Particle-Phase Chemistry of Secondary Organic Material: Modeled Compared to Measured O:C and H:C Elemental Ratios Provide Constraints

Chen, Qi; Liu, Yingjun; Donahue, Neil M.; Shilling, John E.; Martin, Scot T.

doi:10.1021/es104398s

Cited by 182 publications

(271 citation statements)

References 56 publications

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“…The product distribution compares reasonably well with a recent calculation based on a master chemical mechanism simulation of the system (Chen et al, 2011). In the upper panel, the product distribution is shown by blue contours, while in the lower panel the 1-D yields (the vertical sum of the 2-D yields) are shown with green (particle) and white (gas-phase) products for C OA 10 µg m −3 .…”

Section: Soa Formation From Vocsupporting

confidence: 79%

A two-dimensional volatility basis set – Part 2: Diagnostics of organic-aerosol evolution

et al. 2012

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Abstract.We discuss the use of a two-dimensional volatility-oxidation space (2-D-VBS) to describe organicaerosol chemical evolution. The space is built around two coordinates, volatility and the degree of oxidation, both of which can be constrained observationally or specified for known molecules. Earlier work presented the thermodynamics of organics forming the foundation of this 2-D-VBS, allowing us to define the average composition (C, H, and O) of organics, including organic aerosol (OA) based on volatility and oxidation state. Here we discuss how we can analyze experimental data, using the 2-D-VBS to gain fundamental insight into organic-aerosol chemistry. We first present a wellunderstood "traditional" secondary organic aerosol (SOA) system -SOA from α-pinene + ozone, and then turn to two examples of "non-traditional" SOA formation -SOA from wood smoke and dilute diesel-engine emissions. Finally, we discuss the broader implications of this analysis.

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Section: Soa Formation From Vocsupporting

confidence: 79%

A two-dimensional volatility basis set – Part 2: Diagnostics of organic-aerosol evolution

et al. 2012

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“…For the mass concentration of 60-100 µg m −3 , the oxygen-to-carbon (O : C) ratio was 1.08, calculated from the AMS mass spectra following the approach of Chen et al (2011). This value can be compared with the O : C values ranging from 0.9 to 1.3 that were measured for toluene-derived SOM generated in a similar OFR .…”

Section: Production and Collection Of Secondary Organicmentioning

confidence: 99%

Relative humidity-dependent viscosity of secondary organic material from toluene photo-oxidation and possible implications for organic particulate matter over megacities

et al. 2016

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Abstract. To improve predictions of air quality, visibility, and climate change, knowledge of the viscosities and diffusion rates within organic particulate matter consisting of secondary organic material (SOM) is required. Most qualitative and quantitative measurements of viscosity and diffusion rates within organic particulate matter have focused on SOM particles generated from biogenic volatile organic compounds (VOCs) such as α-pinene and isoprene. In this study, we quantify the relative humidity (RH)-dependent viscosities at 295 ± 1 K of SOM produced by photo-oxidation of toluene, an anthropogenic VOC. The viscosities of toluene-derived SOM were 2 × 10 −1 to ∼ 6 × 10 6 Pa s from 30 to 90 % RH, and greater than ∼ 2 × 10 8 Pa s (similar to or greater than the viscosity of tar pitch) for RH ≤ 17 %. These viscosities correspond to Stokes-Einstein-equivalent diffusion coefficients for large organic molecules of ∼ 2 × 10 −15 cm 2 s −1 for 30 % RH, and lower than ∼ 3 × 10 −17 cm 2 s −1 for RH ≤ 17 %. Based on these estimated diffusion coefficients, the mixing time of large organic molecules within 200 nm toluene-derived SOM particles is 0.1-5 h for 30 % RH, and higher than ∼ 100 h for RH ≤ 17 %. As a starting point for understanding the mixing times of large organic molecules in organic particulate matter over cities, we applied the mixing times determined for toluene-derived SOM particles to the world's top 15 most populous megacities. If the organic particulate matter in these megacities is similar to the toluene-derived SOM in this study, in Istanbul, Tokyo, Shanghai, and São Paulo, mixing times in organic particulate matter during certain periods of the year may be very short, and the particles may be wellmixed. On the other hand, the mixing times of large organic molecules in organic particulate matter in Beijing, Mexico City, Cairo, and Karachi may be long and the particles may not be well-mixed in the afternoon (15:00-17:00 LT) during certain times of the year.

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“…This filter was employed over brief intervals throughout each day to derive a time-resolved CO 2 (g) correction factor in combination with the CO 2 (g) measurements described above. Second, the OMrelated signal at H 2 O C was estimated using an H 2 O C :CO C 2 ratio of unity, reflecting laboratory observations Kiendler-Scharr et al 2009;Sun et al 2010;Chen et al 2011). This change was reversed for the literature comparisons in Section 5.2, with minor impact, to the default 0.225.…”

Section: Ams Data Analysismentioning

confidence: 99%

Organic Emissions from a Wood Stove and a Pellet Stove Before and After Simulated Atmospheric Aging

Corbin

Keller

Lohmann

et al. 2015

Aerosol Science and Technology

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Logwood and pellet stoves are popular heating sources around the world. The particulate matter emitted from such stoves contains organic particulate matter (OM), soot, and ash, each of which may have significant effects on climate and health. In this study, the primary OM (POM) emitted from a wood stove and a pellet stove operated according to standard Swiss testing protocols were characterized using aerosol mass spectrometry. The POM mass spectra were found to be highly reproducible, and contained CO C as the dominant ion. Because the POM emitted by such stoves is typically enhanced by the condensation of gaseous organics following atmospheric aging, the secondary OM (SOM) formation potential of these stoves was simulated using the Micro Smog Chamber (MSC) designed by Keller and Burtscher in 2012. In general, OM emission factors from MSCaged aerosols were comparable to lower-time-resolution results from the literature, although the MSC exposed aerosols to much higher concentrations of oxidants and therefore produced OM that was more oxidized than expected for atmospheric samples. In addition, the logwood-stove particles remained highly aspherical even after oxidation, indicating that mixing with an external aerosol is required for these particles to become spherical. The one exception to this observation occurred when the wood failed to ignite and appeared to generate tar-ball OM particles.

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Particle-Phase Chemistry of Secondary Organic Material: Modeled Compared to Measured O:C and H:C Elemental Ratios Provide Constraints

Cited by 182 publications

References 56 publications

A two-dimensional volatility basis set – Part 2: Diagnostics of organic-aerosol evolution

A two-dimensional volatility basis set – Part 2: Diagnostics of organic-aerosol evolution

Relative humidity-dependent viscosity of secondary organic material from toluene photo-oxidation and possible implications for organic particulate matter over megacities

Organic Emissions from a Wood Stove and a Pellet Stove Before and After Simulated Atmospheric Aging

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