Measuring the morphology and density of internally mixed black carbon with  SP2 and VTDMA: new insight into the absorption enhancement of black carbon  in the atmosphere

Zhang, Yuxuan; Zhang, Qiang; Cheng, Yafang; Su, Hang; Kecorius, Simonas; Wang, Zhibin; Wu, Zhijun; Hu, Min; Zhu, Tong; Wiedensohler, Alfred; He, Kebin

doi:10.5194/amt-9-1833-2016

Cited by 84 publications

(87 citation statements)

References 43 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As in previous studies (Sedlacek et al, 2012;Liu et al, 2013;Zhang et al, 2016), the aging degree of BC-containing particles was characterized by the D p / D c ratio in this study. A higher D p / D c ratio for BC-containing particles indicates a higher aging degree, i.e., more coating materials on the BC surface.…”

Section: Aging Degree Of Bc-containing Particlesmentioning

confidence: 77%

“…Furthermore, the scattering cross section of a BC-containing particle is obtained from its scattering signal using the leading-edge-only (LEO) fit method (Gao et al, 2007). Zhang et al (2016) has demonstrated the validity of the LEO fit method for ambient BC-containing particles in China.…”

Section: Sampling Site and Measurementsmentioning

confidence: 99%

“…The light absorption capability of atmospheric BC is complex and poorly quantified, and it changes with the morphology, density and mixing state of the BC-containing particles (Schnaiter et al, 2005;Zhang et al, 2008;Knox et al, 2009;Peng et al, 2016). Previous theoretical (Jacobson, 2001;Moffet et al, 2009;Zhang et al, 2016) and observational (Knox et al, 2009;Cappa et al, 2012;Peng et al, 2016) studies showed a broad range of absorption enhancements (1.05-3.05) of BC-containing particles during the atmospheric aging process. To date, conflicts remain between model-and observation-based studies of the light absorption capability of atmospheric BC-containing particles (Jacobson, 2001;Cappa et al, 2012;Liu et al, 2015;Liu et al, 2017).…”

mentioning

confidence: 99%

“…Although the enhancement of BC light absorption due to coating materials on BC surfaces has already been intensively investigated (Schnaiter et al, 2005;Moffet et al, 2009;Shiraiwa et al, 2010;Zhang et al, 2016), there are few studies on the evolution of the light absorption capability of BC-containing particles with changing air pollution levels. The variation in the light absorption capability of BC-containing particles associated with air pollution can lead to different effects of BC aerosols on air quality and climate under different pollution levels.…”

mentioning

confidence: 99%

See 3 more Smart Citations

Amplification of light absorption of black carbon associated with air pollution

Zhang

Cheng

et al. 2018

Atmos. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

Abstract. The impacts of black carbon (BC) aerosols on air quality, boundary layer dynamics and climate depend not only on the BC mass concentration but also on the light absorption capability of BC. It is well known that the light absorption capability of BC depends on the amount of coating materials (namely other species that condense and coagulate on BC). However, the difference of light absorption capability of ambient BC-containing particles under different air pollution conditions (e.g., clean and polluted conditions) remains unclear due to the complex aging process of BC in the atmosphere. In this work, we investigated the evolution of light absorption capability for BC-containing particles with changing pollution levels in urban Beijing, China. During the campaign period (17 to 30 November 2014), with an increase in PM 1 concentration from ∼ 10 to ∼ 230 µg m −3 , we found that the mass-weighted averages of the aging degree and theoretical light absorption capability of BC-containing particles increased by ∼ 33 % and ∼ 18 %, respectively, indicating stronger light absorption capability of BC-containing particles under more polluted conditions due to more coating materials on the BC surface. By using an effective emission intensity (EEI) model, we further found that aging during regional transport plays an important role in the difference in the light absorption capability of BC-containing particles under different air pollution levels. During the pollution episode, ∼ 63 % of the BC over Beijing originated from regional sources outside of Beijing. These regionally sourced BC-containing particles were characterized by more coating materials on BC surfaces due to more coating precursors within more polluted air, which contributed ∼ 75 % of the increase in theoretical light absorption capability of BC observed in Beijing during the polluted period (PM 1 of ∼ 230 µg m −3 ) compared to that in the clean period (PM 1 of ∼ 10 µg m −3 ). Due to the increase in theoretical light absorption capability of BC associated with air pollution, the direct radiative forcing of BC was estimated to be increased by ∼ 18 % based on a simple radiation transfer model. Our work identified an amplification of theoretical light absorption and direct radiative forcing under a more polluted air environment due to more coating materials on BC. The air pollution control measures may, however, break the amplification effect by reducing emissions of both BC and the coating precursors and achieve co-benefits of both air quality and climate.

show abstract

Section: Aging Degree Of Bc-containing Particlesmentioning

confidence: 77%

Section: Sampling Site and Measurementsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

