『Abstract
　A monitoring program of particular matter was conducted at eight sampling sites in four highly industrialized cities (Shenyang, Anshan, Fushun, and Jinzhou) of Liaoning Province in Northeast China to identify the major potential sources of ambient PM2.5. A total of 814 PM2.5 and PM2.5-10 samples were collected between 2004 and 2005. All PM samples were collected simultaneously in four cities and analyzed gravimetrically for mass concentrations. A sum of 16 elemental species concentrations in the PM samples were determined using inductively coupled plasma atomic emission spectroscopy. Annual means of PM2.5 concentrations ranged from 65.0 to 222.0 μg m^-3 in all the eight sampling sites, and the spatial and seasonal variations were discussed. Enrichment factors were calculated, and Cr, Cu, Zn, As, Cd, and Pb will be pollution-derived elements. Site-to-site comparisons of PM2.5 species in each city were examined using coefficient of divergence, revealing that the two sites in each city are similar in elemental species. Principle component analysis was used for preliminary source analysis of PM2.5. Three or four factors in each city were isolated, and similar sources (crustal source, coal combustion, vehicle exhaust, iron making, or some other metallurgical activities) were identified at four cities.

Keywords: Particulate matter; Enrichment factor; Coefficient of divergence; Principal components analyses』

1. Introduction
2. Materials and methods
　2.1. Area description
　2.2. Experimental protocols
　2.3. Data analysis methods
　　2.3.1. Enrichment factors
　　2.3.2. Coefficient of divergence analysis and mass concentration diagrams
　　2.3.3. Principal component analysis
3. Results and discussion
　3.1. PM concentration
　3.2. Elemental composition in fine particles
　3.3. Enrichment factors
　3.4. CD analysis and mass concentration diagrams
　3.5. PCA results
4. Conclusion
Acknowledgments
References