Seasonal Study of Primary and Secondary Sources of Carbonaceous Species in PM10 from Five Northern Chinese Cities

PM10 samples were collected from five northern Chinese cities (Tianjin, Anyang, Ji'nan, Kaifeng and Taiyuan) during the winter and summer months. Carbonaceous species concentrations in the PM10 samples from these cities were then measured. The concentration values show that PM10, organic carbon (OC) and elemental carbon (EC) exhibited relatively high concentrations during winter months as opposed to the summer months for all five cities. The contributions from primary and secondary sources were estimated using the Chemical Mass Balance (CMB) and the CMB-Iteration models. The results of two models were comparable, and results showed that the coal combustion and crustal dust were the most important source categories for both seasons. Additionally, seasonal variations of species mass fractions in receptors were analyzed, as well as variations in the estimated source percentage contributions. Seasonal variations of species mass fractions agreed with the variations of source percentage contributions for the five cities. Finally, primary organic carbon (POC) and secondary organic carbon (SOC) concentrations, and their seasonal variations, were estimated. We found that SOC showed relatively high concentrations (mu g/m(3)) in the winter, while the SOC/TOC ratios in the summer were higher than those in the winter.