Black carbon over Mexico: the effect of atmospheric transport on mixing state, mass absorption cross-section, and BC/CO ratios

Subramanian, R.; Kok, Gregory L.; Baumgardner, Darrel; Clarke, A. D.; Shinozuka, Y.; Campos, T.; Heizer, C. G.; Stephens, Britton B.; Foy, B. de; Voss, P. B.; Zaveri, Rahul A.

doi:10.5194/acp-10-219-2010

Cited by 149 publications

(177 citation statements)

References 49 publications

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“…The observed thickly coated fraction at that wind condition went up to 41%. This range of values are consistent with past studies, For example, a thickly coated rBC fraction of approximately 30-40% is reported in previous measurements in diverse urban environments (McMeeking et al, 2011a;Shiraiwa et al, 2007;Subramanian et al, 2010). 25 The substantial presence of thinly-coated (fresh) rBC suggested by the SP2 data (Figure 4) is consistent with our independently measured V-TDMA observations of externally-mixed characteristics for LV mode particles (Figure 3, Figure S9).…”

Section: Mixing State Of Near-highway Particlessupporting

confidence: 82%

“…CC BY 4.0 License. Figure 4 explores the mixing state of near-highway BC particles using the SP2 lag-time approach Schwarz et al, 2006;Shiraiwa et al, 2007;Subramanian et al, 2010). The delay time between the occurrence of scattering and incandescence peaks observed in the SP2 can be used as an indicator of relative coating thickness (∆τ = τ incandescence -τ scattering = time to 'boil off' coating) (McMeeking et al, 2011a;Moteki and Kondo, 2007).…”

Section: Mixing State Of Near-highway Particlesmentioning

confidence: 99%

“…The size distribution of rBC-cores was derived based on the mass equivalent diameter (MED) of an rBC-core assuming a density of 1.8 cm −3 . The delay time between the peak of the incandescence and scattering signals is an indicator of the coating thickness (mixing state) , and was used to determine the number fraction of 'thinly coated' and 'thickly coated' rBC particles (McMeeking et al, 2011a;Shiraiwa et al, 2007;Subramanian et al, 2010). 10…”

Section: Data Reductionmentioning

confidence: 99%

“…The mixing state and morphology of BC particles can influence their radiative absorption properties (Cappa et al, 2012) and deposition in the human respiratory tract (Broday and Rosenzweig, 2011). The 25 mixing state and physio-chemical characteristics of BC particles evolve as they undergo atmospheric processing and aging (Adachi and Buseck, 2013;Subramanian et al, 2010). For example, photochemical oxidation of volatile organic compounds (VOCs), intermediate-VOCs (IVOCs), and semi-volatile organic compounds (SVOCs) form condensable vapors.…”

Section: Introductionmentioning

confidence: 99%

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Downwind evolution of the volatility and mixing state of near-road aerosols near a US interstate highway

Saha¹,

Khlystov²,

Grieshop³

2017

Preprint

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Abstract. We present spatial measurements of particle volatility and mixing state at a site near a North Carolina interstate highway (I-40) applying several heating (thermodenuder; TD) experimental approaches. Measurements were conducted in summer 2015 and winter 2016 in a roadside trailer (10 m from road edge) and during downwind transects at different distances 10 from the highway under favorable wind conditions using a mobile platform. Results show that the relative abundance of semivolatile species (SVOCs) in ultrafine particles decreases with downwind distance, consistent with the dilution and mixing of traffic-sourced particles with background air and evaporation of semi-volatile species during downwind transport. An evaporation kinetics model was used to derive particle volatility distributions by fitting TD data. While the TD-derived distribution apportions about 20-30% of particle mass as semi-volatile (SVOCs; effective saturation concentration, C* ≥ 1µ 15 m-3) at 10 m from road edge, approximately 10% of particle mass is attributed to SVOCs at 220 m, showing that the particlephase semi-volatile fraction decreases with downwind distance. The relative abundance of semi-volatile material in the particle-phase increased during winter. Downwind spatial gradients of the less-volatile particle fraction (that remaining after heating at 180°C) was strongly correlated with black carbon (BC). BC size distribution and mixing state measured using a Single Particle Soot Photometer (SP2) at the roadside trailer showed that a large fraction (70-80%) of BC particles were 20 externally-mixed. Heating experiments with a volatility tandem differential mobility analyzer (V-TDMA) also showed that the non-volatile fraction in roadside aerosols are mostly externally mixed. V-TDMA measurements at different distances downwind from the highway indicate that mixing state of roadside aerosols does not change significantly (e.g., BC mostly remains externally mixed) within a few hundred meters from the highway. A preliminary analysis indicates that a superposition of volatility distributions measured in laboratory vehicle tests and of 'background' aerosol can be used to represent 25 the observed partitioning of near-road particles. The results from this study highlight that exposures and impacts of BC and semi-volatile organics containing particles in a near-road microenvironment may differ across seasons and under changing ambient conditions. 30 Atmos. Chem. Phys. Discuss., https://doi

