scholarly journals Ageing and hygroscopicity variation of black carbon particles in Beijing measured by a quasi-atmospheric aerosol evolution study (QUALITY) chamber

2017 ◽  
Vol 17 (17) ◽  
pp. 10333-10348 ◽  
Author(s):  
Jianfei Peng ◽  
Min Hu ◽  
Song Guo ◽  
Zhuofei Du ◽  
Dongjie Shang ◽  
...  
Keyword(s):  
Black Carbon ◽  
Atmospheric Aerosol ◽  
Ambient Air ◽  
Reaction Chamber ◽  
Flow Chamber ◽  
Study Quality ◽  
Hygroscopic Growth ◽  
Coating Materials ◽  
Average Growth ◽  
Evolution Study

Abstract. Measurements of ageing and hygroscopicity variation of black carbon (BC) particles in Beijing were conducted using a 1.2 m3 quasi-atmospheric aerosol evolution study (QUALITY) chamber, which consisted of a bottom flow chamber through which ambient air was pulled continuously and an upper reaction chamber where ageing of BC particles occurred. Within the reaction chamber, transmission of the solar ultraviolet irradiation was approximately 50–60 %, wall loss of primary gaseous pollutants was negligible, and BC exhibited a half-lifetime of about 3–7 h. Typically, equilibrium for the primary gases, temperature and relative humidity between the reaction chamber and ambient air was established within 1 h. Rapid growth of BC particles occurred, with an average total growth of 77 ± 33 nm and average growth rate of 26 ± 11 nm h−1. Secondary organic aerosols (SOA) accounted for more than 90 % of the coating mass. The O ∕ C ratio of SOA was 0.5, lower than the ambient level. The hygroscopic growth factor of BC particles decreased slightly with an initial thin coating layer because of BC reconstruction, but subsequently increased to 1.06–1.08 upon further ageing. The κ (kappa) values for BC particles and coating materials were calculated as 0.035 and 0.040 at the subsaturation and supersaturation conditions, respectively, indicating low hygroscopicity of coated SOA on BC particles. Hence, our results indicate that initial photochemical ageing of BC particles leads to considerable modifications to morphology and optical properties but does not appreciably alter the particle hygroscopicity in Beijing.

scholarly journals Aging and hygroscopicity variation of black carbon particles in Beijing measured by a quasi-atmospheric aerosol evolution study (QUALITY) chamber

2017 ◽  
Author(s):  
Jianfei Peng ◽  
Min Hu ◽  
Song Guo ◽  
Zhuofei Du ◽  
Dongjie Shang ◽  
...  
Keyword(s):  
Black Carbon ◽  
Atmospheric Aerosol ◽  
Ambient Air ◽  
Reaction Chamber ◽  
Flow Chamber ◽  
Study Quality ◽  
Hygroscopic Growth ◽  
Coating Materials ◽  
Average Growth ◽  
Evolution Study

Abstract. Measurements of aging and hygroscopicity variation of black carbon (BC) particles in Beijing were conducted using a 1.2 m3 quasi-atmospheric aerosol evolution study (QUALITY) chamber, which consisted of a bottom flow chamber where ambient air was pulled through continuously and an upper reaction chamber where aging of BC particles occurred. Within the reaction chamber, transmission of the solar ultraviolet irradiation was approximately 50 %–60 %, wall loss of primary gaseous pollutants was negligible, and BC exhibited a half-lifetime about 3–7 hours. Typically, equilibrium for the primary gases, temperature, and relative humidity between the reaction chamber and ambient air was established within 1 hour. Rapid growth of BC particles was observed, with an average total growth of 77 ± 33 nm and average growth rate of 26 ± 11 nm h−1. Secondary organic aerosol (SOA) accounted for more than 90 % of the coating mass. The O / C ratio of SOA was 0.5, lower than the ambient level. The hygroscopic growth factor of BC particles decreased slightly with an initial thin coating layer because of BC reconstruction, but subsequently increased to 1.06–1.08 upon further aging. The κ (kappa) values for BC particles and coating materials were calculated as 0.035 and 0.040 at the subsaturation and supersaturation conditions, respectively, indicating low hygroscopicity of coated SOA on BC particles. Hence, our results indicate that initial photochemical aging of BC particles does not appreciably alter the particle hygroscopicity in Beijing.

