Atmospheric Brown Carbon at Tibetan Plateau: Regional Differences in Chemical Composition and Light Absorption Properties
Authors/Creators
- 1. Northwest Institute of Eco-Environment and Resources, Chinese Academy of Science
- 2. Department of Chemistry, Purdue University
Description
Fine particular matter (PM2.5) filter samples were collected from two high-altitude remote sites located at southern (QOMS) and northern (WLG) regions of the Tibetan Plateau (TP) to explore the regional difference on brown carbon (BrC) properties. Chemical differences in BrC composition representative of these two areas were inferred from molecular-level analysis of the PM2.5 samples using a high-performance liquid chromatography coupled with photo diode array and high-resolution mass spectrometry detectors. The results show that more polar BrC chromophores were abundant in QOMS, while contributions from both polar and less polar chromophores were comparable in WLG. Higher mass absorption coefficient of BrC was observed at QOMS than WLG. Strong BrC chromophores in QOMS samples were identified as oxygenated aromatics and nitrophenol compounds, while organosulfate compounds were found in WLG. The results of this study indicate the regional differences in major BrC chromophores and provide insights into their sources and chemical processes.