Experimental study of solute transport in a carbonate porous media

More than 40 % of carbonate area in Slovenia and development of urban activities, which cause the pollution lead to more frequent researches of solute transport in fractured and karstified rocks. The laboratory experiments were made to study the behaviour (sorption) of tracer in a porous media as preliminary study for in-situ tracer experiments in fractured rocks and final modelling of mass transport. The experiments in saturated zone were carried out in the laboratory of the Institute for Mining, Geotechnology and Environment in three permeameters which were connected successively. There also existed a possibility of sampling after each permeameter. As media there were used three porous materials of different grain size distribution from a close limestone quarry. Salt and uranine were used as tracers. During the tests various measurements like flow, pressure, temperature, pH, conductivity, oxygen content, alkalinity, acidity and uranine content were constantly performed. So far are the results undetermined due to detection problems, so we were forced to perform additional batch-tests to confirm the sorption process. The experiments in a physical model, where unsaturated zone would also be researched, are planned. In-situ experiments were done between a surface and a research tunnel in fractured carbonate rocks. First of all, a precise cartography of the fractures on the rocks over the tunnel and within the research tunnel was performed. Holes for injecting the tracers were located on the basis of the 3-D definition of the fractures between the surface and the research tunnel. The flow rate of the tracer was estimated by measuring the descending tracer concentration in the research tunnel. The tests were made to obtain different paths of water and the distribution of residence time of the tracer. The results of laboratory and in-situ experiments will be used as the input data for a final mass transport model.