scholarly journals Quantifying black carbon light absorption enhancement by a novel statistical approach

2017 ◽  
Author(s):  
Cheng Wu ◽  
Dui Wu ◽  
Jian Zhen Yu
Keyword(s):  
Black Carbon ◽  
Light Absorption ◽  
Seasonal Pattern ◽  
Absorption Efficiency ◽  
Absorption Enhancement ◽  
Hygroscopic Growth ◽  
Pearl River Delta Region ◽  
Coating Materials ◽  
Air Masses ◽  
The Pearl River

Abstract. Black carbon (BC) particles in the atmosphere can absorb more light when coated by non-absorbing or weakly absorbing materials during atmospheric aging, due to the lensing effect. In this study, the light absorption enhancement factor, Eabs, was quantified using one year's measurement of mass absorption efficiency (MAE) in the Pearl River Delta region (PRD). A new approach for calculating primary MAE (MAEp), the key for Eabs estimation, is demonstrated using the Minimum R Squared (MRS) method, exploring the inherent source independency between BC and its coating materials. The annual average Eabs is found to be 1.52, exhibiting a clear seasonal pattern with higher values in summer and lower in the winter. Elevated Eabs in the rainy summer season is likely associated with aged air masses dominating from marine origin, along with long-range transport of biomass burning influenced air masses from Southeast Asia. Eabs induced by hygroscopic growth at elevated RH could be as high as 1.3. Core-shell Mie simulations along with measured Eabs and Angstrom absorption exponent (AAE) constraints suggest that in the PRD, the coating materials are unlikely to be dominated by brown carbon and the coating thickness is higher in the rainy season than the dry season. A negative correlation is found between AAE470–660 and RH, suggesting a dominant particle size of Dcore = 130 nm and Dshell/Dcore range of 2 to 4.

scholarly journals Study of Temporal Variations of Equivalent Black Carbon in a Coastal City in Northwest Spain Using an Atmospheric Aerosol Data Management Software

2021 ◽  
Vol 11 (2) ◽  
pp. 516
Author(s):  
María Piñeiro-Iglesias ◽  
Javier Andrade-Garda ◽  
Sonia Suárez-Garaboa ◽  
Soledad Muniategui-Lorenzo ◽  
Purificación López-Mahía ◽  
...  
Keyword(s):  
Data Management ◽  
Black Carbon ◽  
Light Absorption ◽  
Atmospheric Aerosol ◽  
Urban Areas ◽  
Radiative Properties ◽  
Anthropogenic Sources ◽  
Biomass Combustion ◽  
Management Support ◽  
Diurnal Variability

Light-absorbing carbonaceous aerosols (including black carbon (BC)) pose serious health issues and play significant roles in atmospheric radiative properties. Two-year measurements (2015–2016) of aerosol light absorption, combined with measurements of sub-micrometric particles, were continuously conducted in A Coruña (northwest (NW) Spain) to determine their light absorption properties: absorption coefficients (σabs) and the absorption Ångström exponent (AAE). The mean and standard deviation of equivalent black carbon (eBC) during the period of study were 0.85 ± 0.83 µg m−3, which are lower than other values measured in urban areas of Spain and Europe. High eBC concentrations found in winter are associated with an increase in emissions from anthropogenic sources in combination with lower mixing layer heights and frequent stagnant conditions. The pronounced diurnal variability suggests a strong influence from local sources. AAE had an average value of 1.26 ± 0.22 which implies that both fossil fuel combustion and biomass burning influenced optical aerosol properties. This also highlights biomass combustion in suburban areas, where the use of wood for domestic heating is encouraged, as an important source of eBC. All data treatment was gathered using SCALA© as atmospheric aerosol data management support software program.

scholarly journals Calibration of LACIS as a CCN detector and its use in measuring activation and hygroscopic growth of atmospheric aerosol particles

2006 ◽  
Vol 6 (12) ◽  
pp. 4519-4527 ◽  
Author(s):  
H. Wex ◽  
A. Kiselev ◽  
M. Ziese ◽  
F. Stratmann
Keyword(s):  
Sodium Chloride ◽  
Wall Temperature ◽  
Atmospheric Aerosol ◽  
Volume Fraction ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Urban Aerosol ◽  
Hygroscopic Growth ◽  
Atmospheric Aerosol Particles ◽  
Droplet Activation

