Modeling of Sulfur Dioxide Emissions and Acidic Precipitation at Mesoscale Distances

A steady state mesoscale model developed to predict primary SO₂ concentrations from a single point source is presented. The model was validated with data from the Midwest Interstate Sulfur Transport and Transformation (MISTT) project, with root mean square errors of 9.69 μg m^?3 and 0.42 μg m^?3 for SO₂ and SO₄ respectively. Wet deposition (washout and rainout), eddy dispersivity, dry deposition of SO₂ and mean wind speed were found to be the most important factors controlling sulfur dioxide and sulfate concentrations. Estimation of precipitation acidity was then carried out using scavenging theory. The greatest potential acidification occurred approximately 200 km from the source along plume centerllne, which indicates a rather local effect as opposed to a long distance effect. The cross-plume influence was up to 60 km in width at a distance of 400 km from the source.