Grantee Research Project Results
Final Report: Atmospheric Processing of Organic Particulate Matter: Formation, Properties, Long Range Transport, and Removal
EPA Grant Number: R831081Title: Atmospheric Processing of Organic Particulate Matter: Formation, Properties, Long Range Transport, and Removal
Investigators: Donahue, Neil , Davidson, Cliff I. , Pandis, Spyros N. , Robinson, Allen , Adams, Peter
Institution: Carnegie Mellon University
EPA Project Officer: Chung, Serena
Project Period: September 1, 2003 through August 31, 2006
Project Amount: $449,994
RFA: Measurement, Modeling, and Analysis Methods for Airborne Carbonaceous Fine Particulate Matter (PM2.5) (2003) RFA Text | Recipients Lists
Research Category: Air , Air Quality and Air Toxics , Particulate Matter
Objective:
The objectives are to:
- Determine yields of reaction products forming secondary organic aerosol (SOA) from biogenic and anthropogenic precursors under typical atmospheric conditions, including variations of temperature and volatile organic compound (VOC)/nitrogen oxides (NOx).
- Develop and/or revise computationally efficient mechanisms capable of reproducing the observed SOA production in air quality models.
- Discover, using these new mechanisms, the relative contribution of biogenic and anthropogenic emissions to SOA yields in different regions of the United States.
- Test control strategies for fine particulate matter (PM2.5) in light of these findings, with particular emphasis on multi-objective behavior given observed VOC/NOx variations in SOA yields.
Summary/Accomplishments (Outputs/Outcomes):
Research on this project led to a new understanding of organic particle behavior in the atmosphere. This combines a fundamental picture of organic aerosol aging through gas-heterogeneous and condensed-phase chemistry with practical modules that will greatly enhance policy decision making regarding organic aerosol reductions. This project drew on support from other projects including Science To Achieve Results (STAR) research on primary emissions (Robinson, Donahue, and Adams) as well as National Science Foundation (NSF) support covering hygroscopicity of organic particles (Pandis and Donahue) and the oxidation of isoprene (Donahue, principal investigator [PI]). The end product is a theoretical framework for the formation and transformation of organic particles, coupled with the realization that essentially all organic particulate matter is semi-volatile. Initially this realization challenges the dual notion of secondary and primary organic aerosol. However, we have developed a framework to describe this behavior that facilitates understanding of semi-volatile partitioning and also points to efficient modeling of the partitioning, including evolution of volatility due to progressive chemical transformation during long-range transport of semi-volatile material. Extensive publication of both experimental and modeling results continues.
Objective 1. Reaction Products Forming SOA From Biogenic and Anthropogenic Precursors
Ongoing experiments have addressed SOA generation from ozone-terpene reactions, including: α-pinene, b-pinene, d-limonene, a-humulene, and b-caryophyllene. Experiments have focused on variations in the aerosol mass fraction (aerosol mass produced/precursor mass oxidized), measured with a scanning mobility particle size spectrometer in a 10 m3 Teflon environmental chamber. Experiments were substantially enhanced by an Aerodyne Aerosol Mass Spectrometer (AMS) and an Ionocon Proton Transfer Mass Spectrometer (PTRMS) obtained with an NSF Major Research Instrumentation (MRI) grant. These instruments enabled specific measurements of aerosol parameters and continuous measurement of vapor-phase compounds, including removal of the precursor. Experimental parameters that we varied include (independently): amount of oxidized precursor, oxidant (ozone) level, oxidation temperature, chamber temperature following oxidation, and NOx levels (NO and NO2), with and without supplemental UV illumination. Results are summarized as follows:
- SOA product formation can be interpreted in terms of a “basis set” of product saturation concentrations spanning the full range of organic aerosol concentrations observed in the atmosphere (0.01 μg m-3 for a “non-volatile” product to 1000 μg m-3 for a “volatile” product, with intermediate-volatility products separated by factors of 10). Semi-volatile partitioning follows according to the well-established treatment of Pankow. The basis-set representation puts all organic aerosol on a common basis, thus permitting a complete representation of semi-volatile partitioning with five to seven highly constrained parameters as opposed to the traditional “2-product” formulation in which each precursor produces SOA products with four unconstrained degrees of freedom. This permits:
- Uniform representation of semi-volatile organics in models.
