Vertical distributions of SO₂ and NO₂ in the lower atmosphere in Beijing urban areas, China
2008
Meng, Z.Y. | Ding, G.A. | Xu, X.B. | Xu, X.D. | Yu, H.Q. | Wang, S.F.
Measurements of SO₂ and NO₂ were conducted from January to March 2001 and August 2003 at a 325 m meteorological tower in Beijing. The concentrations of SO₂ and NO₂ observed by passive samplers at ten heights showed complex vertical distributions in winter and summer. The vertical profiles of pollutants were influenced by source emissions, meteorological conditions, urban canopy and other factors. The comparison analysis of winter and summer pollutant concentrations suggests that the decrease in SO₂ concentration was significant in summer, and the reduction of NO₂ was relatively not distinctive. Domestic heating and industrial sources were major sources of SO₂ in urban areas of Beijing. Differing from SO₂, urban NO₂ was closely related to traffic emission. Meteorological evidence suggests that strong temperature inversions influence vertical distribution of air pollutants over urban Beijing. The high levels of SO₂ and NO₂ concentrations were due to the accumulation of pollutants resulting from the stable atmosphere prevalent during the measurement period. The vertical distributions of air pollutants were controlled and affected by atmospheric dynamical characteristics.
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