Urban Scale SO2 Dispersion Model due to Transport Sector in Padang City, Indonesia

Abstract

The main purpose of the study was to model and map the dispersion of Sulfur dioxide (SO2) concentrations from transport activities in Padang City. The sampling of SO2 was carried out for 1 hour at 25 monitoring sites. The samples of SO2 were then analyzed with Pararosanilin methods using a spectrophotometer. SO2 concentration samples were analyzed to develop a statistical model. Statistical models are developed based on traffic volume, traffic density, traffic speed, and wind speed. Validation was carried out to determine whether the model is valid or not statistically. Then, the model used to determine the concentrations of SO2 at 40 monitoring points for traffic characteristics measurements. SO2 concentration modeled ranges from 31.42 to 301.17 g/m3. SO2 concentration model showed a very strong correlation to the volume of traffic (r = 0.822); strong against the traffic density (r = 0.7820); strong against the traffic speeds (r = 0.6939); and weak against wind speed (r = 0.3271). The validation test confirmed that SO2 regression model does not have a significant difference between the model and the measurement results. This means that the model is statistically valid and can be used to predict SO2 concentration. SO2 gas dispersion mapping shows the concentration of SO2 ranges from 25-300 µg/Nm3. The highest concentration of SO2 at 40 monitoring points found located on Khatib Sulaiman Road and Sudirman Road. SO2 concentration value indicated that air quality in Padang City is still below the national air quality standard value (900 µg / Nm3).