2007 Progress Report: Highly Time-Resolved Source Apportionment Techniques for Organic Aerosols Using the Aerodyne Aerosol Mass Spectrometer

EPA Grant Number: R832161
Title: Highly Time-Resolved Source Apportionment Techniques for Organic Aerosols Using the Aerodyne Aerosol Mass Spectrometer
Investigators: Jimenez, Jose-Luis , Hannigan, Michael P. , Schauer, James J. , Zhang, Qi
Institution: University of Colorado at Boulder , University of Wisconsin - Madison
EPA Project Officer: Chung, Serena
Project Period: December 1, 2004 through November 30, 2007 (Extended to November 30, 2008)
Project Period Covered by this Report: December 1, 2006 through November 30, 2007
Project Amount: $450,000
RFA: Source Apportionment of Particulate Matter (2004) RFA Text |  Recipients Lists
Research Category: Particulate Matter , Air Quality and Air Toxics , Air

Objective:

The overall objective of this three-year research project is to develop, validate, and apply source apportionment techniques for organic aerosol (OA) measurements from the Aerodyne Aerosol Mass Spectrometer (AMS), as well as enhanced instrumental techniques that improve the characterization of OA with the AMS. The AMS is the only current real-time instrument that provides quantitative size-resolved organic aerosol data with a time resolution of a few minutes or better. Results prior to the start of the project indicated that AMS organic aerosol data were sufficiently specific to address the critical need for source apportionment of organic aerosols with very high time resolution. The primary result of this project will be to demonstrate and validate source apportionment of organic aerosols with very high time resolution using AMS data. The results of this project are having a rapid and broad impact, in part because the techniques developed here can be applied to datasets acquired by many researchers around the world, including the more than 50 research groups with an AMS. In addition, these techniques and algorithms will also provide the foundation for source apportionment using data from emerging and future quantitative aerosol mass spectrometers.

Progress Summary:

This project has two major components: (1) the development and application of receptor model techniques to AMS OA data, and (2) the field deployment and field data analysis for several new techniques aimed at obtaining more chemically-specific OA information from the AMS for source apportionment purposes. Our work to date is successfully meeting and exceeding the original goals of the project, as summarized below for each of the two major components.

(1) Progress in receptor model development and application

Several statistical source apportionment models for apportioning OA are being investigated, including custom techniques that take advantage of our understanding of the data (Custom Principal Component Analysis, CPCA, and Multiple Component Analysis, MCA), a standard multivariate receptor model (Positive Matrix Factorization, PMF), and hybrid receptor models implemented with the Multilinear Engine (ME). During year 3 of this grant, we carried out significant work with the CPCA, MCA, and PMF models, while starting to evaluate the application of ME to AMS data.

During Year 3, we finalized and published [Zhang et al., GRL, 2007] an MCA analysis of 37 highly time-resolved AMS datasets acquired in the Northern Hemisphere mid-latitudes in 11 urban areas, 5 regions downwind of urban areas, and 11 rural/remote locations (representative of high elevation, forested, pristine, and continentally-influenced marine atmospheres). At most sites the MCA retrieves several types of OOA. The results of this analysis strongly indicate that global models largely underestimate the importance of Secondary Organic Aerosols (SOA) and overestimate the importance of Primary Organic Aerosols (POA). The scientific community has shown very high interest in these results, e.g. this GRL paper is already “Highly Cited” (Top 1% in Citations in GRL). We have also finalized and published an analysis of the effect of acid-catalyzed SOA formation in ambient air [Zhang et al., ES&T, 2007] which shows that the importance of this process in Pittsburgh appears to be much lower (< 25%) than suggested by some chamber experiments (several fold). This paper is a “Most Cited” paper among those published in 2007 in Environmental Science and Technology.

The CPCA and MCA methods have also been applied to datasets from other AMS groups, resulting on several collaborative publications during yr 3 of this project: Kondo et al. [JGR, 2007] concludes that about 90% of the OOA in Tokyo is water soluble while HOA is water insoluble; Cottrell et al. [JGR, 2008] reports that several types of OOA with different origins and tracer correlations dominate the aerosol composition in rural New Hampshire, apparently due to SOA of both anthropogenic and biogenic origin.

