Seasonal variation of water-soluble brown carbon in Qingdao, China: Impacts from marine and terrestrial emissions

Yanan Zhan; Jianlong Li; Narcisse T Tsona; Bing Chen; Caiqing Yan; Christian George; Lin Du

doi:10.1016/j.envres.2022.113144

Seasonal variation of water-soluble brown carbon in Qingdao, China: Impacts from marine and terrestrial emissions

Environ Res. 2022 Sep;212(Pt A):113144. doi: 10.1016/j.envres.2022.113144. Epub 2022 Mar 24.

Authors

Yanan Zhan¹, Jianlong Li¹, Narcisse T Tsona¹, Bing Chen¹, Caiqing Yan¹, Christian George², Lin Du³

Affiliations

¹ Environment Research Institute, Shandong University, Binhai Road 72, Qingdao, 266237, China.
² Université Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, F-69626, Villeurbanne, France.
³ Environment Research Institute, Shandong University, Binhai Road 72, Qingdao, 266237, China. Electronic address: lindu@sdu.edu.cn.

PMID: 35341756
DOI: 10.1016/j.envres.2022.113144

Abstract

Brown carbon (BrC) has been attracting more and more attention owing to its significant effects on climate. However, the limited knowledge on its chemical composition and sources limits the precision of aerosol radiative forcing estimated by climate models. In this study, the chemical components of PM_2.5 and optical properties of water-soluble BrC (WS-BrC) were investigated from atmospheric particles collected in summer and winter in Qingdao, China. On the whole, though there were slight diurnal variations, seasonal differences were more obvious. Due to the influence of emission sources and meteorological conditions, the heavier pollution of carbonaceous aerosols occurred in winter. By comparison, the absorption Ångström exponent (AAE) and mass absorption efficiency of WS-BrC at 365 nm (MAE₃₆₅) showed that WS-BrC in winter had stronger wavelength dependence and light absorption capacity, which might be associated with biomass burning source contributions. This was further confirmed by a strong correlation between the light absorption coefficient at 365 nm (Abs₃₆₅) and non-sea salt K⁺, an indicator for biomass burning emissions. Four fluorescent components (C1∼C4) with high unsaturation in water-soluble organic carbon (WSOC) were identified by excitation-emission matrix fluorescence spectroscopy combined with parallel factor analysis method, which showed that WSOC in Qingdao was mainly related to humic-like chromophores. It is worth noting that C1 was similar to the water-soluble chromophore of simulated marine aerosols, which proved that marine emissions do have a certain impact on atmospheric particulate matter in coastal areas. In addition, the results of source analysis showed that WS-BrC originated from different terrestrial sources in different seasons. The current results may help to improve the knowledge of optical properties of WS-BrC in coastal cities, optimize the global climate model and formulate air management policies.

Keywords: Chromophore; Excitation-emission matrix fluorescence spectroscopy; Marine and terrestrial emissions; Optical properties; PARAFAC; Water-soluble brown carbon.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Aerosols / analysis
Air Pollutants* / analysis
Biomass
Carbon* / analysis
China
Environmental Monitoring / methods
Particulate Matter / analysis
Seasons
Water / chemistry

Substances

Aerosols
Air Pollutants
Particulate Matter
Water
Carbon