资源环境科技发展态势分析平台

In this study, PM2.5 filter samples were collected from two high-elevation sites located in the southern and northern areas of Tibetan Plateau (TP): the Qomolangma Station for Atmospheric Environmental Observation and Research (QOMS) and Waliguan Baseline Observatory (WLG), respectively. Collected samples were analyzed to examine the regional differences in aerosol properties and relate them to potential chemical processes in the TP area. The aerosol mass concentrations inferred from measured chemical components were higher at WLG (11.2 mu g m(-3)) compared to QOMS (6.8 mu g m(-3)). The chemical composition shows higher contribution of organic aerosol at QOMS than that of WLG. The optical properties of water-soluble organic carbon (WSOC) from the QOMS samples show higher light absorption efficient than those collected at WLG. The light absorption of WSOC at QOMS indicates significant pH dependence with enhanced light absorption at higher pH values, while the light absorption of WSOC from WLG samples show very weak pH dependence. The different pH dependence property suggests the different chemical composition between them. The molecular-level chemical composition investigated using high-resolution mass spectrometry (HRMS) assisted with an electrospray ionization (ESI) shows significant differences in WSOC composition representative of two sampling sites. For QOMS samples, CHO and CHON compounds are the major chemical species detected in the negative (-) ESI mode, while CHO and CHOS compounds are the most abundant chemical species detected by the same method in samples collected at WLG. The differences in their molecular composition indicate the different sources and chemical processes in these two regions.