Prediction of ground level concentration of sulfur dioxide using ISCST3 model in Mangalore industrial region of India

摘要

Ambient air quality management in any industrial area is of prime concern in India considering the industrial growth since last two decades. High concentrations of ambient sulfur dioxide (SO_2) in many Indian places are responsible for non-compliance of ambient air quality standards. Dispersion modeling finds an important tool to simulate the ambient air quality of a region and to predict the ground level concentration of SO_2 under various scenarios. Mangalore region covering a wide range of mountains is chosen in the present investigation for the application of a widely used Industrial Source Complex—Short Term Version 3 (ISCST3) model to predict the ground level concentration of SO2 due to a proposed thermal power plant along with other existing industries. In fact, the COMPLEX 1 screening model dispersion algorithms of ISCST3 are used for estimating the ground level concentration patterns for receptors in complex terrain (i.e., terrain above stack height or release height) besides estimation for receptors in simple terrain so as to accurately model the dispersion phenomena in the presence of mountains located in the study area well above the stationary industrial point sources. Impacts of industrial establishments under various scenarios as also the influence of mountains in the study area on the ground level concentration patterns are analyzed in details. Precise model calculations leading to ground level concentration distribution pattern revealed many peaks in both flat and hilly terrains. Such dramatic behavior was explained by the back propagation of the emitting waves after these were caused to bounced back by hitting the mountains and subsequently modified the incoming emitting waves. Model calculationsrnfurther showed that incorporation of SO_2 emission control measures, for instance, implementation of flue gas desul-furization facilities having at least 90% removal efficiency, to selected stacks would result in ambient SO_2 concentration well within the prescribed values under Indian condition both in simple and in complex terrains and would thus curb air pollution in the study area. Any policy recommendation, based on the three considerations in the presented study that led to conservative values of ground level concentrations of SO_2, would be realistic for addressing the proper air quality management in the study area and also it would help in guiding the regulatory authority not only for the present case but also for similar other future situations. In the light of these observations, finally a few policy recommendations are put forward for the policy makers and regulatory authority.