Abstract. A calibration for LACIS (Leipzig Aerosol Cloud Interaction Simulator) for its use as a CCN (cloud condensation nuclei) detector has been developed. For this purpose, sodium chloride and ammonium sulfate particles of known sizes were generated and their grown sizes were detected at the LACIS outlet. From these signals, the effective critical super-saturation was derived as a function of the LACIS wall temperature. With this, LACIS is calibrated for its use as a CCN detector. The applicability of LACIS for measurements of the droplet activation, and also of the hygroscopic growth of atmospheric aerosol particles was tested. The activation of the urban aerosol particles used in the measurements was found to occur at a critical super-saturation of 0.46% for particles with a dry diameter of 75 nm, and at 0.42% for 85 nm, respectively. Hygroscopic growth was measured for atmospheric aerosol particles with dry diameters of 150, 300 and 350 nm at relative humidities of 98 and 99%, and it was found that the larger dry particles contained a larger soluble volume fraction of about 0.85, compared to about 0.6 for the 150 nm particles.

Black carbon linked aerosol hygroscopic growth: Size and mixing state are crucial

2019 ◽  
Vol 200 ◽  
pp. 110-118 ◽  
Author(s):  
Bighnaraj Sarangi ◽  
S. Ramachandran ◽  
T.A. Rajesh ◽  
Vishnu Kumar Dhaker
Keyword(s):  
Black Carbon ◽  
Hygroscopic Growth ◽  
Mixing State

scholarly journals Variation of the radiative properties during black carbon aging: theoretical and experimental intercomparison

2015 ◽  
Vol 15 (14) ◽  
pp. 19835-19872 ◽  
Author(s):  
C. He ◽  
K.-N. Liou ◽  
Y. Takano ◽  
R. Zhang ◽  
M. L. Zamora ◽  
...  
Keyword(s):  
Black Carbon ◽  
Cross Sections ◽  
Theoretical Calculations ◽  
Absorption Enhancement ◽  
Core Shell ◽  
Hygroscopic Growth ◽  
Aging Model ◽  
Scattering Cross ◽  
Coating Morphology ◽  
Scattering Cross Sections

Abstract. A theoretical black carbon (BC) aging model is developed to account for three typical evolution stages, namely, freshly emitted aggregates, coated BC by soluble material, and BC particles undergoing further hygroscopic growth. The geometric-optics surface-wave (GOS) approach is employed to compute the BC single-scattering properties at each aging stage, which are subsequently compared with laboratory measurements. Theoretical calculations are consistent with measurements in extinction and absorption cross sections for fresh BC aggregates, but overestimate the scattering cross sections for BC mobility diameters of 155, 245, and 320 nm, because of uncertainties associated with theoretical calculations for small particles as well as laboratory scattering measurements. The measured optical cross sections for coated BC by sulfuric acid and for those undergoing further hygroscopic growth are captured by theoretical calculations using a concentric core-shell structure, with differences of less than 20 %. This suggests that the core-shell shape represents the realistic BC coating morphology reasonably well in this case, which is consistent with the observed strong structure compaction during aging. We find that the absorption and scattering properties of fresh BC aggregates vary by up to 60 % due to uncertainty in the BC refractive index, which, however, is a factor of two smaller in the case of coated BC particles. Sensitivity analyses on the BC morphology show that the optical properties of fresh BC aggregates are more sensitive to fractal dimension than primary spherule size. The absorption and scattering cross sections of coated BC particles vary by more than a factor of two due to different coating structures. We find an increase of 20–250 % in absorption and a factor of 3–15 in scattering during aging, significantly depending on coating morphology and aging stages. Applying the aging model to CalNex 2010 field measurements, we show that the resulting BC direct radiative forcing (DRF) first increases from 1.5 to 1.7 W m-2 and subsequently decreases to 1.0 W m-2 during the transport from the Los Angeles Basin to downwind regions, as a result of the competition between absorption enhancement due to coating and dilution of BC concentration. The BC DRF can vary by up to a factor of two due to differences in BC coating morphology. Thus, an accurate estimate of BC DRF requires the incorporation of a dynamic BC aging process that accounts for realistic morphology in climate models, particularly for the regional analysis with high atmospheric heterogeneity.

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