The chemical composition and sources of PM2.5 during the 2009 Chinese New Yearʹs holiday in Shanghai

China is virtually shut down during the week-long Chinese New Yearʹs holiday. This implies that the anthropogenic emissions would be greatly decreased during the period thus providing an opportunity to study the air quality in China under reduced emissions, and the drastic emission changes during a short period of time allows the comparison of source contributions under significantly different conditions. Seventeen PM2.5 samples were collected during the 2009 Chinese New Yearʹs holiday in Shanghai to study the composition and sources of the fine particles. Organic carbon (OC), elemental carbon (EC), eight water-soluble ions, fourteen metals and solvent extractable organic compounds (SEOC) including alkanes, hopanes, polycyclic aromatic hydrocarbons (PAHs) and fatty acids were measured. Diagnostic PAH ratios, correlation analysis of OC, EC, n-alkanes, hopanes and PAHs showed that vehicle emissions were the main source of n-alkanes and EC, and an important source of the locally emitted particulate PAHs in urban Shanghai, while coal burning should be the main source of the transported PAHs from the inland areas. The composition of n-fatty acids also provided some clue on the significance of the contribution by kitchen activities. In the New Yearʹs Eveʹs sample, 75% of the particle mass was estimated to be from fireworks, and K+, SO42 −, Cl−, OC, Al and Ba were the main components. Firework fine particles had high OC/EC ratio and low NO3−/SO42 − ratio.