Light attenuation cross-section of black carbon in an urban atmosphere in northern China--颗粒学报PARTICUOLOGY

Cao, J., Zhu, C., Ho, K., Han, Y., Shen, Z., Zhan, C., & Zhang, J. (2015). Light attenuation cross-section of black carbon in an urban atmosphere in northern China. Particuology, 18, 89–95. https://doi.org/10.1016/j.partic.2014.04.011

Light attenuation cross-section of black carbon in an urban atmosphere in northern China

Junji Cao^{a b *}, Chongshu Zhu ^a, Kinfai Ho ^c, Yongming Han ^a, Zhenxing Shen ^d, Changlin Zhan ^e, Jiaquan Zhang ^e

a Key Laboratory of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi’an 710075, China b Institute of Global Environmental Change, Xi’an Jiaotong University, Xi’an 710049, China c The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Shatin, Hong Kong, China d Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China e School of Environmental Science and Engineering, Hubei Polytechnic University, Hubei Key Laboratory of Mine Environmental Pollution Control and Remediation, Huangshi 435000, China

10.1016/j.partic.2014.04.011

Volume 18, February 2015, Pages 89-95

Received 2 September 2013, Revised 28 March 2014, Accepted 2 April 2014, Available online 20 August 2014.

E-mail: cao@loess.llqg.ac.cn; jjcao@ieecas.cn

Highlights

• Two-year's EC contents and BC light attenuation cross-sections (σ_ATN) in Xi’an were investigated.

• BC σ_ATN exhibited pronounced seasonal variability, averaging 23.0 m²/g annually.

• σ_ATN varied inversely with the ratios of EC/PM_2.5, EC/[SO₄²⁻], and EC/[NO₃⁻].

• The variations were mainly attributed to changes in EC loading and mixing mode of EC with sulfate.

Abstract

Fine particulate matter (PM_2.5) samples were collected over two years in Xi’an, China to investigate the relationships between the aerosol composition and the light absorption efficiency of black carbon (BC). Real-time light attenuation of BC at 880 nm was measured with an aethalometer. The mass concentrations and elemental carbon (EC) contents of PM_2.5 were obtained, and light attenuation cross-sections (σ_ATN) of PM_2.5 BC were derived. The mass of EC contributed ∼5% to PM_2.5 on average. BC σ_ATN exhibited pronounced seasonal variability with values averaging 18.6, 24.2, 16.4, and 26.0 m²/g for the spring, summer, autumn, and winter, respectively, while averaging 23.0 m²/g overall. σ_ATN varied inversely with the ratios of EC/PM_2.5, EC/[SO₄²⁻], and EC/[NO₃⁻]. This study of the variability in σ_ATN illustrates the complexity of the interactions among the aerosol constituents in northern China and documents certain effects of the high EC, dust, sulfate and nitrate loadings on light attenuation.

Graphical abstract

Keywords

Light attenuation cross-section; Elemental carbon; Dust; Xi'an

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