Content of the doctoral dissertation

The PhD thesis investigates the dispersion of pollutants in large, abundant and hydrodynamically open aquifers in urban areas, focussing on transport mechanisms in the saturated zone. The starting point is the current problems we face in this area. In most cases, we have data on the occurrence of pollutant concentrations in groundwater that are spatially limited to an existing network of representative sampling sites. Much less is known about the locations, origin and geometry of the sources of contamination. In aquifers, due to heterogeneity and anisotropy at local and regional scales, we are dealing with spatially and temporally variable hydrodynamic conditions that lead to heterogeneous and unevenly distributed contaminant concentrations over large areas. In practise, such pollution is often treated as diffuse source pollution, although in reality it is a multi-point source with overlapping effects in the area concerned. The actual dispersion of pollutants and their origin is very difficult to determine under the circumstances, and it is even more difficult to predict with certainty the direction and speed of their dispersion. In addition, access to potential pollutant sources is usually not possible, especially in urban, densely populated areas.

The doctoral thesis deals with the contamination of groundwater with hexavalent chromium in the area of Ljubljana polje. The main objectives of the thesis are to investigate and interpret the extent of contamination in three-dimensional space, to investigate the main mechanisms of chromium transport in the aquifer in question and to identify possible sources of contamination using advanced geostatistical methods and modelling. From a broader methodological perspective, the expected results may contribute to the understanding of contaminant transport processes in hydrodynamically similar aquifers.