- Consistent evaluation of experimental data.
- Easy separation of source fractions for source attribution.
- Direct representation of temperature effects with realistic ΔHvap.
- Conceptualization and formal representation of aging effects due to secondary chemistry.
- in both the vapor and condensed phases.
This last item will transform thinking and the representation of organic aerosol, including both SOA (the subject of this project) and primary emissions (the subject of a second STAR project, A.L. Robinson, PI). In areas dominated by regional emissions, organic aerosol will not be represented by static “yields” or “emission factors,” but rather by emission of chemically active compounds whose products and thus whose partitioning evolves throughout long-range transport from the source to the receptor site. The approach has received widespread attention recently, with very considerable interest on the part of policy makers for implementations in air-qua lity models.
- Low-volatility, first-generation products revealed in the basis-set representation increase SOA mass production by about a factor of two over the current state-of-the-art 2-product models. This is especially true for total organic aerosol of 5 μg m-3 and below, which is the typical average loading for regions in non-compliance with the 15 μg m-3 annual-average National Ambient Air Quality Standards (NAAQS). It is also directly germane to global modeling studies where models significantly underpredict observed organic aerosol levels. Chamber data using the PTRMS to measure terpene consumption in real time give us the first experimental results to significantly constrain the 0.1–10 μg m-3 region of semi-volatile partitioning. The practical consequence of these findings will be increased SOA production in environments with relatively low OA concentrations.
- SOA production from ozone-terpene reactions is reduced in the presence of UV-A light. A basis-set analysis of experimental data extending to low COA shows a 0.03 reduction in the mass yield of a low-volatility product, with a saturation concentration of 1 μg m-3 for low-NOx conditions only. The practical consequence of these findings is that terpene SOA production in the atmosphere may be significantly lower than suggested by product yields based on parameterizations derived from experiments conducted in dark chambers. It remains to be seen whether extended exposure to UV will further reduce low-NOx SOA during long-range transport.
- SOA production from terpenes depends strongly on VOC/NOx in experiments that isolate the ozone-terpene reaction, with a significant decrease in SOA production for α-pinene occurring as NOx levels increase beyond a VOC/NOx of approximately 8:1 (the traditional spine on the Empirical Kinetic Modeling Approach (EKMA) ozone isopleth graph). A basis-set analysis of these data is consistent with very low product yields with saturation concentrations less than 100 μg m-3 for high-NOx conditions. Experimental data can be reproduced accurately with a simple mixing model based on RO2 radical branching. The practical consequence of these findings is that NOx control strategies will have a dramatic effect on SOA arising from ozonolysis of biogenic precursors (monoterpenes).
- Limonene shows much more complicated chemistry:
- Oxidation of both double bonds produces much lower vapor pressure products and consequently much more SOA than α-pinene. Oxidation of the internal double bond only yields products and SOA very similar to α-pinene.
- At low NOx, the initial gas-phase ozone reaction appears to be rate limiting. Evidence points to oxidation of the second double bond occurring in the condensed phase with a high ozone uptake coefficient. However, it is far from clear that this second oxidation will occur so rapidly on actual atmospheric particles.
- SOA production increases once both double bonds are oxidized at high NOx, but acts much like α-pinene with lowered SOA at high NOx when only the endocyclic double bond is oxidized. This appears to be due to competing effects—NOx products have higher vapor pressure than some of the organic acids produced at low NOx, but the added mass of the nitrate in organic nitrates increases the mass yield of products where low vapor pressures arise from oxidation at a different site (the other double bond). High NOx conditions also appear to dramatically slow the heterogeneous oxidation of the second double bond under chamber conditions.
- It is still unclear how oxidation of the second double bond will proceed in nature, or how that will influence SOA production. It seems probable that a combination of homogeneous and heterogeneous processes, possibly dominated by OH radical, will predominate.
