Implication of Light Absorption Enhancement and Mixing State of Black Carbon (BC) by Coatings in Hong Kong

Guo-Liang Li; Li Sun; Kin-Fai Ho; Ka-Chun Wong; Zhi Ning

doi:10.4209/aaqr.2017.11.0473

Implication of Light Absorption Enhancement and Mixing State of Black Carbon (BC) by Coatings in Hong Kong

Guo-Liang Li, Li Sun, Kin-Fai Ho, Ka-Chun Wong, Zhi Ning^*

^*Corresponding author for this work

School of Energy and Environment

Research output: Journal Publications and Reviews › RGC 21 - Publication in refereed journal › peer-review

14 Citations (Scopus)

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Abstract

Simultaneous measurements of black carbon (BC) and non-refractory PM₁ aerosol chemical compositions were performed in autumn 2016 at a suburban site in Hong Kong. A thermodenuder (TD) was employed at different heating temperatures to remove semi-volatile aerosol fractions to varying degrees. The light absorption enhancement (E_abs) of BC due to semi-volatile coatings at seven wavelengths was evaluated, and the coating fractions were further analyzed. Results showed that the overall E_abs ranged from 1.58 ± 0.13 (470 nm) to 1.64 ± 0.16 (660 nm) at 280°C and increased very little from 50°C (1.02–1.04) to 200°C (1.13–1.20). The lensing-effect-related E_abs was probably attributable to the presence of ammonium and sulfate. Furthermore, the ratio of the coating thickness to the BC core radius was around 1.0–2.0 based on Mie calculations. This work evaluated the E_abs from coatings in Hong Kong and implied the BC mixing state, thus providing a critical reference for climate models on the role of aerosol in global warming.

Original language	English
Pages (from-to)	2753-2763
Journal	Aerosol and Air Quality Research
Volume	18
Issue number	11
DOIs	https://doi.org/10.4209/aaqr.2017.11.0473
Publication status	Published - Nov 2018

Research Keywords

Thermodenuder
BC coating
Mie calculation
BROWN CARBON
ORGANIC AEROSOL
PARTICULATE MATTER
OPTICAL-PROPERTIES
ANGSTROM EXPONENT
DIESEL EXHAUST
URBAN AREA
REAL-TIME
PARTICLES
AETHALOMETER

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title = "Implication of Light Absorption Enhancement and Mixing State of Black Carbon (BC) by Coatings in Hong Kong",

abstract = "Simultaneous measurements of black carbon (BC) and non-refractory PM1 aerosol chemical compositions were performed in autumn 2016 at a suburban site in Hong Kong. A thermodenuder (TD) was employed at different heating temperatures to remove semi-volatile aerosol fractions to varying degrees. The light absorption enhancement (Eabs) of BC due to semi-volatile coatings at seven wavelengths was evaluated, and the coating fractions were further analyzed. Results showed that the overall Eabs ranged from 1.58 ± 0.13 (470 nm) to 1.64 ± 0.16 (660 nm) at 280°C and increased very little from 50°C (1.02–1.04) to 200°C (1.13–1.20). The lensing-effect-related Eabs was probably attributable to the presence of ammonium and sulfate. Furthermore, the ratio of the coating thickness to the BC core radius was around 1.0–2.0 based on Mie calculations. This work evaluated the Eabs from coatings in Hong Kong and implied the BC mixing state, thus providing a critical reference for climate models on the role of aerosol in global warming.",

keywords = "Thermodenuder, BC coating, Mie calculation, BROWN CARBON, ORGANIC AEROSOL, PARTICULATE MATTER, OPTICAL-PROPERTIES, ANGSTROM EXPONENT, DIESEL EXHAUST, URBAN AREA, REAL-TIME, PARTICLES, AETHALOMETER",

author = "Guo-Liang Li and Li Sun and Kin-Fai Ho and Ka-Chun Wong and Zhi Ning",

year = "2018",

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doi = "10.4209/aaqr.2017.11.0473",

language = "English",

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journal = "Aerosol and Air Quality Research",

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T1 - Implication of Light Absorption Enhancement and Mixing State of Black Carbon (BC) by Coatings in Hong Kong

AU - Li, Guo-Liang

AU - Sun, Li

AU - Ho, Kin-Fai

AU - Wong, Ka-Chun

AU - Ning, Zhi

PY - 2018/11

Y1 - 2018/11

N2 - Simultaneous measurements of black carbon (BC) and non-refractory PM1 aerosol chemical compositions were performed in autumn 2016 at a suburban site in Hong Kong. A thermodenuder (TD) was employed at different heating temperatures to remove semi-volatile aerosol fractions to varying degrees. The light absorption enhancement (Eabs) of BC due to semi-volatile coatings at seven wavelengths was evaluated, and the coating fractions were further analyzed. Results showed that the overall Eabs ranged from 1.58 ± 0.13 (470 nm) to 1.64 ± 0.16 (660 nm) at 280°C and increased very little from 50°C (1.02–1.04) to 200°C (1.13–1.20). The lensing-effect-related Eabs was probably attributable to the presence of ammonium and sulfate. Furthermore, the ratio of the coating thickness to the BC core radius was around 1.0–2.0 based on Mie calculations. This work evaluated the Eabs from coatings in Hong Kong and implied the BC mixing state, thus providing a critical reference for climate models on the role of aerosol in global warming.

AB - Simultaneous measurements of black carbon (BC) and non-refractory PM1 aerosol chemical compositions were performed in autumn 2016 at a suburban site in Hong Kong. A thermodenuder (TD) was employed at different heating temperatures to remove semi-volatile aerosol fractions to varying degrees. The light absorption enhancement (Eabs) of BC due to semi-volatile coatings at seven wavelengths was evaluated, and the coating fractions were further analyzed. Results showed that the overall Eabs ranged from 1.58 ± 0.13 (470 nm) to 1.64 ± 0.16 (660 nm) at 280°C and increased very little from 50°C (1.02–1.04) to 200°C (1.13–1.20). The lensing-effect-related Eabs was probably attributable to the presence of ammonium and sulfate. Furthermore, the ratio of the coating thickness to the BC core radius was around 1.0–2.0 based on Mie calculations. This work evaluated the Eabs from coatings in Hong Kong and implied the BC mixing state, thus providing a critical reference for climate models on the role of aerosol in global warming.

KW - Thermodenuder

KW - BC coating

KW - Mie calculation

KW - BROWN CARBON

KW - ORGANIC AEROSOL

KW - PARTICULATE MATTER

KW - OPTICAL-PROPERTIES

KW - ANGSTROM EXPONENT

KW - DIESEL EXHAUST

KW - URBAN AREA

KW - REAL-TIME

KW - PARTICLES

KW - AETHALOMETER

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DO - 10.4209/aaqr.2017.11.0473

M3 - RGC 21 - Publication in refereed journal

SN - 1680-8584

VL - 18

SP - 2753

EP - 2763

JO - Aerosol and Air Quality Research

JF - Aerosol and Air Quality Research

IS - 11

ER -

Implication of Light Absorption Enhancement and Mixing State of Black Carbon (BC) by Coatings in Hong Kong

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