A1 Journal article (refereed), original research

A new method for extraction of methanol-soluble brown carbon: Implications for investigation of its light absorption ability

Open Access publication

Publication Details
Authors: Yan Fangping, Kang Shichang, Sillanpää Mika, Hu Zhaofu, Gao Shaopeng, Chen Pengfei, Gautam Sangita, Reinikainen Satu-Pia, Li Chaoliu
Publisher: Elsevier
Publication year: 2020
Language: English
Related Journal or Series Information: Environmental Pollution
Volume number: 262
Issue number: 114300
Start page: 1
End page: 12
Number of pages: 12
ISSN: 0269-7491
eISSN: 1873-6424
JUFO-Level of this publication: 2
Open Access: Open Access publication
Location of the parallel saved publication: http://urn.fi/URN:NBN:fi-fe2020070646957

As an important component of organic carbon (OC), brown carbon (BrC)
plays a significant role in radiative forcing in the atmosphere.
Water-insoluble OC (WIOC) generally has higher light absorption ability
than water-soluble OC (WSOC). The mass absorption cross-section (MAC) of
WIOC is normally investigated by dissolving OC in methanol. However,
all the current methods have shortcomings due to neglecting the methanol
insoluble particulate carbon that is detached from the filter and
suspended in methanol extracts, which results in MAC uncertainties of
the methanol-soluble BrC and its climate warming estimation. In this
study, by investigating typical biomass combustion sourced aerosols from
the Tibetan Plateau and ambient aerosols from rural and urban areas in
China, we evaluated the light absorption of extractable OC fraction for
the existing methods. Moreover, a new method was developed to overcome
the methanol insoluble particulate carbon detachment problem to achieve
more reliable MAC values. We found that OC can be dissolved in methanol
in a short time (e.g., 1 h) and ultrasonic treatment and long-term
soaking do not significantly increase the extractable OC fraction.
Additionally, we proved that methanol insoluble particulate carbon
detachment in methanol does exist in previous methods, causing
overestimation of the BrC mass extracted by methanol and thus the
underestimation of MAC values. We therefore recommend the newly
developed extraction method in this study to be utilized in future
related studies to quantitatively obtain the light absorption property
of methanol-soluble BrC.

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Last updated on 2020-31-08 at 13:34