The practical consequence of these findings is that limonene may be a very potent SOA precursor, but that SOA may be formed with a substantial time delay following emission due to kinetic effects.
- SOA formation from evaporated primary emissions may be a major unrecognized source of organic aerosol. In a paper just published in Science, we showed that evaporated diesel emissions are a potent SOA source, leading to a doubling in organic aerosol loading in our smog chamber after only a few hours of UV illumination. Combined with recognition that a significant fraction of primary emi ssions can evaporate at ambient organic aerosol concentrations, this transforms the picture of primary emissions from a relatively static case of emission, transport, and deposition to a dynamic mix of emissions, evaporation, oxidation chemistry, condensation, and eventual deposition. Aerosol levels thus evolve dramatically with long-range transport. The practical consequence of this work is a sharp change in urban/regional OA gradients in air-quality models, with corresponding changes in predicted exposure and effective reductions thereof.
- The temperature dependence of SOA partitioning is modest at best. This can be explained within the basis-set formalism, which also shows that the temperature dependence of aged aerosol will be even lower than fresh SOA. The practical consequence of this finding is that models with only a few products and high enthalpies of vaporization will dramatically overestimate the temperature dependence of semi-volatile partitioning.
- Two efficient OH radical sources have been developed. One is the traditional methyl nitrite photolysis source, while the other relies on ozonolysis of tetra-methyl ethylene (TME). The second method shows great promise as a steady, high-yield source capable of maintaining a steady OH production rate with control based on a steady, small flow of TME into the chamber as well as the ozone concentration. These two sources will enable experiments in the coming 18 months on OH-initiated oxidation of anthropogenic precursors.
Objective 2. Parameterizations for Air-Quality Models
- The basis-set formalism described above will transform organic aerosol modeling. We have modified the aerosol modules in the Particulate Matter Comprehensive Air Quality Model with Extensions (PMCAMx) to suit the basis set (this is fairly straightforward) and also to permit gas-phase oxidation of the semi-volatile species carried in the model. An initial implementation has been used to assess both multi-generation SOA evolution and the evolution of primary emissions described above.
- Modeling shows that isoprene SOA may comprise a significant portion of the total SOA in the southeast.
- We have developed a new SOA module for PMCAMx in which various precursors, including terpenes and anthropogenic compounds such as xylenes are unlumped, allowing assessment of the contribution of individual precursors to total SOA. A VOC/NOx dependence (from combined OH and ozone chemistry) is described in the parameterization.
Objective 3. Elucidation of the Biogenic/Anthropogenic Contribution to SOA
- Model runs based on Los Angeles conditions show a large majority (95%) of SOA arising from anthropogenic precursors for typical LA conditions. The practical consequence of this work will be an improved ability to assess the relative contributions of anthropogenic and biogenic emissions to SOA production.
- Consideration of SOA will ultimately require a full life-cycle evaluation of aging. This task will extend well beyond the current project. However, a preliminary assessment supports the “fallacy of the polluting tree.” Specifically, semi-volatile partitioning of biogenic vapors only occurs in the presence of a substantial substrate of anthropogenic low vapor-pressure material. It is thus inappropriate to call biogenic semi-volatile vapors biogenic SOA. The practical consequence of this finding is that reductions in primary organic aerosol will also reduce the SOA fraction by causing higher vapor pressure material to evaporate.
