Source apportionment of VOCs in a suburb of Nanjing, China, in autumn and winter

Abstract

Volatile organic compounds (VOCs) were measured in a suburb of Nanjing by on-line gas chromatography-flame ionization detector (GC-FID) instruments from September 2011 to January 2012. The measured VOC concentrations are dominated by alkanes (47 %), alkenes (25 %) and aromatics (20 %); in which alkenes attributed 57 % to the propylene-equivalent concentrations and 58 % to the ozone formation potential. The benzene to toluene (B/T) ratio was 1.60 ± 1.28, larger than 1, suggesting that the combustion sources might be significant at this site. Based on the measured VOC concentrations, a receptor model (PCA/APCS; principal component analysis/absolute principal component scores) coupled with the measured VOC source profiles was applied to identify the major VOC sources. Five surrogated VOC sources were identified: fossil-fuel/biomass/biofuel combustion accounted for 28 % of the total VOC concentrations, followed by the combination of solvent usage and industrial sources 1 (26 %), fuel evaporations (23 %), vehicular exhaust (18 %) and industrial sources 2 (5 %). Furthermore, the method was applied to analyze VOC sources in four quadrants (northeast, northwest, southeast and southwest) based on wind directions. Industrial sources were the most significant contributors (33 %) in the NE quadrant; VOCs in the NW quadrant were mainly contributed by the combination of fuel evaporation and fossil fuel/biomass/biofuel combustion (50 %). The most important source in the SE quadrant was the combination of solvent usage and industrial sources 1 (35 %), while 51 % of VOC concentrations were attributed to fossil fuel/biomass/biofuel combustion in the SW quadrant, indicating that the source contributions in various quadrants were quite different. This study may provide useful information for establishing effective air pollution control strategies in this region.