A Dispersion Modeling Study of Major VOCs from Non-Point Emission Sources in the Urban Atmospher

摘要

To assist with the understanding and solving of toxic air pollutant problems in urban areas, an atmospheric dispersion model, SKYDM, was developed with three preprocessors (meteorology, emission, and topography), and a physical process and chemical decay term based on NOx-O3-RH photochemistry in the actual atmosphere. SKYDM can work with multicomponents in a single model run, as well as with a single compound in a model run and produces 2D meteorological field results due to an integration approach. The present study aims to develop and evaluate a SKYDM at local spatial scales, in the short term. A comparative study is conducted to estimate the effects of model parameters in defining the applicability limits of dispersion models and to examine the integration approach methodology. All simulations are run for volatile organic compounds (VOCs) such as BTXS (Benzene, Toluene, Xylene, and Styrene) emitted from non-point sources, located at 151villages in seven divisions, in a northeastern portion of Seoul, Korea, with eight different meteorological data sets during 2002. Modeled toluene concentrations are compared with those observed at ten monitoring sites. The main findings of the present study are as follows: (a) Model uncertainties are obviously caused by limitations of meteorological conditions and emission and topographical information, by removal processes, and by user errors or application skills - the chemical decay term was a comparatively significant parameter in the removal of toxic air pollutants, (b) the integration approach indicated a correlation between observations and the model, and (c) the SKYDM showed potential as a useful tool for assessing the air quality in urban areas. In further work, the SKYDM will be upgraded to an improving model algorithm with fully detailed input information, and evaluated in comparison with other Gaussian dispersion models.