Measurements and analyses of nitrogen oxides and ozone in the yard and on the roof of a street-canyon in Suzhou

The concentrations of air pollutants such as nitrogen oxides and ozone characterised by very fast chemical reactions can significantly vary within urban street-canyon due to the short distances between sources and receptor. With the primary objective to analyse this issue, NO, NO2, NOx, O3, BTX, and wind flow field were continuously measured for 1 week at two heights (a street-level yard and a 25-m-high rooftop) in an urban canyon in Suzhou (China). The yard ozone concentrations were found to be up to six times lower than on the roof. Different frequency distributions (FD), dynamical and chemical processes of the pollutant variations from yard to roof are discussed to explain the findings. The predominant factors for the dissimilar pollutant vertical diffusion at the two measurement locations were associated to dissimilar fluid-dynamic and heterogeneous removal effects that likely induced dissimilar ozone chemical processes relative to NOx and BTX precursors.

[1]  J. Seinfeld,et al.  Atmospheric Chemistry and Physics: From Air Pollution to Climate Change , 1997 .

[2]  Ole Hertel,et al.  Effects of reduction of NOx on the NO2 levels in urban streets , 1996 .

[3]  H. Taha.  Modeling impacts of increased urban vegetation on ozone air quality in the South Coast Air Basin , 1996 .

[4]  Martin Weilenmann,et al.  NO2/NO emissions of gasoline passenger cars and light-duty trucks with Euro-2 emission standard , 2003 .

[5]  William M. Cox,et al.  Meteorologically adjusted ozone trends in urban areas A probabilistic approach , 1993 .

[6]  David J. Nowak,et al.  A modeling study of the impact of urban trees on ozone. , 2000 .

[7]  G. T. Johnson,et al.  An investigation of three-dimensional characteristics of flow regimes within the urban canyon , 1992 .

[8]  K. Pericleous,et al.  Modelling air quality in street canyons : a review , 2003 .

[9]  Ari Karppinen,et al.  A measurement campaign in a street canyon in Helsinki and comparison of results with predictions of the OSPM model , 2001 .

[10]  F. Costabile,et al.  A preliminary assessment of major air pollutants in the city of Suzhou, China , 2006 .

[11]  A. Lloyd,et al.  Relative rate constants for reaction of the hydroxyl radical with a series of alkanes, alkenes, and aromatic hydrocarbons , 1976 .

[12]  S. Sillman.  The relation between ozone, NOx and hydrocarbons in urban and polluted rural environments , 1999 .

[13]  S. Kot,et al.  Dispersion of vehicular emission in street canyons, Guangzhou City, South China (P.R.C.) , 1993 .

[14]  David D. Parrish,et al.  Review of observation-based analysis of the regional factors influencing ozone concentrations , 2000 .

[15]  Donald Dabdub,et al.  Chemical Coupling Between Atmospheric Ozone and Particulate Matter , 1997 .

[16]  Alison S. Tomlin,et al.  The spatial variability in concentrations of a traffic-related pollutant in two street canyons in York, UK—Part I: The influence of background winds , 2005 .

[17]  K. Emmerson,et al.  Urban Atmospheric Chemistry During the PUMA Campaign 2: Radical Budgets for OH, HO2 and RO2 , 2005 .

[18]  M. Molina,et al.  Air Quality in the Mexico Megacity , 2002 .

[19]  Christos Zerefos,et al.  Benzene, toluene, ozone, NO2 and SO2 measurements in an urban street canyon in Thessaloniki, Greece , 2002 .

[20]  F. Costabile,et al.  Spatial Distribution of Traffic Air Pollution and Evaluation of Transport Vehicle Emission Dispersion in Ambient Air in Urban Areas , 2006 .

[21]  W. Theurer.  TYPICAL BUILDING ARRANGEMENTS FOR URBAN AIR POLLUTION MODELLING , 1999 .

[22]  M. Väkevä,et al.  Street level versus rooftop concentrations of submicron aerosol particles and gaseous pollutants in an urban street canyon , 1999 .

[23]  Xiaoming Cai,et al.  A study of the dispersion and transport of reactive pollutants in and above street canyons: a large eddy simulation , 2004 .

[24]  Hsin-Chung Lu,et al.  The statistical characters of PM10 concentration in Taiwan area , 2002 .

[25]  F. Palmgren,et al.  Analysis of the St. Petersburg Traffic Data using the OSPM Model , 2002 .