The contributions of high- and low altitude emission sources to the near ground concentrations of air pollutants
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The scale of transport through the atmosphere depends on the effective height of an emission source, the meteorological conditions and the physico-chemical characteristics of the pollutants. Atmospheric surface temperature inversions play a significant role in the problem of air pollution since their upper edge acts as a natural barrier to the vertical dispersion of pollutants. When the altitude of an emission source is lower than the edge of the boundary layer, the pollution remains below the upper edge and spreads by advection inside the lower layer towards the ground. However, if the altitude of the emission source is higher than the edge of the boundary layer, then the pollution spreads above the barrier. An analysis of a pollution episode during one month (August 2004) in an urban atmosphere of industrial city, using results of continuous monitoring of minute-by-minute fluctuations of the pollutants' concentrations, is presented. Region of a developed industrial town as a model wa...s investigated. The investigated region is characterized by maximum number of surface temperature inversions during the nights in August and their furlough during the day time. With a combination of local meteorological information, that is the number of surface temperature inversions of the atmosphere, the results showed that the concentrations of pollutants originating from low altitude emission sources, e.g. organic pollutants, were higher at night. The near ground concentrations of SO2, originating from high-(industrial stacks) and low altitude (traffic) sources, and the PM10 originating from various sources i.e. from complex mechanisms of formation e.g. traffic emissions, SOA mechanisms and re-suspensions, were the same during the night and during the day. However, concentrations of NH3 from high altitude sources (fertilizer plant) were higher during the day. Cluster Analysis and Principal Component Analysis showed associations of highest correlation between pollutants, which are constituents of non-methane volatile organic compounds (NMVOCs), which signify strong influences of emission from low altitude sources e.g. oil pollutants from near industrial zone.
Keywords:emission sources / near ground air pollution / urban-industrial area
Source:Atmospheric Research, 2008, 87, 2, 170-182
- Elsevier Science Inc, New York