Amplification of light absorption of black carbon associated with air pollution

Zhang

Cheng

et al. 2018

Atmos. Chem. Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is the ratio of the drag force exerted on the irregular particle to the drag force exerted on its mass-equivalent sphere, when traveling at the same speed. The void space fraction (F vs ), i.e., volume of voids / total volume of particles derived from the mobility diameter, is estimated from the D me and D p of fresh and coated soot (Baron and Willeke, 2001;Zhang et al, 2016):…”

Section: Resultsmentioning

confidence: 99%

Morphological transformation of soot: investigation of microphysical processes during the condensation of sulfuric acid and limonene ozonolysis product vapors

et al. 2018

View full text Add to dashboard Cite

Abstract. The morphological transformation of soot particles via condensation of low-volatility materials constitutes a dominant atmospheric process with serious implications for the optical and hygroscopic properties, as well as atmospheric lifetime of the soot. We consider the morphological transformation of soot aggregates under the influence of condensation of vapors of sulfuric acid, and/or limonene ozonolysis products. This influence was systematically investigated using a Differential Mobility Analyzer coupled with an Aerosol Particle Mass Analyzer (DMA-APM) and the Tandem DMA techniques integrated with a laminar flowtube system. We hypothesize that the morphology transformation of soot results (in general) from a two-step process, i.e., (i) filling of void space within the aggregate and (ii) growth of the particle diameter. Initially, the transformation was dominated by the filling process followed by growth, which led to the accumulation of sufficient material that exerted surface forces, which eventually facilitated further filling. The filling of void space was constrained by the initial morphology of the fresh soot as well as the nature and the amount of condensed material. This process continued in several sequential steps until all void space within the soot aggregate was filled. And then "growth" of a spherical particle continued as long as vapors condensed on it. We developed a framework for quantifying the microphysical transformation of soot upon the condensation of various materials. This framework used experimental data and the hypothesis of "ideal sphere growth" and void filling to quantify the distribution of condensed materials in the complementary filling and growth processes. Using this framework, we quantified the percentage of material consumed by these processes at each step of the transformation. For the largest coating experiments, 6, 10, 24, and 58 % of condensed material went to filling process, while 94, 90, 76, and 42 % of condensed material went to growth process for 75, 100, 150, and 200 nm soot particles, respectively. We also used the framework to estimate the fraction of internal voids and open voids. This information was then used to estimate the volume-equivalent diameter of the soot aggregate containing internal voids and to calculate the dynamic shape factor, accounting for internal voids. The dynamic shape factor estimated based on the traditional assumption (of no internal voids) differed significantly from the value obtained in this study. Internal voids are accounted for in the experimentally derived dynamic shape factor determined in the present study. In fact, the dynamic shape factor adjusted for internal voids was close to 1 for the fresh soot particles considered in this study, indicating the particles were largely spherical. The effective density was strongly correlated with the morphological transformation responses to the condensed material on the soot particle, and the resultant effective density was determined by the (i) nature of the condensed material an...

show abstract

Numerical Investigation on Absorption Enhancement of Black Carbon Aerosols Partially Coated With Nonabsorbing Organics

et al. 2018

View full text Add to dashboard Cite

This study numerically evaluates the effects of aerosol microphysics, including coated volume fraction of black carbon (BC), shell/core ratio, and size distribution, on the absorption enhancement (Eab) of polydisperse BC aggregates partially coated by organics, which is calculated by the exact multiple‐sphere T‐matrix method. The coated volume fraction of BC plays a substantial role in determining the absorption enhancement of partially coated BC aggregates, which typically have an Eab in the range of ~1.0–2.0 with a larger value for larger coated volume fraction of BC as the shell/core ratio, BC geometry, and size distribution are fixed. The shell/core ratio, BC geometry, and size distribution have little impact on the Eab of coated BC with small coated volume fraction of BC, while they become significant for large coated volume fraction of BC. The Eab of partially coated BC particles can be slightly less than 1.0 for the large BC in the accumulation mode exhibiting large shell/core ratio and small coated volume fraction of BC, indicating that the absorption shows even slight decrease relative to uncoated BC particles. For partially coated BC aggregates in the accumulation and coarse modes, the refractive index uncertainties of BC result in the Eab differences of less than 9% and 2%, respectively, while those of organics can induce larger variations with the maximum differences up to 22% and 18%, respectively. Our study indicates that accounting for particle coating microphysics, particularly the coated volume fraction of BC, can potentially help to understand the differences in observations of largely variable absorption enhancements over various regions.

show abstract

Measuring the morphology and density of internally mixed black carbon with SP2 and VTDMA: new insight into the absorption enhancement of black carbon in the atmosphere

Cited by 84 publications

References 43 publications

Amplification of light absorption of black carbon associated with air pollution

Amplification of light absorption of black carbon associated with air pollution

Morphological transformation of soot: investigation of microphysical processes during the condensation of sulfuric acid and limonene ozonolysis product vapors

Numerical Investigation on Absorption Enhancement of Black Carbon Aerosols Partially Coated With Nonabsorbing Organics

Contact Info

Product

Resources

About