Major chemical compositions, possible sources, and mass closure analysis of PM2.5 in Jinan, China

Abstract

The fine particulate matter samples for 24 h were carried out at the Environment Monitoring Station (EMS) and Shandong Jianzhu University (SJU) sites during 2010 in Jinan City, China. Eight water-soluble ion species were analyzed by ion chromatography, while organic carbon (OC) and elemental carbon (EC) were determined with the IMPROVE thermal optical reflectance method, and 20 inorganic elements were measured by inductively coupled plasma-atomic emission spectrometer and inductively coupled plasma-mass spectroscopy. The annual average mass concentration of PM2.5 was 168.85 μg m−3 at EMS and 148.67 μg m−3 at SJU. The coefficient of divergence was 0.14, 0.19, 0.23, and 0.23 in spring, summer, fall, and winter, respectively, indicating that there was no obvious spatial difference at the two sampling sites. The highest PM2.5, OC, and OC/EC ratio were in winter because of the enhanced emissions from coal combustion for heating and poor atmospheric dispersion. By the method of enrichment factors, the 20 inorganic elements were divided into three types owing to their sources. Al, Si, and Ti were mainly contributed by crustal sources. Na, Mg, P, K, Ca, V, Cr, Mn, Fe, Co, Ni, Ba, and Sr were from both natural emissions and anthropogenic sources. Cu, Zn, Pb, and Sn mainly originated from anthropogenic sources such as vehicular exhaust and industrial emission. Chemical mass closure calculation estimated that SO4 2− was the largest contributor and explained 29.66 % of PM2.5 mass at EMS, while 31.64 % was at SJU. The organic matter, crustal matter, and NO3 –, respectively, accounted for 15.12, 12.87, and 13.77 % to PM2.5 at EMS, while it accounted for 13.46, 13.96, and 14.93 % at SJU, respectively. By the positive matrix factorization analysis, the coal combustion and biomass burning, secondary sulfate, soil dust, secondary nitrate, and vehicle emissions were identified as the major emission sources.