Water-soluble brown carbon in atmospheric aerosols along the transport pathway of Asian dust: Optical properties, chemical compositions, and potential sources

Hui Wen; Yue Zhou; Xuanye Xu; Tianshuang Wang; Quanliang Chen; Qingcai Chen; Weijun Li; Zhe Wang; Zhongwei Huang; Tian Zhou; Jinsen Shi; Jianrong Bi; Mingxia Ji; Xin Wang

doi:10.1016/j.scitotenv.2021.147971

Water-soluble brown carbon in atmospheric aerosols along the transport pathway of Asian dust: Optical properties, chemical compositions, and potential sources

Sci Total Environ. 2021 Oct 1:789:147971. doi: 10.1016/j.scitotenv.2021.147971. Epub 2021 May 24.

Authors

Hui Wen¹, Yue Zhou², Xuanye Xu³, Tianshuang Wang², Quanliang Chen³, Qingcai Chen⁴, Weijun Li⁵, Zhe Wang⁶, Zhongwei Huang², Tian Zhou², Jinsen Shi², Jianrong Bi², Mingxia Ji², Xin Wang⁷

Affiliations

¹ Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China; Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China.
² Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China.
³ College of Atmospheric Sciences, Chengdu University of Information Technology, Chengdu 610225, China.
⁴ School of Environmental Science and Engineering, Shaanxi University of Science and Technology, Xi'an 710021, China.
⁵ Department of Atmospheric Sciences, School of Earth Sciences, Zhejiang University, Hangzhou 320007, China.
⁶ Division of Environment and Sustainability, The Hong Kong University of Science and Technology, Hong Kong, China.
⁷ Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China; Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin 300072, China. Electronic address: wxin@lzu.edu.cn.

PMID: 34082197
DOI: 10.1016/j.scitotenv.2021.147971

Abstract

As an important type of light-absorbing aerosol, brown carbon (BrC) has the potential to affect the atmospheric photochemistry and Earth's energy budget. A comprehensive field campaign was carried out along the transport pathway of Asian dust during the spring of 2016, including a desert site (Erenhot), a rural site (Zhangbei), and an urban site (Jinan), in northern China. Optical properties, bulk chemical compositions, and potential sources of water-soluble brown carbon (WS-BrC) were investigated in atmospheric total suspended particulate (TSP) samples. Samples from Zhangbei had higher mass absorption efficiency at 365 nm (MAE₃₆₅, 1.32 ± 0.34 m² g^-1) than those from Jinan (1.00 ± 0.23 m² g^-1) and Erenhot (0.84 ± 0.30 m² g^-1). Compere to the non-dust samples, elevated water-soluble organic carbon (WSOC) concentrations and MAE₃₆₅ values of dust samples from Erenhot are related to the input of high molecular weight organic compounds and biogenic matter from the Gobi Desert, while lower values from Zhangbei and Jinan are attributed to the dilution effect caused by strong northwesterly winds. Based on fluorescence excitation-emission matrix spectra and parallel factor analysis, two humic-like (C1 and C2) and two protein-like (C3 and C4) substances were identified. Together, C1 and C2 accounted for ~64% of total fluorescence intensity at the highly polluted urban Jinan site; C3 represented ~45% at the rural Zhangbei site where local biomass burning affects; and C4 contributed ~24% in the desert region (Erenhot) due to dust-sourced biogenic substances. The relative absorptive forcing of WS-BrC compared to black carbon at 300-400 nm was about 31.3%, 13.9%, and 9.2% during non-dust periods at Erenhot, Zhangbei, and Jinan, respectively, highlighting that WS-BrC may significantly affect the radiative balance of Earth's climate system and should be included in radiative forcing models.

Keywords: Brown carbon; Fluorescence excitation–emission matrix spectra; PARAFAC; Radiative forcing efficiency; Source apportionment.

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Carbon / analysis
China
Dust*
Environmental Monitoring
Particulate Matter / analysis
Water

Substances

Aerosols
Air Pollutants
Dust
Particulate Matter
Water
Carbon