Much of our effort in year 3 was dedicated to the evaluation and application of the PMF model. A PMF software evaluation tool has been developed that greatly facilitates the use of PMF and the evaluation of its very complex solutions. This tool will be released to the community as a free open source code in the near future, likely at the Sep. 2008 AMS Users Meeting in Manchester, UK. A paper evaluating the use of PMF in detail for AMS data has been published [Ulbrich et al., ACPD, 2008] where the reanalysis of the Pittsburgh dataset with PMF shows results highly consistent with the previous CPCA results [Zhang et al., ES&T, 2005; ACP, 2005] with two major oxygenated OA (OOA-I) and hydrocarbon-like OA (HOA) components which are very similar to the previous findings, but also show a small (~9%) OOA-II component that appears to be fresher semivolatile SOA. Results from the SOAR study have also been analyzed with PMF, as described below.

We have also used the results from PMF in several additional studies. Nemitz et al. [AS&T, 2008] use PMF with a mixed OA concentration / eddy covariance flux AMS dataset from Boulder, CO, to quantify the fluxes OOA-I, OOA-II, and HOA. We find that while the more regional OOA-I is undergoing net deposition, the more local HOA and OOA-II have a net emission flux at this location. Johnson et al. [ES&T, 2008] compare the AMS OA with the OA estimated from Proton Elastic Scattering Analysis (PESA) measurements of hydrogen for the 2003 Mexico City Metropolitan Area (MCMA-2003). Major findings include that 75% of the OA evaporated before PESA analysis, and that the OOA correlates better with the remaining PESA OA, which is consistent with the lower volatility of this component deduced from thermal denuder measurements (below).

The identification of spectra from statistical techniques necessitates the use of standard spectra for known sources. For this purpose, we have created three public web-based mass spectral databases: the unit-resolution AMS database, the high-resolution AMS database, and the thermal-desorption / thermal denuder database (see e.g. http://cires.colorado.edu/jimenez-group/AMSsd/ Exit ). These databases are growing as new spectra are added from our group and others in the AMS community, and now contain over 100 spectra or spectra/volatility profiles.

(2) Deployment in Field Studies and Data Analysis of New Techniques

The second component of this project focuses on the field deployment and field data analysis of enhanced AMS instrumentation. Much of the work is focusing on the application of the high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), which was only developed after the writing of the original proposal by a collaboration of Aerodyne, our group, and Tofwerk AG, [DeCarlo et al., Anal. Chem. 2006], and whose first ever ambient deployment was at the SOAR campaign. The high-resolution capability of this instrument has enabled us to directly separate the inorganic from organic aerosol spectra, to enhance the spectral differences that are critical to the success of statistical methods such as PMF [Docherty et al., ES&T, 2008], and to develop a method for the direct measurement of organic elemental composition (O/C, N/C, H/C, and OM/OC) [Aiken et al., Anal. Chem. 2007; ES&T, 2008]. The latter paper applies the elemental analysis method for ambient, chamber, and laboratory biomass burning spectra, with results consistent with those of other techniques. One important result is that the OOA/SOA found in the atmosphere is significantly more oxygenated than the SOA made in traditional chamber experiments. Two additional instrumental developments are the use of a thermal denuder (TD) in front of the AMS [Huffman et al., AS&T, 2008; ES&T, 2008], and the use of variable vaporizer temperature in the AMS [Docherty et al., in preparation]. Both methods have been used in two month-long ambient field campaigns, in conjunction with the HR-ToF-AMS.

A major field campaign was carried out in Riverside, CA (Study of Organic Aerosols in Riverside, SOAR, http://cires.colorado.edu/jimenez-group/Field/Riverside05/ Exit ), which quickly grew to be the most complete characterization of organic aerosols to date, to our knowledge, including most of the state-of-the-art ambient instruments available at the time. A key objective of SOAR was to demonstrate and apply the enhanced instrumental techniques described above, which were mainly used to sample ambient OA but also chamber-generated SOA. Another important objective was to compare the AMS apportionment of OA with the well-established chemical mass balance method of organic molecular markers (CMB-OMM). We have submitted a paper [Docherty et al., ES&T, 2008] which compares the PMF-AMS method with CMB-OMM and with three other SOA apportionment methods: the EC-tracer method, the CO-tracer method, and water-soluble organic carbon measurement. All methods produce consistent results, which indicate that OA during SOAR is overwhelmingly secondary in nature during a period of several weeks with moderate ozone concentrations, and that SOA is the single largest component of PM1 aerosol in Riverside. Average SOA contributions of >80% were observed during mid-day periods while minimum SOA contributions of ~50% were observed during peak morning traffic periods. These results are contrary to previous estimates of SOA throughout the Los Angeles Basin which reported that, other than during severe photochemical smog episodes, SOA was lower than primary OA. We have used the SOAR source apportionment results in a study of cloud condensation nuclei and cloud properties for urban aerosol [Cubison et al., ACPD, 2008] showing that not just the composition but also the mixing state of OA is critical for successful CCN closure, and compared it to the results at other locations [Ervens et al., in preparation].

