Abstract

Air dispersion modeling system (ADMS)-urban was used as air dispersion tool to model the atmospheric pollutants composition over Lagos air shed. The model runs with single point source showing the variation of concentrations of air pollutants (NO₂, NO_x, O₃, and SO₂) with ambient air dispersion over the city of Lagos, Nigeria. This city is located in the coastal area, and is highly congested with a high intensity of marine, vehicular, and industrial activities. The model was run with input data collected during dry and wet seasons using ADMS-urban. The dispersion pattern of NO_x is during both seasons was significantly different. Whereas, a Gaussian type curve was observed during dry season, a Sigmoid curve was obtained during the wet season. It is noteworthy that the elevation was higher for the dry season than the wet season due to higher photochemical activities. The modelled results obtained in ppb are: O_3,: 6.13, 23.36; NOx: 2.02, 3.99; SO₂: 9.54, 6.01 during wet and dry seasons, respectively. These predicted concentration values from theoretical model compared fairly with the measured values.

Key words: Seasonal variation, air dispersion modeling system, air pollutants, theoretical and empirical models, photochemical activities.