This research produced 24 peer-reviewed publications, including 16 published [1-16] (1 in Science [10]), 6 under review [17-22], and 2 about to be submitted [23-24]; and 30+ presentations at national meetings. The grant substantially supported two Ph.D. dissertations (A.A. Presto, 2005; T.E. Lane, 2007) and significantly supported two more (J. Zhang, 2006; A.M. Sage, 2007); and trained two post-doctoral associates (K.E. Huff Hartz, now at Southern Illinois, and R.K. Pathak). This work greatly advanced our understanding of SOA behavior and our ability to model SOA for regulatory purposes. Laboratory work addressed the volatility of SOA products from terpene-ozone reactions, emphasizing changes driven by UV light, NOx, and temperature. We showed that UV light can reduce SOA formation by up to a factor of two under atmospherically relevant conditions [4, 9] and a strong NOx effect consistent with gas-phase VOC oxidation, producing almost no low-volatility first-generation products in high-NOx pathways [5]. Work at low aerosol mass showed that parameterizations based on higher mass literature data had extrapolation errors of a factor of three in the atmospheric range [8, 16]. SOA production varies much less with temperature than many models assume: we find a 1–2% K-1 increase with dropping temperature [13, 16, 23], probably caused by a wide distribution of product volatility [1]. Substantial contributions to SOA experimental methods included separating reaction temperature from volatility temperature dependence [13, 16, 23] and observing real-time SOA formation to constrain low-mass SOA formation relevant to the atmosphere [8]. We applied dilution sampling (DS) to chamber experiments to test reversibility of SOA formation (SOA-DS) [21], and developed a long-residence time thermal denuder (TD) (SOA-TD). Both SOA-DS and SOA-TD measurements show that α-pinene SOA condensation is reversible, with significant consequences for interpretation and modeling of SOA oligomerization.
We addressed SOA aging, including cloud condensation nuclei (CCN) activity [6], heterogeneous kinetics [2, 12], and major reviews of the aging literature [11] and organic aerosol in climate models [3].
We modeled effects of isoprene on SOA formation [14] and compared modeled primary emissions with chemical mass balance estimates [15]. We have begun to understand multiple-generation evolution of SOA [1], including both gas-phase and heterogeneous oxidation of terpenes [9, 18] and extremely significant oxidation of vapors from primary particles [19, 20, 10].
To unify and simplify representation of SOA formation, volatility, and aging, we developed a “volatility basis set” for organic aerosol [7], extending the work of Pankow and Odum in a framework describing how material of many fixed vapor pressures behaves in a mixture (a liquid or a waxy solid). Material is grouped into volatility bins with characteristic saturation mass concentrations, C*i, expressed in μg m-3. The bins are separated by powers of 10, ranging from 0.01 μg m-3 to 106 μg m-3 at 300 K, and they shift with temperature. Within each bin, the mass fraction in the condensed phase, ξi, is given by
ξi = (1+ C*i /COA)-1; COA= Ci ξi (1),
where COA is the total organic aerosol mass loading of material forming a solution. SOA formation experiments plot the mass fraction in the aerosol, ξ. The AMF is ξ = COA/ΔCROG and ξ’ is the normalized AMF used when aerosol volume is measured with a Scanning Mobility Particle Sizer (SMPS) (assuming unit density). In Figure 1, we show data for α-pinene + O3 [4, 5, 8] and the essence of the basis-set fit associated with those data, where the reaction is described as
Precursor + Ox → α1 p1 + α2 p2 + α3 p3 +... C*1 = 0.01 μg m-3, C*2 = 0.1 μg m-3, ...
This is readily implemented in air-quality models, and we have published basis-set parameterizations for first-generation terpene SOA formation [17, 23, 22]. It also simplifies description of multiple-generation chemistry; vapors integral to partitioning theory are highly reactive in the gas phase, and those reactions must influence organic aerosol levels. We have implemented a first version in PMCAMx, addressing the role of evaporation and subsequent oxidation of diesel emissions [10] and SOA formation and aging [22]. Secondary aging of SOA vapors can increase SOA levels by more than a factor of two.
Conference Presentations and Seminars. More than 70 presentations were given that included substantial components derived from this project. These included invited talks by the PI and co-PIs in several international meetings, Gordon Conferences, and a major environmental health conference in Pittsburgh. In addition to the talks listed here were 12 presentations at the 2004 AAAR meeting, 17 presentations at the 2005 AAAR meeting, and 15 presentations at the 2006 International Aerosol Conference.
References:
- Donahue NM, Huff Hartz KE, Chuong B, Presto AA, Stanier CO, Rosenhorn T, Robinson AL, Pandis SN. Critical factors determining the variation in SOA yields from terpene ozonolysis: a combined experimental and computational study. Faraday Discussions 2005;130:295-309.