Three additional field experiments were carried out with support from this project: (a) a local field experiment in April/May 2007 to characterize the high-resolution and thermal denuder spectra from meat cooking, trash burning, and motor vehicle emissions. This experiment was motivated by questions arising from the analysis of the SOAR and MILAGRO campaigns. Mohr et al. [ES&T, 2008] presents the results of this experiment, which shows with high resolution data that OA emitted by combustion engines and plastic burning are dominated by hydrocarbon-like (reduced) organic compounds. Meat cooking and especially paper burning contain significant fractions of oxygenated organic compounds; however, their unit-resolution mass spectral signatures are very similar to mass spectral signatures from hydrocarbon-like OA or primary OA, and very different from the mass spectra of ambient secondary or oxygenated OA (OOA). Thus, primary OA from any of these sources is very unlikely to be a significant direct source of ambient OOA.

(b) Two laboratory biomass burning experiments (FLAME-1 and FLAME-2 campaigns) that were carried out in 2006 and 2007 at the Missoula, MT Biomass Burning Chamber operated by the US Forest Service. The objective of this deployment was to obtain the first signatures of biomass burning aerosols using the HR-ToF-AMS and the thermal denuder. During FLAME-2 we demonstrated a new high time-resolution (up to 100 Hz) mode of the ToF-AMS software that allows capturing rapid fluctuations on the emissions and easily separate flaming vs. smoldering emissions during stack burns. Results from the FLAME project highlight the diversity of mass spectral signatures and volatilities of BBOA. The O/C of BBOA is on the range 0.3-0.45 [Huffman et al., ES&T, 2008], which are very similar to the values derived from PMF of ambient measurements [Aiken et al., ES&T, 2008].

The thermal denuder + AMS system has been demonstrated [Huffman et al., AS&T, 2008] and deployed in several campaigns, including SOAR-1, SOAR-2, MILAGRO, FLAME-1, FLAME­2, and the meat cooking experiments in Niwot. So far results are surprising: most primary OA, including HOA and ambient BBOA in Mexico are very volatile, while OOA/SOA is less volatile than HOA and much less volatile than its current model representation [Huffman et al.; ES&T, 2008]. Work is ongoing to apply PMF to the time series of TD-AMS data.

A separate project involved the first real-time determination of PAHs in submicron aerosols from aerosol mass spectrometry data [Marr et al., ACP, 2006; Dzepina et al., IJMS, 2007]. This technique was developed using data from the MCMA-2003 field study, and the AMS measurements showed good correlation with those from two separate techniques, but also identified some very reactive PAHs that are likely being destroyed by reaction artifacts on traditional filter-sampling techniques.

Future Activities:

The plan for the final year (year 4, no cost extension) includes: (a) Revising and finalizing the several papers that are under review or in preparation; (b) Applying PMF to several additional datasets, including the aircraft dataset from the MILAGRO campaign in Mexico City, and several of the urban studies that had previously been studied with the MCA method; (c) Further investigating of the application of the ME2 method to AMS data, and intercomparison with the results of PMF for well-characterized case studies such as Pittsburgh and Houston Supersites. ME2 allows partial constraint in source profiles, which allows the exploration of “mixed PMF­CMB” models; (d) Documenting in a publication of the increased source resolution with PMF using high-resolution AMS data; (e) Evaluating of whether the thermal denuder and/or variable vaporizer temperature data allow the identification of additional components for the organic aerosol; (f) Finalizing and publishing the intercomparisons of PMF of AMS data and CMB of organic molecular markers for the MILAGRO dataset; (g) Comparing the AMS-PMF results with results from the one-hour molecular marker data from the Thermal Desorption Aerosol GC­MS (TAG) from the SOAR-1 study; (h) Analyzing the nitrogen content (N/C) of OA from ambient OA at several locations, PMF components, chamber SOA, laboratory BBOA, and emissions from motor vehicles, meat cooking, and trash burning.


