Coatings and their enhancement of black carbon light absorption in the tropical atmosphere

Schwarz, J. P.; Spackman, J. R.; Fahey, D. W.; Gao, R. S.; Lohmann, Ulrike; Stier, Philip; Watts, L. A.; Thomson, D. S.; Lack, D. A.; Pfister, L.; Mahoney, Michael J.; Baumgardner, Darrel; Wilson, J. C.; Reeves, J. M.

doi:10.1029/2007jd009042

Cited by 313 publications

(356 citation statements)

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“…Furthermore, the mass size distributions during the CLY and weekdays exhibit similar patterns. The primary mode has a peak at ~205 nm, consistent with the results obtained in the lower troposphere at a site in Texas, USA [32], the surface atmosphere of San Jose, USA [14], and Shenzhen, China [28]. A secondary mode in our samples peaks at ~102 nm, and it contains ~5% of the total rBC mass.…”

Section: Rbc Mass Size and Mixing Statesupporting

confidence: 76%

“…Most studies (e.g., [12,13]) in China have used filter-based techniques that measure bulk aerosol absorption rather than the BC mass concentrations directly. Previous studies indicate that key properties of the BC aerosol, that is the particle's concentration, size, shape and mixing state, vary in complex ways and that these properties depend on many interacting environmental factors [14,15]. Due to the systematic limitations of most of the current filter-based BC measurements [3], direct examination of the BC size distribution and mixing state are not possible.…”

Section: Introductionmentioning

confidence: 99%

“…There are two possible mechanisms to explain this relationship. First, greater convection in the afternoon would bring more aged air masses from the upper atmosphere to the sampling site, and this aged air would tend to contain more internally-mixed rBC particles [14,15]. Second, the strong solar irradiance in the mid-afternoon would favour photochemical oxidation processes that would lead to the mixing of rBC with other chemical species.…”

Section: Rbc Mass Size and Mixing Statementioning

confidence: 99%

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Characteristics of Black Carbon Aerosol during the Chinese Lunar Year and Weekdays in Xi’an, China

et al. 2015

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Black carbon (BC) aerosol plays an important role in climate forcing. The net radiative effect is strongly dependent on the physical properties of BC particles. A single particle soot photometer and a carbon monoxide analyser were deployed during the Chinese Lunar Year (CLY) and on weekdays at Xi'an, China, to investigate the characteristics of refractory black carbon aerosol (rBC). The rBC mass on weekdays (8.4 μg·m −3 ) exceeds that during the CLY (1.9 μg·m −3 ), presumably due to the lower anthropogenic emissions during the latter. The mass size distribution of rBC shows a primary mode peak at ~205 nm and a small secondary mode peak at ~102-nm volume-equivalent diameter assuming 2 g·cm −3 in void-free density in both sets of samples. More than half of the rBC cores are thickly coated during the CLY (fBC = 57.5%); the percentage is slightly lower (fBC = 48.3%) on weekdays. Diurnal patterns in rBC mass and mixing state differ for the two sampling periods, which are attributed to the distinct anthropogenic activities. The rBC mass and CO mixing ratios are strongly correlated with slopes of 0.0070 and 0.0016 μg·m

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Section: Rbc Mass Size and Mixing Statesupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Section: Rbc Mass Size and Mixing Statementioning

confidence: 99%

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Characteristics of Black Carbon Aerosol during the Chinese Lunar Year and Weekdays in Xi’an, China

et al. 2015

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“…1,7 In particular, sulfate particles internally mixed with soot should be investigated because the mix can enhance the light absorption of soot particles by at least 30%. 8 In addition to physical attachment, heterogeneous reactions of sea salt and mineral dust particles in the atmosphere can affect their properties. 2,3 Through laboratory experiments it is becoming increasingly clear that ubiquitous sea salt and alkaline mineral dust can heterogeneously react with acidic gases (e.g., SO 2 , NO 2 , HNO 3 , and organic acids).…”

Section: Introductionmentioning

confidence: 99%

Internally Mixed Sea Salt, Soot, and Sulfates at Macao, a Coastal City in South China

