Volume 13, No. 2, April 2013, Pages 574-583 PDF(1.32 MB)
Characterization and Source Apportionment of PM2.5 in an Urban Environment in Beijing
Lingda Yu1,2, Guangfu Wang1,3, Renjian Zhang2, Leiming Zhang2,4, Yu Song5, Bingbing Wu1, Xufang Li1, Kun An1, Junhan Chu1
1 Key Laboratory of Beam technology and Materials Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China
2 Key Laboratory of Regional Climate-Environment Research for Temperate East Asia (RCE-TEA), Institute of Atmospheric Physics, Chinese Academy of Science, Beijing 100029, China
3 Beijing Radiation Center, Beijing 100875, China
4 Air Quality Research Division, Science and Technology Branch, Environment Canada, Toronto, Canada
5 Department of Environmental Sciences, Peking University, Beijing 100871, China
Daily 24-hour PM2.5 samples were collected continuously from January 1 to December 31, 2010. Elemental concentrations from Al to Pb were obtained using particle induced X-ray emission (PIXE) method. This was the first full year continuous daily PM2.5 elemental composition dataset in Beijing. Source apportionment analysis was conducted on this dataset using the positive matrix factorization method. Seven sources and their contributions to the total PM2.5 mass were identified and quantified. These include secondary sulphur– 13.8 μg/m3, 26.5%; vehicle exhaust– 8.9 μg/m3, 17.1%; fossil fuel combustion– 8.3 μg/m3, 16%; road dust– 6.6 μg/m3, 12.7%; biomass burning– 5.8 μg/m3, 11.2%; soil dust– 5.4 μg/m3, 10.4%; and metal processing– 3.1 μg/m3, 6.0%. Fugitive dusts (including soil dust and road dust) showed the highest contribution of 20.7 μg/m3 in the spring, doubling those in other seasons. On the contrary, contributions of the combustion source types (including biomass burning and fossil fuel combustion) were significantly higher in the fall (14.2 μg/m3) and in the winter (24.5 μg/m3) compared to those in the spring and summer (9.6 and 8.0 μg/m3, respectively). Secondary sulphur contributed the most in the summer while vehicle exhaust and metal processing sources did not show any clear seasonal pattern. The different seasonal highs and lows from different sources compensated each other. This explains the very small seasonal variations (< 20%) in the total PM2.5.
Aerosol emission sources; Elemental composition; Particle induced X-ray emission; Positive matrix factorization.