Journal Articles on this Report : 12 Displayed | Download in RIS Format

Other project views: All 115 publications 31 publications in selected types All 31 journal articles
Type Citation Project Document Sources
Journal Article Aiken AC, DeCarlo PF, Jimenez JL. Elemental analysis of organic species with electron ionization high-resolution mass spectrometry. Analytical Chemistry 2007;79(21):8350-8358. R832161 (2007)
R832161 (Final)
  • Abstract from PubMed
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  • Abstract: ACS-Abstract
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  • Other: ACS-Full Text PDF
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  • Journal Article Cottrell LD, Griffin RJ, Jimenez JL, Zhang Q, Ulbrich I, Ziemba LD, Beckman PJ, Sive BC, Talbot RW. Submicron particles at Thompson Farm during ICARTT measured using aerosol mass spectrometry. Journal of Geophysical Research-Atmospheres 2008;113(D8):D08212. R832161 (2007)
    R832161 (Final)
  • Full-text: Wiley-Full Text PDF
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  • Abstract: Wiley-Abstract HTML
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  • Journal Article Cubison MJ, Ervens B, Feingold G, Docherty KS, Ulbrich IM, Shields L, Prather K, Hering S, Jimenez JL. The influence of chemical composition and mixing state of Los Angeles urban aerosol on CCN number and cloud properties. Atmospheric Chemistry and Physics 2008;8(18):5649-5667. R832161 (2007)
    R832161 (Final)
    R831080 (Final)
  • Full-text: ACP-Full Text PDF
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  • Abstract: ACP-Abstract
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  • Journal Article DeCarlo PF, Kimmel JR, Trimborn A, Northway MJ, Jayne JT, Aiken AC, Gonin M, Fuhrer K, Horvath T, Docherty KS, Worsnop DR, Jimenez JL. Field-deployable, high-resolution, time-of-flight aerosol mass spectrometer. Analytical Chemistry 2006;78(24):8281-8289. R832161 (2006)
    R832161 (2007)
    R832161 (Final)
  • Abstract from PubMed
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  • Abstract: ACS-Abstract
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  • Journal Article Dzepina K, Arey J, Marr LC, Worsnop DR, Salcedo D, Zhang Q, Onasch TB, Molina LT, Molina MJ, Jimenez JL. Detection of particle-phase polycyclic aromatic hydrocarbons in Mexico City using an aerosol mass spectrometer. International Journal of Mass Spectrometry 2007;263(2-3):152-170. R832161 (2006)
    R832161 (2007)
    R832161 (Final)
  • Full-text: CIRES-Full Text PDF
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  • Abstract: ScienceDirect-Abstract
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  • Journal Article Huffman JA, Ziemann PJ, Jayne JT, Worsnop DR, Jimenez JL. Development and characterization of a fast-stepping/scanning thermodenuder for chemically-resolved aerosol volatility measurements. Aerosol Science & Technology 2008;42(5):395-407. R832161 (2007)
    R832161 (Final)
    R831080 (Final)
    R833747 (Final)
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  • Abstract: Taylor&Francis-Abstract
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  • Journal Article Kondo Y, Miyazaki Y, Takegawa N, Miyakawa T, Weber RJ, Jimenez JL, Zhang Q, Worsnop DR. Oxygenated and water-soluble organic aerosols in Tokyo. Journal of Geophysical Research-Atmospheres 2007;112(D1):D01203. R832161 (2006)
    R832161 (2007)
    R832161 (Final)
  • Full-text: Wiley-Full-text PDF
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  • Abstract: Wiley-Abstract & Full-text HTML
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  • Journal Article Takegawa N, Miyakawa T, Kondo Y, Jimenez JL, Zhang Q, Worsnop DR, Fukuda M. Seasonal and diurnal variations of submicron organic aerosol in Tokyo observed using the Aerodyne aerosol mass spectrometer (AMS). Journal of Geophysical Research-Atmospheres 2006;111(D11):D11206. R832161 (2005)
    R832161 (2006)
    R832161 (2007)
    R832161 (Final)
  • Full-text: Wiley-Full-text PDF
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  • Journal Article Zhang Q, Worsnop DR, Canagaratna MR, Jimenez JL. Hydrocarbon-like and oxygenated organic aerosols in Pittsburgh: insights into sources and processes of organic aerosols. Atmospheric Chemistry and Physics 2005;5(12):3289-3311. R832161 (2005)
    R832161 (2006)
    R832161 (2007)
    R832161 (Final)
    R831080 (Final)
  • Full-text: ACP-Full Text PDF
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  • Abstract: ACP-Abstract
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  • Other: Hal Archives-Full Text PDF
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  • Journal Article Zhang Q, Alfarra MR, Worsnop DR, Allan JD, Coe H, Canagaratna MR, Jimenez JL. Deconvolution and quantification of hydrocarbon-like and oxygenated organic aerosols based on aerosol mass spectrometry. Environmental Science & Technology 2005;39(13):4938-4952. R832161 (2005)
    R832161 (2006)
    R832161 (2007)
    R832161 (Final)
    R831080 (Final)
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  • Abstract: ES&T-Abstract
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  • Journal Article Zhang Q, Jimenez JL, Canagaratna MR, Allan JD, Coe H, Ulbrich I, Alfarra MR, Takami A, Middlebrook AM, Sun YL, Dzepina K, Dunlea E, Docherty K, DeCarlo PF, Salcedo D, Onasch T, Jayne JT, Miyoshi T, Shimono A, Hatakeyama S, Takegawa N, Kondo Y, Schneider J, Drewnick F, Borrmann S, Weimer S, Demerjian K, Williams P, Bower K, Bahreini R, Cottrell L, Griffin RJ, Rautiainen J, Sun JY, Zhang YM, Worsnop DR. Ubiquity and dominance of oxygenated species in organic aerosols in anthropogenically-influenced Northern Hemisphere midlatitudes. Geophysical Research Letters 2007;34(13):L13801. R832161 (2007)
    R832161 (Final)
    R831080 (Final)
    R831454 (Final)
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  • Abstract: Wiley-Abstract & Full Text HTML
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  • Journal Article Zhang Q, Jimenez JL, Worsnop DR, Canagaratna M. A case study of urban particle acidity and its influence on secondary organic aerosol. Environmental Science & Technology 2007;41(9):3213-3219. R832161 (2006)
    R832161 (2007)
    R832161 (Final)
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  • Full-text: ES&T-Full Text HTML
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  • Abstract: ES&T-Abstract
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  • Supplemental Keywords:

    ambient air, tropospheric, air pollution, particulates, environmental chemistry, monitoring, carbonaceous particles, combustion aerosols, source apportionment, primary organic aerosols, secondary organic aerosols, ToF-AMS, thermal denuder,, RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, particulate matter, Air Quality, Environmental Chemistry, Monitoring/Modeling, Environmental Monitoring, Environmental Engineering, particulate organic carbon, atmospheric dispersion models, atmospheric measurements, model-based analysis, time resolved apportionment, source apportionment, chemical characteristics, emissions monitoring, environmental measurement, airborne particulate matter, air quality models, air quality model, air sampling, speciation, particulate matter mass, analytical chemistry, aerodyne aerosol mass spectrometry, monitoring of organic particulate matter, modeling studies, chemical transport models, real-time monitoring, aerosol analyzers, chemical speciation sampling, particle size measurement

    Relevant Websites:

    http://cires.colorado.edu/jimenez Exit
    http://cires.colorado.edu/jimenez-group/Field/Riverside05/ Exit
    http://cires.colorado.edu/jimenez-group/AMSsd/ Exit
    http://cires.colorado.edu/jimenez-group/TDPBMSsd/ Exit
    http://cires.colorado.edu/jimenez-group/TDPBMSsd/ Exit
    http://cires.colorado.edu/jimenez-group/ToFAMSResources/ Exit
    http://cires.colorado.edu/jimenez-group/ToFAMSResources/ToFSoftware/SquirrelInfo/ Exit
    http://cires.colorado.edu/jimenez-group/ToFAMSResources/ToFSoftware/PikaInfo/ Exit
    http://www.engr.wisc.edu/cee/faculty/schauer_james.html Exit
    http://spot.colorado.edu/~hannigan/ Exit
    http://www.asrc.cestm.albany.edu/qz/ Exit

    Progress and Final Reports:

    Original Abstract
  • 2005 Progress Report
  • 2006 Progress Report
  • Final Report