Evaluation of pollution levels at an abandoned coal mine site in Turkey with the aid of GIS

Determination of the level of pollution at contaminated sites can be costly due to the number of samples required to identify the areas with higher contaminant concentrations. Yet, if pollution transport pathways can be found, then contamination level can be detected with fewer samples. In this case study, pollution levels at an abandoned coal mine site at Ovacik–Yaprakli (Cankiri, Turkey) are evaluated with respect to topography and surface runoff pathways derived using Geographical Information System (GIS) tools. First, surface runoff pathways are identified using ArcGIS 9.3. Then, the concentrations of trace elements (Mn, Cr, V, Cu, Ni, Zn, Ba, and Sr), pH, Fe and S contents in soil samples taken at random locations around the mine area are determined in a laboratory. In addition, pH and electrical conductivity (EC) are measured in flowing waters in-situ at different locations using pH and EC probes. The spatial distribution of pollutant concentrations is evaluated with respect to the surface runoff pathways and locations of potential contamination sources (i.e. open pit, coal storage and dump sites). Finally, the contamination level in the study area is assessed based on the limit values stated in the Soil Pollution Control Regulation of Turkey (SPCR). Results indicate that the site is contaminated with Cr, Ni, and Cu. In general, pollutant concentrations are higher close to the contamination sources and along the surface runoff pathways determined by the ArcGIS. Results indicate that GIS can aid in locating the areas that are more likely to have high pollutant concentrations. This would in return prevent overlooking highly contaminated spots which may be located far away from contamination sources. Moreover, these areas can be determined using a smaller number of samples which would decrease the sampling costs.

Research Highlights
► Surface runoff pathways and topography impact contaminant transport.
► GIS can be useful in prediction of the high risk areas subject to contamination.
► The area around the Ovacik-Yaprakli coal mine site is contaminated.