Airborne fine particulate pollution in Jinan, China: Concentrations, chemical compositions and influence on visibility impairment

Daily PM2.5 samples were collected simultaneously at an urban site (SD) and a rural site (MP) in Jinan, China from March 2006 to February 2007. The samples were analyzed for major inorganic and organic water-soluble ions, 24 elements and carbonaceous species to determine the spatial and temporal variations of PM2.5 mass concentrations and chemical compositions and evaluate their contributions to visibility impairment. The annual average concentrations of PM2.5 were 148.71 μg m−3 and 97.59 μg m−3 at SD and MP, respectively. The predominant component of PM2.5 was (NH4)2SO4 at SD and organic mass at MP, which accounted for 28.71% and 37.25% of the total mass, respectively. The higher SOR (sulfur oxidation ratio) and ratios of OC/EC at SD indicated that the formation of secondary inorganic ions and secondary organic aerosols (SOA) could be accelerated in the urban area. Large size (NH4)2SO4 and large size organic mass were the most important contributors to visibility impairment at SD and MP, accounting for 43.80% and 41.02% of the light extinction coefficient, respectively.