Source identification of lead pollution in the atmosphere of Shanghai Cityby analyzing single aerosol particles (SAP)

A new method combining the pattern recognition (PR) technique with micro-PI XE spectrum was used for direct assessment of lead pollution in the atmosph ere of Shanghai City. Single aerosol particles (SAP) of PM10 (<10 mu m) wer e analyzed using the nuclear microprobe. Every particle is characterized wi th its micro-PIXE spectrum, which can be considered its fingerprint. The PR technique was applied to trace a lead contaminated aerosol particle back t o its source. The discrimination of different pollutant sources was enhance d with investigating the individual aerosol particles. The results showed t hat the lead contamination from automobile exhaust should not be neglected. The lead concentration with low level was detected in most unleaded gasoli ne particles; however, the highest lead level of 1500 ppm was found in one of them. Furthermore, four other main pollutant sources contributing to the lead contamination in the Shanghai atmosphere were clearly identified by t his method. They are the cement industry, the coal combustion, the oil comb ustion, and the metallurgic industry. Some other unidentified particles sug gested that some more lead emitters might also exist in Shanghai.