Wet Deposition in Khartoum State. Sudan

Abstract

This study sole objective is to estimate the wet deposition in Khartoum State. Eleven samples were collected from seven rain events during 2007 rain season , from three different stations; first class residential area, second class unpaved area and industrial area. The measurement of the wet deposition pollutants carried out for Dissolve Oxygen, pH, and main contaminants BOD, COD, Ammonia, Carbonate, Nitrates, Sulphate and Total Phosphorus. The accuracy of the analysis checked with charge balance estimation, the high resulted percentage difference was according to significant missing measurements. The calculation of the weighted average concentrations showed that the southern wind is loaded with high concentration of SO4 2-, CO3 2- and NO3 1-. Also the average weighted concentration analyzed by MINTEQA2 program to estimate the percentage difference, species and pH which confirmed the calculated charge balance. The loads of the concentrations were used to perceive the contributions of different land uses to the air pollution and the resulted loads in kg per Km2 were 196.9 SO4 2-, 57.8 NO3 1-, 429 CO3 2-, 2.6 TP, 329.8 NH3, 190 COD and 170 BOD. Moreover the analysis were acquiescent with the variation of wet deposition pollutants concentrations according to rainfall conditions like time of the day, the surrounded area and heights besides the variability of the concentrations within the single precipitation events. Most of the precipitation samples were collected from urban centers and away from major point sources of pollution, to provide more regional/national perspective on precipitation chemistry. The results acquired from this thesis assure that there is no acidic deposition in Khartoum State, high amount of suspended solids in the state due to unpaved streets, and high concentrations of the wet deposition pollutants in the industrial areas which needs environmental management and restricted regulations to maintain the air clean. The requirement of pilot studies to focus on the wet deposition variation in Khartoum State is essential as the urbanization and industrial revolution are certainly going to affect the rain quality.