Groundwater pollution by contaminant transport from soil to fractured rock
Kai Witthüser, Barbara Čenčur Curk - (29/1,2000)
Water flow and contaminant transport from soil to underlying fractured rock is mainly controlled by the hydraulic conditions of the soil-bedrock boundary. In respect to the necessary understanding of contaminant transport at the soil-bedrock boundary the identification of flow paths within both the soil cover and the fractured media is decisive on the one side. On the other hand substance-specific behaviour of the often reactive pollutants compared to water flow has to be known in detail. Field scale tracer tests with different tracers (uranine and salts) and a potential pollutant as a reactive tracer (nitrate) were performed at the IRGO field research facility Sinji Vrh (SI). Injection points are located on the surface, in the soil, at the soil-rock interface and in the fractured rock, water is sampled in an underground tunnel with the help of two subhorizontal boreholes equipped with sampling devices and a special construction for collecting water seeping from the ceiling. The goal of these experiments is to identify the flow paths of solutes to the underground tunnel and to estimate their residence time dependent on the injection point. So far only some conclusions regarding the waterflux into the tunnel could be drawn.