Stable sulfur isotope ratios and chemical compositions of fine aerosols (PM2.5) in Beijing, China

Lianfang Wei; Siyao Yue; Wanyu Zhao; Wenyi Yang; Yingjie Zhang; Lujie Ren; Xiaokun Han; Qingjun Guo; Yele Sun; Zifa Wang; Pingqing Fu

doi:10.1016/j.scitotenv.2018.03.153

Stable sulfur isotope ratios and chemical compositions of fine aerosols (PM_2.5) in Beijing, China

Sci Total Environ. 2018 Aug 15:633:1156-1164. doi: 10.1016/j.scitotenv.2018.03.153. Epub 2018 Mar 30.

Authors

Lianfang Wei¹, Siyao Yue¹, Wanyu Zhao¹, Wenyi Yang², Yingjie Zhang², Lujie Ren³, Xiaokun Han⁴, Qingjun Guo⁵, Yele Sun¹, Zifa Wang¹, Pingqing Fu⁶

Affiliations

¹ State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; University of Chinese Academy of Sciences, Beijing 100049, China.
² State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
³ Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China.
⁴ Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China; Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China.
⁵ Center for Environmental Remediation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
⁶ Institute of Surface-Earth System Science, Tianjin University, Tianjin 300072, China; State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: fupingqing@tju.edu.cn.

PMID: 29758867
DOI: 10.1016/j.scitotenv.2018.03.153

Abstract

Pervasive particulate pollution has been observed over large areas of the North China Plain. The high level of sulfate, a major component in fine particles, is pronounced during heavy pollution periods. Being different from source apportionments by atmospheric chemistry-transport model and receptor modeling methods, here we utilize sulfur isotopes to discern the potential emission sources. Sixty-five daily PM_2.5 samples were collected at an urban site in Beijing between September 2013 and July 2014. Inorganic ions, organic/elemental carbon and stable sulfur isotopes of sulfate were analyzed. The "fingerprint" characteristics of stable sulfur isotopic composition, together with trajectory clustering modeled by HYSPLIT-4 (HYbrid Single-Particle Lagrangian Integrated Trajectory) and FLEXPART ("FLEXible PARTicle dispersion model"), was employed to identify potential aerosol sources in Beijing. Results exhibited a distinctive seasonality with sulfate, nitrate, ammonium, organic matter, and element carbon being the dominant species of PM_2.5. Elevated concentrations of chloride with high organic matter were found in autumn and winter as a result of enhanced fossil fuel (mainly coal) combustion. The δ³⁴S values of the Beijing aerosols ranged from 2.8‰ to 9.9‰ with an average of 6.0 ± 1.8‰, further indicating that the major sulfur source was direct coal burning emission. Owing to the changing patterns between oxidation pathways of S(IV) in different seasons, δ³⁴S values varied with a winter maximum (8.2 ± 1.1‰) and a summer minimum (4.9 ± 1.9‰). The results of trajectory clustering and FLEXPART demonstrated that higher concentrations of sulfate with lower sulfur isotope ratios (4.6 ± 0.8‰) were associated with air masses from the south or east, whereas lower sulfate concentrations with heavier sulfur isotope ratios (6.7 ± 1.6‰) were observed when the air masses were mainly from the north or northwest. These results suggested that the fine aerosol pollution in Beijing, especially sulfate pollution, was mainly due to coal combustion sources from regional and local regions.

Keywords: PM(2.5); Seasonal variation; Sources; Sulfate; Sulfur isotope.