Sorption and degradation of pharmaceuticals in the unsaturated zone

Determining the transport characteristics of pollutants in a gravel unsaturated zone is particularly difficult, owing to the heterogeneity of the geological media. Understanding the mechanisms and rates of movement of pollutants in the unsaturated zone is an important issue in the process of groundwater protection. One of the most valuable ways of investigating the characteristics, groundwater flow and solute transport in the unsaturated zone is by conducting experimental research, namely tracer experiments. Flow and transport parameters of propyphenazone, caffeine and carbamazepine have been studied with tracer experiments using a lysimeter facility in the Selniška Dobrava (NE Slovenia). The lysimeter site is designed as a field laboratory. The dimensions are 2x2 m, 5 m deep, with 0.2 m thick walls. There are 10 sampling and measuring points at different depths (from JV-1 to JV-10) with approximately equal distances in depth. For the purpose of sampling groundwater in the unsaturated zone, drainage samplers were installed and connected to a water sampling system. The tracer experiment lasted over a time period of approximately two years. The organic pollutants selected to determine the processes of migration and degradation through the aquifer were carbamazepine, propyphenazone and caffeine. Compounds differ in their physical and chemical properties, which results in different transport paths and velocities of individual pollutants through the aquifer. Due to its conservative behaviour, deuterated water was used as the conservative tracer. For the evaluation of flow and transport parameters the HYDRUS 1-D software was used. In the conference contribution, modelling and estimation of hydraulic properties of the soil and selected pharmaceuticals within a coarse gravel unsaturated zone will be presented.