Shao

Shen

et al. 2011

Journal of the Air & Waste Management Association

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Direct observation of the mixing state of aerosol particles in a coastal urban city is critical to understand atmospheric processing and hygroscopic growth in humid air. Morphology, composition, and mixing state of individual aerosol particles from Macao, located south of the Pearl River Delta (PRD) and 100 km west of Hong Kong, were investigated using scanning electron microscopy (SEM) and transmission electron microscopy coupled with energy-dispersive X-ray spectrometry (TEM/EDX). SEM images show that soot and roughly spherical particles are prevalent in the samples. Based on the compositions of individual aerosol particles, aerosol particles with roughly spherical shape are classified into coarse Na-rich and fine S-rich particles. TEM/EDX indicates that each Na-rich particle consists of a Na-S core and NaNO 3 shell. Even in the absence of heavy pollution, the marine sea salt particles were completely depleted in chloride, and Na-related sulfates and nitrates were enriched in Macao air. The reason could be that SO 2 from the polluted PRD and ships in the South China Sea and NO 2 from vehicles in the city sped up the chlorine depletion in sea salt through heterogeneous reactions. Fresh soot particles from vehicular emissions mainly occur near curbside. However, there are many aged soot particles in the sampling site surrounded by main roads 200 to 400 m away, suggesting that the fresh soot likely underwent a quick aging. Overall, secondary nitrates and sulfates internally mixed with soot and sea salt particles can totally change their surface hygroscopicity in coastal cities. INTRODUCTIONAerosols in the atmosphere can undergo heterogeneous reactions and alter trace gas-phase species. Aerosol particles from different sources become internal mixtures of both water-soluble and insoluble components due to condensation and coagulation. As a result of the atmospheric processing, aerosols show diverse changes in their chemical and physical properties, such as chemical composition, size, morphology, and hygroscopicity.

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“…Atmospheric aging of soot has been assessed via aircraft (Schwarz et al, 2008) and balloon measurements (Renard et al, 2005) and indicate a fast mixing of soot particles with, for example, sulfate species (Johnson et al, 2005) and coating with secondary organic products (Moffet and Prather, 2009). This fast mixing impedes a direct comparison of fresh particles with their corresponding aged particles.…”

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confidence: 99%

Aging induced changes on NEXAFS fingerprints in individual combustion particles

et al. 2011

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Abstract. Soot particles can significantly influence the Earth's climate by absorbing and scattering solar radiation as well as by acting as cloud condensation nuclei. However, despite their environmental (as well as economic and political) importance, the way these properties are affected by atmospheric processing of the combustion exhaust gases is still a subject of discussion. In this work, individual soot particles emitted from two different vehicles, a EURO 2 transporter, a EURO 3 passenger car, and a wood stove were investigated on a single-particle basis. The emitted exhaust, including the particulate and the gas phase, was processed in a smog chamber with artificial solar radiation. Single particle specimens of both unprocessed and aged soot were characterized using near edge X-ray absorption fine structure spectroscopy (NEXAFS) and scanning electron microscopy. Comparison of NEXAFS spectra from the unprocessed particles and those resulting from exhaust photooxidation in the chamber revealed changes in the carbon functional group content. For the wood stove emissions, these changes were minor, related to the relatively mild oxidation conditions. For the EURO 2 transporter emissions, the most apparent change was that of carboxylic carbon from oxidized organic compounds condensing on the primary soot particles. For the EURO 3 car emissions oxidation of primary soot particles upon photochemical aging has likely contributed as well. Overall, Correspondence to: M. Ammann (markus.ammann@psi.ch) the changes in the NEXAFS fingerprints were in qualitative agreement with data from an aerosol mass spectrometer. Furthermore, by taking full advantage of our in situ microreactor concept, we show that the soot particles from all three combustion sources changed their ability to take up water under humid conditions upon photochemical aging of the exhaust. Due to the selectivity and sensitivity of the NEXAFS technique for the water mass, also small amounts of water taken up into the internal voids of agglomerated particles could be detected. Because such small amounts of water uptake do not lead to measurable changes in particle diameter, it may remain beyond the limits of volume growth measurements, especially for larger agglomerated particles.

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Coatings and their enhancement of black carbon light absorption in the tropical atmosphere

Cited by 313 publications

References 40 publications

Characteristics of Black Carbon Aerosol during the Chinese Lunar Year and Weekdays in Xi’an, China

Characteristics of Black Carbon Aerosol during the Chinese Lunar Year and Weekdays in Xi’an, China

Internally Mixed Sea Salt, Soot, and Sulfates at Macao, a Coastal City in South China

Aging induced changes on NEXAFS fingerprints in individual combustion particles

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