Spatial-Temporal Variations of Sulphur Dioxide Concentration, Source, and Probability Assessment Using a GIS-Based Geostatistical Approach

Ground-level sulphur dioxide is one of the air pollutants of high concern as a typical indicator of urban air quality. To inform decisions regarding, for instance, the protection of public health from elevated SO2 levels in the city of Balikesir, an understanding of spatial-temporal variance of SO2 patterns is necessary. Therefore, the aim of this study is to locate sample points, characterize distribution patterns, perform the probability map, and map SO2 distributions by means of spatial information sciences. In this work, the data were compiled from 48 sampling sites using passive sampling on 10-17 March 2010 (in winter) and on 13-20 August 2010 (in summer). The estimations of SO2 levels at unsampled locations were carried out with the inverse distance weighted method. Finally, locations exceeding the Turkish Air Quality Standard threshold value were determined in the Balikesir by use of geostatistical algorithms (Indicator kriging). The capability of the methods to predict air quality data in an area with multiple land-use types and pollution sources were then discussed. The results of the passive sampling study show that the winter and summer average concentrations are 32.79 μg/m and 28.27 μg/m for SO2, respectively. It is expected that where industrial activity is not excessively important, traffic and domestic heating systems are the main source of SO2 precursors. Moreover, using Indicator Kriging, results show that there are multiple hotspots for SO2 concentrations and they are strongly correlated to the locations of industrial plants, traffic, and domestic heating systems in Balikesir.