Chemical characterization of marine aerosols from two cruises over the South China Sea: Importance of biomass burning and secondary formation

Yinxi Yao; Yingyi Zhang; Junwei Song; Qi Yuan; Shan Wang; Xiaoying Li; Yuqing Zhang; Xiang Ding; Weihai Xu; Xiang Su; Senchao Lai

doi:10.1016/j.scitotenv.2023.161551

Chemical characterization of marine aerosols from two cruises over the South China Sea: Importance of biomass burning and secondary formation

Sci Total Environ. 2023 Apr 1:867:161551. doi: 10.1016/j.scitotenv.2023.161551. Epub 2023 Jan 11.

Authors

Yinxi Yao¹, Yingyi Zhang¹, Junwei Song², Qi Yuan¹, Shan Wang¹, Xiaoying Li¹, Yuqing Zhang³, Xiang Ding³, Weihai Xu⁴, Xiang Su⁴, Senchao Lai⁵

Affiliations

¹ The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
² Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, Eggenstein-Leopoldshafen, Germany. Electronic address: junwei.song@kit.edu.
³ State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China.
⁴ Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.
⁵ The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, School of Environment and Energy, South China University of Technology, Guangzhou 510006, China. Electronic address: sclai@scut.edu.cn.

PMID: 36640875
DOI: 10.1016/j.scitotenv.2023.161551

Abstract

Total suspended particle (TSP) samples were collected during June-July 2015 in the northern South China Sea (NSCS) and August-September 2016 in the western South China Sea (WSCS). Water-soluble ions (WSIs), organic carbon (OC), elemental carbon (EC), and organic compounds were measured. The average concentrations of WSIs, OC, EC and organic compounds were 19.4 ± 10.9 μg m^-3, 2.48 ± 1.54 μgC m^-3, 0.31 ± 0.25 μgC m^-3 and 789 ± 217 ng m^-3 in the NSCS, and were 10.2 ± 4.71 μg m^-3, 1.76 ± 1.82 μgC m^-3, 0.43 ± 0.32 μgC m^-3 and 781 ± 342 ng m^-3 in the WSCS. In both cruises, sea salt ions (Na⁺ and Cl^-) and secondary inorganic ions (SO₄^2-, NO₃^-, and NH₄⁺) were the main species of WSIs, accounting for 54.0 % and 43.6 % in the NSCS, and for 35.0 % and 54.0 % in the WSCS. The secondary products (dicarboxylic acids and aromatic acids) (NSCS: 73.3 %; WSCS: 73.9 %) and saccharides (NSCS: 19.0 %; WSCS: 18.0 %) accounted large fractions of organic compounds in aerosol particles over the SCS. These results suggest sea salt emissions and secondary formation are the main sources of the aerosols over the SCS in summer. The positive correlations between the biomass burning tracers (nss-K⁺ and levoglucosan) and OC as well as organic compounds indicated that biomass burning from nearby continents was also an important source of organic aerosols over the SCS. Based on back-trajectory analysis and satellite fire spots, Indochina Peninsula and China were proposed as the main continental source areas of non-sea salt WSIs and organic compounds. Our results highlight the significant contribution of continental outflow especially biomass burning and photochemical secondary oxidation to the organic compositions of aerosol particles over the SCS in summertime.

Keywords: Aerosol composition; Biomass burning; Secondary organic aerosols; South China Sea; Terrestrial outflow.