstract
  • 2010 Progress Report
  • 2011 Progress Report