Spatiotemporal variations of ambient PM₁₀ source contributions in Beijing in 2004 using positive matrix factorization

S. Xie (1) , Z. Liu (1) , T. Chen (2) , L. Hua (2)

1 College of Environmental Sciences and Engineering [Peking]
2 Beijing Municipal Environmental Monitoring Center

Source contributions to ambient PM₁₀ (particles with an aerodynamic diameter of 10 ?m or less) in Beijing, China were determined with positive matrix factorization (PMF) based on ambient PM₁₀ composition data including concentrations of organic carbon (OC), elemental carbon (EC), ions and metal elements, which were simultaneously obtained at six sites through January, April, July and October in 2004. Results from PMF indicated that seven major sources of ambient PM₁₀ were urban fugitive dust, crustal soil, coal combustion, secondary sulfate, secondary nitrate, biomass burning and vehicle emission, respectively. In paticular, urban fugitive dust and crustal soil as two types of dust sources with similar chemical characteristics were differentiated by PMF. Urban fugitive dust contributed the most, accounting for 34.4% of total PM₁₀ mass on an annual basis, with relatively high contributions in all four months, and even covered 50% in April. It also showed higher contributions in southwestern and southeastern areas than in central urban areas. Coal combustion was found to be the primary contributor in January, showing higher contributions in urban areas than in suburban areas with seasonal variation peaking in winter, which accounted for 15.5% of the annual average PM₁₀ concentration. Secondary sulfate and secondary nitrate combined as the largest contributor to PM₁₀ in July and October, with strong seasonal variation peaking in summer, accounting for 38.8% and 31.5% of the total PM₁₀ mass in July and October, respectively. Biomass burning contributions were found in all four months and accounted for 9.8% of the annual average PM₁₀ mass concentration, with obviously higher contribution in October than in other months. Incineration sources were probably located in southwestern Beijing. Contribution from vehicle emission accounted for 5.0% and exhibited no significant seasonal variation. In sum, PM₁₀ source contributions in Beijing showed not only significant seasonal variations but also spatial differences.

Domaines: Océan, Atmosphère

S. Xie, Z. Liu, T. Chen, L. Hua. Spatiotemporal variations of ambient PM₁₀ source contributions in Beijing in 2004 using positive matrix factorization. Atmospheric Chemistry and Physics Discussions, 2008, 8 (1), pp.569-599. ⟨hal-00303248⟩