Atmos. Chem. Phys. Discuss., 11, 6919-6956, 2011
www.atmos-chem-phys-discuss.net/11/6919/2011/
doi:10.5194/acpd-11-6919-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Review Status
This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Gaseous pollutants in Beijing urban area during the heating period 2007–2008: variability, sources, meteorological and chemical impacts
W. Lin1, X. Xu1, B. Ge2, and X. Liu3
1Key Laboratory for Atmospheric Chemistry, Centre for Atmosphere Watch & Services, Chinese Academy of Meteorological Sciences, Beijing 100081, China
2LAPC/NZC, Institute of Atmospheric Physics, Chinese Academy of Science, Beijing 100029, China
3Wuhan Central Meteorological Observatory, Wuhan 430074, China

Abstract. Gaseous pollutants, NOy/NOx, SO2, CO, and O3, were measured at an urban site in Beijing from 17 November 2007 to 15 March 2008. The average concentrations (with ±1σ) of NO, NO2, NOx, NOy, CO, SO2 and O3 were 29.0±2.7 ppb, 33.7±1.4 ppb, 62.7±4.0 ppb, 72.8±4.5 ppb, 1.99±0.13 ppm, 31.9±2.0 ppb and 11.9±0.8 ppb, respectively, with hourly maxima of 200.7 ppb, 113.5 ppb, 303.9 ppb, 323.2 ppb, 15.06 ppm, 147.3 ppb and 69.7 ppb, respectively. The concentrations of the pollutants show "saw-toothed" patterns, which are attributable mainly to changes in wind direction and speed. The frequency distributions of the hourly mean concentrations of NOy, SO2, CO, and O3 can all be decomposed in the two Lorentz curves, with their peak concentrations representing background levels under different conditions. During the observation period, the average ratio NOx/NOy was 0.86±0.10, suggesting that the gaseous pollutants in Beijing in winter are mainly from local emissions. Data of O3, NOz, and NOx/NOy indicate that photochemistry can take place in Beijing even in the cold winter period. Based on the measurements of O3, NOx, and NOy, ozone production efficiency (OPE) is estimated to be 0.76 for the winter 2007–2008 in Beijing. This low OPE would cause a photochemical O3 source of 4 ppb/day, which is small but significant for surface O3 in winter in Beijing. Downward transport of O3-rich air from the free troposphere is the more important factor for the enhancement of the O3 level in the surface layer, while high NO level for the destruction of O3. The concentrations of SO2, CO, and NOx are strongly correlated among each other, indicating that they are emitted by some common sources. Multiple linear regression analysis is applied to the concentrations of NOy, SO2, and CO and empirical equations are obtained for the NOy concentration. Based the equations, the relative contributions from mobile and point sources to NOy is estimated to be 66±30% and 40±16%, respectively, suggesting that even in the heating period, mobile sources in Beijing contribute more to NOy than point sources.

Citation: Lin, W., Xu, X., Ge, B., and Liu, X.: Gaseous pollutants in Beijing urban area during the heating period 2007–2008: variability, sources, meteorological and chemical impacts, Atmos. Chem. Phys. Discuss., 11, 6919-6956, doi:10.5194/acpd-11-6919-2011, 2011.
 
Search ACPD
Discussion Paper
    XML
    Citation
    Final Revised Paper
    Share