Non-polar organic compounds in autumn and winter aerosols in a typical city of eastern China: Size distribution and impact of gas-particle partitioning on PM2.5 source apportionment

Abstract

Aerosol-associated non-polar organic compounds (NPOCs), including 15 polycyclic aromatic hydrocarbons (PAHs), 30 n-alkanes, 2 iso-alkanes, 5 hopanes and 5 steranes, were identified and quantified in PM2.5 samples using the thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) method. The samples were mainly collected in autumn and winter in a typical city of eastern China. The total concentrations of NPOCs were 31.7-388.7 ng mĝ'3, and n-alkanes were the most abundant species (67.2 %). The heavy-molecular-weight PAHs (four- and five-ring) contributed 67.9 % of the total PAHs, and the middle-chain-length n-alkanes (C25-C34) were the most abundant (72.3 %) in n-alkanes. PAHs and n-alkanes were mainly distributed in the 0.56-1.00 μm fraction, while