- Donahue NM, Robinson AL, Huff Hartz KE, Sage AM, Weitkamp EA. Competitive oxidation in atmospheric aerosols: the case for relative kinetics. Geophysical Research Letters 2005;32;L16805, doi:10.1029/2005GL022893.
- Kanakidou M, Seinfeld JH, Pandis SN, Barnes I, Dentener FJ, Facchini MC, Van Dingenen R, Ervens B, Nenes A, Nielsen CJ, Swietlicki E, Putaud JP, Balkanski Y, Fuzzi S, Horth J, Moortgat GK, Winterhalter R, Myhre CEL, Tsigaridis K, Vignati E, Stephanou EG, Wilson J. Organic aerosol and global climate modelling: a review. Atmospheric Chemistry and Physics 2005;5(4):1053-1123.
- Presto AA, Huff Hartz KE, Donahue NM. Secondary organic aerosol production from terpene ozonolysis 1. Effect of UV radiation. Environmental Science & Technology 2005;39(18):7036-7045.
- Presto AA, Huff Hartz KE, Donahue NM. Secondary organic aerosol production from terpene ozonolysis 2. Effect of NOx concentration. Environmental Science & Technology 2005;39(18):7046-7054.
- Huff Hartz KE, Roseno rn T, Ferchak SR, Raymond TM, Bilde M, Donahue NM, Pandis SN. Cloud condensation nuclei activation of monoterpene and sesquiterpene secondary organic aerosol. Journal of Geophysical Research 2005;110:D14208, doi:10.1029/2004JD005754.
- Donahue NM, Robinson AL, Stanier CO, Pandis SN. Coupled partitioning, dilution, and chemical aging of semivolatile organics. Environmental Science & Technology 2006;40(8):2635-2643.
- Presto AA, Donahue NM. Investigation of α-pinene + ozone secondary organic aerosol formation at low total aerosol mass. Environmental Science & Technology 2006;40(11):3536-3543.
- Zhang J, Donahue NM. Constraining the mechanism and kinetics of OH + NO2 and HO2 + NO using the multiple-well master equation. Journal of Physical Chemistry A 2006;110(21):6898-6911.
- Robinson AL, Donahue NM, Shrivastava MK, Weitkamp EA, Sage AM, Greishop AP, Lane TE, Pierce JR, Pandis SN. Rethinking organic aerosols: semivolatile emissions and photochemical aging. Science 2007;315(5816):1259-1262.
- Rudich Y, Donahue NM, Mentel TF. Aging of organic aerosol: bridging the gap between laboratory and field studies. Annual Review of Physical Chemistry 2007;58:321-352.
- Lambe AT, Zhang J, Sage AM, Donahue NM. Controlled OH radical production via ozone-alkene reactions for use in aerosol aging studies. Environmental Science & Technology 2007;41(7):2357-2363.
- Stanier CO, Pathak RK, Pandis SN. Measurements of the volatility of aerosols from α-pinene ozonolysis. Environmental Science & Technology 2007;41(8):2756-2763.
- Lane TE, Pandis SN. Predicted secondary organic aerosol concentrations from the oxidation of isoprene in the Eastern United States. Environmental Science & Technology 2007;41(11):3984-3990.
- Lane TE, Pinder RW, Shrivastava M, Robinson AL, Pandis SN. Source contributions to primary organic aerosol: comparison of the results of a source-resolved model and the chemical mass balance approach. Atmospheric Environment 2007 ;41(18):3758-3776.
- Pathak RK, Stanier CO, Donahue NM, Pandis SN. Ozonolysis of α-pinene at atmospherically relevant concentrations: temperature dependence of aerosol mass fractions (yields). Journal of Geophysical Research 2007;112:D03201, doi:10.1029/2006JD007436.
- Pathak RK, Presto AA, Lane TE, Stanier CO, Donahue NM, Pandis SN. Ozonolysis of α-pinene: parameterization of secondary organic aerosol mass fraction. Atmospheric Chemistry and Physics Discussions 2007;7(1):1941-1967.
- Donahue NM, Tischuk JE, Marquis B, Huff Hartz KE. Secondary organic aerosol from limonaketone: insights into terpene ozonolysis via synthesis of key intermediates. Physical Chemistry Chemical Physics (submitted, 2007).
