Particulate Elemental Carbon in the Atmosphere

Wolff, George T.

doi:10.1080/00022470.1981.10465298

Cited by 72 publications

(26 citation statements)

References 17 publications

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“…The past three decades have seen increasing interest in black carbon (BC) and elemental carbon (EC), both of which originate from the incomplete combustion of carbonaceous combustibles, due to their strong light-absorbing properties and their possible health effects (Johnson and Huntzicker 1979;Wolff 1981;Turco et al 1983;Molnar et al 1999;Jacobson 2000Jacobson , 2001Ramanathan and Carmichael 2008;Allen et al 2012). EC represents thermally refractory carbon with a graphitic structure, whereas BC is commonly used to define the extent to which an aerosol sample exhibits light-absorbing properties (Salako et al 2012;Gray and Cass 1998;Huntzicker et al 1982;Watson et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Comparison of elemental and black carbon measurements during normal and heavy haze periods: implications for research

Zhi

Chen

Xue

et al. 2014

Environ Monit Assess

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Studies specifically addressing the elemental carbon (EC)/black carbon (BC) relationship during the transition from clean-normal (CN) air quality to heavy haze (HH) are rare but have important health and climate implications. The present study, in which EC levels are measured using a thermal-optical method and BC levels are measured using an optical method (aethalometer), provides a preliminary insight into this issue. The average daily EC concentration was 3.08±1.10 μg/m 3 during the CN stage but climbed to 11.77±2.01 μg/m 3 during the HH stage. More importantly, the BC/EC ratio averaged 0.92±0.14 during the CN state and increased to 1.88± 0.30 during the HH state. This significant increase in BC/ EC ratio has been confirmed to result partially from an increase in the in situ light absorption efficiency (σ ap ) due to an enhanced internal mixing of the EC with other species. However, the exact enhancement of σ ap was unavailable because our monitoring scheme could not acquire the in situ absorption (b ap ) essential for σ ap calculation. This reveals a need to perform simultaneous measurement of EC and b ap over a time period that includes both the CN and HH stages. In addition, the sensitivity of EC to both anthropogenic emissions and HH conditions implies a need to systematically study how to include EC complex (EC concentration, OC/EC ratio, and σ ap ) as an indicator in air quality observations, in alert systems that assess air quality, and in the governance of emissions and human behaviors.

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Section: Introductionmentioning

confidence: 99%

Comparison of elemental and black carbon measurements during normal and heavy haze periods: implications for research

Zhi

Chen

Xue

et al. 2014

Environ Monit Assess

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“…Light attenuation by absorption was attributed entirely to black carbon (BC) (Gundel et al, 1984;Wolff, 1984).…”

Section: The Aircraft and Its Instrumentationmentioning

confidence: 99%

Airborne measurements of aerosol extinction in the lower and middle troposphere over Wyoming, USA

Han

Montague

Snider

2003

Atmospheric Environment

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Particle size distributions, and scattering and absorption coefficients were measured over the Green River basin of Wyoming during the Southwest Wyoming Visibility Study (SWYVIS) in February and March 1996. Eleven flights were carried out, using the Wyoming King Air research aircraft. In the least polluted regions of the planetary boundary layer, particle number densities detected in the diameter range 0.13-3.0 mm were o100 cm À3 . Aloft, in the stable air of the free troposphere, they were generally even lower, often falling to a few tens of particles per cm 3 . Analyses of bulk aerosol filter samples showed that organic carbonaceous material was the dominant chemical component, with sulfate and refractory species being the largest inorganic components. Combining the filter data with separately measured black carbon mass loading values allowed refractive indices for the aerosol to be calculated, so that PCASP measured size distributions could be revised. Characterizing size parameters were obtained by fitting particle populations to bimodal lognormal distributions. Particle size distributions were somewhat broader at higher altitudes so that larger particles made greater contributions to extinction. Optical closure was attempted by comparing scattering and total extinctions computed by Mie theory with the corresponding values derived from the observations. While the calculated and measured single scattering albedo average values were in reasonably good agreement, even though individual pairs of values sometimes differed significantly, computed scattering coefficients often exceeded those derived from the measurements, by an average of 60%. Reasons for this discrepancy are explored, including the possible modification of the size distribution by partial or total volatilization of particles within the nephelometer and its inlet. r

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“…As a vehicle passed, the mixing ratio x of its exhaust into the sampled air would increase from zero to a maximum value on a time scale of some 10 to 30 seconds, and would then decay. However, the maximum value of x was always small (less than 0.001, as will be shown below); so we may simplify Equations 6 to the following form for the timedependent concentration of CO2 and BC measured at the roadside in the dispersing plume of the vehicle after it has passed: 2 ]F could be determined from the ratio of instantaneous measurements; however, large inaccuracies might be introduced due to the different inherent time responses of the measuring instruments. Instead, we chose to integrate the excess BC and CO 2 over the duration of each individual plume event and then calculate the emission factor as:…”

Section: Measurement Approachmentioning

confidence: 99%

Individual Measurements of the Emission Factor of Aerosol Black Carbon in Automobile Plumes

Hansen

Rosen

1990

Journal of the Air & Waste Management Association

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Particulate Elemental Carbon in the Atmosphere

Cited by 72 publications

References 17 publications

Comparison of elemental and black carbon measurements during normal and heavy haze periods: implications for research

Comparison of elemental and black carbon measurements during normal and heavy haze periods: implications for research

Airborne measurements of aerosol extinction in the lower and middle troposphere over Wyoming, USA

Individual Measurements of the Emission Factor of Aerosol Black Carbon in Automobile Plumes

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