Variations in the Order of Reaction: An Implication on Atmospheric Diffusion with Transformation and Deposition of SO₂ in Smoke Plume

An unsteady state Lagrangian diffusion model with consideration for the removal of sulphur dioxide through chemical transformation in the planetary boundary layer has been developed and evaluated in comparison with 2 existing models. The data used were from episodes of industrial emissions in a sub-urban area monitoring studies in South Africa. The effect of varying transformation rate was investigated using the three different overall rate constants for the advection of SO2 in smoke plume between a source (power station smoke stack) and a receptor point (ground based sampling site) under the influence of the local meteorology. The concentration distribution in the along-wind direction revealed that SO2 oxidation rate as second order with deposition as first order predicted the observed ambient concentration to an accuracy of about 91.9%.