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Section: Mixing State Of Near-highway Particlessupporting

confidence: 82%

Section: Mixing State Of Near-highway Particlesmentioning

confidence: 99%

Section: Data Reductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Downwind evolution of the volatility and mixing state of near-road aerosols near a US interstate highway

Saha¹,

Khlystov²,

Grieshop³

2017

Preprint

View full text Add to dashboard Cite

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“…We expect a lower artifact for the MAAP since the scattering by filter fibers is accounted by the reflectance measurements, but using our instrumentation we are not able to estimate the artifact coming from embedded BC absorption being modified by organic aerosol deposition. There are only few field studies that present Another study in Mexico City, using PSAP for absorption measurements at λ = 660 nm, found a MAC of 11.2 m² g -1 (interpolated to 637 nm) (Subramanian et al, 2010).…”

Section: Moranmentioning

confidence: 99%

Black and brown carbon over central Amazonia: Long-term aerosol measurements at the ATTO site

Saturno¹,

Holanda²,

Pöhlker³

et al. 2017

Preprint

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Abstract. The Amazon rain forest is considered a very sensitive ecosystem that could be significantly affected by a changing climate. It is still one of the few places on Earth where the atmosphere in the continent approaches near-pristine conditions for some periods of the year. The Amazon Tall Tower Observatory (ATTO) has been built in central Amazonia to monitor the atmospheric and forest ecosystem conditions. The atmospheric conditions at the ATTO site oscillate between biogenic and biomass burning (BB) dominated states. By using a comprehensive ground-based aerosol measurement setup, we studied the physical and chemical properties of aerosol particles at the ATTO site. This parameterization of å abs as a function of the BC to OA mass ratio was investigated and was found applicable to tropical forest emissions but further investigation is required, especially by segregating fuel types. Additionally, important enhancements of the BC mass absorption cross-section (α abs ) were found over the measurement period. This enhancement could be linked to heavy coating of the BC aerosol particles. In the future, the BC mixing state should be systematically investigated by using different instrumental approaches.

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Aerosol emissions from prescribed fires in the United States: A synthesis of laboratory and aircraft measurements

May

McMeeking

Lee

et al. 2014

J. Geophys. Res. Atmos.

142

226

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Aerosol emissions from prescribed fires can affect air quality on regional scales. Accurate representation of these emissions in models requires information regarding the amount and composition of the emitted species. We measured a suite of submicron particulate matter species in young plumes emitted from prescribed fires (chaparral and montane ecosystems in California; coastal plain ecosystem in South Carolina) and from open burning of over 15 individual plant species in the laboratory. We report emission ratios and emission factors for refractory black carbon (rBC) and submicron nonrefractory aerosol and compare field and laboratory measurements to assess the representativeness of our laboratory-measured emissions. Laboratory measurements of organic aerosol (OA) emission factors for some fires were an order of magnitude higher than those derived from any of our aircraft observations; these are likely due to higher-fuel moisture contents, lower modified combustion efficiencies, and less dilution compared to field studies. Nonrefractory inorganic aerosol emissions depended more strongly on fuel type and fuel composition than on combustion conditions. Laboratory and field measurements for rBC were in good agreement when differences in modified combustion efficiency were considered; however, rBC emission factors measured both from aircraft and in the laboratory during the present study using the Single Particle Soot Photometer were generally higher than values previously reported in the literature, which have been based largely on filter measurements. Although natural variability may account for some of these differences, an increase in the BC emission factors incorporated within emission inventories may be required, pending additional field measurements for a wider variety of fires.

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Black carbon over Mexico: the effect of atmospheric transport on mixing state, mass absorption cross-section, and BC/CO ratios

Cited by 149 publications

References 49 publications

Downwind evolution of the volatility and mixing state of near-road aerosols near a US interstate highway

Downwind evolution of the volatility and mixing state of near-road aerosols near a US interstate highway

Black and brown carbon over central Amazonia: Long-term aerosol measurements at the ATTO site

Aerosol emissions from prescribed fires in the United States: A synthesis of laboratory and aircraft measurements

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