To better understand the sources of atmospheric aerosols in winter, we collected size-resolved (9-stage) aerosols at Tianjin, North China, and studied for inorganic ions, carbonaceous components, diacids and related compounds. Inorganic ions were measured using ion chromatography (ICS-5000 System, China, Dai An). Organic carbon (OC) and elemental carbon (EC) were measured using OC/EC analyzer (USA, Sunset Laboratory Inc.), based on thermal light reflectance following the IMPROVE protocol of the protective visual environment. Water-soluble organic carbon (WSOC) was measured using the total organic carbon (TOC) analyzer (model: OI, 1030W + 1088). Concentrations of diacids and related compounds were measured using a capillary gas chromatography (GC; Agilent 7890B). Peak identification was carried out with reference to authentic standards retention time measured by GC-FID and mass spectra performed using a GC-mass spectrometry (GC-MS) system. Based on the results obtained, we found that the atmospheric aerosols over the Tianjin region, North China were derived from mixed: both anthropogenic and biogenic, sources and the subsequent secondary formation/transformations were also important in winter.

This study was in part supported by the National Natural Science Foundation of China (NSFC, Grant-in-Aid No.: 41775120) and National Key R&D Program of China (Grant-in-Aid No.: 2017YFC0212700), China.