- Weitkamp E, Sage AM, Pierce JR, Donahue NM, Robinson AL. Organic aerosol formation from photochemical oxidation of diesel exhaust. Environmental Science & Technology (submitted, 2007).
- Sage AM, Weitkamp EA, Robinson AL, Donahue NM. Production of oxidized organic aerosol mass spectra from diesel oxidation: invariant factors vs. time-evolving spectra. Atmospheric Chemistry Physics Discussions (submitted, 2007).
- Grieshop AP, Donahue NM, Robinson AL. Is the gas-particle partitioning in alpha-pinene secondary organic aerosol reversible? Geophysical Research Letters (submitted, 2007).
- Pathak RK, Huff Hartz KE, Donahue NM, Pandis SN. Temperature and ozone dependence of secondary organic aerosol production from β-pinene ozonolysis. Atmospheric Environment (submitted, 2007).
- Lane TE, Donahue NM, Pandis SN. Implementation of the volatility basis set in PMCAMx. Journal of Geophysical Research A (in preparation, 2007).
- Pierce J, Adams PJ, Robinson AL, Donahue NM. Treatment of particle wall losses with simultaneous, size-resolved deposition, condensation, and evaporation of semi-volatile organics. Aerosol Science and Technology (in preparation, 2007).
Journal Articles on this Report : 20 Displayed | Download in RIS Format
Other project views: | All 58 publications | 20 publications in selected types | All 20 journal articles |
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Chow JC, Watson JG, Lowenthal DH, Park K, Doraiswamy P, Bowers K, Bode R. Continuous and filter-based measurements of PM2.5 nitrate and sulfate at the Fresno Supersite. Environmental Monitoring and Assessment 2008;144(1-3):179-189. |
R831081 (Final) |
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Donahue NM, Huff Hartz KE, Chuong B, Presto AA, Stanier CO, Rosenhorn T, Robinson AL, Pandis SN. Critical factors determining the variation in SOA yields from terpene ozonolysis:a combined experimental and computational study. Faraday Discussions 2005;130:295-309. |
R831081 (2004) R831081 (2005) R831081 (Final) |
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Donahue NM, Robinson AL, Stanier CO, Pandis SN. Coupled partitioning, dilution, and chemical aging of semivolatile organics. Environmental Science & Technology 2006;40(8):2635-2643. |
R831081 (2005) R831081 (Final) R832162 (2005) R832162 (2006) R832162 (Final) |
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Donahue NM, Tischuk JE, Marquis BJ, Huff Hartz KE. Secondary organic aerosol from limona ketone:insights into terpene ozonolysis via synthesis of key intermediates. Physical Chemistry Chemical Physics 2007;9(23):2991-2998. |
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Grieshop AP, Donahue NM, Robinson AL. Is the gas-particle partitioning in alpha-pinene secondary organic aerosol reversible? Geophysical Research Letters 2007;34:L14810. |
R831081 (Final) R832162 (Final) |
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Huff Hartz KE, Rosenorn T, Ferchak SR, Raymond TM, Bilde M, Donahue NM, Pandis SN. Cloud condensation nuclei activation of monoterpene and sesquiterpene secondary organic aerosol. Journal of Geophysical Research--Atmospheres 2005;110(D14):D14208 (8 pp.). |
R831081 (2005) R831081 (Final) |
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Pathak RK, Stanier CO, Donahue NM, Pandis SN. Ozonolysis of α-pinene at atmospherically relevant concentrations: temperature dependence of aerosol mass fractions (yields). Journal of Geophysical Research--Atmospheres 2007;112(D3):D03201 (8 pp.). |
R831081 (2005) R831081 (Final) |
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Pathak RK, Presto AA, Lane TE, Stanier CO, Donahue NM, Pandis SN. Ozonolysis of α-pinene:parameterization of secondary organic aerosol mass fraction. Atmospheric Chemistry and Physics 2007;7(14):3811-3821. |
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Pathak R, Donahue NM, Pandis SN. Ozonolysis of β-pinene: temperature dependence of secondary organic aerosol mass fraction. Environmental Science & Technology 2008;42(14):5081-5086. |
