Assimilative capacity and dispersion of pollutants due to industrial sources in Visakhapatnam bowl area

The assimilative capacity and the dispersion of pollutants due to industrial sources have been studied in the Visakhapatnam bowl area situated in coastal Andhra Pradesh, India. Visakhapatnam hosts several major industries. These industries contribute significantly to the air pollution in this coastal city. The assimilative capacity of the Visakhapatnam bowl areaʹs atmosphere has been studied using two different approaches in two seasons, namely, summer and winter of 2002–2003. The first approach is based on ventilation coefficient, which is determined through micro-meteorological data, and the second approach is based on pollution potential in terms of concentration of pollutants determined using air pollution dispersion models. The concentrations of two gaseous pollutants sulphur dioxide and oxides of nitrogen have been computed using two models, namely, Gaussian Plume Model (GPM) and Industrial Source Complex Short Term (ISCST-3) model in the Visakhapatnam bowl area in the summer and winter seasons, respectively. The concentrations of the gaseous pollutants have been measured as 8-h averages at 10 monitoring stations in summer season and at 12 monitoring stations in winter season. The computed 8-h averaged concentrations have been compared with those monitored concentrations at different receptors in both the seasons. The validation of the models has been carried out through quantile–quantile (Q–Q) plots and by computing several statistical errors. The results indicate that both models’ predictions have shown a similar trend with those observed concentrations in the study area. The GPM shows a slight overprediction whereas the ISCST-3 model shows an underprediction in comparison with the observed concentrations.