Combination of Micro-PIXE with the Pattern Recognition Technique for the Source Identification of Individual Aerosol Particles

Abstract

In order to identify the sources of individual aerosol particles, we developed an identification system based on the combination of the micro-PIXE (particle-induced X-ray emission) technique with the pattern recognition (PR) technique. It uses the micro-PIXE spectrum of an individual aerosol particle as its fingerprint to identify the origin of the particles. A total of 294 micro-PIXE spectra of individual aerosol particles, collected at Shanghai City in China, were applied to test the PR system. These particles were collected from several pollution sources and a local environment monitor site. Most of the environment particles were identified, and the most probable sources were assigned by the PR system. It was found that cement factories and vehicle exhaust are the major contributors. About 14% of the particles from the environment monitor site could not be identified by their spectra. They might have come from some other sources we have not yet investigated. The validity and the efficiency of the system are evaluated and discussed. It is demonstrated that the combination of micro-PIXE with the pattern recognition technique offers a new, powerful tool for the source identification of individual aerosol particles.