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Presto AA, Huff Hartz KE, Donahue NM. Secondary organic aerosol production from terpene ozonolysis. 1. Effect of UV radiation. Environmental Science & Technology 2005;39(18):7036-7045. |
R831081 (2005) R831081 (Final) R832162 (Final) |
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Presto AA, Huff Hartz KE, Donahue NM. Secondary organic aerosol production from terpene ozonolysis. 2. Effect of NOx concentration. Environmental Science & Technology 2005;39(18):7046-7054. |
R831081 (2005) R831081 (Final) R832162 (Final) |
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Presto AA, Donahue NM. Investigation of α-pinene + ozone secondary organic aerosol formation at low total aerosol mass. Environmental Science & Technology 2006;40(11):3536-3543. |
R831081 (2005) R831081 (Final) |
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Robinson AL, Donahue NM, Shrivastava MK, Weitkamp EA, Sage AM, Grieshop AP, Lane TE, Pierce JR, Pandis SN. Rethinking organic aerosols: semivolatile emissions and photochemical aging. Science 2007;315(5816):1259-1262. |
R831081 (Final) R832162 (2006) R832162 (Final) |
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Rudich Y, Donahue NM, Mentel TF. Aging of organic aerosol: bridging the gap between laboratory and field studies. Annual Review of Physical Chemistry 2007;58:321-352. |
R831081 (Final) R832162 (Final) |
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Sage AM, Weitkamp EA, Robinson AL, Donahue NM. Evolving mass spectra of the oxidized component of organic aerosol: results from aerosol mass spectrometer analyses of aged diesel emissions. Atmospheric Chemistry and Physics 2008;8(5):1139-1152. |
R831081 (Final) R832162 (Final) |
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Shrivastava MK, Lane TE, Donahue NM, Pandis SN, Robinson AL. Effects of gas particle partitioning and aging of primary emissions on urban and regional organic aerosol concentrations. Journal of Geophysical Research-Atmospheres 2008;113(D18):D18301 (16 pp.). |
R831081 (Final) R832162 (Final) R833748 (2008) R833748 (2009) R833748 (2010) R833748 (Final) |
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Stanier CO, Pathak RK, Pandis SN. Measurements of the volatility of aerosols from α-pinene ozonolysis. Environmental Science & Technology 2007;41(8):2756-2763. |
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Stanier CO, Donahue N, Pandis SN. Parameterization of secondary organic aerosol mass fractions from smog chamber data. Atmospheric Environment 2008;42(10):2276-2299. |
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Weitkamp EA, Sage AM, Pierce JR, Donahue NM, Robinson AL. Organic aerosol formation from photochemical oxidation of diesel exhaust in a smog chamber. Environmental Science & Technology 2007;41(20):6969-6975. |
R831081 (Final) R832162 (Final) |
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Zhang J, Huff Hartz KE, Pandis SN, Donahue NM. Secondary organic aerosol formation from limonene ozonolysis: homogeneous and heterogeneous influences as a function of NOx. The Journal of Physical Chemistry A 2006;110(38):11053-11063. |
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Supplemental Keywords:
air quality modeling, smog, particulate matter, organics,, RFA, Scientific Discipline, Air, Ecosystem Protection/Environmental Exposure & Risk, particulate matter, Air Quality, air toxics, Environmental Chemistry, Air Pollution Effects, Monitoring/Modeling, Environmental Monitoring, Engineering, Chemistry, & Physics, Environmental Engineering, carbon aerosols, air quality modeling, particle size, atmospheric particulate matter, health effects, particulate organic carbon, aerosol particles, atmospheric particles, chemical characteristics, PM 2.5, air modeling, air quality models, airborne particulate matter, air sampling, carbon particles, air quality model, emissions, particulate matter mass, ultrafine particulate matter, particle phase molecular markers, transport modeling, modeling studies, thermal properties, particle dispersion, aerosol analyzers, measurement methods, chemical speciation samplingRelevant Websites:
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.