Présentations Colloques

Pharmaceuticals, personal care products, life style products, and pesticides have been detected in groundwater at low concentrations worldwide. **Organic trace compounds may pose a risk to safe drinking water as their effects as single compounds or as combination of a multitude of compounds is still unknown. However, concentration levels are generally very low, rarely exceeding the Ig L level and far below a toxicological effect concentration. Due to high analytical precision these concentrations can be analyzed quite easily, allowing to analyze a whole set of compounds with different physical and chemical properties. This properties can be used to characterize subsurface transport processes. Unlike a real tracer test, e.g. with dye tracers, the input function of these compounds is almost always unknown. Using emerging contaminants as tracers needs another approach. If concentrations in groundwater along a known groundwater flow path are analyzed these measurements can be used to deduce transport processes between the two measuring points.**At the Gallusquelle karst spring on the Swabian Alb, southern Germany, the artificial sweeteners acesulfame and cyclamate have been used to identify a sewage input into this rural catchment. The catchment had been studied intensively in the past, including geology, hydrogeology, and groundwater flow. Acesulfame and cyclamate have been used to identify an input of sewage water into the system after intensive rainfall events. The spring water at Gallusquelle was analyzed for more the 50 emerging contaminants, among them pharmaceuticals and the herbicides isoproturon and atrazine. Based on the results, we were able to distinguish the arrival of relatively old from new water components in the spring. These old and new components match quite closely with the fast and slow flow fractions in the water indicating the effect of groundwater recharge on the local flow regime. These results coincided very well with data on turbidity and microbiology which was measured at the same time.**